ETag computation needs to honor changes in other changes

If `submitWholetopic` is enabled a change may stay unchanged,
but a change in the same topic can influence submittability.

Change-Id: I5c958369e9deec9546bc691629f14266d6755721

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeResource.java

@@ -57,17 +57,15 @@ public class ChangeResource implements RestResource, HasETag {
     return getControl().getNotes();
   }
 
-  @Override
-  public String getETag() {
-    CurrentUser user = control.getCurrentUser();
-    Hasher h = Hashing.md5().newHasher()
-      .putLong(getChange().getLastUpdatedOn().getTime())
+
+  // This includes all information relevant for ETag computation
+  // unrelated to the UI.
+  public void prepareETag(Hasher h, CurrentUser user) {
+    h.putLong(getChange().getLastUpdatedOn().getTime())
       .putInt(getChange().getRowVersion())
-      .putBoolean(user.getStarredChanges().contains(getChange().getId()))
       .putInt(user.isIdentifiedUser()
           ? ((IdentifiedUser) user).getAccountId().get()
           : 0);
-
     byte[] buf = new byte[20];
     ObjectId noteId;
     try {
@@ -82,6 +80,14 @@ public class ChangeResource implements RestResource, HasETag {
     for (ProjectState p : control.getProjectControl().getProjectState().tree()) {
       hashObjectId(h, p.getConfig().getRevision(), buf);
     }
+  }
+
+  @Override
+  public String getETag() {
+    CurrentUser user = control.getCurrentUser();
+    Hasher h = Hashing.md5().newHasher()
+        .putBoolean(user.getStarredChanges().contains(getChange().getId()));
+    prepareETag(h, user);
     return h.hash().toString();
   }
 

gerrit-server/src/main/java/com/google/gerrit/server/change/GetRevisionActions.java

@@ -14,22 +14,59 @@
 
 package com.google.gerrit.server.change;
 
+import com.google.common.base.Strings;
+import com.google.common.hash.Hasher;
+import com.google.common.hash.Hashing;
+import com.google.gerrit.extensions.restapi.ETagView;
 import com.google.gerrit.extensions.restapi.Response;
-import com.google.gerrit.extensions.restapi.RestReadView;
+import com.google.gerrit.server.CurrentUser;
+import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.query.change.ChangeData;
+import com.google.gerrit.server.query.change.InternalChangeQuery;
+import com.google.gwtorm.server.OrmException;
+import com.google.gwtorm.server.OrmRuntimeException;
 import com.google.inject.Inject;
+import com.google.inject.Provider;
 import com.google.inject.Singleton;
 
-@Singleton
-public class GetRevisionActions implements RestReadView<RevisionResource> {
-  private final ActionJson delegate;
+import org.eclipse.jgit.lib.Config;
 
+@Singleton
+public class GetRevisionActions implements ETagView<RevisionResource> {
+  private final ActionJson delegate;
+  private final Provider<InternalChangeQuery> queryProvider;
+  private final Config config;
   @Inject
-  GetRevisionActions(ActionJson delegate) {
+  GetRevisionActions(
+      ActionJson delegate,
+      Provider<InternalChangeQuery> queryProvider,
+      @GerritServerConfig Config config) {
     this.delegate = delegate;
+    this.queryProvider = queryProvider;
+    this.config = config;
   }
 
   @Override
   public Object apply(RevisionResource rsrc) {
     return Response.withMustRevalidate(delegate.format(rsrc));
   }
+
+  @Override
+  public String getETag(RevisionResource rsrc) {
+    String topic = rsrc.getChange().getTopic();
+    if (!Submit.wholeTopicEnabled(config)
+        || Strings.isNullOrEmpty(topic)) {
+      return rsrc.getETag();
+    }
+    Hasher h = Hashing.md5().newHasher();
+    CurrentUser user = rsrc.getControl().getCurrentUser();
+    try {
+      for (ChangeData c : queryProvider.get().byTopicOpen(topic)) {
+        new ChangeResource(c.changeControl()).prepareETag(h, user);
+      }
+    } catch (OrmException e){
+      throw new OrmRuntimeException(e);
+    }
+    return h.hash().toString();
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/change/Submit.java

@@ -169,7 +169,7 @@ public class Submit implements RestModifyView<RevisionResource, SubmitInput>,
     this.titlePattern = new ParameterizedString(MoreObjects.firstNonNull(
         cfg.getString("change", null, "submitTooltip"),
         DEFAULT_TOOLTIP));
-    submitWholeTopic = cfg.getBoolean("change", null, "submitWholeTopic" , false);
+    submitWholeTopic = wholeTopicEnabled(cfg);
     this.submitTopicLabel = MoreObjects.firstNonNull(
         Strings.emptyToNull(cfg.getString("change", null, "submitTopicLabel")),
         "Submit whole topic");
@@ -654,6 +654,10 @@ public class Submit implements RestModifyView<RevisionResource, SubmitInput>,
     return new RevisionResource(changes.parse(target), rsrc.getPatchSet());
   }
 
+  static boolean wholeTopicEnabled(Config config) {
+    return config.getBoolean("change", null, "submitWholeTopic" , false);
+  }
+
   public static class CurrentRevision implements
       RestModifyView<ChangeResource, SubmitInput> {
     private final Provider<ReviewDb> dbProvider;