Add Cherry-Pick mode. Users can specify 'cherryPickMode = True' in the global section of automerger.config to enable this mode. Also, logging all exceptions thrown in event handler worker threads. Bug: 361415628 Change-Id: I7ce71d24f6f95184e6673af6286fcd363b43feb2

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergeChangeAction.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergeChangeAction.java
index dad77dc..346b4b9 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergeChangeAction.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergeChangeAction.java

@@ -72,7 +72,7 @@
     }
     String revision = rev.getPatchSet().commitId().name();
 
-    MultipleDownstreamMergeInput mdsMergeInput = new MultipleDownstreamMergeInput();
+    MultipleDownstreamChangeInput mdsMergeInput = new MultipleDownstreamChangeInput();
     mdsMergeInput.dsBranchMap = branchMap;
     mdsMergeInput.changeNumber = change.getId().get();
     mdsMergeInput.patchsetNumber = rev.getPatchSet().number();
@@ -85,7 +85,7 @@
     logger.atFine().log("Multiple downstream merge input: %s", mdsMergeInput.dsBranchMap);
 
     try {
-      dsCreator.createMergesAndHandleConflicts(mdsMergeInput, config.getContextUserId());
+      dsCreator.createChangesAndHandleConflicts(mdsMergeInput, config.getContextUserId());
     } catch (ConfigInvalidException e) {
       throw new ResourceConflictException(
           "Automerger configuration file is invalid: " + e.getMessage());

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergeMode.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergeMode.java
new file mode 100644
index 0000000..8601f8b
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergeMode.java

@@ -0,0 +1,51 @@
+package com.googlesource.gerrit.plugins.automerger;
+
+import com.google.gerrit.extensions.restapi.ResourceConflictException;
+import com.google.gerrit.extensions.restapi.Response;
+import com.google.gerrit.extensions.restapi.RestApiException;
+import com.google.gerrit.extensions.restapi.RestReadView;
+import com.google.gerrit.server.config.ConfigResource;
+import com.google.inject.Inject;
+import java.io.IOException;
+import org.eclipse.jgit.errors.ConfigInvalidException;
+
+/**
+ * AutomergeMode will return the configured mode to create downstream changes.
+ */
+class AutomergeMode implements RestReadView<ConfigResource> {
+
+  protected ConfigLoader config;
+
+  /**
+   * Initializer for this class that sets the config.
+   *
+   * @param config Config for this plugin.
+   */
+  @Inject
+  public AutomergeMode(ConfigLoader config) {
+    this.config = config;
+  }
+
+  /**
+   * Return the Automerger mode: either MERGE or CHERRY-PICK.
+   *
+   * @return Either MERGE or CHERRY-PICK.
+   * @throws RestApiException
+   * @throws IOException
+   */
+  @Override
+  public Response<String> apply(ConfigResource configResource)
+      throws RestApiException, IOException {
+
+    try {
+      if(config.changeMode() == ChangeMode.CHERRY_PICK){
+        return Response.ok("CHERRY-PICK");
+      } else {
+        return Response.ok("MERGE");
+      }
+    } catch (ConfigInvalidException e) {
+      throw new ResourceConflictException(
+          "Automerger configuration file is invalid: " + e.getMessage());
+    }
+  }
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergerModule.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergerModule.java
index b588a2f..4c34126 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergerModule.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/AutomergerModule.java

@@ -15,6 +15,7 @@
 package com.googlesource.gerrit.plugins.automerger;
 
 import static com.google.gerrit.server.change.RevisionResource.REVISION_KIND;
+import static com.google.gerrit.server.config.ConfigResource.CONFIG_KIND;
 import static com.google.gerrit.server.project.BranchResource.BRANCH_KIND;
 
 import com.google.gerrit.extensions.events.ChangeAbandonedListener;
@@ -40,6 +41,7 @@
     DynamicSet.bind(binder(), RevisionCreatedListener.class).to(DownstreamCreator.class);
     DynamicSet.bind(binder(), TopicEditedListener.class).to(DownstreamCreator.class);
     DynamicSet.bind(binder(), MergeValidationListener.class).to(MergeValidator.class);
+    bind(ChangeCreatorApi.class).toProvider(ChangeCreatorProvider.class);
     install(
         new RestApiModule() {
           @Override
@@ -47,6 +49,7 @@
             post(REVISION_KIND, "automerge-change").to(AutomergeChangeAction.class);
             post(REVISION_KIND, "config-downstream").to(ConfigDownstreamAction.class);
             get(BRANCH_KIND, "all-config-downstream").to(AllConfigDownstreamAction.class);
+            get(CONFIG_KIND, "automerge-mode").to(AutomergeMode.class);
           }
         });
     DynamicSet.bind(binder(), WebUiPlugin.class).toInstance(new JavaScriptPlugin("automerger.js"));

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeCreatorApi.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeCreatorApi.java
new file mode 100644
index 0000000..3d3f939
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeCreatorApi.java

@@ -0,0 +1,16 @@
+package com.googlesource.gerrit.plugins.automerger;
+
+import com.google.gerrit.exceptions.StorageException;
+import com.google.gerrit.extensions.api.changes.ChangeApi;
+import com.google.gerrit.extensions.restapi.RestApiException;
+import org.eclipse.jgit.errors.ConfigInvalidException;
+
+/** ChangeCreatorApi is the interface used to create or update downstream changes. */
+public interface ChangeCreatorApi {
+  ChangeApi create(SingleDownstreamChangeInput sdsChangeInput, String currentTopic)
+      throws RestApiException, ConfigInvalidException, InvalidQueryParameterException,
+      StorageException;
+
+  void update(UpdateDownstreamChangeInput updateDownstreamChangeInput)
+      throws RestApiException, ConfigInvalidException, InvalidQueryParameterException;
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeCreatorProvider.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeCreatorProvider.java
new file mode 100644
index 0000000..6d1d770
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeCreatorProvider.java

@@ -0,0 +1,44 @@
+package com.googlesource.gerrit.plugins.automerger;
+
+import com.google.common.flogger.FluentLogger;
+import com.google.gerrit.extensions.api.GerritApi;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+import org.eclipse.jgit.errors.ConfigInvalidException;
+
+/**
+ * ChangeCreatorProvider provides the appropriate ChangeCreatorApi implementation based on the
+ * plugin's configuration.
+ */
+public class ChangeCreatorProvider implements Provider<ChangeCreatorApi> {
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+  private final GerritApi gApi;
+  private final ConfigLoader config;
+
+  @Inject
+  public ChangeCreatorProvider(
+      GerritApi gApi,
+      ConfigLoader config
+  ) {
+    this.gApi = gApi;
+    this.config = config;
+  }
+
+  @Override
+  public ChangeCreatorApi get() {
+    ChangeMode changeMode = ChangeMode.MERGE;
+    try {
+      changeMode = config.changeMode();
+    } catch (ConfigInvalidException e) {
+      logger.atWarning().log(
+          "Unable to read the config for cherryPickMode value. Defaulting to legacy merge-mode behavior");
+    }
+
+    if(changeMode == ChangeMode.CHERRY_PICK){
+      return new CherryPickChangeCreator(gApi);
+    } else {
+      return new MergeChangeCreator(gApi);
+    }
+  }
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeMode.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeMode.java
new file mode 100644
index 0000000..a4218ef
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeMode.java

@@ -0,0 +1,9 @@
+package com.googlesource.gerrit.plugins.automerger;
+
+/**
+ * ChangeMode defines the mode for creating downstream changes.
+ */
+public enum ChangeMode {
+  MERGE,
+  CHERRY_PICK
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeUtils.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeUtils.java
new file mode 100644
index 0000000..f240498
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/ChangeUtils.java

@@ -0,0 +1,214 @@
+package com.googlesource.gerrit.plugins.automerger;
+
+import com.google.common.base.Joiner;
+import com.google.common.flogger.FluentLogger;
+import com.google.gerrit.extensions.api.GerritApi;
+import com.google.gerrit.extensions.api.changes.ChangeApi;
+import com.google.gerrit.extensions.api.changes.NotifyHandling;
+import com.google.gerrit.extensions.api.changes.ReviewInput;
+import com.google.gerrit.extensions.client.ListChangesOption;
+import com.google.gerrit.extensions.common.ChangeInfo;
+import com.google.gerrit.extensions.common.CommitInfo;
+import com.google.gerrit.extensions.common.RevisionInfo;
+import com.google.gerrit.extensions.restapi.AuthException;
+import com.google.gerrit.extensions.restapi.RestApiException;
+import java.util.ArrayList;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Map;
+
+/** ChangeUtils is a utility class for interacting with Gerrit changes */
+public final class ChangeUtils {
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+  public static final String AUTOMERGER_TAG = "autogenerated:Automerger";
+  private static final String SKIPPED_PREFIX = "skipped";
+  private static final String CURRENT = "current";
+
+  private ChangeUtils(){
+    throw new UnsupportedOperationException("ChangeUtils should not be instantiated.");
+  }
+
+  public static QueryBuilder constructTopicQuery(String topic) throws InvalidQueryParameterException {
+    QueryBuilder queryBuilder = new QueryBuilder();
+    queryBuilder.addParameter("topic", topic);
+    queryBuilder.addParameter("status", "open");
+    return queryBuilder;
+  }
+
+  public static List<ChangeInfo> getChangesInTopicAndBranch(GerritApi gApi, String topic, String downstreamBranch)
+      throws InvalidQueryParameterException, RestApiException {
+    QueryBuilder queryBuilder = constructTopicQuery(topic);
+    queryBuilder.addParameter("branch", downstreamBranch);
+    return gApi.changes()
+        .query(queryBuilder.get())
+        .withOptions(ListChangesOption.ALL_REVISIONS, ListChangesOption.CURRENT_COMMIT)
+        .get();
+  }
+
+  public static List<String> getChangeParents(GerritApi gApi, int changeNumber, String currentRevision)
+      throws RestApiException {
+    ChangeApi change = gApi.changes().id(changeNumber);
+    List<String> parents = new ArrayList<>();
+    Map<String, RevisionInfo> revisionMap =
+        change.get(EnumSet.of(ListChangesOption.ALL_REVISIONS, ListChangesOption.CURRENT_COMMIT))
+            .revisions;
+    List<CommitInfo> changeParents = revisionMap.get(currentRevision).commit.parents;
+    for (CommitInfo commit : changeParents) {
+      parents.add(commit.commit);
+    }
+    return parents;
+  }
+
+  /**
+   * Create subject line for downstream change with metadata from upstream change.
+   *
+   * <p>The downstream subject will be in the format: "[subjectPrefix] upstreamSubject am:
+   * upstreamRevision". If it is a skip, "am" will be replaced with "skipped", and [subjectPrefix]
+   * replaced with [subjectPrefix skipped].
+   *
+   * @param upstreamSubject Subject line of the upstream change
+   * @param upstreamRevision Commit SHA1 of the upstream change
+   * @param skipped Whether or not the merge is done with "-s ours"
+   * @return Subject line for downstream merge
+   */
+  public static String getSubjectForDownstreamChange(
+      String subjectPrefix, String upstreamSubject, String upstreamRevision, boolean skipped) {
+    if (!upstreamSubject.startsWith("[" + subjectPrefix)) {
+      String prefix = "[" + subjectPrefix + "]";
+      if (skipped) {
+        prefix = "[" + subjectPrefix + " " + SKIPPED_PREFIX + "]";
+      }
+      upstreamSubject = Joiner.on(" ").join(prefix, upstreamSubject);
+    }
+    String denotationString = skipped ? "skipped:" : "am:";
+    return Joiner.on(" ")
+        .join(upstreamSubject, denotationString, upstreamRevision.substring(0, 10));
+  }
+
+  public static String getTopic(GerritApi gApi, String revision) throws InvalidQueryParameterException, RestApiException {
+    QueryBuilder queryBuilder = new QueryBuilder();
+    queryBuilder.addParameter("commit", revision);
+    List<ChangeInfo> changes =
+        gApi.changes()
+            .query(queryBuilder.get())
+            .withOption(ListChangesOption.CURRENT_REVISION)
+            .get();
+    if (!changes.isEmpty()) {
+      for (ChangeInfo change : changes) {
+        if (change.currentRevision.equals(revision) && !"".equals(change.topic)) {
+          return change.topic;
+        }
+      }
+    }
+    return null;
+  }
+
+  public static void tagChange(GerritApi gApi, ChangeInfo change, String message) throws RestApiException {
+    ReviewInput reviewInput = new ReviewInput();
+    reviewInput.message(message);
+    reviewInput.notify = NotifyHandling.NONE;
+    reviewInput.tag = AUTOMERGER_TAG;
+    try {
+      gApi.changes().id(change.id).revision(CURRENT).review(reviewInput);
+    } catch (AuthException e) {
+      logger.atSevere().withCause(e).log("Automerger could not set label, but still continuing.");
+    }
+  }
+
+  public static String getSkipHashtag(String downstreamBranch){
+    return "am_skip_" + downstreamBranch;
+  }
+
+  public static boolean isDownstreamCherryPick(GerritApi gApi, String upstreamRevision, ChangeInfo downstreamChange){
+    try {
+      ChangeInfo upstreamChange = gApi.changes().id(upstreamRevision).get();
+      int upstreamPatchset = upstreamChange.revisions.get(upstreamRevision)._number;
+
+      if(downstreamChange.cherryPickOfChange == null)
+        return false;
+
+      return downstreamChange.cherryPickOfChange.equals(upstreamChange._number) &&
+          downstreamChange.cherryPickOfPatchSet == upstreamPatchset;
+    } catch (RestApiException e) {
+      logger.atSevere().withCause(e).log(
+          "Unable to lookup change with revision %s", upstreamRevision);
+      return false;
+    }
+  }
+
+  public static boolean isDownstreamMerge(String upstreamRevision, ChangeInfo downstreamChange){
+    String changeRevision = downstreamChange.currentRevision;
+    RevisionInfo revision = downstreamChange.revisions.get(changeRevision);
+    List<CommitInfo> parents = revision.commit.parents;
+    if (parents.size() > 1) {
+      String secondParent = parents.get(1).commit;
+      if (secondParent.equals(upstreamRevision)) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  public static boolean isDownstreamChange(GerritApi gApi, String upstreamRevision, ChangeInfo downstreamChange, ChangeMode changeMode) {
+    boolean downstreamExists = (changeMode == ChangeMode.CHERRY_PICK) && isDownstreamCherryPick(gApi, upstreamRevision, downstreamChange);
+    downstreamExists |= (changeMode == ChangeMode.MERGE) && isDownstreamMerge(upstreamRevision, downstreamChange);
+
+    return downstreamExists;
+  }
+
+  /**
+   * Get the base change ID that the downstream change should be based off of, given the parents.
+   *
+   * <p>Given changes A and B where A is the first parent of B (stacked changes), and where A' is
+   * the downstream change autogenerated by A, and B' is the downstream change autogenerated by A,
+   * the first parent of B' should be A'.
+   *
+   * @param parents Parent commit SHAs of the change
+   * @return The base change ID that the change should be based off of, null if there is none.
+   * @throws InvalidQueryParameterException
+   * @throws RestApiException
+   */
+  private static ChangeInfo getBaseChangeInfo(GerritApi gApi, List<String> parents, String branch, ChangeMode changeMode)
+      throws InvalidQueryParameterException, RestApiException {
+    if (parents.isEmpty()) {
+      logger.atInfo().log("No base change id for change with no parents.");
+      return null;
+    }
+    // 1) Get topic of first parent
+    String firstParentTopic = ChangeUtils.getTopic(gApi, parents.get(0));
+    if (firstParentTopic == null) {
+      return null;
+    }
+    // 2) query that topic and use that to find A'
+    List<ChangeInfo> changesInTopic = ChangeUtils.getChangesInTopicAndBranch(gApi, firstParentTopic, branch);
+    String firstParent = parents.get(0);
+    for (ChangeInfo change : changesInTopic) {
+      if(isDownstreamChange(gApi, firstParent, change, changeMode)){
+        return change;
+      }
+    }
+    return null;
+  }
+  public static String getBaseChangeIdForMerge(GerritApi gApi, List<String> parents, String branch)
+      throws InvalidQueryParameterException, RestApiException {
+    ChangeInfo change = getBaseChangeInfo(gApi, parents, branch, ChangeMode.MERGE);
+
+    if(change == null)
+      return null;
+
+    return String.valueOf(change._number);
+  }
+
+  public static String getBaseChangeRevisionForCherryPick(GerritApi gApi, List<String> parents, String branch)
+      throws InvalidQueryParameterException, RestApiException {
+    ChangeInfo change = getBaseChangeInfo(gApi, parents, branch, ChangeMode.CHERRY_PICK);
+
+    if(change == null)
+      return null;
+
+    return change.currentRevision;
+  }
+
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/CherryPickChangeCreator.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/CherryPickChangeCreator.java
new file mode 100644
index 0000000..6eac9f6
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/CherryPickChangeCreator.java

