Allow AdminApiFactory to be replaced dynamically Since change Ie760bf3e1 the GerritSshApi class is no longer a singleton, and is instead instantiated on demand by a new AdminApiFactory. This breaks implementations that consume the replication plugin as a library and extend the GerritSshApi, since the extended class no longer gets instantiated in place of GerritSshApi. Refactor it so that AdminApiFactory is an interface with a default implementation that gets bound as a dynamic item, which can be replaced by derived implementations. Change-Id: Ia150d6802e11015fa00ee9144b3dfbfa696c7a0d Signed-off-by: David Pursehouse <dpursehouse@collab.net>

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/AdminApiFactory.java b/src/main/java/com/googlesource/gerrit/plugins/replication/AdminApiFactory.java
index e5a1628..30e8245 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/AdminApiFactory.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/AdminApiFactory.java

@@ -19,37 +19,49 @@
 import java.util.Optional;
 import org.eclipse.jgit.transport.URIish;
 
-@Singleton
-public class AdminApiFactory {
+/** Factory for creating an {@link AdminApi} instance for a remote URI. */
+public interface AdminApiFactory {
+  /**
+   * Create an {@link AdminApi} for the given remote URI.
+   *
+   * @param uri the remote URI.
+   * @return An API for the given remote URI, or {@code Optional.empty} if there is no appropriate
+   *     API for the URI.
+   */
+  Optional<AdminApi> create(URIish uri);
 
-  private final SshHelper sshHelper;
-  private final GerritRestApi.Factory gerritRestApiFactory;
+  @Singleton
+  static class DefaultAdminApiFactory implements AdminApiFactory {
+    protected final SshHelper sshHelper;
+    private final GerritRestApi.Factory gerritRestApiFactory;
 
-  @Inject
-  AdminApiFactory(SshHelper sshHelper, GerritRestApi.Factory gerritRestApiFactory) {
-    this.sshHelper = sshHelper;
-    this.gerritRestApiFactory = gerritRestApiFactory;
-  }
-
-  public Optional<AdminApi> create(URIish uri) {
-    if (isGerrit(uri)) {
-      return Optional.of(new GerritSshApi(sshHelper, uri));
-    } else if (!uri.isRemote()) {
-      return Optional.of(new LocalFS(uri));
-    } else if (isSSH(uri)) {
-      return Optional.of(new RemoteSsh(sshHelper, uri));
-    } else if (isGerritHttp(uri)) {
-      return Optional.of(gerritRestApiFactory.create(uri));
+    @Inject
+    public DefaultAdminApiFactory(SshHelper sshHelper, GerritRestApi.Factory gerritRestApiFactory) {
+      this.sshHelper = sshHelper;
+      this.gerritRestApiFactory = gerritRestApiFactory;
     }
-    return Optional.empty();
+
+    @Override
+    public Optional<AdminApi> create(URIish uri) {
+      if (isGerrit(uri)) {
+        return Optional.of(new GerritSshApi(sshHelper, uri));
+      } else if (!uri.isRemote()) {
+        return Optional.of(new LocalFS(uri));
+      } else if (isSSH(uri)) {
+        return Optional.of(new RemoteSsh(sshHelper, uri));
+      } else if (isGerritHttp(uri)) {
+        return Optional.of(gerritRestApiFactory.create(uri));
+      }
+      return Optional.empty();
+    }
   }
 
-  public static boolean isGerrit(URIish uri) {
+  static boolean isGerrit(URIish uri) {
     String scheme = uri.getScheme();
     return scheme != null && scheme.toLowerCase().equals("gerrit+ssh");
   }
 
-  public static boolean isSSH(URIish uri) {
+  static boolean isSSH(URIish uri) {
     if (!uri.isRemote()) {
       return false;
     }

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/CreateProjectTask.java b/src/main/java/com/googlesource/gerrit/plugins/replication/CreateProjectTask.java
index e3d57de..a8dede3 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/CreateProjectTask.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/CreateProjectTask.java

@@ -16,6 +16,7 @@
 
 import static com.googlesource.gerrit.plugins.replication.ReplicationQueue.repLog;
 
+import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.inject.Inject;
 import com.google.inject.assistedinject.Assisted;
@@ -31,7 +32,7 @@
 
   private final RemoteConfig config;
   private final ReplicationConfig replicationConfig;
-  private final AdminApiFactory adminApiFactory;
+  private final DynamicItem<AdminApiFactory> adminApiFactory;
   private final Project.NameKey project;
   private final String head;
 
@@ -39,7 +40,7 @@
   CreateProjectTask(
       RemoteConfig config,
       ReplicationConfig replicationConfig,
-      AdminApiFactory adminApiFactory,
+      DynamicItem<AdminApiFactory> adminApiFactory,
       @Assisted Project.NameKey project,
       @Assisted String head) {
     this.config = config;
@@ -58,7 +59,7 @@
   }
 
   private boolean createProject(URIish replicateURI, Project.NameKey projectName, String head) {
-    Optional<AdminApi> adminApi = adminApiFactory.create(replicateURI);
+    Optional<AdminApi> adminApi = adminApiFactory.get().create(replicateURI);
     if (adminApi.isPresent() && adminApi.get().createProject(projectName, head)) {
       return true;
     }

