Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  Limit the number of changes that can be submitted together

Release-Notes: skip
Change-Id: I263d636ec38f043ad5f6f8157ea5a57e12e7b145

3 files changed, 58 insertions, 6 deletions

diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index 6d98877225..b39cd18e32 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -1210,6 +1210,13 @@ in change tables and user dashboards.
 +
 By default 500.
 
+[[change.maxSubmittableAtOnce]]change.maxSubmittableAtOnce::
++
+Maximum number of changes that can be chained together in the same repository
+to be submitted at once.
++
+Default is 32767.
+
 [[change.move]]change.move::
 +
 Whether the link:rest-api-changes.html#move-change[Move Change] REST
diff --git a/java/com/google/gerrit/server/submit/LocalMergeSuperSetComputation.java b/java/com/google/gerrit/server/submit/LocalMergeSuperSetComputation.java
index 1219124fb3..8e2f44f7d4 100644
--- a/java/com/google/gerrit/server/submit/LocalMergeSuperSetComputation.java
+++ b/java/com/google/gerrit/server/submit/LocalMergeSuperSetComputation.java
@@ -30,6 +30,7 @@ import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.reviewdb.client.Branch;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.CurrentUser;
+import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.permissions.ChangePermission;
 import com.google.gerrit.server.permissions.PermissionBackend;
 import com.google.gerrit.server.permissions.PermissionBackendException;
@@ -53,6 +54,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
+import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.revwalk.RevCommit;
@@ -65,6 +67,8 @@ import org.eclipse.jgit.revwalk.RevSort;
 public class LocalMergeSuperSetComputation implements MergeSuperSetComputation {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
+  public static final int MAX_SUBMITTABLE_CHANGES_AT_ONCE_DEFAULT = 1024;
+
   public static class Module extends AbstractModule {
     @Override
     protected void configure() {
@@ -91,19 +95,24 @@ public class LocalMergeSuperSetComputation implements MergeSuperSetComputation {
   private final Map<Branch.NameKey, Optional<RevCommit>> heads;
   private final ProjectCache projectCache;
   private final ChangeIsVisibleToPredicate.Factory changeIsVisibleToPredicateFactory;
+  private final int maxSubmittableChangesAtOnce;
 
   @Inject
   LocalMergeSuperSetComputation(
       PermissionBackend permissionBackend,
       Provider<InternalChangeQuery> queryProvider,
       ProjectCache projectCache,
-      ChangeIsVisibleToPredicate.Factory changeIsVisibleToPredicateFactory) {
+      ChangeIsVisibleToPredicate.Factory changeIsVisibleToPredicateFactory,
+      @GerritServerConfig Config gerritConfig) {
     this.projectCache = projectCache;
     this.permissionBackend = permissionBackend;
     this.queryProvider = queryProvider;
     this.queryCache = new HashMap<>();
     this.heads = new HashMap<>();
     this.changeIsVisibleToPredicateFactory = changeIsVisibleToPredicateFactory;
+    this.maxSubmittableChangesAtOnce =
+        gerritConfig.getInt(
+            "change", "maxSubmittableAtOnce", MAX_SUBMITTABLE_CHANGES_AT_ONCE_DEFAULT);
   }
 
   @Override
@@ -149,8 +158,10 @@ public class LocalMergeSuperSetComputation implements MergeSuperSetComputation {
       }
 
       Set<String> visibleHashes =
-          walkChangesByHashes(visibleCommits, Collections.emptySet(), or, b);
-      Set<String> nonVisibleHashes = walkChangesByHashes(nonVisibleCommits, visibleHashes, or, b);
+          walkChangesByHashes(
+              visibleCommits, Collections.emptySet(), or, b, maxSubmittableChangesAtOnce);
+      Set<String> nonVisibleHashes =
+          walkChangesByHashes(nonVisibleCommits, visibleHashes, or, b, maxSubmittableChangesAtOnce);
 
       ChangeSet partialSet =
           byCommitsOnBranchNotMerged(or, b, visibleHashes, nonVisibleHashes, user);
@@ -252,7 +263,11 @@ public class LocalMergeSuperSetComputation implements MergeSuperSetComputation {
   }
 
   private Set<String> walkChangesByHashes(
-      Collection<RevCommit> sourceCommits, Set<String> ignoreHashes, OpenRepo or, Branch.NameKey b)
+      Collection<RevCommit> sourceCommits,
+      Set<String> ignoreHashes,
+      OpenRepo or,
+      Branch.NameKey b,
+      int limit)
       throws IOException {
     Set<String> destHashes = new HashSet<>();
     or.rw.reset();
@@ -262,7 +277,11 @@ public class LocalMergeSuperSetComputation implements MergeSuperSetComputation {
       if (ignoreHashes.contains(name)) {
         continue;
       }
-      destHashes.add(name);
+      if (destHashes.size() < limit) {
+        destHashes.add(name);
+      } else {
+        break;
+      }
       or.rw.markStart(c);
     }
     for (RevCommit c : or.rw) {
@@ -270,7 +289,11 @@ public class LocalMergeSuperSetComputation implements MergeSuperSetComputation {
       if (ignoreHashes.contains(name)) {
         continue;
       }
-      destHashes.add(name);
+      if (destHashes.size() < limit) {
+        destHashes.add(name);
+      } else {
+        break;
+      }
     }
 
     return destHashes;
diff --git a/javatests/com/google/gerrit/acceptance/server/change/SubmittedTogetherIT.java b/javatests/com/google/gerrit/acceptance/server/change/SubmittedTogetherIT.java
index 389859cde2..4224953841 100644
--- a/javatests/com/google/gerrit/acceptance/server/change/SubmittedTogetherIT.java
+++ b/javatests/com/google/gerrit/acceptance/server/change/SubmittedTogetherIT.java
@@ -19,7 +19,9 @@ import static com.google.gerrit.acceptance.GitUtil.pushHead;
 import static com.google.gerrit.extensions.api.changes.SubmittedTogetherOption.NON_VISIBLE_CHANGES;
 
 import com.google.gerrit.acceptance.AbstractDaemonTest;
+import com.google.gerrit.acceptance.GerritConfig;
 import com.google.gerrit.acceptance.GitUtil;
+import com.google.gerrit.acceptance.Sandboxed;
 import com.google.gerrit.acceptance.TestProjectInput;
 import com.google.gerrit.acceptance.testsuite.project.ProjectOperations;
 import com.google.gerrit.acceptance.testsuite.request.RequestScopeOperations;
@@ -184,6 +186,26 @@ public class SubmittedTogetherIT extends AbstractDaemonTest {
   }
 
   @Test
+  @Sandboxed
+  @GerritConfig(name = "change.maxSubmittableAtOnce", value = "2")
+  public void submittedTogetherWithMaxChangesLimit() throws Exception {
+    String targetRef = "refs/for/master";
+
+    commitBuilder().add("a.txt", "1").message("subject: 1").create();
+    pushHead(testRepo, targetRef, false);
+
+    RevCommit c2_1 = commitBuilder().add("b.txt", "2").message("subject: 2").create();
+    String id2 = getChangeId(c2_1);
+    pushHead(testRepo, targetRef, false);
+
+    RevCommit c3_1 = commitBuilder().add("b.txt", "3").message("subject: 3").create();
+    String id3 = getChangeId(c3_1);
+    pushHead(testRepo, targetRef, false);
+
+    assertSubmittedTogether(id3, id3, id2);
+  }
+
+  @Test
   public void respectTopicsOnAncestors() throws Exception {
     RevCommit initialHead = getRemoteHead();