@@ -0,0 +1,159 @@
+package com.googlesource.gerrit.plugins.automerger;
+
+import com.google.common.flogger.FluentLogger;
+import com.google.gerrit.exceptions.StorageException;
+import com.google.gerrit.extensions.api.GerritApi;
+import com.google.gerrit.extensions.api.changes.AbandonInput;
+import com.google.gerrit.extensions.api.changes.ChangeApi;
+import com.google.gerrit.extensions.api.changes.CherryPickInput;
+import com.google.gerrit.extensions.api.changes.HashtagsInput;
+import com.google.gerrit.extensions.api.changes.NotifyHandling;
+import com.google.gerrit.extensions.common.ChangeInfo;
+import com.google.gerrit.extensions.restapi.RestApiException;
+import com.google.inject.Inject;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import org.eclipse.jgit.errors.ConfigInvalidException;
+
+/**
+ * CherryPickChangeCreator handles creation and updating of downstream changes as cherry-picks.
+ */
+public class CherryPickChangeCreator implements ChangeCreatorApi {
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+  private static final String SUBJECT_PREFIX = "autocherry";
+  private final GerritApi gApi;
+  @Inject
+  public CherryPickChangeCreator(
+      GerritApi gApi) {
+    this.gApi = gApi;
+  }
+
+  /**
+   * Create a single downstream cherry-pick.
+   *
+   * <p>On a skip, only a hashtag is applied to the upstream change.</p>
+   *
+   * @param sdsChangeInput Input containing metadata for the cherry-pick.
+   * @param currentTopic Current topic to create change in.
+   * @throws RestApiException
+   * @throws ConfigInvalidException
+   * @throws InvalidQueryParameterException
+   * @throws StorageException
+   */
+  @Override
+  public ChangeApi create(SingleDownstreamChangeInput sdsChangeInput, String currentTopic)
+      throws RestApiException, ConfigInvalidException, InvalidQueryParameterException, StorageException {
+
+    if (!sdsChangeInput.doChange) {
+      logger.atFine().log(
+          "Skipping cherry-pick for %s to %s",
+          sdsChangeInput.currentRevision, sdsChangeInput.downstreamBranch);
+
+      applySkipHashtag(sdsChangeInput);
+
+      return null;
+    }
+
+    // This mirrors the MergeChangeCreator, although I don't believe it is possible with
+    // cherry-picks. Merge mode can encounter this scenario in diamond merges.
+    if (isAlreadyCherryPicked(sdsChangeInput, currentTopic)) {
+      logger.atInfo().log(
+          "Commit %s already cherry-picked into %s, not cherry-picking again.",
+          sdsChangeInput.currentRevision, sdsChangeInput.downstreamBranch);
+      return null;
+    }
+
+    removeSkipHashtag(sdsChangeInput);
+
+    CherryPickInput cherryPickInput = new CherryPickInput();
+    cherryPickInput.base =
+        ChangeUtils.getBaseChangeRevisionForCherryPick(gApi,
+            ChangeUtils.getChangeParents(gApi, sdsChangeInput.changeNumber, sdsChangeInput.currentRevision),
+            sdsChangeInput.downstreamBranch);
+    cherryPickInput.message =
+        ChangeUtils.getSubjectForDownstreamChange(SUBJECT_PREFIX, sdsChangeInput.subject, sdsChangeInput.currentRevision, !sdsChangeInput.doChange);
+    cherryPickInput.destination = sdsChangeInput.downstreamBranch;
+    cherryPickInput.notify = NotifyHandling.NONE;
+    cherryPickInput.topic = currentTopic;
+
+    return gApi.changes().id(sdsChangeInput.changeNumber).current().cherryPick(cherryPickInput);
+  }
+
+  private Set<String> getSkipHashtagSet(String downstreamBranch) {
+    Set<String> set = new HashSet<>();
+    set.add(ChangeUtils.getSkipHashtag(downstreamBranch));
+    return set;
+  }
+
+  private void applySkipHashtag(SingleDownstreamChangeInput sdsChangeInput) throws RestApiException {
+    ChangeApi originalChange = gApi.changes().id(sdsChangeInput.changeNumber);
+    Set<String> set = getSkipHashtagSet(sdsChangeInput.downstreamBranch);
+    originalChange.setHashtags(new HashtagsInput(set));
+  }
+
+  private void removeSkipHashtag(SingleDownstreamChangeInput sdsChangeInput) throws RestApiException {
+    ChangeApi originalChange = gApi.changes().id(sdsChangeInput.changeNumber);
+    Set<String> set = getSkipHashtagSet(sdsChangeInput.downstreamBranch);
+
+    // It is safe to blindly attempt to remove the hashtag.
+    originalChange.setHashtags(new HashtagsInput(null, set));
+  }
+
+  @Override
+  public void update(UpdateDownstreamChangeInput updateDownstreamChangeInput)
+      throws RestApiException, ConfigInvalidException, InvalidQueryParameterException {
+
+    // For cherry-picks, we don't update the prior existing commit with a patch application.
+    // Doing this will not update the 'Cherry pick of' metadata with the correct patchset.
+    // Instead, we abandon the old one and create a new one.
+    AbandonInput abandonInput = new AbandonInput();
+    abandonInput.notify = NotifyHandling.NONE;
+    if(!updateDownstreamChangeInput.doChange){
+      abandonInput.message = "The cherry-pick from upstream is now skipped";
+    } else {
+      abandonInput.message = "The upstream patch set is no longer current";
+    }
+    gApi.changes().id(updateDownstreamChangeInput.downstreamChangeNumber).abandon(abandonInput);
+
+    SingleDownstreamChangeInput sdsChangeInput = getSingleDownstreamChangeInput(
+        updateDownstreamChangeInput);
+
+    // We still "create" in the event of a skip to apply the appropriate hashtag.
+    ChangeApi newDownstream = create(sdsChangeInput, updateDownstreamChangeInput.topic);
+    if(newDownstream != null) {
+      ChangeUtils.tagChange(gApi, newDownstream.get(), "Automerger change created!");
+    }
+  }
+
+  private static SingleDownstreamChangeInput getSingleDownstreamChangeInput(
+      UpdateDownstreamChangeInput updateDownstreamChangeInput) {
+
+    SingleDownstreamChangeInput sdsChangeInput = new SingleDownstreamChangeInput();
+    sdsChangeInput.subject =
+        ChangeUtils.getSubjectForDownstreamChange(SUBJECT_PREFIX,
+            updateDownstreamChangeInput.upstreamSubject,
+            updateDownstreamChangeInput.upstreamRevision, !updateDownstreamChangeInput.doChange);
+    sdsChangeInput.changeNumber = updateDownstreamChangeInput.upstreamChangeNumber;
+    sdsChangeInput.patchsetNumber = updateDownstreamChangeInput.patchSetNumber;
+    sdsChangeInput.doChange = updateDownstreamChangeInput.doChange;
+    sdsChangeInput.currentRevision = updateDownstreamChangeInput.upstreamRevision;
+    sdsChangeInput.downstreamBranch = updateDownstreamChangeInput.downstreamBranch;
+    return sdsChangeInput;
+  }
+
+  boolean isAlreadyCherryPicked(SingleDownstreamChangeInput sdsChangeInput, String currentTopic)
+      throws InvalidQueryParameterException, RestApiException {
+
+    List<ChangeInfo> changes =
+        ChangeUtils.getChangesInTopicAndBranch(gApi, currentTopic, sdsChangeInput.downstreamBranch);
+    for (ChangeInfo change : changes) {
+      if(change.cherryPickOfChange.equals(sdsChangeInput.changeNumber)
+          && change.cherryPickOfPatchSet == sdsChangeInput.patchsetNumber) {
+        return true;
+      }
+    }
+    return false;
+  }
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/ConfigLoader.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/ConfigLoader.java
index 5845f59..d2171e5 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/automerger/ConfigLoader.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/ConfigLoader.java

@@ -400,4 +400,10 @@
     projects.removeAll(ignoreProjects);
     return projects;
   }
+
+  public ChangeMode changeMode() throws ConfigInvalidException {
+    boolean cherryPickMode = getConfig().getBoolean("global", "cherryPickMode", false);
+
+    return cherryPickMode ? ChangeMode.CHERRY_PICK : ChangeMode.MERGE;
+  }
 }

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreator.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreator.java
index d46f242..6c480c6 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreator.java

@@ -23,16 +23,10 @@
 import com.google.gerrit.extensions.api.changes.AbandonInput;
 import com.google.gerrit.extensions.api.changes.ChangeApi;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
-import com.google.gerrit.extensions.api.changes.RestoreInput;
 import com.google.gerrit.extensions.api.changes.ReviewInput;
-import com.google.gerrit.extensions.client.ChangeStatus;
 import com.google.gerrit.extensions.client.ListChangesOption;
 import com.google.gerrit.extensions.common.ChangeInfo;
-import com.google.gerrit.extensions.common.ChangeInput;
-import com.google.gerrit.extensions.common.CommitInfo;
 import com.google.gerrit.extensions.common.LabelInfo;
-import com.google.gerrit.extensions.common.MergeInput;
-import com.google.gerrit.extensions.common.MergePatchSetInput;
 import com.google.gerrit.extensions.common.RevisionInfo;
 import com.google.gerrit.extensions.events.ChangeAbandonedListener;
 import com.google.gerrit.extensions.events.ChangeRestoredListener;
@@ -45,6 +39,7 @@
 import com.google.gerrit.json.OutputFormat;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.FanOutExecutor;
+import com.google.gerrit.server.submit.IntegrationConflictException;
 import com.google.gerrit.server.util.ManualRequestContext;
 import com.google.gerrit.server.util.OneOffRequestContext;
 import com.google.gson.Gson;
@@ -77,10 +72,7 @@
         RevisionCreatedListener,
         TopicEditedListener {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
-  private static final String AUTOMERGER_TAG = "autogenerated:Automerger";
   private static final String MERGE_CONFLICT_TAG = "autogenerated:MergeConflict";
-  private static final String SUBJECT_PREFIX = "automerger";
-  private static final String SKIPPED_PREFIX = "skipped";
   private static final String CURRENT = "current";
   private static final Gson GSON = OutputFormat.JSON_COMPACT.newGson();
 
@@ -89,6 +81,7 @@
   private final ExecutorService executorService;
   private final OneOffRequestContext oneOffRequestContext;
   private final Provider<CurrentUser> user;
+  private final Provider<ChangeCreatorApi> changeCreator;
 
   @Inject
   public DownstreamCreator(
@@ -96,12 +89,15 @@
       ConfigLoader config,
       OneOffRequestContext oneOffRequestContext,
       @FanOutExecutor ExecutorService executorService,
-      Provider<CurrentUser> user) {
+      Provider<CurrentUser> user,
+      Provider<ChangeCreatorApi> changeCreator
+      ) {
     this.gApi = gApi;
     this.config = config;
     this.oneOffRequestContext = oneOffRequestContext;
     this.executorService = executorService;
     this.user = user;
+    this.changeCreator = changeCreator;
   }
 
   /**
@@ -131,7 +127,7 @@
           gApi.changes().id(change._number).revision(revisionNumber).commit(false).commit;
       logger.atFine().log("Detected revision %s abandoned on %s.", revision, change.project);
       abandonDownstream(change, revision, accountId);
-    } catch (ConfigInvalidException | StorageException | RestApiException e) {
+    } catch (Exception e) {
       logger.atSevere().withCause(e).log(
           "Automerger plugin failed onChangeAbandoned for %s", change.id);
     }
@@ -187,7 +183,7 @@
         return;
       }
 
-      // If change is empty, prevent someone breaking topic.
+      // If change is empty, prevent someone breaking topic by reapplying the old topic.
       if (isNullOrEmpty(change.topic)) {
         try {
           gApi.changes().id(change._number).topic(oldTopic);
@@ -205,7 +201,7 @@
         for (String downstreamBranch : downstreamBranches) {
           try {
             List<Integer> existingDownstream =
-                getExistingMergesOnBranch(revision, oldTopic, downstreamBranch, accountId);
+                getExistingChangesOnBranch(revision, oldTopic, downstreamBranch, accountId);
             for (Integer changeNumber : existingDownstream) {
               logger.atFine().log("Setting topic %s on %s", change.topic, changeNumber);
               gApi.changes().id(changeNumber).topic(change.topic);
@@ -215,7 +211,7 @@
           }
         }
       }
-    } catch (StorageException | ConfigInvalidException e) {
+    } catch (Exception e) {
       logger.atSevere().withCause(e).log(
           "Automerger plugin failed onTopicEdited for %s", eventChange.id);
     }
@@ -270,7 +266,7 @@
       for (String downstreamBranch : downstreamBranches) {
         try {
           List<Integer> existingDownstream =
-              getExistingMergesOnBranch(revision, change.topic, downstreamBranch, accountId);
+              getExistingChangesOnBranch(revision, change.topic, downstreamBranch, accountId);
           for (Integer changeNumber : existingDownstream) {
             ChangeInfo downstreamChange =
                 gApi.changes().id(changeNumber).get(EnumSet.of(ListChangesOption.CURRENT_REVISION));
@@ -293,7 +289,7 @@
               "Exception when updating downstream votes of %s", change.id);
         }
       }
-    } catch (StorageException | ConfigInvalidException | RestApiException | IOException e) {
+    } catch (Exception e) {
       logger.atSevere().withCause(e).log(
           "Automerger plugin failed onCommentAdded for %s", change.id);
     }
@@ -323,11 +319,7 @@
   private void onChangeRestoredImpl(ChangeInfo change, RevisionInfo revision, Account.Id accountId) {
     try (ManualRequestContext ctx = oneOffRequestContext.openAs(accountId)) {
       automergeChanges(change, revision, accountId);
-    } catch (RestApiException
-        | IOException
-        | ConfigInvalidException
-        | InvalidQueryParameterException
-        | StorageException e) {
+    } catch (Exception e) {
       logger.atSevere().withCause(e).log(
           "Automerger plugin failed onChangeRestored for %s", change.id);
     }
@@ -358,18 +350,14 @@
   public void onRevisionCreatedImpl(ChangeInfo change, RevisionInfo revision, Account.Id accountId) {
     try (ManualRequestContext ctx = oneOffRequestContext.openAs(accountId)) {
       automergeChanges(change, revision, accountId);
-    } catch (RestApiException
-        | IOException
-        | ConfigInvalidException
-        | InvalidQueryParameterException
-        | StorageException e) {
+    } catch (Exception e){
       logger.atSevere().withCause(e).log(
           "Automerger plugin failed onRevisionCreated for %s", change.id);
     }
   }
 
   public String getOrSetTopic(int sourceId, String topic, Account.Id accountId)
-      throws RestApiException, ConfigInvalidException {
+      throws RestApiException {
     try (ManualRequestContext ctx = oneOffRequestContext.openAs(accountId)) {
       if (isNullOrEmpty(topic)) {
         topic = "am-" + UUID.randomUUID();
@@ -381,29 +369,29 @@
   }
 
