Remove nbrPatchSets from Change

The nbrPatchSets counter was used to generate the next PatchSetId.
Instead, find the first reference after the currentPatchSetId() that
does not exist by examining the references themselves.

Also in a few locations, the use of currPatchSetId() was corrected
to be currentPatchSetId().

Change-Id: I06bcf52798f1dad1ea602f914784dfcbc7d97086

gerrit-server/src/main/java/com/google/gerrit/server/ChangeUtil.java

@@ -47,6 +47,7 @@ import org.eclipse.jgit.lib.CommitBuilder;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectInserter;
 import org.eclipse.jgit.lib.PersonIdent;
+import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.RefUpdate;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.FooterLine;
@@ -63,6 +64,7 @@ import java.util.Collections;
 import java.util.Date;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.regex.Matcher;
 
@@ -243,10 +245,10 @@ public class ChangeUtil {
           new Change.Id(db.nextChangeId()),
           user.getAccountId(),
           changeToRevert.getDest());
-      change.nextPatchSetId();
       change.setTopic(changeToRevert.getTopic());
 
-      final PatchSet ps = new PatchSet(change.currPatchSetId());
+      PatchSet.Id id = nextPatchSetId(git, change.currentPatchSetId());
+      final PatchSet ps = new PatchSet(id);
       ps.setCreatedOn(change.getCreatedOn());
       ps.setUploader(change.getOwner());
       ps.setRevision(new RevId(revertCommit.name()));
@@ -356,10 +358,9 @@ public class ChangeUtil {
           oi.release();
         }
 
-        change.nextPatchSetId();
-
         final PatchSet originalPS = db.patchSets().get(patchSetId);
-        final PatchSet newPatchSet = new PatchSet(change.currPatchSetId());
+        PatchSet.Id id = nextPatchSetId(git, change.currentPatchSetId());
+        final PatchSet newPatchSet = new PatchSet(id);
         newPatchSet.setCreatedOn(new Timestamp(now.getTime()));
         newPatchSet.setUploader(user.getAccountId());
         newPatchSet.setRevision(new RevId(newCommit.name()));
@@ -381,19 +382,8 @@ public class ChangeUtil {
 
         db.changes().beginTransaction(change.getId());
         try {
-          Change updatedChange =
-              db.changes().atomicUpdate(change.getId(), new AtomicUpdate<Change>() {
-                @Override
-                public Change update(Change change) {
-                  if (change.getStatus().isOpen()) {
-                    change.updateNumberOfPatchSets(newPatchSet.getPatchSetId());
-                    return change;
-                  } else {
-                    return null;
-                  }
-                }
-              });
-          if (updatedChange != null) {
+          Change updatedChange = db.changes().get(change.getId());
+          if (updatedChange != null && updatedChange.getStatus().isOpen()) {
             change = updatedChange;
           } else {
             throw new InvalidChangeOperationException(String.format(
@@ -528,6 +518,23 @@ public class ChangeUtil {
     c.setSortKey(sortKey(lastUpdated, id));
   }
 
+  public static PatchSet.Id nextPatchSetId(Map<String, Ref> allRefs,
+      PatchSet.Id id) {
+    PatchSet.Id next = nextPatchSetId(id);
+    while (allRefs.containsKey(next.toRefName())) {
+      next = nextPatchSetId(next);
+    }
+    return next;
+  }
+
+  public static PatchSet.Id nextPatchSetId(Repository git, PatchSet.Id id) {
+    return nextPatchSetId(git.getAllRefs(), id);
+  }
+
+  private static PatchSet.Id nextPatchSetId(PatchSet.Id id) {
+    return new PatchSet.Id(id.getParentKey(), id.get() + 1);
+  }
+
   private static final char[] hexchar =
       {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', //
           'a', 'b', 'c', 'd', 'e', 'f'};