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/DeleteProjectTask.java b/src/main/java/com/googlesource/gerrit/plugins/replication/DeleteProjectTask.java
index 96d8c70..f9b2ad7 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/DeleteProjectTask.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/DeleteProjectTask.java

@@ -16,6 +16,7 @@
 
 import static com.googlesource.gerrit.plugins.replication.ReplicationQueue.repLog;
 
+import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.ioutil.HexFormat;
 import com.google.gerrit.server.util.IdGenerator;
@@ -29,14 +30,14 @@
     DeleteProjectTask create(URIish replicateURI, Project.NameKey project);
   }
 
-  private final AdminApiFactory adminApiFactory;
+  private final DynamicItem<AdminApiFactory> adminApiFactory;
   private final int id;
   private final URIish replicateURI;
   private final Project.NameKey project;
 
   @Inject
   DeleteProjectTask(
-      AdminApiFactory adminApiFactory,
+      DynamicItem<AdminApiFactory> adminApiFactory,
       IdGenerator ig,
       @Assisted URIish replicateURI,
       @Assisted Project.NameKey project) {
@@ -48,7 +49,7 @@
 
   @Override
   public void run() {
-    Optional<AdminApi> adminApi = adminApiFactory.create(replicateURI);
+    Optional<AdminApi> adminApi = adminApiFactory.get().create(replicateURI);
     if (adminApi.isPresent()) {
       adminApi.get().deleteProject(project);
       return;

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java b/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
index 2677152..0a6d9d2 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java

@@ -173,7 +173,11 @@
                 install(new FactoryModuleBuilder().build(CreateProjectTask.Factory.class));
                 install(new FactoryModuleBuilder().build(DeleteProjectTask.Factory.class));
                 install(new FactoryModuleBuilder().build(UpdateHeadTask.Factory.class));
-                bind(AdminApiFactory.class);
+
+                DynamicItem.itemOf(binder(), AdminApiFactory.class);
+                DynamicItem.bind(binder(), AdminApiFactory.class)
+                    .to(AdminApiFactory.DefaultAdminApiFactory.class);
+
                 install(new FactoryModuleBuilder().build(GerritRestApi.Factory.class));
                 bind(CloseableHttpClient.class)
                     .toProvider(HttpClientProvider.class)

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/UpdateHeadTask.java b/src/main/java/com/googlesource/gerrit/plugins/replication/UpdateHeadTask.java
index db58f49..70452b4 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/UpdateHeadTask.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/UpdateHeadTask.java

@@ -16,6 +16,7 @@
 
 import static com.googlesource.gerrit.plugins.replication.ReplicationQueue.repLog;
 
+import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.ioutil.HexFormat;
 import com.google.gerrit.server.util.IdGenerator;
@@ -25,7 +26,7 @@
 import org.eclipse.jgit.transport.URIish;
 
 public class UpdateHeadTask implements Runnable {
-  private final AdminApiFactory adminApiFactory;
+  private final DynamicItem<AdminApiFactory> adminApiFactory;
   private final int id;
   private final URIish replicateURI;
   private final Project.NameKey project;
@@ -37,7 +38,7 @@
 
   @Inject
   UpdateHeadTask(
-      AdminApiFactory adminApiFactory,
+      DynamicItem<AdminApiFactory> adminApiFactory,
       IdGenerator ig,
       @Assisted URIish replicateURI,
       @Assisted Project.NameKey project,
@@ -51,7 +52,7 @@
 
   @Override
   public void run() {
-    Optional<AdminApi> adminApi = adminApiFactory.create(replicateURI);
+    Optional<AdminApi> adminApi = adminApiFactory.get().create(replicateURI);
     if (adminApi.isPresent()) {
       adminApi.get().updateHead(project, newHead);
       return;

diff --git a/src/main/resources/Documentation/extension-point.md b/src/main/resources/Documentation/extension-point.md
index 345fd8f..076aded 100644
--- a/src/main/resources/Documentation/extension-point.md
+++ b/src/main/resources/Documentation/extension-point.md

@@ -1,7 +1,7 @@
 @PLUGIN@ extension points
 ==============
 
-The replication plugin exposes an extension point to allow influencing the behaviour of the replication events from another plugin or a script.
+The replication plugin exposes an extension point to allow influencing its behaviour from another plugin or a script.
 Extension points can be defined from the replication plugin only when it is loaded as [libModule](/config-gerrit.html#gerrit.installModule) and
 implemented by another plugin by declaring a `provided` dependency from the replication plugin.
 
@@ -35,5 +35,19 @@
   Example:
 
   ```
-  DynamicItem.bind(binder(),ReplicationPushFilter.class).to(ReplicationPushFilterImpl.class);
+  DynamicItem.bind(binder(), ReplicationPushFilter.class).to(ReplicationPushFilterImpl.class);
+  ```
+
+* `com.googlesource.gerrit.plugins.replication.AdminApiFactory`
+
+  Create an instance of `AdminApi` for a given remote URL. The default implementation
+  provides API instances for local FS, remote SSH, and remote Gerrit.
+
+  Only one factory at a time is supported. The implementation needs to be bound as a
+  `DynamicItem`.
+
+  Example:
+
+  ```
+  DynamicItem.bind(binder(), AdminApiFactory.class).to(AdminApiFactoryImpl.class);
   ```