java/com/google/gerrit/entities/Change.java - gerrit.git - Git at Google

 // Copyright (C) 2008 The Android Open Source Project
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 // http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package com.google.gerrit.entities;

 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.gerrit.entities.RefNames.REFS_CHANGES;
 import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.auto.value.AutoValue;
 import com.google.common.primitives.Ints;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.client.ChangeStatus;
 import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
 import java.sql.Timestamp;
 import java.util.Arrays;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectInserter;

 /**
  * A change proposed to be merged into a branch.
  *
  * <p>The data graph rooted below a Change can be quite complex:
  *
  * <pre>
  *   {@link Change}
  *     |
  *     +- {@link ChangeMessage}: &quot;cover letter&quot; or general comment.
  *     |
  *     +- {@link PatchSet}: a single variant of this change.
  *          |
  *          +- {@link PatchSetApproval}: a +/- vote on the change's current state.
  *          |
  *          +- {@link Comment}: comment about a specific line
  * </pre>
  *
  * <p>
  *
  * <h5>PatchSets</h5>
  *
  * <p>Every change has at least one PatchSet. A change starts out with one PatchSet, the initial
  * proposal put forth by the change owner. This {@link Account} is usually also listed as the author
  * and committer in the PatchSetInfo.
  *
  * <p>Each PatchSet contains zero or more Patch records, detailing the file paths impacted by the
  * change (otherwise known as, the file paths the author added/deleted/modified). Sometimes a merge
  * commit can contain zero patches, if the merge has no conflicts, or has no impact other than to
  * cut off a line of development.
  *
  * <p>Each Comment is a draft or a published comment about a single line of the associated file.
  * These are the inline comment entities created by users as they perform a review.
  *
  * <p>When additional PatchSets appear under a change, these PatchSets reference <i>replacement</i>
  * commits; alternative commits that could be made to the project instead of the original commit
  * referenced by the first PatchSet.
  *
  * <p>A change has at most one current PatchSet. The current PatchSet is updated when a new
  * replacement PatchSet is uploaded. When a change is submitted, the current patch set is what is
  * merged into the destination branch.
  *
  * <p>
  *
  * <h5>ChangeMessage</h5>
  *
  * <p>The ChangeMessage entity is a general free-form comment about the whole change, rather than
  * Comment's file and line specific context. The ChangeMessage appears at the start of any email
  * generated by Gerrit, and is shown on the change overview page, rather than in a file-specific
  * context. Users often use this entity to describe general remarks about the overall concept
  * proposed by the change.
  *
  * <p>
  *
  * <h5>PatchSetApproval</h5>
  *
  * <p>PatchSetApproval entities exist to fill in the <i>cells</i> of the approvals table in the web
  * UI. That is, a single PatchSetApproval record's key is the tuple {@code
  * (PatchSet,Account,ApprovalCategory)}. Each PatchSetApproval carries with it a small score value,
  * typically within the range -2..+2.
  *
  * <p>If an Account has created only PatchSetApprovals with a score value of 0, the Change shows in
  * their dashboard, and they are said to be CC'd (carbon copied) on the Change, but are not a direct
  * reviewer. This often happens when an account was specified at upload time with the {@code --cc}
  * command line flag, or have published comments, but left the approval scores at 0 ("No Score").
  *
  * <p>If an Account has one or more PatchSetApprovals with a score != 0, the Change shows in their
  * dashboard, and they are said to be an active reviewer. Such individuals are highlighted when
  * notice of a replacement patch set is sent, or when notice of the change submission occurs.
  */
 public final class Change {
   private static final SecureRandom rng;

   static {
     try {
       rng = SecureRandom.getInstance("SHA1PRNG");
     } catch (NoSuchAlgorithmException e) {
       throw new RuntimeException("Cannot create RNG for Change-Id generator", e);
     }
   }

   public static Id id(int id) {
     return new AutoValue_Change_Id(id);
   }

   @AutoValue
   public abstract static class Id {
     /** Parse a Change.Id out of a string representation. */
     public static Id parse(String str) {
       Integer id = Ints.tryParse(str);
       checkArgument(id != null, "invalid change ID: %s", str);
       return Change.id(id);
     }

     public static Id fromRef(String ref) {
       if (RefNames.isRefsEdit(ref)) {
         return fromEditRefPart(ref);
       }
       int cs = startIndex(ref);
       if (cs < 0) {
         return null;
       }
       int ce = nextNonDigit(ref, cs);
       if (ref.substring(ce).equals(RefNames.META_SUFFIX)
           || ref.substring(ce).equals(RefNames.ROBOT_COMMENTS_SUFFIX)
           || PatchSet.Id.fromRef(ref, ce) >= 0) {
         return Change.id(Integer.parseInt(ref.substring(cs, ce)));
       }
       return null;
     }

     public static Id fromAllUsersRef(String ref) {
       if (ref == null) {
         return null;
       }
       String prefix;
       if (ref.startsWith(RefNames.REFS_STARRED_CHANGES)) {
         prefix = RefNames.REFS_STARRED_CHANGES;
       } else if (ref.startsWith(RefNames.REFS_DRAFT_COMMENTS)) {
         prefix = RefNames.REFS_DRAFT_COMMENTS;
       } else {
         return null;
       }
       int cs = startIndex(ref, prefix);
       if (cs < 0) {
         return null;
       }
       int ce = nextNonDigit(ref, cs);
       if (ce < ref.length() && ref.charAt(ce) == '/' && isNumeric(ref, ce + 1)) {
         return Change.id(Integer.parseInt(ref.substring(cs, ce)));
       }
       return null;
     }