   /**
-   * Creates merges downstream, and votes on the automerge label if we have a failed merge.
+   * Creates changes downstream, and votes on the automerge label if we have a failed merge.
    *
-   * @param mdsMergeInput Input containing the downstream branch map and source change ID.
+   * @param mdsChangeInput Input containing the downstream branch map and source change ID.
    * @param accountId Account ID to authorize Gerrit API calls.
    * @throws RestApiException Throws if we fail a REST API call.
    * @throws ConfigInvalidException Throws if we get a malformed configuration
    * @throws InvalidQueryParameterException Throws if we attempt to add an invalid value to query.
    * @throws StorageException Throws if we fail to open the request context
    */
-  public void createMergesAndHandleConflicts(MultipleDownstreamMergeInput mdsMergeInput, Account.Id accountId)
+  public void createChangesAndHandleConflicts(MultipleDownstreamChangeInput mdsChangeInput, Account.Id accountId)
       throws RestApiException, ConfigInvalidException, InvalidQueryParameterException,
           StorageException {
     try (ManualRequestContext ctx = oneOffRequestContext.openAs(accountId)) {
       ReviewInput reviewInput = new ReviewInput();
       Map<String, Short> labels = new HashMap<>();
       try {
-        createDownstreamMerges(mdsMergeInput, accountId);
+        createDownstreamChanges(mdsChangeInput, accountId);
 
         reviewInput.message =
             "Automerging change "
-                + mdsMergeInput.changeNumber
+                + mdsChangeInput.changeNumber
                 + " to "
-                + Joiner.on(", ").join(mdsMergeInput.dsBranchMap.keySet())
+                + Joiner.on(", ").join(mdsChangeInput.dsBranchMap.keySet())
                 + " succeeded!";
         reviewInput.notify = NotifyHandling.NONE;
       } catch (FailedMergeException e) {
@@ -419,7 +407,7 @@
 
       // Make the vote on the original change
       ChangeInfo originalChange =
-          getOriginalChange(mdsMergeInput.changeNumber, mdsMergeInput.currentRevision);
+          getOriginalChange(mdsChangeInput.changeNumber, mdsChangeInput.currentRevision);
       // if this fails, i.e. -2 is restricted, catch it and still post message without a vote.
       try {
         gApi.changes().id(originalChange._number).revision(CURRENT).review(reviewInput);
@@ -436,9 +424,9 @@
   }
 
   /**
-   * Creates merge downstream.
+   * Creates changes downstream.
    *
-   * @param mdsMergeInput Input containing the downstream branch map and source change ID.
+   * @param mdsChangeInput Input containing the downstream branch map and source change ID.
    * @param accountId Account ID to authorize Gerrit API calls.
    * @throws RestApiException Throws if we fail a REST API call.
    * @throws FailedMergeException Throws if we get a merge conflict when merging downstream.
@@ -446,7 +434,7 @@
    * @throws InvalidQueryParameterException Throws if we attempt to add an invalid value to query.
    * @throws StorageException Throws if we fail to open the request context
    */
-  private void createDownstreamMerges(MultipleDownstreamMergeInput mdsMergeInput, Account.Id accountId)
+  private void createDownstreamChanges(MultipleDownstreamChangeInput mdsChangeInput, Account.Id accountId)
       throws RestApiException, FailedMergeException, ConfigInvalidException,
           InvalidQueryParameterException, StorageException {
     try (ManualRequestContext ctx = oneOffRequestContext.openAs(accountId)) {
@@ -454,31 +442,35 @@
       Map<String, String> failedMergeBranchMap = new TreeMap<>();
 
       List<Integer> existingDownstream;
-      for (String downstreamBranch : mdsMergeInput.dsBranchMap.keySet()) {
-        // If there are existing downstream merges, update them
+      for (String downstreamBranch : mdsChangeInput.dsBranchMap.keySet()) {
+        // If there are existing downstream changes, update them
         // Otherwise, create them.
         boolean createDownstreams = true;
-        if (mdsMergeInput.obsoleteRevision != null) {
+        if (mdsChangeInput.obsoleteRevision != null) {
           existingDownstream =
-              getExistingMergesOnBranch(
-                  mdsMergeInput.obsoleteRevision, mdsMergeInput.topic, downstreamBranch, accountId);
+              getExistingChangesOnBranch(
+                  mdsChangeInput.obsoleteRevision, mdsChangeInput.topic, downstreamBranch, accountId);
           if (!existingDownstream.isEmpty()) {
             logger.atFine().log(
                 "Attempting to update downstream merge of %s on branch %s",
-                mdsMergeInput.currentRevision, downstreamBranch);
+                mdsChangeInput.currentRevision, downstreamBranch);
             // existingDownstream should almost always be of length one, but
             // it's possible to construct it so that it's not
             for (Integer dsChangeNumber : existingDownstream) {
               try {
-                updateDownstreamMerge(
-                    mdsMergeInput.currentRevision,
-                    mdsMergeInput.subject,
-                    dsChangeNumber,
-                    mdsMergeInput.dsBranchMap.get(downstreamBranch),
-                    mdsMergeInput.changeNumber,
-                    downstreamBranch);
+                UpdateDownstreamChangeInput updateDownstreamChangeInput = new UpdateDownstreamChangeInput();
+                updateDownstreamChangeInput.upstreamRevision = mdsChangeInput.currentRevision;
+                updateDownstreamChangeInput.upstreamSubject = mdsChangeInput.subject;
+                updateDownstreamChangeInput.downstreamChangeNumber = dsChangeNumber;
+                updateDownstreamChangeInput.doChange = mdsChangeInput.dsBranchMap.get(downstreamBranch);
+                updateDownstreamChangeInput.upstreamChangeNumber = mdsChangeInput.changeNumber;
+                updateDownstreamChangeInput.patchSetNumber = mdsChangeInput.patchsetNumber;
+                updateDownstreamChangeInput.downstreamBranch = downstreamBranch;
+                updateDownstreamChangeInput.topic = mdsChangeInput.topic;
+
+                changeCreator.get().update(updateDownstreamChangeInput);
                 createDownstreams = false;
-              } catch (MergeConflictException e) {
+              } catch (MergeConflictException | IntegrationConflictException e) {
                 failedMergeBranchMap.put(downstreamBranch, e.getMessage());
                 logger.atFine().log(
                     "Abandoning existing, obsolete %s due to merge conflict.", dsChangeNumber);
@@ -489,19 +481,20 @@
         }
         if (createDownstreams) {
           logger.atFine().log(
-              "Attempting to create downstream merge of %s on branch %s",
-              mdsMergeInput.currentRevision, downstreamBranch);
-          SingleDownstreamMergeInput sdsMergeInput = new SingleDownstreamMergeInput();
-          sdsMergeInput.currentRevision = mdsMergeInput.currentRevision;
-          sdsMergeInput.changeNumber = mdsMergeInput.changeNumber;
-          sdsMergeInput.project = mdsMergeInput.project;
-          sdsMergeInput.topic = mdsMergeInput.topic;
-          sdsMergeInput.subject = mdsMergeInput.subject;
-          sdsMergeInput.downstreamBranch = downstreamBranch;
-          sdsMergeInput.doMerge = mdsMergeInput.dsBranchMap.get(downstreamBranch);
+              "Attempting to create downstream change of %s on branch %s",
+              mdsChangeInput.currentRevision, downstreamBranch);
+          SingleDownstreamChangeInput sdsChangeInput = new SingleDownstreamChangeInput();
+          sdsChangeInput.currentRevision = mdsChangeInput.currentRevision;
+          sdsChangeInput.changeNumber = mdsChangeInput.changeNumber;
+          sdsChangeInput.patchsetNumber = mdsChangeInput.patchsetNumber;
+          sdsChangeInput.project = mdsChangeInput.project;
+          sdsChangeInput.topic = mdsChangeInput.topic;
+          sdsChangeInput.subject = mdsChangeInput.subject;
+          sdsChangeInput.downstreamBranch = downstreamBranch;
+          sdsChangeInput.doChange = mdsChangeInput.dsBranchMap.get(downstreamBranch);
           try {
-            createSingleDownstreamMerge(sdsMergeInput, accountId);
-          } catch (MergeConflictException e) {
+            createSingleDownstreamChange(sdsChangeInput, accountId);
+          } catch (MergeConflictException | IntegrationConflictException e) {
             failedMergeBranchMap.put(downstreamBranch, e.getMessage());
           }
         }
@@ -509,28 +502,27 @@
 
       if (!failedMergeBranchMap.isEmpty()) {
         String conflictMessage = config.getConflictMessage();
-        if (mdsMergeInput.project.equals(config.getManifestProject())) {
+        if (mdsChangeInput.project.equals(config.getManifestProject())) {
           conflictMessage = config.getManifestConflictMessage();
         }
         throw new FailedMergeException(
             failedMergeBranchMap,
-            mdsMergeInput.currentRevision,
+            mdsChangeInput.currentRevision,
             config.getHostName(),
-            mdsMergeInput.project,
-            mdsMergeInput.changeNumber,
-            mdsMergeInput.patchsetNumber,
+            mdsChangeInput.project,
+            mdsChangeInput.changeNumber,
+            mdsChangeInput.patchsetNumber,
             conflictMessage,
-            mdsMergeInput.topic);
+            mdsChangeInput.topic);
       }
     }
   }
 
   /**
-   * Get change IDs of the immediately downstream changes of the revision on the branch.
+   * Get change numbers of the immediately downstream changes of the revision on the branch.
    *
-   * @param upstreamRevision Revision of the original change.
    * @param topic Topic of the original change.
-   * @param downstreamBranch Branch to check for existing merge CLs.
+   * @param downstreamBranch Branch to check for existing automerger CLs.
    * @param accountId Account ID to authorize Gerrit API calls.
    * @return List of change numbers that are downstream of the given branch.
    * @throws RestApiException Throws when we fail a REST API call.
@@ -538,25 +530,21 @@
    * @throws ConfigInvalidException Throws if we fail to read the config
    * @throws StorageException Throws if we fail to open the request context
    */
-  private List<Integer> getExistingMergesOnBranch(
+  private List<Integer> getExistingChangesOnBranch(
       String upstreamRevision, String topic, String downstreamBranch, Account.Id accountId)
       throws RestApiException, InvalidQueryParameterException, StorageException,
           ConfigInvalidException {
     try (ManualRequestContext ctx = oneOffRequestContext.openAs(accountId)) {
       List<Integer> downstreamChangeNumbers = new ArrayList<>();
-      List<ChangeInfo> changes = getChangesInTopicAndBranch(topic, downstreamBranch);
+      List<ChangeInfo> changes = ChangeUtils.getChangesInTopicAndBranch(gApi, topic, downstreamBranch);
 
+      ChangeMode changeMode = config.changeMode();
       for (ChangeInfo change : changes) {
-        String changeRevision = change.currentRevision;
-        RevisionInfo revision = change.revisions.get(changeRevision);
-        List<CommitInfo> parents = revision.commit.parents;
-        if (parents.size() > 1) {
-          String secondParent = parents.get(1).commit;
-          if (secondParent.equals(upstreamRevision)) {
-            downstreamChangeNumbers.add(change._number);
-          }
+        if(ChangeUtils.isDownstreamChange(gApi, upstreamRevision, change, changeMode)) {
+          downstreamChangeNumbers.add(change._number);
         }
       }
+
       return downstreamChangeNumbers;
     }
   }
@@ -564,94 +552,24 @@
   /**
    * Create a single downstream merge.
    *
-   * @param sdsMergeInput Input containing metadata for the merge.
+   * @param sdsChangeInput Input containing metadata for the merge.
    * @param accountId Account ID to authorize Gerrit API calls.
    * @throws RestApiException
    * @throws ConfigInvalidException
    * @throws InvalidQueryParameterException
    * @throws StorageException
    */
-  private void createSingleDownstreamMerge(SingleDownstreamMergeInput sdsMergeInput, Account.Id accountId)
+  private void createSingleDownstreamChange(SingleDownstreamChangeInput sdsChangeInput, Account.Id accountId)
       throws RestApiException, ConfigInvalidException, InvalidQueryParameterException,
           StorageException {
     try (ManualRequestContext ctx = oneOffRequestContext.openAs(accountId)) {
-      String currentTopic = getOrSetTopic(sdsMergeInput.changeNumber, sdsMergeInput.topic, accountId);
+      String currentTopic = getOrSetTopic(sdsChangeInput.changeNumber, sdsChangeInput.topic, accountId);
 
