Replace most ChangeAccess queries with searches

Use the secondary index rather than depending on SQL indexes, which
will not be available in a notedb world. For the most part this change
is pretty straightforward, as the interface for InternalChangeQuery is
almost the same as for ChangeAccess. It also provides a bit more
functionality, such as limiting the results.

By default, all of these queries should bypass visibility checks,
since things like the submit queue necessarily need to see everything.
Even if it is properly running as InternalUser and that is hard-coded
to have visibility, it is simpler to just bypass the checks entirely.

The biggest complication comes from converting callers that previously
opened a new ReviewDb in a try/finally block and called a ChangeAccess
method directly from that. In the InternalChangeQuery model,
Provider<ReviewDb> needs to be injected, so we need to set the
ThreadLocalRequestContext with the manually-opened DB. To simplify
this code, add an AutoCloseable RequestContext implementation.

To save future schema churn, this change does not include a schema
change to drop the indexes.

Change-Id: I99de8a2cf2aba01971059b89df33b1676cd8546e

gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java

@@ -65,11 +65,13 @@ import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.project.ProjectState;
 import com.google.gerrit.server.project.SubmitRuleEvaluator;
 import com.google.gerrit.server.query.change.ChangeData;
+import com.google.gerrit.server.query.change.InternalChangeQuery;
 import com.google.gerrit.server.util.RequestScopePropagator;
 import com.google.gwtorm.server.AtomicUpdate;
 import com.google.gwtorm.server.OrmException;
 import com.google.gwtorm.server.SchemaFactory;
 import com.google.inject.Inject;
+import com.google.inject.Provider;
 import com.google.inject.assistedinject.Assisted;
 
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
@@ -148,6 +150,7 @@ public class MergeOp {
   private final MergeValidators.Factory mergeValidatorsFactory;
   private final PatchSetInfoFactory patchSetInfoFactory;
   private final ProjectCache projectCache;
+  private final Provider<InternalChangeQuery> queryProvider;
   private final RequestScopePropagator requestScopePropagator;
   private final SchemaFactory<ReviewDb> schemaFactory;
   private final SubmitStrategyFactory submitStrategyFactory;
@@ -191,6 +194,7 @@ public class MergeOp {
       MergeValidators.Factory mergeValidatorsFactory,
       PatchSetInfoFactory patchSetInfoFactory,
       ProjectCache projectCache,
+      Provider<InternalChangeQuery> queryProvider,
       RequestScopePropagator requestScopePropagator,
       SchemaFactory<ReviewDb> schemaFactory,
       SubmitStrategyFactory submitStrategyFactory,
@@ -216,6 +220,7 @@ public class MergeOp {
     this.mergeValidatorsFactory = mergeValidatorsFactory;
     this.patchSetInfoFactory = patchSetInfoFactory;
     this.projectCache = projectCache;
+    this.queryProvider = queryProvider;
     this.requestScopePropagator = requestScopePropagator;
     this.schemaFactory = schemaFactory;
     this.submitStrategyFactory = submitStrategyFactory;
@@ -256,7 +261,7 @@ public class MergeOp {
       boolean reopen = false;
 
       ListMultimap<SubmitType, Change> toSubmit =
-          validateChangeList(db.changes().submitted(destBranch).toList());
+          validateChangeList(queryProvider.get().submitted(destBranch));
       ListMultimap<SubmitType, CodeReviewCommit> toMergeNextTurn =
           ArrayListMultimap.create();
       List<CodeReviewCommit> potentiallyStillSubmittableOnNextRun =
@@ -444,9 +449,14 @@ public class MergeOp {
         branchTip = null;
         branchUpdate.setExpectedOldObjectId(ObjectId.zeroId());
       } else {
-        for (Change c : db.changes().submitted(destBranch).toList()) {
-          setNew(c, message(c, "Your change could not be merged, "
-              + "because the destination branch does not exist anymore."));
+        for (ChangeData cd : queryProvider.get().submitted(destBranch)) {
+          try {
+            Change c = cd.change();
+            setNew(c, message(c, "Your change could not be merged, "
+                + "because the destination branch does not exist anymore."));
+          } catch (OrmException e) {
+            log.error("Error setting change new", e);
+          }
         }
       }
       return branchUpdate;
@@ -481,7 +491,7 @@ public class MergeOp {
   }
 
   private ListMultimap<SubmitType, Change> validateChangeList(
-      List<Change> submitted) throws MergeException {
+      List<ChangeData> submitted) throws MergeException {
     ListMultimap<SubmitType, Change> toSubmit = ArrayListMultimap.create();
 
     Map<String, Ref> allRefs;
@@ -496,15 +506,16 @@ public class MergeOp {
       tips.add(r.getObjectId());
     }
 
-    for (Change chg : submitted) {
+    for (ChangeData cd : submitted) {
       ChangeControl ctl;
+      Change chg;
       try {
-        ctl = changeControlFactory.controlFor(chg,
-            identifiedUserFactory.create(chg.getOwner()));
-      } catch (NoSuchChangeException e) {
+        ctl = cd.changeControl();
+        chg = cd.change();
+      } catch (OrmException e) {
         throw new MergeException("Failed to validate changes", e);
       }
-      Change.Id changeId = chg.getId();
+      Change.Id changeId = cd.getId();
       if (chg.currentPatchSetId() == null) {
         logError("Missing current patch set on change " + changeId);
         commits.put(changeId, CodeReviewCommit.noPatchSet(ctl));
@@ -514,7 +525,7 @@ public class MergeOp {
 
       PatchSet ps;
       try {
-        ps = db.patchSets().get(chg.currentPatchSetId());
+        ps = cd.currentPatchSet();
       } catch (OrmException e) {
         throw new MergeException("Cannot query the database", e);
       }
@@ -565,6 +576,7 @@ public class MergeOp {
         continue;
       }
 
+      // TODO(dborowitz): Consider putting ChangeData in CodeReviewCommit.
       commit.setControl(ctl);
       commit.setPatchsetId(ps.getId());
       commits.put(changeId, commit);
@@ -733,7 +745,7 @@ public class MergeOp {
 
   private void updateChangeStatus(List<Change> submitted)
       throws NoSuchChangeException {
-    logDebug("Updating change status for {} changes", submitted);
+    logDebug("Updating change status for {} changes", submitted.size());
     for (Change c : submitted) {
       CodeReviewCommit commit = commits.get(c.getId());
       CommitMergeStatus s = commit != null ? commit.getStatusCode() : null;
@@ -747,7 +759,8 @@ public class MergeOp {
       }
 
       String txt = s.getMessage();
-      logDebug("Status of change {} on {}: {}", c.getId(), c.getDest(), s);
+      logDebug("Status of change {} ({}) on {}: {}", c.getId(), commit.name(),
+          c.getDest(), s);
 
       try {
         switch (s) {
@@ -1207,9 +1220,9 @@ public class MergeOp {
     Exception err = null;
     try {
       openSchema();
-      for (Change c
-          : db.changes().byProjectOpenAll(destBranch.getParentKey())) {
-        abandonOneChange(c);
+      for (ChangeData cd
+          : queryProvider.get().byProjectOpen(destBranch.getParentKey())) {
+        abandonOneChange(cd.change());
       }
       db.close();
       db = null;