     private static boolean isNumeric(String s, int off) {
       if (off >= s.length()) {
         return false;
       }
       for (int i = off; i < s.length(); i++) {
         if (!Character.isDigit(s.charAt(i))) {
           return false;
         }
       }
       return true;
     }

     public static Id fromEditRefPart(String ref) {
       int startChangeId = ref.indexOf(RefNames.EDIT_PREFIX) + RefNames.EDIT_PREFIX.length();
       int endChangeId = nextNonDigit(ref, startChangeId);
       String id = ref.substring(startChangeId, endChangeId);
       if (id != null && !id.isEmpty()) {
         return Change.id(Integer.parseInt(id));
       }
       return null;
     }

     public static Id fromRefPart(String ref) {
       Integer id = RefNames.parseShardedRefPart(ref);
       return id != null ? Change.id(id) : null;
     }

     static int startIndex(String ref) {
       return startIndex(ref, REFS_CHANGES);
     }

     static int startIndex(String ref, String expectedPrefix) {
       if (ref == null || !ref.startsWith(expectedPrefix)) {
         return -1;
       }

       // Last 2 digits.
       int ls = expectedPrefix.length();
       int le = nextNonDigit(ref, ls);
       if (le - ls != 2 || le >= ref.length() || ref.charAt(le) != '/') {
         return -1;
       }

       // Change ID.
       int cs = le + 1;
       if (cs >= ref.length() || ref.charAt(cs) == '0') {
         return -1;
       }
       int ce = nextNonDigit(ref, cs);
       if (ce >= ref.length() || ref.charAt(ce) != '/') {
         return -1;
       }
       switch (ce - cs) {
         case 0:
           return -1;
         case 1:
           if (ref.charAt(ls) != '0' || ref.charAt(ls + 1) != ref.charAt(cs)) {
             return -1;
           }
           break;
         default:
           if (ref.charAt(ls) != ref.charAt(ce - 2) || ref.charAt(ls + 1) != ref.charAt(ce - 1)) {
             return -1;
           }
           break;
       }
       return cs;
     }

     static int nextNonDigit(String s, int i) {
       while (i < s.length() && s.charAt(i) >= '0' && s.charAt(i) <= '9') {
         i++;
       }
       return i;
     }

     abstract int id();

     public int get() {
       return id();
     }

     public String toRefPrefix() {
       return refPrefixBuilder().toString();
     }

     StringBuilder refPrefixBuilder() {
       StringBuilder r = new StringBuilder(32).append(REFS_CHANGES);
       int m = get() % 100;
       if (m < 10) {
         r.append('0');
       }
       return r.append(m).append('/').append(get()).append('/');
     }

     @Override
     public final String toString() {
       return Integer.toString(get());
     }
   }

   public static ObjectId generateChangeId() {
     byte[] rand = new byte[Constants.OBJECT_ID_STRING_LENGTH];
     rng.nextBytes(rand);
     String randomString = new String(rand, UTF_8);

     try (ObjectInserter f = new ObjectInserter.Formatter()) {
       return f.idFor(Constants.OBJ_COMMIT, Constants.encode(randomString));
     }
   }

   public static Key generateKey() {
     return key("I" + generateChangeId().name());
   }

   public static Key key(String key) {
     return new AutoValue_Change_Key(key);
   }

   /**
    * Globally unique identification of this change. This generally takes the form of a string
    * "Ixxxxxx...", and is stored in the Change-Id footer of a commit.
    */
   @AutoValue
   public abstract static class Key {
     // TODO(dborowitz): This hardly seems worth it: why would someone pass a URL-encoded change key?
     // Ideally the standard key() factory method would enforce the format and throw IAE.
     public static Key parse(String str) {
       return Change.key(KeyUtil.decode(str));
     }

     abstract String key();

     public String get() {
       return key();
     }

     /** Construct a key that is after all keys prefixed by this key. */
     public Key max() {
       final StringBuilder revEnd = new StringBuilder(get().length() + 1);
       revEnd.append(get());
       revEnd.append('\u9fa5');
       return Change.key(revEnd.toString());
     }

     /** Obtain a shorter version of this key string, using a leading prefix. */
     public String abbreviate() {
       final String s = get();
       return s.substring(0, Math.min(s.length(), 9));
     }

     @Override
     public final String toString() {
       return get();
     }
   }

   /** Minimum database status constant for an open change. */
   private static final char MIN_OPEN = 'a';
   /** Database constant for {@link Status#NEW}. */
   public static final char STATUS_NEW = 'n';
   /** Maximum database status constant for an open change. */
   private static final char MAX_OPEN = 'z';

   /** Database constant for {@link Status#MERGED}. */
   public static final char STATUS_MERGED = 'M';

   /** ID number of the first patch set in a change. */
   public static final int INITIAL_PATCH_SET_ID = 1;