-      if (isAlreadyMerged(sdsMergeInput, currentTopic)) {
-        logger.atInfo().log(
-            "Commit %s already merged into %s, not automerging again.",
-            sdsMergeInput.currentRevision, sdsMergeInput.downstreamBranch);
-        return;
-      }
-
-      MergeInput mergeInput = new MergeInput();
-      mergeInput.source = sdsMergeInput.currentRevision;
-      mergeInput.strategy = "recursive";
-
-      logger.atFine().log("Creating downstream merge for %s", sdsMergeInput.currentRevision);
-      ChangeInput downstreamChangeInput = new ChangeInput();
-      downstreamChangeInput.project = sdsMergeInput.project;
-      downstreamChangeInput.branch = sdsMergeInput.downstreamBranch;
-      downstreamChangeInput.subject =
-          getSubjectForDownstreamMerge(sdsMergeInput.subject, sdsMergeInput.currentRevision, false);
-      downstreamChangeInput.topic = currentTopic;
-      downstreamChangeInput.merge = mergeInput;
-      downstreamChangeInput.notify = NotifyHandling.NONE;
-
-      downstreamChangeInput.baseChange =
-          getBaseChangeId(
-              getChangeParents(sdsMergeInput.changeNumber, sdsMergeInput.currentRevision),
-              sdsMergeInput.downstreamBranch);
-
-      if (!sdsMergeInput.doMerge) {
-        mergeInput.strategy = "ours";
-        downstreamChangeInput.subject =
-            getSubjectForDownstreamMerge(
-                sdsMergeInput.subject, sdsMergeInput.currentRevision, true);
-        logger.atFine().log(
-            "Skipping merge for %s to %s",
-            sdsMergeInput.currentRevision, sdsMergeInput.downstreamBranch);
-      }
-
-      ChangeApi downstreamChange = gApi.changes().create(downstreamChangeInput);
-      tagChange(downstreamChange.get(), "Automerger change created!");
-    }
-  }
-
-  /**
-   * Get the base change ID that the downstream change should be based off of, given the parents.
-   *
-   * <p>Given changes A and B where A is the first parent of B, and where A' is the change whose
-   * second parent is A, and B' is the change whose second parent is B, the first parent of B'
-   * should be A'.
-   *
-   * @param parents Parent commit SHAs of the change
-   * @return The base change ID that the change should be based off of, null if there is none.
-   * @throws InvalidQueryParameterException
-   * @throws RestApiException
-   */
-  private String getBaseChangeId(List<String> parents, String branch)
-      throws InvalidQueryParameterException, RestApiException {
-    if (parents.isEmpty()) {
-      logger.atInfo().log("No base change id for change with no parents.");
-      return null;
-    }
-    // 1) Get topic of first parent
-    String firstParentTopic = getTopic(parents.get(0));
-    if (firstParentTopic == null) {
-      return null;
-    }
-    // 2) query that topic and use that to find A'
-    List<ChangeInfo> changesInTopic = getChangesInTopicAndBranch(firstParentTopic, branch);
-    String firstParent = parents.get(0);
-    for (ChangeInfo change : changesInTopic) {
-      List<CommitInfo> topicChangeParents =
-          change.revisions.get(change.currentRevision).commit.parents;
-      if (topicChangeParents.size() > 1 && topicChangeParents.get(1).commit.equals(firstParent)) {
-        return String.valueOf(change._number);
+      ChangeApi downstreamChange = changeCreator.get().create(sdsChangeInput, currentTopic);
+      if(downstreamChange != null) {
+        ChangeUtils.tagChange(gApi, downstreamChange.get(), "Automerger change created!");
       }
     }
-    return null;
   }
 
   private void automergeChanges(ChangeInfo change, RevisionInfo revisionInfo, Account.Id accountId)
@@ -681,7 +599,7 @@
     ChangeApi currentChange = gApi.changes().id(change._number);
     String previousRevision = getPreviousRevision(currentChange, revisionInfo._number);
 
-    MultipleDownstreamMergeInput mdsMergeInput = new MultipleDownstreamMergeInput();
+    MultipleDownstreamChangeInput mdsMergeInput = new MultipleDownstreamChangeInput();
     mdsMergeInput.dsBranchMap = dsBranchMap;
     mdsMergeInput.changeNumber = change._number;
     mdsMergeInput.patchsetNumber = revisionInfo._number;
@@ -691,7 +609,7 @@
     mdsMergeInput.obsoleteRevision = previousRevision;
     mdsMergeInput.currentRevision = currentRevision;
 
-    createMergesAndHandleConflicts(mdsMergeInput, accountId);
+    createChangesAndHandleConflicts(mdsMergeInput, accountId);
   }
 
   private void abandonDownstream(ChangeInfo change, String revision, Account.Id accountId)
@@ -706,7 +624,7 @@
 
       for (String downstreamBranch : downstreamBranches) {
         List<Integer> existingDownstream =
-            getExistingMergesOnBranch(revision, change.topic, downstreamBranch, accountId);
+            getExistingChangesOnBranch(revision, change.topic, downstreamBranch, accountId);
         logger.atFine().log("Abandoning existing downstreams: %s", existingDownstream);
         for (Integer changeNumber : existingDownstream) {
           abandonChange(changeNumber);
@@ -725,7 +643,7 @@
     labels.put(label, vote);
     reviewInput.labels = labels;
     reviewInput.notify = NotifyHandling.NONE;
-    reviewInput.tag = AUTOMERGER_TAG;
+    reviewInput.tag = ChangeUtils.AUTOMERGER_TAG;
     try {
       gApi.changes().id(change.id).revision(CURRENT).review(reviewInput);
     } catch (AuthException e) {
@@ -733,56 +651,6 @@
     }
   }
 
-  private void tagChange(ChangeInfo change, String message) throws RestApiException {
-    ReviewInput reviewInput = new ReviewInput();
-    reviewInput.message(message);
-    reviewInput.notify = NotifyHandling.NONE;
-    reviewInput.tag = AUTOMERGER_TAG;
-    try {
-      gApi.changes().id(change.id).revision(CURRENT).review(reviewInput);
-    } catch (AuthException e) {
-      logger.atSevere().withCause(e).log("Automerger could not set label, but still continuing.");
-    }
-  }
-
-  private void updateDownstreamMerge(
-      String newParentRevision,
-      String upstreamSubject,
-      Integer sourceNum,
-      boolean doMerge,
-      Integer upstreamChangeNumber,
-      String downstreamBranch)
-      throws RestApiException, InvalidQueryParameterException {
-    MergeInput mergeInput = new MergeInput();
-    mergeInput.source = newParentRevision;
-
-    MergePatchSetInput mergePatchSetInput = new MergePatchSetInput();
-
-    mergePatchSetInput.subject =
-        getSubjectForDownstreamMerge(upstreamSubject, newParentRevision, false);
-    if (!doMerge) {
-      mergeInput.strategy = "ours";
-      mergePatchSetInput.subject =
-          getSubjectForDownstreamMerge(upstreamSubject, newParentRevision, true);
-      logger.atFine().log("Skipping merge for %s on %s", newParentRevision, sourceNum);
-    }
-    mergePatchSetInput.merge = mergeInput;
-
-    mergePatchSetInput.baseChange =
-        getBaseChangeId(
-            getChangeParents(upstreamChangeNumber, newParentRevision), downstreamBranch);
-
-    ChangeApi originalChange = gApi.changes().id(sourceNum);
-
-    if (originalChange.info().status == ChangeStatus.ABANDONED) {
-      RestoreInput restoreInput = new RestoreInput();
-      restoreInput.message = "Restoring change due to upstream automerge.";
-      originalChange.restore(restoreInput);
-    }
-
-    originalChange.createMergePatchSet(mergePatchSetInput);
-  }
-
   private String getPreviousRevision(ChangeApi change, int currentPatchSetNumber)
       throws RestApiException {
     String previousRevision = null;
@@ -802,9 +670,24 @@
     return previousRevision;
   }
 
-  private ChangeInfo getOriginalChange(int changeNumber, String currentRevision)
+  private ChangeInfo getOriginalChangeCherryPickMode(int changeNumber)
       throws RestApiException, InvalidQueryParameterException {
-    List<String> parents = getChangeParents(changeNumber, currentRevision);
+
+    ChangeInfo current = gApi.changes().id(changeNumber).get();
+    String topic = current.topic;
+    List<ChangeInfo> changesInTopic = getChangesInTopic(topic);
+    for (ChangeInfo change : changesInTopic) {
+      if(ChangeUtils.isDownstreamCherryPick(gApi, change.currentRevision, current)){
+        return getOriginalChangeCherryPickMode(change._number);
+      }
+    }
+
+    return current;
+  }
+
+  private ChangeInfo getOriginalChangeMergeMode(int changeNumber, String currentRevision)
+      throws RestApiException, InvalidQueryParameterException {
+    List<String> parents = ChangeUtils.getChangeParents(gApi, changeNumber, currentRevision);
     if (parents.size() >= 2) {
       String secondParentRevision = parents.get(1);
       String topic = gApi.changes().id(changeNumber).topic();
@@ -818,114 +701,36 @@
     return gApi.changes().id(changeNumber).get();
   }
 
-  private List<String> getChangeParents(int changeNumber, String currentRevision)
-      throws RestApiException {
-    ChangeApi change = gApi.changes().id(changeNumber);
-    List<String> parents = new ArrayList<>();
-    Map<String, RevisionInfo> revisionMap =
-        change.get(EnumSet.of(ListChangesOption.ALL_REVISIONS, ListChangesOption.CURRENT_COMMIT))
-            .revisions;
-    List<CommitInfo> changeParents = revisionMap.get(currentRevision).commit.parents;
-    for (CommitInfo commit : changeParents) {
-      parents.add(commit.commit);
+  private ChangeInfo getOriginalChange(int changeNumber, String currentRevision)
+      throws RestApiException, InvalidQueryParameterException {
+    ChangeMode changeMode = ChangeMode.MERGE;
+    try {
+      changeMode = config.changeMode();
+    } catch (ConfigInvalidException e) {
+      logger.atSevere().withCause(e).log("Automerger could not read config, but still continuing.");
     }
-    return parents;
+
+    if(changeMode == ChangeMode.CHERRY_PICK){
+      return getOriginalChangeCherryPickMode(changeNumber);
+    } else {
+      return getOriginalChangeMergeMode(changeNumber, currentRevision);
+    }
   }
 
   private void abandonChange(Integer changeNumber) throws RestApiException {
     logger.atFine().log("Abandoning change: %s", changeNumber);
     AbandonInput abandonInput = new AbandonInput();
     abandonInput.notify = NotifyHandling.NONE;
-    abandonInput.message = "Merge parent updated; abandoning due to upstream conflict.";
+    abandonInput.message = "Upstream change updated; abandoning due to upstream conflict.";
     gApi.changes().id(changeNumber).abandon(abandonInput);
   }
 
-  private String getTopic(String revision) throws InvalidQueryParameterException, RestApiException {
-    QueryBuilder queryBuilder = new QueryBuilder();
-    queryBuilder.addParameter("commit", revision);
-    List<ChangeInfo> changes =
-        gApi.changes()
-            .query(queryBuilder.get())
-            .withOption(ListChangesOption.CURRENT_REVISION)
-            .get();
-    if (!changes.isEmpty()) {
-      for (ChangeInfo change : changes) {
-        if (change.currentRevision.equals(revision) && !"".equals(change.topic)) {
-          return change.topic;
-        }
-      }
-    }
-    return null;
-  }
-
-  private QueryBuilder constructTopicQuery(String topic) throws InvalidQueryParameterException {
-    QueryBuilder queryBuilder = new QueryBuilder();
-    queryBuilder.addParameter("topic", topic);
-    queryBuilder.addParameter("status", "open");
-    return queryBuilder;
-  }
-
   private List<ChangeInfo> getChangesInTopic(String topic)
       throws InvalidQueryParameterException, RestApiException {
-    QueryBuilder queryBuilder = constructTopicQuery(topic);
+    QueryBuilder queryBuilder = ChangeUtils.constructTopicQuery(topic);
     return gApi.changes()
         .query(queryBuilder.get())
         .withOptions(ListChangesOption.ALL_REVISIONS, ListChangesOption.CURRENT_COMMIT)
         .get();
   }
-
-  private List<ChangeInfo> getChangesInTopicAndBranch(String topic, String downstreamBranch)
-      throws InvalidQueryParameterException, RestApiException {
-    QueryBuilder queryBuilder = constructTopicQuery(topic);
-    queryBuilder.addParameter("branch", downstreamBranch);
-    return gApi.changes()
-        .query(queryBuilder.get())
-        .withOptions(ListChangesOption.ALL_REVISIONS, ListChangesOption.CURRENT_COMMIT)
-        .get();
-  }
-
-  private boolean isAlreadyMerged(SingleDownstreamMergeInput sdsMergeInput, String currentTopic)
-      throws InvalidQueryParameterException, RestApiException {
-    // If we've already merged this commit to this branch, don't do it again.
-    List<ChangeInfo> changes =
-        getChangesInTopicAndBranch(currentTopic, sdsMergeInput.downstreamBranch);
-    for (ChangeInfo change : changes) {
-      if (change.branch.equals(sdsMergeInput.downstreamBranch)) {
-        List<CommitInfo> parents = change.revisions.get(change.currentRevision).commit.parents;
-        if (parents.size() > 1) {
-          String secondParent = parents.get(1).commit;
-          if (secondParent.equals(sdsMergeInput.currentRevision)) {
-            return true;
-          }
-        }
-      }
-    }
-    return false;
-  }
-
-  /**
-   * Create subject line for downstream merge with metadata from upstream change.
-   *
-   * <p>The downstream subject will be in the format: "[automerger] upstreamSubject am:
-   * upstreamRevision". If it is a skip, "am" will be replaced with "skipped", and [automerger]
-   * replaced with [automerger skipped].
-   *
-   * @param upstreamSubject Subject line of the upstream change
-   * @param upstreamRevision Commit SHA1 of the upstream change
-   * @param skipped Whether or not the merge is done with "-s ours"
-   * @return Subject line for downstream merge
-   */
-  private String getSubjectForDownstreamMerge(
-      String upstreamSubject, String upstreamRevision, boolean skipped) {
-    if (!upstreamSubject.startsWith("[" + SUBJECT_PREFIX)) {
-      String prefix = "[" + SUBJECT_PREFIX + "]";
-      if (skipped) {
-        prefix = "[" + SUBJECT_PREFIX + " " + SKIPPED_PREFIX + "]";
-      }
-      upstreamSubject = Joiner.on(" ").join(prefix, upstreamSubject);
-    }
-    String denotationString = skipped ? "skipped:" : "am:";
-    return Joiner.on(" ")
-        .join(upstreamSubject, denotationString, upstreamRevision.substring(0, 10));
-  }
 }

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/MergeChangeCreator.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/MergeChangeCreator.java
new file mode 100644
index 0000000..7ed8e1d
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/MergeChangeCreator.java