   /** Change-Id pattern. */
   public static final String CHANGE_ID_PATTERN = "^[iI][0-9a-f]{4,}.*$";

   /**
    * Current state within the basic workflow of the change.
    *
    * <p>Within the database, lower case codes ('a'..'z') indicate a change that is still open, and
    * that can be modified/refined further, while upper case codes ('A'..'Z') indicate a change that
    * is closed and cannot be further modified.
    */
   public enum Status {
     /**
      * Change is open and pending review, or review is in progress.
      *
      * <p>This is the default state assigned to a change when it is first created in the database. A
      * change stays in the NEW state throughout its review cycle, until the change is submitted or
      * abandoned.
      *
      * <p>Changes in the NEW state can be moved to:
      *
      * <ul>
      *   <li>{@link #MERGED} - when the Submit Patch Set action is used;
      *   <li>{@link #ABANDONED} - when the Abandon action is used.
      * </ul>
      */
     NEW(STATUS_NEW, ChangeStatus.NEW),

     /**
      * Change is closed, and submitted to its destination branch.
      *
      * <p>Once a change has been merged, it cannot be further modified by adding a replacement patch
      */
     MERGED(STATUS_MERGED, ChangeStatus.MERGED),

     /**
      * Change is closed, but was not submitted to its destination branch.
      *
      * <p>Once a change has been abandoned, it cannot be further modified by adding a replacement
      * patch set, and it cannot be merged. Draft comments however may be published, permitting
      * reviewers to send constructive feedback.
      */
     ABANDONED('A', ChangeStatus.ABANDONED);

     static {
       boolean ok = true;
       if (Status.values().length != ChangeStatus.values().length) {
         ok = false;
       }
       for (Status s : Status.values()) {
         ok &= s.name().equals(s.changeStatus.name());
       }
       if (!ok) {
         throw new IllegalStateException(
             "Mismatched status mapping: "
                 + Arrays.asList(Status.values())
                 + " != "
                 + Arrays.asList(ChangeStatus.values()));
       }
     }

     private final char code;
     private final boolean closed;
     private final ChangeStatus changeStatus;

     Status(char c, ChangeStatus cs) {
       code = c;
       closed = !(MIN_OPEN <= c && c <= MAX_OPEN);
       changeStatus = cs;
     }

     public char getCode() {
       return code;
     }

     public boolean isOpen() {
       return !closed;
     }

     public boolean isClosed() {
       return closed;
     }

     public ChangeStatus asChangeStatus() {
       return changeStatus;
     }

     public static Status forCode(char c) {
       for (Status s : Status.values()) {
         if (s.code == c) {
           return s;
         }
       }

       return null;
     }

     public static Status forChangeStatus(ChangeStatus cs) {
       for (Status s : Status.values()) {
         if (s.changeStatus == cs) {
           return s;
         }
       }
       return null;
     }
   }

   /** Locally assigned unique identifier of the change */
   protected Id changeId;

   /** Globally assigned unique identifier of the change */
   protected Key changeKey;

   /** optimistic locking */
   protected int rowVersion;

   /** When this change was first introduced into the database. */
   protected Timestamp createdOn;

   /**
    * When was a meaningful modification last made to this record's data
    *
    * <p>Note, this update timestamp includes its children.
    */
   protected Timestamp lastUpdatedOn;

   // DELETED: id = 6 (sortkey)

   protected Account.Id owner;

   /** The branch (and project) this change merges into. */
   protected BranchNameKey dest;

   // DELETED: id = 9 (open)

   /** Current state code; see {@link Status}. */
   protected char status;

   // DELETED: id = 11 (nbrPatchSets)

   /** The current patch set. */
   protected int currentPatchSetId;

   /** Subject from the current patch set. */
   protected String subject;

   /** Topic name assigned by the user, if any. */
   @Nullable protected String topic;

   // DELETED: id = 15 (lastSha1MergeTested)
   // DELETED: id = 16 (mergeable)

   /**
    * First line of first patch set's commit message.
    *
    * <p>Unlike {@link #subject}, this string does not change if future patch sets change the first
    * line.
    */
   @Nullable protected String originalSubject;

   /**
    * Unique id for the changes submitted together assigned during merging. Only set if the status is
    * MERGED.
    */
   @Nullable protected String submissionId;

   /** Allows assigning a change to a user. */
   @Nullable protected Account.Id assignee;

   /** Whether the change is private. */
   protected boolean isPrivate;

   /** Whether the change is work in progress. */
   protected boolean workInProgress;

   /** Whether the change has started review. */
   protected boolean reviewStarted;

   /** References a change that this change reverts. */
   @Nullable protected Id revertOf;

   protected Change() {}

   public Change(
       Change.Key newKey,
       Change.Id newId,
       Account.Id ownedBy,
       BranchNameKey forBranch,
       Timestamp ts) {
     changeKey = newKey;
     changeId = newId;
     createdOn = ts;
     lastUpdatedOn = createdOn;
     owner = ownedBy;
     dest = forBranch;
     setStatus(Status.NEW);
   }

   public Change(Change other) {
     assignee = other.assignee;
     changeId = other.changeId;
     changeKey = other.changeKey;
     rowVersion = other.rowVersion;
     createdOn = other.createdOn;
     lastUpdatedOn = other.lastUpdatedOn;
     owner = other.owner;
     dest = other.dest;
     status = other.status;
     currentPatchSetId = other.currentPatchSetId;
     subject = other.subject;
     originalSubject = other.originalSubject;
     submissionId = other.submissionId;
     topic = other.topic;
     isPrivate = other.isPrivate;
     workInProgress = other.workInProgress;
     reviewStarted = other.reviewStarted;
     revertOf = other.revertOf;
   }

   /** Legacy 32 bit integer identity for a change. */
   public Change.Id getId() {
     return changeId;
   }

   /** Legacy 32 bit integer identity for a change. */
   public int getChangeId() {
     return changeId.get();
   }

   /** The Change-Id tag out of the initial commit, or a natural key. */
   public Change.Key getKey() {
     return changeKey;
   }

   public void setKey(Change.Key k) {
     changeKey = k;
   }

   public Account.Id getAssignee() {
     return assignee;
   }

   public void setAssignee(Account.Id a) {
     assignee = a;
   }

   public Timestamp getCreatedOn() {
     return createdOn;
   }

   public void setCreatedOn(Timestamp ts) {
     createdOn = ts;
   }

   public Timestamp getLastUpdatedOn() {
     return lastUpdatedOn;
   }

   public void setLastUpdatedOn(Timestamp now) {
     lastUpdatedOn = now;
   }

   public int getRowVersion() {
     return rowVersion;
   }

   public Account.Id getOwner() {
     return owner;
   }

   public void setOwner(Account.Id owner) {
     this.owner = owner;
   }

   public BranchNameKey getDest() {
     return dest;
   }

   public void setDest(BranchNameKey dest) {
     this.dest = dest;
   }

   public Project.NameKey getProject() {
     return dest.project();
   }

   public String getSubject() {
     return subject;
   }

   public String getOriginalSubject() {
     return originalSubject != null ? originalSubject : subject;
   }

   public String getOriginalSubjectOrNull() {
     return originalSubject;
   }

   /** Get the id of the most current {@link PatchSet} in this change. */
   public PatchSet.Id currentPatchSetId() {
     if (currentPatchSetId > 0) {
       return PatchSet.id(changeId, currentPatchSetId);
     }
     return null;
   }

   public void setCurrentPatchSet(PatchSetInfo ps) {
     if (originalSubject == null && subject != null) {
       // Change was created before schema upgrade. Use the last subject
       // associated with this change, as the most recent discussion will
       // be under that thread in an email client such as GMail.
       originalSubject = subject;
     }

     currentPatchSetId = ps.getKey().get();
     subject = ps.getSubject();

     if (originalSubject == null) {
       // Newly created changes remember the first commit's subject.
       originalSubject = subject;
     }
   }

   public void setCurrentPatchSet(PatchSet.Id psId, String subject, String originalSubject) {
     if (!psId.changeId().equals(changeId)) {
       throw new IllegalArgumentException("patch set ID " + psId + " is not for change " + changeId);
     }
     currentPatchSetId = psId.get();
     this.subject = subject;
     this.originalSubject = originalSubject;
   }

   public void clearCurrentPatchSet() {
     currentPatchSetId = 0;
     subject = null;
     originalSubject = null;
   }

   public String getSubmissionId() {
     return submissionId;
   }

   public void setSubmissionId(String id) {
     this.submissionId = id;
   }

   public Status getStatus() {
     return Status.forCode(status);
   }

   public void setStatus(Status newStatus) {
     status = newStatus.getCode();
   }

   public boolean isNew() {
     return getStatus().equals(Status.NEW);
   }

   public boolean isMerged() {
     return getStatus().equals(Status.MERGED);
   }

   public boolean isAbandoned() {
     return getStatus().equals(Status.ABANDONED);
   }

   public boolean isClosed() {
     return isAbandoned() || isMerged();
   }

   public String getTopic() {
     return topic;
   }

   public void setTopic(String topic) {
     this.topic = topic;
   }

   public boolean isPrivate() {
     return isPrivate;
   }

   public void setPrivate(boolean isPrivate) {
     this.isPrivate = isPrivate;
   }

   public boolean isWorkInProgress() {
     return workInProgress;
   }

   public void setWorkInProgress(boolean workInProgress) {
     this.workInProgress = workInProgress;
   }

   public boolean hasReviewStarted() {
     return reviewStarted;
   }

   public void setReviewStarted(boolean reviewStarted) {
     this.reviewStarted = reviewStarted;
   }

   public void setRevertOf(Id revertOf) {
     this.revertOf = revertOf;
   }

   public Id getRevertOf() {
     return this.revertOf;
   }

   @Override
   public String toString() {
     return new StringBuilder(getClass().getSimpleName())
         .append('{')
         .append(changeId)
         .append(" (")
         .append(changeKey)
         .append("), ")
         .append("dest=")
         .append(dest)
         .append(", ")
         .append("status=")
         .append(status)
         .append('}')
         .toString();
   }
 }
	// Copyright (C) 2008 The Android Open Source Project
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package com.google.gerrit.entities;

	import static com.google.common.base.Preconditions.checkArgument;
	import static com.google.gerrit.entities.RefNames.REFS_CHANGES;
	import static java.nio.charset.StandardCharsets.UTF_8;

	import com.google.auto.value.AutoValue;
	import com.google.common.primitives.Ints;
	import com.google.gerrit.common.Nullable;
	import com.google.gerrit.extensions.client.ChangeStatus;
	import java.security.NoSuchAlgorithmException;
	import java.security.SecureRandom;
	import java.sql.Timestamp;
	import java.util.Arrays;
	import org.eclipse.jgit.lib.Constants;
	import org.eclipse.jgit.lib.ObjectId;
	import org.eclipse.jgit.lib.ObjectInserter;