@@ -0,0 +1,136 @@
+package com.googlesource.gerrit.plugins.automerger;
+
+import com.google.common.flogger.FluentLogger;
+import com.google.gerrit.exceptions.StorageException;
+import com.google.gerrit.extensions.api.GerritApi;
+import com.google.gerrit.extensions.api.changes.ChangeApi;
+import com.google.gerrit.extensions.api.changes.NotifyHandling;
+import com.google.gerrit.extensions.api.changes.RestoreInput;
+import com.google.gerrit.extensions.client.ChangeStatus;
+import com.google.gerrit.extensions.common.ChangeInfo;
+import com.google.gerrit.extensions.common.ChangeInput;
+import com.google.gerrit.extensions.common.CommitInfo;
+import com.google.gerrit.extensions.common.MergeInput;
+import com.google.gerrit.extensions.common.MergePatchSetInput;
+import com.google.gerrit.extensions.restapi.RestApiException;
+import com.google.inject.Inject;
+import java.util.List;
+import org.eclipse.jgit.errors.ConfigInvalidException;
+
+/**
+ * MergeChangeCreator handles creation and updating of downstream changes as merges.
+ */
+public class MergeChangeCreator implements ChangeCreatorApi {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+  private static final String SUBJECT_PREFIX = "automerger";
+  private final GerritApi gApi;
+  @Inject
+  public MergeChangeCreator(
+      GerritApi gApi) {
+    this.gApi = gApi;
+  }
+  /**
+   * Create a single downstream merge.
+   *
+   * @param sdsChangeInput Input containing metadata for the merge.
+   * @param currentTopic Current topic to create change in.
+   * @throws RestApiException
+   * @throws ConfigInvalidException
+   * @throws InvalidQueryParameterException
+   * @throws StorageException
+   */
+  @Override
+  public ChangeApi create(SingleDownstreamChangeInput sdsChangeInput,
+      String currentTopic)
+      throws RestApiException, ConfigInvalidException, InvalidQueryParameterException, StorageException {
+
+    if (isAlreadyMerged(sdsChangeInput, currentTopic)) {
+      logger.atInfo().log(
+          "Commit %s already merged into %s, not automerging again.",
+          sdsChangeInput.currentRevision, sdsChangeInput.downstreamBranch);
+      return null;
+    }
+
+    MergeInput mergeInput = new MergeInput();
+    mergeInput.source = sdsChangeInput.currentRevision;
+    mergeInput.strategy = "recursive";
+
+    logger.atFine().log("Creating downstream merge for %s", sdsChangeInput.currentRevision);
+    ChangeInput downstreamChangeInput = new ChangeInput();
+    downstreamChangeInput.project = sdsChangeInput.project;
+    downstreamChangeInput.branch = sdsChangeInput.downstreamBranch;
+    downstreamChangeInput.subject =
+        ChangeUtils.getSubjectForDownstreamChange(SUBJECT_PREFIX, sdsChangeInput.subject, sdsChangeInput.currentRevision, !sdsChangeInput.doChange);
+    downstreamChangeInput.topic = currentTopic;
+    downstreamChangeInput.merge = mergeInput;
+    downstreamChangeInput.notify = NotifyHandling.NONE;
+
+    downstreamChangeInput.baseChange =
+        ChangeUtils.getBaseChangeIdForMerge(gApi,
+            ChangeUtils.getChangeParents(gApi, sdsChangeInput.changeNumber, sdsChangeInput.currentRevision),
+            sdsChangeInput.downstreamBranch);
+
+    if (!sdsChangeInput.doChange) {
+      mergeInput.strategy = "ours";
+      logger.atFine().log(
+          "Skipping merge for %s to %s",
+          sdsChangeInput.currentRevision, sdsChangeInput.downstreamBranch);
+    }
+
+    return gApi.changes().create(downstreamChangeInput);
+  }
+
+  @Override
+  public void update(UpdateDownstreamChangeInput updateDownstreamChangeInput)
+      throws RestApiException, ConfigInvalidException, InvalidQueryParameterException {
+
+    MergeInput mergeInput = new MergeInput();
+    mergeInput.source = updateDownstreamChangeInput.upstreamRevision;
+
+    MergePatchSetInput mergePatchSetInput = new MergePatchSetInput();
+
+    mergePatchSetInput.subject =
+        ChangeUtils.getSubjectForDownstreamChange(SUBJECT_PREFIX,
+            updateDownstreamChangeInput.upstreamSubject,
+            updateDownstreamChangeInput.upstreamRevision, !updateDownstreamChangeInput.doChange);
+    if (!updateDownstreamChangeInput.doChange) {
+      mergeInput.strategy = "ours";
+      logger.atFine().log("Skipping merge for %s on %s",
+          updateDownstreamChangeInput.upstreamRevision, updateDownstreamChangeInput.downstreamChangeNumber);
+    }
+    mergePatchSetInput.merge = mergeInput;
+
+    mergePatchSetInput.baseChange =
+        ChangeUtils.getBaseChangeIdForMerge(gApi,
+            ChangeUtils.getChangeParents(gApi, updateDownstreamChangeInput.upstreamChangeNumber,
+                updateDownstreamChangeInput.upstreamRevision), updateDownstreamChangeInput.downstreamBranch);
+
+    ChangeApi originalChange = gApi.changes().id(updateDownstreamChangeInput.downstreamChangeNumber);
+
+    if (originalChange.info().status == ChangeStatus.ABANDONED) {
+      RestoreInput restoreInput = new RestoreInput();
+      restoreInput.message = "Restoring change due to upstream automerge.";
+      originalChange.restore(restoreInput);
+    }
+
+    originalChange.createMergePatchSet(mergePatchSetInput);
+  }
+
+  boolean isAlreadyMerged(SingleDownstreamChangeInput sdsChangeInput, String currentTopic)
+      throws InvalidQueryParameterException, RestApiException {
+    // If we've already merged this commit to this branch, don't do it again.
+    List<ChangeInfo> changes =
+        ChangeUtils.getChangesInTopicAndBranch(gApi, currentTopic, sdsChangeInput.downstreamBranch);
+    for (ChangeInfo change : changes) {
+      List<CommitInfo> parents = change.revisions.get(change.currentRevision).commit.parents;
+      if (parents.size() > 1) {
+        String secondParent = parents.get(1).commit;
+        if (secondParent.equals(sdsChangeInput.currentRevision)) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/MergeValidator.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/MergeValidator.java
index 16459a6..b5c13fc 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/automerger/MergeValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/MergeValidator.java

@@ -23,8 +23,6 @@
 import com.google.gerrit.extensions.api.GerritApi;
 import com.google.gerrit.extensions.client.ListChangesOption;
 import com.google.gerrit.extensions.common.ChangeInfo;
-import com.google.gerrit.extensions.common.CommitInfo;
-import com.google.gerrit.extensions.common.RevisionInfo;
 import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.git.CodeReviewCommit;
@@ -105,6 +103,7 @@
       throws RestApiException, IOException, ConfigInvalidException, InvalidQueryParameterException {
     Set<String> missingDownstreamBranches = new HashSet<>();
 
+    ChangeMode changeMode = config.changeMode();
     Set<String> downstreamBranches =
         config.getDownstreamBranches(upstreamChange.branch, upstreamChange.project);
     for (String downstreamBranch : downstreamBranches) {
@@ -115,6 +114,9 @@
         missingDownstreamBranches.add(downstreamBranch);
         continue;
       }
+      if(cherryPickSkipped(upstreamChange, downstreamBranch)){
+        continue;
+      }
       queryBuilder.addParameter("topic", upstreamChange.topic);
       queryBuilder.addParameter("branch", downstreamBranch);
       queryBuilder.addParameter("status", "open");
@@ -124,14 +126,9 @@
               .withOptions(ListChangesOption.ALL_REVISIONS, ListChangesOption.CURRENT_COMMIT)
               .get();
       for (ChangeInfo change : changes) {
-        RevisionInfo revision = change.revisions.get(change.currentRevision);
-        List<CommitInfo> parents = revision.commit.parents;
-        if (parents.size() > 1) {
-          String secondParent = parents.get(1).commit;
-          if (secondParent.equals(upstreamChange.currentRevision)) {
-            dsExists = true;
-            break;
-          }
+        if(ChangeUtils.isDownstreamChange(gApi, upstreamChange.currentRevision, change, changeMode)) {
+          dsExists = true;
+          break;
         }
       }
       if (!dsExists) {
@@ -140,4 +137,16 @@
     }
     return missingDownstreamBranches;
   }
+
+  private boolean cherryPickSkipped(ChangeInfo change, String downstreamBranch){
+    try {
+      if(config.changeMode() == ChangeMode.MERGE){
+        return false;
+      }
+    } catch (ConfigInvalidException e) {
+      return false;
+    }
+
+    return change.hashtags.contains(ChangeUtils.getSkipHashtag(downstreamBranch));
+  }
 }

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/MultipleDownstreamMergeInput.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/MultipleDownstreamChangeInput.java
similarity index 85%
rename from src/main/java/com/googlesource/gerrit/plugins/automerger/MultipleDownstreamMergeInput.java
rename to src/main/java/com/googlesource/gerrit/plugins/automerger/MultipleDownstreamChangeInput.java
index a62d9a7..476c5d4 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/automerger/MultipleDownstreamMergeInput.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/MultipleDownstreamChangeInput.java

@@ -17,9 +17,10 @@
 import java.util.Map;
 
 /**
- * Class to hold input for a set of merges from a single source change, with associated metadata.
+ * Class to hold input for a set of downstream changes from a single source change, with associated
+ * metadata.
  */
-public class MultipleDownstreamMergeInput {
+public class MultipleDownstreamChangeInput {
   public Map<String, Boolean> dsBranchMap;
   public int changeNumber;
   public int patchsetNumber;

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/SingleDownstreamMergeInput.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/SingleDownstreamChangeInput.java
similarity index 84%
rename from src/main/java/com/googlesource/gerrit/plugins/automerger/SingleDownstreamMergeInput.java
rename to src/main/java/com/googlesource/gerrit/plugins/automerger/SingleDownstreamChangeInput.java
index 5a5f0e7..6804d70 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/automerger/SingleDownstreamMergeInput.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/SingleDownstreamChangeInput.java

@@ -14,8 +14,8 @@
 
 package com.googlesource.gerrit.plugins.automerger;
 
-/** Class to hold input for a merge for a single source change and destination branch. */
-public class SingleDownstreamMergeInput {
+/** Class to hold input for a downstream change from a single source change. */
+public class SingleDownstreamChangeInput {
   public String currentRevision;
   public int changeNumber;
   public int patchsetNumber;
@@ -23,5 +23,5 @@
   public String topic;
   public String subject;
   public String downstreamBranch;
-  public boolean doMerge;
+  public boolean doChange;
 }

diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/UpdateDownstreamChangeInput.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/UpdateDownstreamChangeInput.java
new file mode 100644
index 0000000..edaa6cc
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/UpdateDownstreamChangeInput.java

@@ -0,0 +1,13 @@
+package com.googlesource.gerrit.plugins.automerger;
+
+/** Class to hold input for a downstream change update from a single source change. */
+public class UpdateDownstreamChangeInput {
+  public String upstreamRevision;
+  public String upstreamSubject;
+  public int downstreamChangeNumber;
+  public int upstreamChangeNumber;
+  public int patchSetNumber;
+  public String downstreamBranch;
+  public String topic;
+  public boolean doChange;
+}

diff --git a/src/main/resources/Documentation/about.md b/src/main/resources/Documentation/about.md
index 13f69f8..1e17aa7 100644
--- a/src/main/resources/Documentation/about.md
+++ b/src/main/resources/Documentation/about.md

@@ -17,3 +17,5 @@
 A UI button "Recreate automerges" has been added so that users can skip
 downstream merges. Unchecking a branch's checkbox will skip that branch and
 all automerges downstream of that branch.
+
+The plugin can be configured to perform cherry-picks instead of merges.
\ No newline at end of file

diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index 6e629b3..b494fcb 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md

@@ -17,6 +17,7 @@
     blankMerge = .*RESTRICT AUTOMERGE.*
     blankMerge = .*SKIP UNLESS MERGEALL SET.*
     missingDownstreamsMessage = there is no ${missingDownstreams}
+    cherryPickMode = False
 
   [automerger "branch1:branch2"]
     setProjects = some/project
@@ -133,6 +134,12 @@
   credentials of this user ID instead of the credentials of the user doing the
   upstream operation.
 
+global.cherryPickMode
+: If this is true, cherry-picks will be executed instead of merges.
+
+When a change is skipped in cherry-pick mode, a downstream change is not created
+and a "am_skip_<branch>" hashtag is added to the upstream commit.
+
 automerger.branch1:branch2.setProjects
 : Projects to automerge for.
 

diff --git a/src/main/resources/Documentation/rest-api.md b/src/main/resources/Documentation/rest-api.md
index 3b0b5b6..a25522f 100644
--- a/src/main/resources/Documentation/rest-api.md
+++ b/src/main/resources/Documentation/rest-api.md