	/**
	* A change proposed to be merged into a branch.
	*
	* <p>The data graph rooted below a Change can be quite complex:
	*
	* <pre>
	* {@link Change}
	* \|
	* +- {@link ChangeMessage}: "cover letter" or general comment.
	* \|
	* +- {@link PatchSet}: a single variant of this change.
	* \|
	* +- {@link PatchSetApproval}: a +/- vote on the change's current state.
	* \|
	* +- {@link Comment}: comment about a specific line
	* </pre>
	*
	* <p>
	*
	* <h5>PatchSets</h5>
	*
	* <p>Every change has at least one PatchSet. A change starts out with one PatchSet, the initial
	* proposal put forth by the change owner. This {@link Account} is usually also listed as the author
	* and committer in the PatchSetInfo.
	*
	* <p>Each PatchSet contains zero or more Patch records, detailing the file paths impacted by the
	* change (otherwise known as, the file paths the author added/deleted/modified). Sometimes a merge
	* commit can contain zero patches, if the merge has no conflicts, or has no impact other than to
	* cut off a line of development.
	*
	* <p>Each Comment is a draft or a published comment about a single line of the associated file.
	* These are the inline comment entities created by users as they perform a review.
	*
	* <p>When additional PatchSets appear under a change, these PatchSets reference <i>replacement</i>
	* commits; alternative commits that could be made to the project instead of the original commit
	* referenced by the first PatchSet.
	*
	* <p>A change has at most one current PatchSet. The current PatchSet is updated when a new
	* replacement PatchSet is uploaded. When a change is submitted, the current patch set is what is
	* merged into the destination branch.
	*
	* <p>
	*
	* <h5>ChangeMessage</h5>
	*
	* <p>The ChangeMessage entity is a general free-form comment about the whole change, rather than
	* Comment's file and line specific context. The ChangeMessage appears at the start of any email
	* generated by Gerrit, and is shown on the change overview page, rather than in a file-specific
	* context. Users often use this entity to describe general remarks about the overall concept
	* proposed by the change.
	*
	* <p>
	*
	* <h5>PatchSetApproval</h5>
	*
	* <p>PatchSetApproval entities exist to fill in the <i>cells</i> of the approvals table in the web
	* UI. That is, a single PatchSetApproval record's key is the tuple {@code
	* (PatchSet,Account,ApprovalCategory)}. Each PatchSetApproval carries with it a small score value,
	* typically within the range -2..+2.
	*
	* <p>If an Account has created only PatchSetApprovals with a score value of 0, the Change shows in
	* their dashboard, and they are said to be CC'd (carbon copied) on the Change, but are not a direct
	* reviewer. This often happens when an account was specified at upload time with the {@code --cc}
	* command line flag, or have published comments, but left the approval scores at 0 ("No Score").
	*
	* <p>If an Account has one or more PatchSetApprovals with a score != 0, the Change shows in their
	* dashboard, and they are said to be an active reviewer. Such individuals are highlighted when
	* notice of a replacement patch set is sent, or when notice of the change submission occurs.
	*/
	public final class Change {
	private static final SecureRandom rng;

	static {
	try {
	rng = SecureRandom.getInstance("SHA1PRNG");
	} catch (NoSuchAlgorithmException e) {
	throw new RuntimeException("Cannot create RNG for Change-Id generator", e);
	}
	}

	public static Id id(int id) {
	return new AutoValue_Change_Id(id);
	}

	@AutoValue
	public abstract static class Id {
	/** Parse a Change.Id out of a string representation. */
	public static Id parse(String str) {
	Integer id = Ints.tryParse(str);
	checkArgument(id != null, "invalid change ID: %s", str);
	return Change.id(id);
	}

	public static Id fromRef(String ref) {
	if (RefNames.isRefsEdit(ref)) {
	return fromEditRefPart(ref);
	}
	int cs = startIndex(ref);
	if (cs < 0) {
	return null;
	}
	int ce = nextNonDigit(ref, cs);
	if (ref.substring(ce).equals(RefNames.META_SUFFIX)
	\|\| ref.substring(ce).equals(RefNames.ROBOT_COMMENTS_SUFFIX)
	\|\| PatchSet.Id.fromRef(ref, ce) >= 0) {
	return Change.id(Integer.parseInt(ref.substring(cs, ce)));
	}
	return null;
	}

	public static Id fromAllUsersRef(String ref) {
	if (ref == null) {
	return null;
	}
	String prefix;
	if (ref.startsWith(RefNames.REFS_STARRED_CHANGES)) {
	prefix = RefNames.REFS_STARRED_CHANGES;
	} else if (ref.startsWith(RefNames.REFS_DRAFT_COMMENTS)) {
	prefix = RefNames.REFS_DRAFT_COMMENTS;
	} else {
	return null;
	}
	int cs = startIndex(ref, prefix);
	if (cs < 0) {
	return null;
	}
	int ce = nextNonDigit(ref, cs);
	if (ce < ref.length() && ref.charAt(ce) == '/' && isNumeric(ref, ce + 1)) {
	return Change.id(Integer.parseInt(ref.substring(cs, ce)));
	}
	return null;
	}

	private static boolean isNumeric(String s, int off) {
	if (off >= s.length()) {
	return false;
	}
	for (int i = off; i < s.length(); i++) {
	if (!Character.isDigit(s.charAt(i))) {
	return false;
	}
	}
	return true;
	}

	public static Id fromEditRefPart(String ref) {
	int startChangeId = ref.indexOf(RefNames.EDIT_PREFIX) + RefNames.EDIT_PREFIX.length();
	int endChangeId = nextNonDigit(ref, startChangeId);
	String id = ref.substring(startChangeId, endChangeId);
	if (id != null && !id.isEmpty()) {
	return Change.id(Integer.parseInt(id));
	}
	return null;
	}

	public static Id fromRefPart(String ref) {
	Integer id = RefNames.parseShardedRefPart(ref);
	return id != null ? Change.id(id) : null;
	}

	static int startIndex(String ref) {
	return startIndex(ref, REFS_CHANGES);
	}

	static int startIndex(String ref, String expectedPrefix) {
	if (ref == null \|\| !ref.startsWith(expectedPrefix)) {
	return -1;
	}

	// Last 2 digits.
	int ls = expectedPrefix.length();
	int le = nextNonDigit(ref, ls);
	if (le - ls != 2 \|\| le >= ref.length() \|\| ref.charAt(le) != '/') {
	return -1;
	}

	// Change ID.
	int cs = le + 1;
	if (cs >= ref.length() \|\| ref.charAt(cs) == '0') {
	return -1;
	}
	int ce = nextNonDigit(ref, cs);
	if (ce >= ref.length() \|\| ref.charAt(ce) != '/') {
	return -1;
	}
	switch (ce - cs) {
	case 0:
	return -1;
	case 1:
	if (ref.charAt(ls) != '0' \|\| ref.charAt(ls + 1) != ref.charAt(cs)) {
	return -1;
	}
	break;
	default:
	if (ref.charAt(ls) != ref.charAt(ce - 2) \|\| ref.charAt(ls + 1) != ref.charAt(ce - 1)) {
	return -1;
	}
	break;
	}
	return cs;
	}

	static int nextNonDigit(String s, int i) {
	while (i < s.length() && s.charAt(i) >= '0' && s.charAt(i) <= '9') {
	i++;
	}
	return i;
	}

	abstract int id();

	public int get() {
	return id();
	}

	public String toRefPrefix() {
	return refPrefixBuilder().toString();
	}

	StringBuilder refPrefixBuilder() {
	StringBuilder r = new StringBuilder(32).append(REFS_CHANGES);
	int m = get() % 100;
	if (m < 10) {
	r.append('0');
	}
	return r.append(m).append('/').append(get()).append('/');
	}

	@Override
	public final String toString() {
	return Integer.toString(get());
	}
	}

	public static ObjectId generateChangeId() {
	byte[] rand = new byte[Constants.OBJECT_ID_STRING_LENGTH];
	rng.nextBytes(rand);
	String randomString = new String(rand, UTF_8);

	try (ObjectInserter f = new ObjectInserter.Formatter()) {
	return f.idFor(Constants.OBJ_COMMIT, Constants.encode(randomString));
	}
	}

	public static Key generateKey() {
	return key("I" + generateChangeId().name());
	}

	public static Key key(String key) {
	return new AutoValue_Change_Key(key);
	}

	/**
	* Globally unique identification of this change. This generally takes the form of a string
	* "Ixxxxxx...", and is stored in the Change-Id footer of a commit.
	*/
	@AutoValue
	public abstract static class Key {
	// TODO(dborowitz): This hardly seems worth it: why would someone pass a URL-encoded change key?
	// Ideally the standard key() factory method would enforce the format and throw IAE.
	public static Key parse(String str) {
	return Change.key(KeyUtil.decode(str));
	}

	abstract String key();

	public String get() {
	return key();
	}

	/** Construct a key that is after all keys prefixed by this key. */
	public Key max() {
	final StringBuilder revEnd = new StringBuilder(get().length() + 1);
	revEnd.append(get());
	revEnd.append('\u9fa5');
	return Change.key(revEnd.toString());
	}

	/** Obtain a shorter version of this key string, using a leading prefix. */
	public String abbreviate() {
	final String s = get();
	return s.substring(0, Math.min(s.length(), 9));
	}

	@Override
	public final String toString() {
	return get();
	}
	}

	/** Minimum database status constant for an open change. */
	private static final char MIN_OPEN = 'a';
	/** Database constant for {@link Status#NEW}. */
	public static final char STATUS_NEW = 'n';
	/** Maximum database status constant for an open change. */
	private static final char MAX_OPEN = 'z';