@@ -85,4 +85,25 @@
 
 ```
   HTTP/1.1 204 No Content
-```
\ No newline at end of file
+```
+
+### <a id="config-downstream"> Cherry Pick Mode
+GET /config/server/automerger~automerge-mode
+
+Returns either "CHERRY-PICK" or "MERGE".
+
+#### Request
+
+```
+  GET /config/server/automerger~automerge-mode HTTP/1.1
+```
+
+#### Response
+
+```
+  HTTP/1.1 200 OK
+  Content-Disposition: attachment
+  Content-Type: application/json;charset=utf-8
+  )]}'
+  "CHERRY-PICK"
+```

diff --git a/src/test/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreatorIT.java b/src/test/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreatorIT.java
index 254942f..3a5f8b3 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreatorIT.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreatorIT.java

@@ -18,6 +18,7 @@
 import static com.google.common.truth.OptionalSubject.optionals;
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.Truth.assertWithMessage;
+import static com.google.gerrit.acceptance.testsuite.project.TestProjectUpdate.allow;
 import static com.google.gerrit.acceptance.testsuite.project.TestProjectUpdate.allowLabel;
 import static com.google.gerrit.acceptance.testsuite.project.TestProjectUpdate.blockLabel;
 import static com.google.gerrit.acceptance.testsuite.project.TestProjectUpdate.labelPermissionKey;
@@ -41,12 +42,14 @@
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.entities.AccountGroup;
 import com.google.gerrit.entities.BranchNameKey;
+import com.google.gerrit.entities.Permission;
 import com.google.gerrit.entities.Project;
 import com.google.gerrit.entities.RefNames;
 import com.google.gerrit.extensions.api.accounts.AccountApi;
 import com.google.gerrit.extensions.api.changes.ChangeApi;
 import com.google.gerrit.extensions.api.changes.RebaseInput;
 import com.google.gerrit.extensions.api.changes.ReviewInput;
+import com.google.gerrit.extensions.client.ChangeStatus;
 import com.google.gerrit.extensions.common.ApprovalInfo;
 import com.google.gerrit.extensions.common.ChangeInfo;
 import com.google.gerrit.extensions.common.ChangeMessageInfo;
@@ -88,8 +91,7 @@
     return cfg;
   }
 
-  @Test
-  public void testExpectedFlow() throws Exception {
+  private void expectedFlow(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
     PushOneCommit.Result result =
@@ -98,7 +100,7 @@
     String projectName = result.getChange().project().get();
     createBranch(BranchNameKey.create(projectName, "ds_one"));
     createBranch(BranchNameKey.create(projectName, "ds_two"));
-    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two");
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", changeMode);
     // After we upload our config, we upload a new patchset to create the downstreams
     amendChange(result.getChangeId());
     result.assertOkStatus();
@@ -109,7 +111,6 @@
             .withOption(CURRENT_REVISION)
             .get();
     assertThat(changesInTopic).hasSize(3);
-
     List<ChangeInfo> sortedChanges = sortedChanges(changesInTopic);
 
     ChangeInfo dsOneChangeInfo = sortedChanges.get(0);
@@ -127,21 +128,32 @@
     // Ensure that commit subjects are correct
     String masterSubject = masterChangeInfo.subject;
     String shortMasterSha = masterChangeInfo.currentRevision.substring(0, 10);
-    assertThat(masterChangeInfo.subject).doesNotContainMatch("automerger");
+    String tag = getTag(changeMode);
+    assertThat(masterChangeInfo.subject).doesNotContainMatch(tag);
     assertThat(dsOneChangeInfo.subject)
-        .isEqualTo("[automerger] " + masterSubject + " am: " + shortMasterSha);
+        .isEqualTo("[" + tag + "] " + masterSubject + " am: " + shortMasterSha);
     assertThat(dsTwoChangeInfo.subject)
-        .isEqualTo("[automerger] " + masterSubject + " am: " + shortMasterSha);
+        .isEqualTo("[" + tag + "] " + masterSubject + " am: " + shortMasterSha);
 
     // +2 and submit
     merge(result);
     assertCodeReview(masterChangeInfo.id, 2, null);
     assertCodeReview(dsOneChangeInfo.id, 2, "autogenerated:Automerger");
     assertCodeReview(dsTwoChangeInfo.id, 2, "autogenerated:Automerger");
+
   }
 
   @Test
-  public void testDiamondMerge() throws Exception {
+  public void testExpectedFlow() throws Exception {
+    expectedFlow(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testExpectedFlowCherryPickMode() throws Exception {
+    expectedFlow(ChangeMode.CHERRY_PICK);
+  }
+
+  private void diamondMerge(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     ObjectId initial = repo().exactRef("HEAD").getLeaf().getObjectId();
     // Create initial change
@@ -172,7 +184,7 @@
     // For this test, right != left
     assertThat(leftRevision).isNotEqualTo(rightRevision);
     createBranch(BranchNameKey.create(projectName, "bottom"));
-    pushDiamondConfig(manifestNameKey.get(), projectName);
+    pushDiamondConfig(manifestNameKey.get(), projectName, changeMode);
     // After we upload our config, we upload a new patchset to create the downstreams
     testRepo.reset(masterWithMergedChange);
     PushOneCommit.Result result =
@@ -210,39 +222,55 @@
     assertThat(rightChangeInfo.branch).isEqualTo("right");
     assertCodeReview(rightChangeInfo.id, 2, "autogenerated:Automerger");
 
+    String tag = getTag(changeMode);
+
     // Ensure that commit subjects are correct
     String masterSubject = masterChangeInfo.subject;
     String shortMasterSha = masterChangeInfo.currentRevision.substring(0, 10);
     String shortLeftSha = leftChangeInfo.currentRevision.substring(0, 10);
     String shortRightSha = rightChangeInfo.currentRevision.substring(0, 10);
-    assertThat(masterChangeInfo.subject).doesNotContainMatch("automerger");
+    assertThat(masterChangeInfo.subject).doesNotContainMatch(tag);
     assertThat(leftChangeInfo.subject)
-        .isEqualTo("[automerger] " + masterSubject + " am: " + shortMasterSha);
+        .isEqualTo("[" + tag + "] " + masterSubject + " am: " + shortMasterSha);
     assertThat(rightChangeInfo.subject)
-        .isEqualTo("[automerger] " + masterSubject + " am: " + shortMasterSha);
+        .isEqualTo("[" + tag + "] " + masterSubject + " am: " + shortMasterSha);
 
     // Either bottomChangeInfoA came from left and bottomChangeInfoB came from right, or vice versa
     // We don't know which, so we use the if condition to check
-    String bottomChangeInfoASecondParent = getParent(bottomChangeInfoA, 1);
-    if (bottomChangeInfoASecondParent.equals(leftChangeInfo.currentRevision)) {
+    String bottomChangeInfoATarget = "";
+    if(changeMode == ChangeMode.CHERRY_PICK){
+      bottomChangeInfoATarget = getCherryPickFrom(bottomChangeInfoA);
+    } else {
+      bottomChangeInfoATarget = getParent(bottomChangeInfoA, 1);
+    }
+    if (bottomChangeInfoATarget.equals(leftChangeInfo.currentRevision)) {
       assertThat(bottomChangeInfoA.subject)
           .isEqualTo(
-              "[automerger] " + masterSubject + " am: " + shortMasterSha + " am: " + shortLeftSha);
+              "[" + tag + "] " + masterSubject + " am: " + shortMasterSha + " am: " + shortLeftSha);
       assertThat(bottomChangeInfoB.subject)
           .isEqualTo(
-              "[automerger] " + masterSubject + " am: " + shortMasterSha + " am: " + shortRightSha);
+              "[" + tag + "] " + masterSubject + " am: " + shortMasterSha + " am: " + shortRightSha);
     } else {
       assertThat(bottomChangeInfoA.subject)
           .isEqualTo(
-              "[automerger] " + masterSubject + " am: " + shortMasterSha + " am: " + shortRightSha);
+              "[" + tag + "] " + masterSubject + " am: " + shortMasterSha + " am: " + shortRightSha);
       assertThat(bottomChangeInfoB.subject)
           .isEqualTo(
-              "[automerger] " + masterSubject + " am: " + shortMasterSha + " am: " + shortLeftSha);
+              "[" + tag + "] " + masterSubject + " am: " + shortMasterSha + " am: " + shortLeftSha);
     }
   }
 
   @Test
-  public void testChangeStack() throws Exception {
+  public void testDiamondMerge() throws Exception {
+    diamondMerge(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testDiamondMergeCherryPickMode() throws Exception {
+    diamondMerge(ChangeMode.CHERRY_PICK);
+  }
+
+  private void changeStack(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
     PushOneCommit.Result result =
@@ -250,7 +278,7 @@
     // Project name is scoped by test, so we need to get it from our initial change
     String projectName = result.getChange().project().get();
     createBranch(BranchNameKey.create(projectName, "ds_one"));
-    pushSimpleConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one");
+    pushSimpleConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", changeMode);
     // After we upload our config, we upload a new patchset to create the downstreams
     amendChange(result.getChangeId());
     result.assertOkStatus();
@@ -286,13 +314,23 @@
     assertThat(bFirstParent).isEqualTo(a.currentRevision);
 
     // Ensure that commit subjects are correct
+    String tag = getTag(changeMode);
     String shortASha = a.currentRevision.substring(0, 10);
-    assertThat(a.subject).doesNotContainMatch("automerger");
-    assertThat(aPrime.subject).isEqualTo("[automerger] test commit am: " + shortASha);
+    assertThat(a.subject).doesNotContainMatch(tag);
+    assertThat(aPrime.subject).isEqualTo("[" + tag + "] test commit am: " + shortASha);
   }
 
   @Test
-  public void testChangeStack_rebaseAfterUpload() throws Exception {
+  public void testChangeStack() throws Exception {
+    changeStack(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testChangeStackCherryPickMode() throws Exception {
+    changeStack(ChangeMode.CHERRY_PICK);
+  }
+
+  private void changeStack_rebaseAfterUpload(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     // Save initial ref at HEAD
     ObjectId initial = repo().exactRef("HEAD").getLeaf().getObjectId();
@@ -302,7 +340,7 @@
     // Project name is scoped by test, so we need to get it from our initial change
     String projectName = result.getChange().project().get();
     createBranch(BranchNameKey.create(projectName, "ds_one"));
-    pushSimpleConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one");
+    pushSimpleConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", changeMode);
     // After we upload our config, we upload a new patchset to create the downstreams
     amendChange(result.getChangeId());
     result.assertOkStatus();
@@ -352,12 +390,36 @@
     String bAfterRebaseFirstParent = getParent(bAfterRebase, 0);
     assertThat(bAfterRebaseFirstParent).isEqualTo(a.currentRevision);
 
+    // In cherry-pick mode, we expect original bPrime to be removed, and a new bPrime to
+    // be created.
+    if(changeMode == ChangeMode.CHERRY_PICK){
+      assertThat(gApi.changes().id(bPrime.id).get().status).isEqualTo(ChangeStatus.ABANDONED);
+      changesInTopic =
+          gApi.changes()
+              .query("topic: " + gApi.changes().id(result.getChangeId()).topic() + " status:open")
+              .withOptions(ALL_REVISIONS, CURRENT_COMMIT)
+              .get();
+      assertThat(changesInTopic).hasSize(4);
+      sortedChanges = sortedChanges(changesInTopic);
+      bPrime = sortedChanges.get(1);
+    }
+
     ChangeInfo bPrimeAfterRebase = gApi.changes().id(bPrime.changeId).get();
     String bPrimeAfterRebaseFirstParent = getParent(bPrimeAfterRebase, 0);
     assertThat(bPrimeAfterRebaseFirstParent).isEqualTo(aPrime.currentRevision);
   }
 
   @Test
+  public void testChangeStack_rebaseAfterUpload() throws Exception {
+    changeStack_rebaseAfterUpload(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testChangeStack_rebaseAfterUploadCherryPickMode() throws Exception {
+    changeStack_rebaseAfterUpload(ChangeMode.CHERRY_PICK);
+  }
+
+  @Test
   public void testBlankMerge() throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
@@ -368,7 +430,7 @@
     String projectName = result.getChange().project().get();
     createBranch(BranchNameKey.create(projectName, "ds_one"));
     createBranch(BranchNameKey.create(projectName, "ds_two"));
-    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two");
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", ChangeMode.MERGE);
     // After we upload our config, we upload a new patchset to create the downstreams
     amendChange(result.getChangeId(), "DO NOT MERGE subject", "filename", "content");
     result.assertOkStatus();
@@ -415,6 +477,52 @@
   }
 
   @Test
+  public void testBlankMergeCherryPickMode() throws Exception {
+    Project.NameKey manifestNameKey = defaultSetup();
+    // Create initial change
+    PushOneCommit.Result result =
+        createChange(
+            testRepo, "master", "DO NOT MERGE subject", "filename", "content", "testtopic");
+    // Project name is scoped by test, so we need to get it from our initial change
+    String projectName = result.getChange().project().get();
+    createBranch(BranchNameKey.create(projectName, "ds_one"));
+    createBranch(BranchNameKey.create(projectName, "ds_two"));
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", ChangeMode.CHERRY_PICK);
+    // After we upload our config, we upload a new patchset to create the downstreams
+    amendChange(result.getChangeId(), "DO NOT MERGE subject", "filename", "content");
+    result.assertOkStatus();
+
+    ChangeApi change = gApi.changes().id(result.getChangeId());
+    BinaryResult content = change.current().file("filename").content();
+
+    List<ChangeInfo> changesInTopic =
+        gApi.changes().query("topic: " + change.topic()).withOption(CURRENT_REVISION).get();
+    assertThat(changesInTopic).hasSize(2);
+
+    List<ChangeInfo> sortedChanges = sortedChanges(changesInTopic);
+
+    ChangeInfo dsTwoChangeInfo = sortedChanges.get(0);
+    assertThat(dsTwoChangeInfo.branch).isEqualTo("ds_two");
+    assertAutomergerChangeCreatedMessage(dsTwoChangeInfo.id);
+    // It should not skip ds_two, since it is marked with mergeAll: true
+    ChangeApi dsTwoChange = gApi.changes().id(dsTwoChangeInfo._number);
+    assertThat(dsTwoChange.get().subject).doesNotContain("skipped:");
+    BinaryResult dsTwoContent = dsTwoChange.current().file("filename").content();
+    assertThat(dsTwoContent.asString()).isEqualTo(content.asString());
+
+    ChangeInfo masterChangeInfo = sortedChanges.get(1);
+    assertCodeReviewMissing(masterChangeInfo.id);
+    assertThat(masterChangeInfo.branch).isEqualTo("master");
+
+    // Ensure that commit subjects are correct
+    String masterSubject = masterChangeInfo.subject;
+    String shortMasterSha = masterChangeInfo.currentRevision.substring(0, 10);
+    assertThat(masterChangeInfo.subject).doesNotContainMatch("autocherry");
+    assertThat(dsTwoChangeInfo.subject)
+        .isEqualTo("[autocherry] " + masterSubject + " am: " + shortMasterSha);
+  }
+
+  @Test
   public void testAlwaysBlankMerge() throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
@@ -430,7 +538,7 @@
     String projectName = result.getChange().project().get();
     createBranch(BranchNameKey.create(projectName, "ds_one"));
     createBranch(BranchNameKey.create(projectName, "ds_two"));
-    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two");
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", ChangeMode.MERGE);
     // After we upload our config, we upload a new patchset to create the downstreams
     amendChange(result.getChangeId(), "DO NOT MERGE ANYWHERE subject", "filename", "content");
     result.assertOkStatus();
@@ -475,7 +583,36 @@
   }
 
   @Test
-  public void testDownstreamMergeConflict() throws Exception {
+  public void testAlwaysBlankMergeCherryPickMode() throws Exception {
+    Project.NameKey manifestNameKey = defaultSetup();
+    // Create initial change
+    PushOneCommit.Result result =
+        createChange(
+            testRepo,
+            "master",
+            "DO NOT MERGE ANYWHERE subject",
+            "filename",
+            "content",
+            "testtopic");
+    // Project name is scoped by test, so we need to get it from our initial change
+    String projectName = result.getChange().project().get();
+    createBranch(BranchNameKey.create(projectName, "ds_one"));
+    createBranch(BranchNameKey.create(projectName, "ds_two"));