	/** Database constant for {@link Status#MERGED}. */
	public static final char STATUS_MERGED = 'M';

	/** ID number of the first patch set in a change. */
	public static final int INITIAL_PATCH_SET_ID = 1;

	/** Change-Id pattern. */
	public static final String CHANGE_ID_PATTERN = "^[iI][0-9a-f]{4,}.*$";

	/**
	* Current state within the basic workflow of the change.
	*
	* <p>Within the database, lower case codes ('a'..'z') indicate a change that is still open, and
	* that can be modified/refined further, while upper case codes ('A'..'Z') indicate a change that
	* is closed and cannot be further modified.
	*/
	public enum Status {
	/**
	* Change is open and pending review, or review is in progress.
	*
	* <p>This is the default state assigned to a change when it is first created in the database. A
	* change stays in the NEW state throughout its review cycle, until the change is submitted or
	* abandoned.
	*
	* <p>Changes in the NEW state can be moved to:
	*
	* <ul>
	* <li>{@link #MERGED} - when the Submit Patch Set action is used;
	* <li>{@link #ABANDONED} - when the Abandon action is used.
	* </ul>
	*/
	NEW(STATUS_NEW, ChangeStatus.NEW),

	/**
	* Change is closed, and submitted to its destination branch.
	*
	* <p>Once a change has been merged, it cannot be further modified by adding a replacement patch
	*/
	MERGED(STATUS_MERGED, ChangeStatus.MERGED),

	/**
	* Change is closed, but was not submitted to its destination branch.
	*
	* <p>Once a change has been abandoned, it cannot be further modified by adding a replacement
	* patch set, and it cannot be merged. Draft comments however may be published, permitting
	* reviewers to send constructive feedback.
	*/
	ABANDONED('A', ChangeStatus.ABANDONED);

	static {
	boolean ok = true;
	if (Status.values().length != ChangeStatus.values().length) {
	ok = false;
	}
	for (Status s : Status.values()) {
	ok &= s.name().equals(s.changeStatus.name());
	}
	if (!ok) {
	throw new IllegalStateException(
	"Mismatched status mapping: "
	+ Arrays.asList(Status.values())
	+ " != "
	+ Arrays.asList(ChangeStatus.values()));
	}
	}

	private final char code;
	private final boolean closed;
	private final ChangeStatus changeStatus;

	Status(char c, ChangeStatus cs) {
	code = c;
	closed = !(MIN_OPEN <= c && c <= MAX_OPEN);
	changeStatus = cs;
	}

	public char getCode() {
	return code;
	}

	public boolean isOpen() {
	return !closed;
	}

	public boolean isClosed() {
	return closed;
	}

	public ChangeStatus asChangeStatus() {
	return changeStatus;
	}

	public static Status forCode(char c) {
	for (Status s : Status.values()) {
	if (s.code == c) {
	return s;
	}
	}

	return null;
	}

	public static Status forChangeStatus(ChangeStatus cs) {
	for (Status s : Status.values()) {
	if (s.changeStatus == cs) {
	return s;
	}
	}
	return null;
	}
	}

	/** Locally assigned unique identifier of the change */
	protected Id changeId;

	/** Globally assigned unique identifier of the change */
	protected Key changeKey;

	/** optimistic locking */
	protected int rowVersion;

	/** When this change was first introduced into the database. */
	protected Timestamp createdOn;

	/**
	* When was a meaningful modification last made to this record's data
	*
	* <p>Note, this update timestamp includes its children.
	*/
	protected Timestamp lastUpdatedOn;

	// DELETED: id = 6 (sortkey)

	protected Account.Id owner;

	/** The branch (and project) this change merges into. */
	protected BranchNameKey dest;

	// DELETED: id = 9 (open)

	/** Current state code; see {@link Status}. */
	protected char status;

	// DELETED: id = 11 (nbrPatchSets)

	/** The current patch set. */
	protected int currentPatchSetId;

	/** Subject from the current patch set. */
	protected String subject;

	/** Topic name assigned by the user, if any. */
	@Nullable protected String topic;

	// DELETED: id = 15 (lastSha1MergeTested)
	// DELETED: id = 16 (mergeable)

	/**
	* First line of first patch set's commit message.
	*
	* <p>Unlike {@link #subject}, this string does not change if future patch sets change the first
	* line.
	*/
	@Nullable protected String originalSubject;

	/**
	* Unique id for the changes submitted together assigned during merging. Only set if the status is
	* MERGED.
	*/
	@Nullable protected String submissionId;

	/** Allows assigning a change to a user. */
	@Nullable protected Account.Id assignee;

	/** Whether the change is private. */
	protected boolean isPrivate;

	/** Whether the change is work in progress. */
	protected boolean workInProgress;

	/** Whether the change has started review. */
	protected boolean reviewStarted;