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", ChangeMode.CHERRY_PICK);
+    // After we upload our config, we upload a new patchset to create the downstreams
+    amendChange(result.getChangeId(), "DO NOT MERGE ANYWHERE subject", "filename", "content");
+    result.assertOkStatus();
+
+    ChangeApi change = gApi.changes().id(result.getChangeId());
+    List<ChangeInfo> changesInTopic =
+        gApi.changes().query("topic: " + change.topic()).withOption(CURRENT_REVISION).get();
+    assertThat(changesInTopic).hasSize(1);
+    assertThat(changesInTopic.get(0).hashtags.size()).isEqualTo(2);
+    assertThat(changesInTopic.get(0).hashtags.contains("am_skip_ds_one")).isEqualTo(true);
+    assertThat(changesInTopic.get(0).hashtags.contains("am_skip_ds_two")).isEqualTo(true);
+  }
+
+  private void downstreamMergeConflict(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     ObjectId initial = repo().exactRef("HEAD").getLeaf().getObjectId();
     // Create initial change
@@ -496,7 +633,7 @@
     merge(ds1Result);
     // Reset to allow our merge conflict to come
     testRepo.reset(initial);
-    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two");
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", changeMode);
     // After we upload our config, we upload a new change to create the downstreams
     PushOneCommit.Result masterResult =
         pushFactory
@@ -532,13 +669,23 @@
     // Ensure that commit subjects are correct
     String masterSubject = masterChangeInfo.subject;
     String shortMasterSha = masterChangeInfo.currentRevision.substring(0, 10);
+    String tag = getTag(changeMode);
     assertThat(masterChangeInfo.subject).doesNotContainMatch("automerger");
     assertThat(dsTwoChangeInfo.subject)
-        .isEqualTo("[automerger] " + masterSubject + " am: " + shortMasterSha);
+        .isEqualTo("[" + tag + "] " + masterSubject + " am: " + shortMasterSha);
   }
 
   @Test
-  public void testRestrictedVotePermissions() throws Exception {
+  public void testDownstreamMergeConflict() throws Exception {
+    downstreamMergeConflict(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testDownstreamMergeConflictCherryPickMode() throws Exception {
+    downstreamMergeConflict(ChangeMode.CHERRY_PICK);
+  }
+
+  private void restrictedVotePermissions(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     ObjectId initial = repo().exactRef("HEAD").getLeaf().getObjectId();
     // Create initial change
@@ -559,7 +706,7 @@
     merge(ds1Result);
     // Reset to allow our merge conflict to come
     testRepo.reset(initial);
-    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two");
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", changeMode);
 
     // Block Code Review label to test restrictions
     projectOperations
@@ -606,15 +753,25 @@
     assertThat(messages).contains("Patch Set 1:\n\nMerge conflict found on ds_one");
 
     // Ensure that commit subjects are correct
+    String tag = getTag(changeMode);
     String masterSubject = masterChangeInfo.subject;
     String shortMasterSha = masterChangeInfo.currentRevision.substring(0, 10);
     assertThat(masterChangeInfo.subject).doesNotContainMatch("automerger");
     assertThat(dsTwoChangeInfo.subject)
-        .isEqualTo("[automerger] " + masterSubject + " am: " + shortMasterSha);
+        .isEqualTo("[" + tag + "] " + masterSubject + " am: " + shortMasterSha);
   }
 
   @Test
-  public void testTopicEditedListener() throws Exception {
+  public void testRestrictedVotePermissions() throws Exception {
+    restrictedVotePermissions(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testRestrictedVotePermissionsCherryPickMode() throws Exception {
+    restrictedVotePermissions(ChangeMode.CHERRY_PICK);
+  }
+
+  private void topicEditedListener(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
     PushOneCommit.Result result =
@@ -623,12 +780,47 @@
     String projectName = result.getChange().project().get();
     createBranch(BranchNameKey.create(projectName, "ds_one"));
     createBranch(BranchNameKey.create(projectName, "ds_two"));
-    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two");
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", changeMode);
     // After we upload our config, we upload a new patchset to create the downstreams
     amendChange(result.getChangeId());
     result.assertOkStatus();
-    gApi.changes().id(result.getChangeId()).topic("multiple words");
-    gApi.changes().id(result.getChangeId()).topic("singlewordagain");
+    gApi.changes().id(result.getChangeId()).topic(name("multiple words"));
+    gApi.changes().id(result.getChangeId()).topic(name("singlewordagain"));
+    // Check that there are the correct number of changes in the topic
+    List<ChangeInfo> changesInTopic =
+        gApi.changes()
+            .query("topic:\"" + gApi.changes().id(result.getChangeId()).topic() + "\"")
+            .get();
+    assertThat(changesInTopic).hasSize(3);
+    // +2 and submit
+    merge(result);
+  }
+
+  @Test
+  public void testTopicEditedListener() throws Exception {
+    topicEditedListener(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testTopicEditedListenerCherryPickMode() throws Exception {
+    topicEditedListener(ChangeMode.CHERRY_PICK);
+  }
+
+  private void topicEditedListener_withBraces(ChangeMode changeMode) throws Exception {
+    Project.NameKey manifestNameKey = defaultSetup();
+    // Create initial change
+    PushOneCommit.Result result =
+        createChange(testRepo, "master", "subject", "filename", "content", "testtopic");
+    // Project name is scoped by test, so we need to get it from our initial change
+    String projectName = result.getChange().project().get();
+    createBranch(BranchNameKey.create(projectName, "ds_one"));
+    createBranch(BranchNameKey.create(projectName, "ds_two"));
+    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two", changeMode);
+    // After we upload our config, we upload a new patchset to create the downstreams
+    amendChange(result.getChangeId());
+    result.assertOkStatus();
+    gApi.changes().id(result.getChangeId()).topic(name("multiple words"));
+    gApi.changes().id(result.getChangeId()).topic(name("with{braces}inside"));
     // Check that there are the correct number of changes in the topic
     List<ChangeInfo> changesInTopic =
         gApi.changes()
@@ -641,32 +833,15 @@
 
   @Test
   public void testTopicEditedListener_withBraces() throws Exception {
-    Project.NameKey manifestNameKey = defaultSetup();
-    // Create initial change
-    PushOneCommit.Result result =
-        createChange(testRepo, "master", "subject", "filename", "content", "testtopic");
-    // Project name is scoped by test, so we need to get it from our initial change
-    String projectName = result.getChange().project().get();
-    createBranch(BranchNameKey.create(projectName, "ds_one"));
-    createBranch(BranchNameKey.create(projectName, "ds_two"));
-    pushDefaultConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", "ds_two");
-    // After we upload our config, we upload a new patchset to create the downstreams
-    amendChange(result.getChangeId());
-    result.assertOkStatus();
-    gApi.changes().id(result.getChangeId()).topic("multiple words");
-    gApi.changes().id(result.getChangeId()).topic("with{braces}inside");
-    // Check that there are the correct number of changes in the topic
-    List<ChangeInfo> changesInTopic =
-        gApi.changes()
-            .query("topic:\"" + gApi.changes().id(result.getChangeId()).topic() + "\"")
-            .get();
-    assertThat(changesInTopic).hasSize(3);
-    // +2 and submit
-    merge(result);
+    topicEditedListener_withBraces(ChangeMode.MERGE);
   }
 
   @Test
-  public void testTopicEditedListener_branchWithBracesAndQuotes() throws Exception {
+  public void testTopicEditedListener_withBracesCherryPickMode() throws Exception {
+    topicEditedListener_withBraces(ChangeMode.CHERRY_PICK);
+  }
+
+  private void topicEditedListener_branchWithBracesAndQuotes(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
     PushOneCommit.Result result =
@@ -680,7 +855,8 @@
         manifestNameKey.get(),
         projectName,
         "branch{}braces",
-        "branch\"quotes");
+        "branch\"quotes",
+        changeMode);
     // After we upload our config, we upload a new patchset to create the downstreams
     amendChange(result.getChangeId());
     result.assertOkStatus();
@@ -695,7 +871,16 @@
   }
 
   @Test
-  public void testTopicEditedListener_emptyTopic() throws Exception {
+  public void testTopicEditedListener_branchWithBracesAndQuotes() throws Exception {
+    topicEditedListener_branchWithBracesAndQuotes(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testTopicEditedListener_branchWithBracesAndQuotesCherryPickMode() throws Exception {
+    topicEditedListener_branchWithBracesAndQuotes(ChangeMode.CHERRY_PICK);
+  }
+
+  private void topicEditedListener_emptyTopic(ChangeMode changeMode) throws Exception {
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
     PushOneCommit.Result result =
@@ -703,7 +888,7 @@
     // Project name is scoped by test, so we need to get it from our initial change
     String projectName = result.getChange().project().get();
     createBranch(BranchNameKey.create(projectName, "ds_one"));
-    pushSimpleConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one");
+    pushSimpleConfig("automerger.config", manifestNameKey.get(), projectName, "ds_one", changeMode);
     // After we upload our config, we upload a new patchset to create the downstreams
     amendChange(result.getChangeId());
     result.assertOkStatus();
@@ -716,7 +901,16 @@
   }
 
   @Test
-  public void testContextUser() throws Exception {
+  public void testTopicEditedListener_emptyTopic() throws Exception {
+    topicEditedListener_emptyTopic(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testTopicEditedListener_emptyTopicCherryPickMode() throws Exception {
+    topicEditedListener_emptyTopic(ChangeMode.CHERRY_PICK);
+  }
+
+  private void contextUser(ChangeMode changeMode) throws Exception {
     // Branch flow for contextUser is master -> ds_one -> ds_two
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
@@ -746,9 +940,28 @@
                 .group(AccountGroup.UUID.parse(gApi.groups().id(contextUserGroup).get().id))
                 .range(-2, 2))
         .setExclusiveGroup(labelPermissionKey("Code-Review").ref("refs/heads/ds_one"), true)
+        .add(
+            allow(Permission.EDIT_HASHTAGS)
+                .ref("refs/heads/*")
+                .group(AccountGroup.UUID.parse(gApi.groups().id(contextUserGroup).get().id))
+        )
         .update();
+
+    if(changeMode == ChangeMode.CHERRY_PICK) {
+      // Grant EDIT_HASHTAGS permission
+      projectOperations
+          .project(projectNameKey)
+          .forUpdate()
+          .add(
+              allow(Permission.EDIT_HASHTAGS)
+                  .ref("refs/heads/*")
+                  .group(AccountGroup.UUID.parse(gApi.groups().id(contextUserGroup).get().id))
+          )
+          .update();
+    }
+
     pushContextUserConfig(
-        manifestNameKey.get(), projectName, contextUserApi.get()._accountId.toString());
+        manifestNameKey.get(), projectName, contextUserApi.get()._accountId.toString(), changeMode);
 
     // After we upload our config, we upload a new patchset to create the downstreams
     PushOneCommit.Result result =
@@ -783,7 +996,16 @@
   }
 
   @Test
-  public void testContextUser_downstreamHighestVote() throws Exception {
+  public void testContextUser() throws Exception {
+    contextUser(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testContextUserCherryPickMode() throws Exception {
+    contextUser(ChangeMode.CHERRY_PICK);
+  }
+
+  private void contextUser_downstreamHighestVote(ChangeMode changeMode) throws Exception {
     // Branch flow for contextUser is master -> ds_one -> ds_two
     Project.NameKey manifestNameKey = defaultSetup();
     // Create initial change
@@ -813,8 +1035,22 @@
                 .group(AccountGroup.UUID.parse(gApi.groups().id(contextUserGroup).get().id))
                 .range(-2, 2))
         .update();
+
+    if(changeMode == ChangeMode.CHERRY_PICK) {
+      // Grant EDIT_HASHTAGS permission
+      projectOperations
+          .project(projectNameKey)
+          .forUpdate()
+          .add(
+              allow(Permission.EDIT_HASHTAGS)
+                  .ref("refs/heads/*")
+                  .group(AccountGroup.UUID.parse(gApi.groups().id(contextUserGroup).get().id))
+          )
+          .update();
+    }
+
     pushContextUserConfig(
-        manifestNameKey.get(), projectName, contextUserApi.get()._accountId.toString());
+        manifestNameKey.get(), projectName, contextUserApi.get()._accountId.toString(), changeMode);
 
     // After we upload our config, we upload a new patchset to create the downstreams
     PushOneCommit.Result result =
@@ -858,7 +1094,16 @@
   }
 
   @Test
-  public void testContextUser_mergeConflictOnDownstreamVotesOnTopLevel() throws Exception {
+  public void testContextUser_downstreamHighestVote() throws Exception {
+    contextUser_downstreamHighestVote(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testContextUser_downstreamHighestVoteCherryPickMode() throws Exception {
+    contextUser_downstreamHighestVote(ChangeMode.CHERRY_PICK);
+  }
+
+  private void contextUser_mergeConflictOnDownstreamVotesOnTopLevel(ChangeMode changeMode) throws Exception {
     // Branch flow for contextUser is master -> ds_one -> ds_two
     Project.NameKey manifestNameKey = defaultSetup();
     ObjectId initial = repo().exactRef("HEAD").getLeaf().getObjectId();
@@ -906,8 +1151,22 @@
                 .group(AccountGroup.UUID.parse(gApi.groups().id(contextUserGroup).get().id))
                 .range(-2, 2))
         .update();
+
+    if(changeMode == ChangeMode.CHERRY_PICK) {
+      // Grant EDIT_HASHTAGS permission
+      projectOperations
+          .project(projectNameKey)
+          .forUpdate()
+          .add(
+              allow(Permission.EDIT_HASHTAGS)
+                  .ref("refs/heads/*")
+                  .group(AccountGroup.UUID.parse(gApi.groups().id(contextUserGroup).get().id))
+          )
+          .update();
+    }
+
     pushContextUserConfig(
-        manifestNameKey.get(), projectName, contextUserApi.get()._accountId.toString());
+        manifestNameKey.get(), projectName, contextUserApi.get()._accountId.toString(), changeMode);
 
     // After we upload our config, we upload a new patchset to create the downstreams
     PushOneCommit.Result result =
@@ -919,15 +1178,195 @@
             .query("topic: " + gApi.changes().id(result.getChangeId()).topic())
             .withOptions(CURRENT_REVISION, CURRENT_COMMIT)
             .get();
-    // There should only be two, as ds_one to ds_two should be a merge conflict
-    assertThat(changesInTopic).hasSize(2);
 
+    if(changeMode == ChangeMode.MERGE) {
+      // In merge mode, there should be a conflict
+      // There should only be two, as ds_one to ds_two should be a merge conflict
+      assertThat(changesInTopic).hasSize(2);
+
+      List<ChangeInfo> sortedChanges = sortedChanges(changesInTopic);
+
+      // Check that master is at Code-Review -2
+      ChangeInfo masterChangeInfo = sortedChanges.get(1);
+      assertThat(masterChangeInfo.branch).isEqualTo("master");
+      assertCodeReview(masterChangeInfo.id, -2, "autogenerated:MergeConflict");
+    } else {
+      // In cherry-pick mode, there will not be a conflict
+      assertThat(changesInTopic).hasSize(3);
+
+      // Check that master is at Code-Review 0
+      List<ChangeInfo> sortedChanges = sortedChanges(changesInTopic);
+      ChangeInfo masterChangeInfo = sortedChanges.get(2);
+      assertThat(masterChangeInfo.branch).isEqualTo("master");
+      assertCodeReviewMissing(masterChangeInfo.id);
+    }
+  }
+
+  @Test
+  public void testContextUser_mergeConflictOnDownstreamVotesOnTopLevel() throws Exception {
+    contextUser_mergeConflictOnDownstreamVotesOnTopLevel(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testContextUser_mergeConflictOnDownstreamVotesOnTopLevelCherryPickMode() throws Exception {
+    contextUser_mergeConflictOnDownstreamVotesOnTopLevel(ChangeMode.CHERRY_PICK);
+  }
+
+  private void abandon(ChangeMode changeMode) throws Exception {
+    Project.NameKey manifestNameKey = defaultSetup();
+    // Create initial change
+    PushOneCommit.Result result =
+        createChange(testRepo, "master", "subject", "filename", "content", "testtopic");
+    // Project name is scoped by test, so we need to get it from our initial change
+    String projectName = result.getChange().project().get();
+    createBranch(BranchNameKey.create(projectName, "ds_one"));
+    createBranch(BranchNameKey.create(projectName, "ds_two"));
+    createBranch(BranchNameKey.create(projectName, "ds_three"));
+    pushFourInChainConfig("automerger.config", manifestNameKey.get(), projectName, changeMode);
+    // After we upload our config, we upload a new patchset to create the downstreams
+    amendChange(result.getChangeId());
+    result.assertOkStatus();
+    // Check that there are the correct number of changes in the topic
+    List<ChangeInfo> changesInTopic =
+        gApi.changes()
+            .query("topic: " + gApi.changes().id(result.getChangeId()).topic())
+            .withOptions(ALL_REVISIONS, CURRENT_COMMIT)
+            .get();
+    assertThat(changesInTopic).hasSize(4);
     List<ChangeInfo> sortedChanges = sortedChanges(changesInTopic);
+    ChangeInfo masterChangeInfo = sortedChanges.get(3);
 
-    // Check that master is at Code-Review -2
-    ChangeInfo masterChangeInfo = sortedChanges.get(1);
-    assertThat(masterChangeInfo.branch).isEqualTo("master");
+    // All changes should be abandoned after the head of the chain is abandoned.
+    gApi.changes().id(masterChangeInfo.id).abandon();
+    changesInTopic =
+        gApi.changes()
+            .query("topic: " + gApi.changes().id(result.getChangeId()).topic() + " status:open")
+            .withOptions(ALL_REVISIONS, CURRENT_COMMIT)
+            .get();
+    assertThat(changesInTopic).hasSize(0);
+  }
+
+  @Test
+  public void testAbandon() throws Exception {
+    abandon(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testAbandonCherryPickMode() throws Exception {
+    abandon(ChangeMode.CHERRY_PICK);
+  }
+
+  private void multiAmend(ChangeMode changeMode) throws Exception {
+    Project.NameKey manifestNameKey = defaultSetup();
+    // Create initial change
+    PushOneCommit.Result result =
+        createChange(testRepo, "master", "subject", "filename", "content", "testtopic");
+    // Project name is scoped by test, so we need to get it from our initial change
+    String projectName = result.getChange().project().get();
+    createBranch(BranchNameKey.create(projectName, "ds_one"));
+    createBranch(BranchNameKey.create(projectName, "ds_two"));
+    createBranch(BranchNameKey.create(projectName, "ds_three"));
+    pushFourInChainConfig("automerger.config", manifestNameKey.get(), projectName, changeMode);
+    // After we upload our config, we upload a new patchset to create the downstreams
+    amendChange(result.getChangeId());
+    result.assertOkStatus();
+    // Check that there are the correct number of changes in the topic
+    List<ChangeInfo> changesInTopic =
+        gApi.changes()
+            .query("topic: " + gApi.changes().id(result.getChangeId()).topic())
+            .withOptions(ALL_REVISIONS, CURRENT_COMMIT)
+            .get();
+    assertThat(changesInTopic).hasSize(4);
+    List<ChangeInfo> sortedChanges = sortedChanges(changesInTopic);
+    ChangeInfo masterChangeInfo = sortedChanges.get(3);
+
+    // Amend the change again.
+    // Both merge and cherry-pick mode should see 4 open changes.
+    amendChange(result.getChangeId());
+    changesInTopic =
+        gApi.changes()
+            .query("topic: " + gApi.changes().id(result.getChangeId()).topic() + " status:open")
+            .withOptions(ALL_REVISIONS, CURRENT_COMMIT)
+            .get();
+    assertThat(changesInTopic).hasSize(4);
+
+    // Cherry-pick mode should see 3 abandoned changes.
+    changesInTopic =
+        gApi.changes()
+            .query("topic: " + gApi.changes().id(result.getChangeId()).topic() + " status:abandoned")
+            .withOptions(ALL_REVISIONS, CURRENT_COMMIT)
+            .get();
+
+    if(changeMode == ChangeMode.CHERRY_PICK) {
+      assertThat(changesInTopic).hasSize(3);
+    } else {
+      assertThat(changesInTopic).hasSize(0);
+    }
+  }
+
+  @Test
+  public void testMultiAmend() throws Exception {
+    multiAmend(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testMultiAmendCherryPick() throws Exception {
+    multiAmend(ChangeMode.CHERRY_PICK);
+  }
+
+  private void conflictFourInChainAtTail(ChangeMode changeMode) throws Exception {
+    Project.NameKey manifestNameKey = defaultSetup();
+    ObjectId initial = repo().exactRef("HEAD").getLeaf().getObjectId();
+    // Create initial change
+    PushOneCommit.Result result =
+        createChange(testRepo, "master", "subject", "filename", "content", "testtopic");
+    ObjectId masterChangeId = repo().exactRef("HEAD").getLeaf().getObjectId();
+    // Project name is scoped by test, so we need to get it from our initial change
+    String projectName = result.getChange().project().get();
+    createBranch(BranchNameKey.create(projectName, "ds_one"));
+    createBranch(BranchNameKey.create(projectName, "ds_two"));
+    createBranch(BranchNameKey.create(projectName, "ds_three"));
+
+    // Reset to create a sibling
+    testRepo.reset(initial);
+    // Create an edit in ds_three that will have a conflict
+    PushOneCommit.Result ds3Result =
+        createChange(
+            testRepo, "ds_three", "subject", "filename", "conflicting", "randtopic");
+    ds3Result.assertOkStatus();
+    merge(ds3Result);
+
+    pushFourInChainConfig("automerger.config", manifestNameKey.get(), projectName, changeMode);
+    // After we upload our config, we upload a new patchset to create the downstreams and force conflict
+    testRepo.reset(masterChangeId);
+    amendChange(result.getChangeId());
+    result.assertOkStatus();
+    // Check that there are the correct number of changes in the topic.
+    List<ChangeInfo> changesInTopic =
+        gApi.changes()
+            .query("topic: " + gApi.changes().id(result.getChangeId()).topic())
+            .withOptions(ALL_REVISIONS, CURRENT_COMMIT)
+            .get();
+    assertThat(changesInTopic).hasSize(3);
+    List<ChangeInfo> sortedChanges = sortedChanges(changesInTopic);
+    ChangeInfo dsOneChangeInfo = sortedChanges.get(0);
+    ChangeInfo dsTwoChangeInfo = sortedChanges.get(1);
+    ChangeInfo masterChangeInfo = sortedChanges.get(2);
+
+    // All 3 should have -2.
     assertCodeReview(masterChangeInfo.id, -2, "autogenerated:MergeConflict");
+    assertCodeReview(dsOneChangeInfo.id, -2, "autogenerated:Automerger");
+    assertCodeReview(dsTwoChangeInfo.id, -2, "autogenerated:Automerger");
+  }
+
+  @Test
+  public void testConflictFourInChainAtTail() throws Exception {
+    conflictFourInChainAtTail(ChangeMode.MERGE);
+  }
+
+  @Test
+  public void testConflictFourInChainAtTailCherryPickMode() throws Exception {
+    conflictFourInChainAtTail(ChangeMode.CHERRY_PICK);
   }
 
   private Project.NameKey defaultSetup() throws Exception {
@@ -976,26 +1415,29 @@
   }
 
   private void pushSimpleConfig(
-      String resourceName, String manifestName, String project, String branch1) throws Exception {
+      String resourceName, String manifestName, String project, String branch1, ChangeMode changeMode) throws Exception {
     List<ConfigOption> options = new ArrayList<>();
     options.add(new ConfigOption("global", null, "manifestProject", manifestName));
+    options.add(new ConfigOption("global", null, "cherryPickMode", cherryPickMode(changeMode)));
     options.add(new ConfigOption("automerger", "master:" + branch1, "setProjects", project));
     pushConfig(options, resourceName);
   }
 
   private void pushDefaultConfig(
-      String resourceName, String manifestName, String project, String branch1, String branch2)
+      String resourceName, String manifestName, String project, String branch1, String branch2, ChangeMode changeMode)
       throws Exception {
     List<ConfigOption> options = new ArrayList<>();
     options.add(new ConfigOption("global", null, "manifestProject", manifestName));
+    options.add(new ConfigOption("global", null, "cherryPickMode", cherryPickMode(changeMode)));
     options.add(new ConfigOption("automerger", "master:" + branch1, "setProjects", project));
     options.add(new ConfigOption("automerger", "master:" + branch2, "setProjects", project));
     pushConfig(options, resourceName);
   }
 
-  private void pushDiamondConfig(String manifestName, String project) throws Exception {
+  private void pushDiamondConfig(String manifestName, String project, ChangeMode changeMode) throws Exception {
     List<ConfigOption> options = new ArrayList<>();
     options.add(new ConfigOption("global", null, "manifestProject", manifestName));
+    options.add(new ConfigOption("global", null, "cherryPickMode", cherryPickMode(changeMode)));
     options.add(new ConfigOption("automerger", "master:left", "setProjects", project));
     options.add(new ConfigOption("automerger", "master:right", "setProjects", project));
     options.add(new ConfigOption("automerger", "left:bottom", "setProjects", project));
@@ -1003,16 +1445,29 @@
     pushConfig(options, "diamond.config");
   }
 
-  private void pushContextUserConfig(String manifestName, String project, String contextUserId)
+  private void pushContextUserConfig(String manifestName, String project, String contextUserId, ChangeMode changeMode)
       throws Exception {
     List<ConfigOption> options = new ArrayList<>();
     options.add(new ConfigOption("global", null, "manifestProject", manifestName));
     options.add(new ConfigOption("global", null, "contextUserId", contextUserId));
+    options.add(new ConfigOption("global", null, "cherryPickMode", cherryPickMode(changeMode)));
     options.add(new ConfigOption("automerger", "master:ds_one", "setProjects", project));
     options.add(new ConfigOption("automerger", "ds_one:ds_two", "setProjects", project));
     pushConfig(options, "context_user.config");
   }
 
+  private void pushFourInChainConfig(
+      String resourceName, String manifestName, String project, ChangeMode changeMode)
+      throws Exception {
+    List<ConfigOption> options = new ArrayList<>();
+    options.add(new ConfigOption("global", null, "manifestProject", manifestName));
+    options.add(new ConfigOption("global", null, "cherryPickMode", cherryPickMode(changeMode)));
+    options.add(new ConfigOption("automerger", "master:" + "ds_one", "setProjects", project));
+    options.add(new ConfigOption("automerger", "ds_one:" + "ds_two", "setProjects", project));
+    options.add(new ConfigOption("automerger", "ds_two:" + "ds_three", "setProjects", project));
+    pushConfig(options, resourceName);
+  }
+
   private Optional<ApprovalInfo> getCodeReview(String id) throws RestApiException {
     List<ApprovalInfo> approvals =
         gApi.changes().id(id).get(DETAILED_LABELS).labels.get("Code-Review").all;
@@ -1055,4 +1510,20 @@
   public String getParent(ChangeInfo info, int number) {
     return info.revisions.get(info.currentRevision).commit.parents.get(number).commit;
   }
+  private String getCherryPickFrom(ChangeInfo info){
+    try {
+      return gApi.changes().id(info.cherryPickOfChange).get().currentRevision;
+    } catch (RestApiException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  private String getTag(ChangeMode changeMode){
+    return changeMode == ChangeMode.CHERRY_PICK ? "autocherry" : "automerger";
+  }
+
+  private String cherryPickMode(ChangeMode changeMode){
+    return changeMode == ChangeMode.CHERRY_PICK ? "True" : "False";
+  }
+
 }

diff --git a/src/test/java/com/googlesource/gerrit/plugins/automerger/MergeValidatorIT.java b/src/test/java/com/googlesource/gerrit/plugins/automerger/MergeValidatorIT.java
index c5b37ff..9519e14 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/automerger/MergeValidatorIT.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/automerger/MergeValidatorIT.java

@@ -24,6 +24,7 @@
 import com.google.gerrit.acceptance.TestPlugin;
 import com.google.gerrit.entities.BranchNameKey;
 import com.google.gerrit.entities.RefNames;
+import com.google.gerrit.extensions.api.changes.HashtagsInput;
 import com.google.gerrit.extensions.client.ListChangesOption;
 import com.google.gerrit.extensions.common.ChangeInfo;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
@@ -33,7 +34,9 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 import org.eclipse.jgit.internal.storage.dfs.InMemoryRepository;
 import org.eclipse.jgit.junit.TestRepository;
 import org.eclipse.jgit.lib.Config;
@@ -43,7 +46,7 @@
     name = "automerger",
     sysModule = "com.googlesource.gerrit.plugins.automerger.AutomergerModule")
 public class MergeValidatorIT extends LightweightPluginDaemonTest {
-  private void pushConfig(String resourceName, String project, String branch) throws Exception {
+  private void pushConfig(String resourceName, String project, String branch, ChangeMode changeMode) throws Exception {
     TestRepository<InMemoryRepository> allProjectRepo = cloneProject(allProjects, admin);
     GitUtil.fetch(allProjectRepo, RefNames.REFS_CONFIG + ":config");
     allProjectRepo.reset("config");
@@ -51,8 +54,10 @@
       String resourceString =
           CharStreams.toString(new InputStreamReader(in, StandardCharsets.UTF_8));
 
+      String cherryPickMode = (changeMode == ChangeMode.MERGE) ? "False" : "True";
       Config cfg = new Config();
       cfg.fromText(resourceString);
+      cfg.setString("global", null, "cherryPickMode", cherryPickMode);
       // Update manifest project path to the result of createProject(resourceName), since it is
       // scoped to the test method
       cfg.setString("automerger", "master:" + branch, "setProjects", project);
@@ -63,6 +68,10 @@
     }
   }
 
+  private void pushConfig(String resourceName, String project, String branch) throws Exception {
+    pushConfig(resourceName, project, branch, ChangeMode.MERGE);
+  }
+
   @Test
   public void testNoMissingDownstreamMerges() throws Exception {
     // Create initial change
@@ -197,6 +206,25 @@
                 + ": there is no ds_one");
   }
 
+  @Test
+  public void testSkippedCherryPick() throws Exception {
+    // Create initial change
+    PushOneCommit.Result result =
+        createChange(testRepo, "master", "subject", "filename", "content", "testtopic");
+
+    // Add the skip hashtag.
+    Set set = new HashSet<>();
+    set.add("am_skip_ds_one");
+    HashtagsInput input = new HashtagsInput(set);
+    gApi.changes().id(result.getChangeId()).setHashtags(input);
+
+    pushConfig("automerger.config", result.getChange().project().get(), "ds_one", ChangeMode.CHERRY_PICK);
+    result.assertOkStatus();
+
+    // Should be able to merge successfully.
+    merge(result);
+  }
+
   private List<ChangeInfo> sortedChanges(List<ChangeInfo> changes) {
     List<ChangeInfo> listCopy = new ArrayList<>(changes);
     Collections.sort(

diff --git a/web/automerger.ts b/web/automerger.ts
index e43f1f6..91ea27e 100644
--- a/web/automerger.ts
+++ b/web/automerger.ts

@@ -71,6 +71,8 @@
 
   private downstreamConfigMap: ConfigMap = {};
 
+  private mergeMode: string = "";
+
   readonly plugin: PluginApi;
 
   constructor(readonly p: PluginApi) {
@@ -145,7 +147,7 @@
       }
     };
     const button = document.createElement('gr-button');
-    button.appendChild(document.createTextNode('Merge'));
+    button.appendChild(document.createTextNode(this.mergeMode));
     button.addEventListener('click', onClick);
     return button;
   }
@@ -193,9 +195,18 @@
     });
   }
 
+  private getMode() {
+    const url = `/config/server/automerger~automerge-mode`;
+    this.plugin.restApi().get<string>(url).then(resp => {
+      this.mergeMode = resp;
+    });
+  }
+
   onShowChange(change: ChangeInfo) {
     this.change = change;
     this.downstreamConfigMap = {};
+    this.mergeMode = "";
+    this.getMode();
     this.getDownstreamConfigMap();
   }