	/** References a change that this change reverts. */
	@Nullable protected Id revertOf;

	protected Change() {}

	public Change(
	Change.Key newKey,
	Change.Id newId,
	Account.Id ownedBy,
	BranchNameKey forBranch,
	Timestamp ts) {
	changeKey = newKey;
	changeId = newId;
	createdOn = ts;
	lastUpdatedOn = createdOn;
	owner = ownedBy;
	dest = forBranch;
	setStatus(Status.NEW);
	}

	public Change(Change other) {
	assignee = other.assignee;
	changeId = other.changeId;
	changeKey = other.changeKey;
	rowVersion = other.rowVersion;
	createdOn = other.createdOn;
	lastUpdatedOn = other.lastUpdatedOn;
	owner = other.owner;
	dest = other.dest;
	status = other.status;
	currentPatchSetId = other.currentPatchSetId;
	subject = other.subject;
	originalSubject = other.originalSubject;
	submissionId = other.submissionId;
	topic = other.topic;
	isPrivate = other.isPrivate;
	workInProgress = other.workInProgress;
	reviewStarted = other.reviewStarted;
	revertOf = other.revertOf;
	}

	/** Legacy 32 bit integer identity for a change. */
	public Change.Id getId() {
	return changeId;
	}

	/** Legacy 32 bit integer identity for a change. */
	public int getChangeId() {
	return changeId.get();
	}

	/** The Change-Id tag out of the initial commit, or a natural key. */
	public Change.Key getKey() {
	return changeKey;
	}

	public void setKey(Change.Key k) {
	changeKey = k;
	}

	public Account.Id getAssignee() {
	return assignee;
	}

	public void setAssignee(Account.Id a) {
	assignee = a;
	}

	public Timestamp getCreatedOn() {
	return createdOn;
	}

	public void setCreatedOn(Timestamp ts) {
	createdOn = ts;
	}

	public Timestamp getLastUpdatedOn() {
	return lastUpdatedOn;
	}

	public void setLastUpdatedOn(Timestamp now) {
	lastUpdatedOn = now;
	}

	public int getRowVersion() {
	return rowVersion;
	}

	public Account.Id getOwner() {
	return owner;
	}

	public void setOwner(Account.Id owner) {
	this.owner = owner;
	}

	public BranchNameKey getDest() {
	return dest;
	}

	public void setDest(BranchNameKey dest) {
	this.dest = dest;
	}

	public Project.NameKey getProject() {
	return dest.project();
	}

	public String getSubject() {
	return subject;
	}

	public String getOriginalSubject() {
	return originalSubject != null ? originalSubject : subject;
	}

	public String getOriginalSubjectOrNull() {
	return originalSubject;
	}

	/** Get the id of the most current {@link PatchSet} in this change. */
	public PatchSet.Id currentPatchSetId() {
	if (currentPatchSetId > 0) {
	return PatchSet.id(changeId, currentPatchSetId);
	}
	return null;
	}

	public void setCurrentPatchSet(PatchSetInfo ps) {
	if (originalSubject == null && subject != null) {
	// Change was created before schema upgrade. Use the last subject
	// associated with this change, as the most recent discussion will
	// be under that thread in an email client such as GMail.
	originalSubject = subject;
	}

	currentPatchSetId = ps.getKey().get();
	subject = ps.getSubject();

	if (originalSubject == null) {
	// Newly created changes remember the first commit's subject.
	originalSubject = subject;
	}
	}

	public void setCurrentPatchSet(PatchSet.Id psId, String subject, String originalSubject) {
	if (!psId.changeId().equals(changeId)) {
	throw new IllegalArgumentException("patch set ID " + psId + " is not for change " + changeId);
	}
	currentPatchSetId = psId.get();
	this.subject = subject;
	this.originalSubject = originalSubject;
	}

	public void clearCurrentPatchSet() {
	currentPatchSetId = 0;
	subject = null;
	originalSubject = null;
	}

	public String getSubmissionId() {
	return submissionId;
	}

	public void setSubmissionId(String id) {
	this.submissionId = id;
	}

	public Status getStatus() {
	return Status.forCode(status);
	}

	public void setStatus(Status newStatus) {
	status = newStatus.getCode();
	}

	public boolean isNew() {
	return getStatus().equals(Status.NEW);
	}

	public boolean isMerged() {
	return getStatus().equals(Status.MERGED);
	}

	public boolean isAbandoned() {
	return getStatus().equals(Status.ABANDONED);
	}

	public boolean isClosed() {
	return isAbandoned() \|\| isMerged();
	}

	public String getTopic() {
	return topic;
	}

	public void setTopic(String topic) {
	this.topic = topic;
	}

	public boolean isPrivate() {
	return isPrivate;
	}

	public void setPrivate(boolean isPrivate) {
	this.isPrivate = isPrivate;
	}

	public boolean isWorkInProgress() {
	return workInProgress;
	}

	public void setWorkInProgress(boolean workInProgress) {
	this.workInProgress = workInProgress;
	}

	public boolean hasReviewStarted() {
	return reviewStarted;
	}

	public void setReviewStarted(boolean reviewStarted) {
	this.reviewStarted = reviewStarted;
	}

	public void setRevertOf(Id revertOf) {
	this.revertOf = revertOf;
	}

	public Id getRevertOf() {
	return this.revertOf;
	}

	@Override
	public String toString() {
	return new StringBuilder(getClass().getSimpleName())
	.append('{')
	.append(changeId)
	.append(" (")
	.append(changeKey)
	.append("), ")
	.append("dest=")
	.append(dest)
	.append(", ")
	.append("status=")
	.append(status)
	.append('}')
	.toString();
	}
	}