Move common intra-Gerrit change queries to their own class

This is intended to replace most or all of the primary database index
queries in ChangeAccess.

Change-Id: I14fad0a46090b9fa3ef125c400c1d0a47d36381d

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

@@ -111,7 +111,7 @@ import com.google.gerrit.server.project.ProjectControl;
 import com.google.gerrit.server.project.ProjectState;
 import com.google.gerrit.server.project.RefControl;
 import com.google.gerrit.server.query.change.ChangeData;
-import com.google.gerrit.server.query.change.QueryProcessor;
+import com.google.gerrit.server.query.change.InternalChangeQuery;
 import com.google.gerrit.server.ssh.SshInfo;
 import com.google.gerrit.server.util.LabelVote;
 import com.google.gerrit.server.util.MagicBranch;
@@ -337,7 +337,7 @@ public class ReceiveCommits {
 
   @Inject
   ReceiveCommits(final ReviewDb db,
-      final Provider<QueryProcessor> queryProcessor,
+      final Provider<InternalChangeQuery> queryProvider,
       final SchemaFactory<ReviewDb> schemaFactory,
       final ChangeData.Factory changeDataFactory,
       final ChangeUpdate.Factory updateFactory,
@@ -474,7 +474,7 @@ public class ReceiveCommits {
     });
     advHooks.add(rp.getAdvertiseRefsHook());
     advHooks.add(new ReceiveCommitsAdvertiseRefsHook(
-        db, queryProcessor, projectControl.getProject().getNameKey()));
+        db, queryProvider, projectControl.getProject().getNameKey()));
     rp.setAdvertiseRefsHook(AdvertiseRefsHookChain.newChain(advHooks));
   }
 

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

@@ -22,11 +22,8 @@ import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.reviewdb.server.ReviewDb;
-import com.google.gerrit.server.query.Predicate;
-import com.google.gerrit.server.query.QueryParseException;
 import com.google.gerrit.server.query.change.ChangeData;
-import com.google.gerrit.server.query.change.ChangeQueryBuilder;
-import com.google.gerrit.server.query.change.QueryProcessor;
+import com.google.gerrit.server.query.change.InternalChangeQuery;
 import com.google.gerrit.server.util.MagicBranch;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Provider;
@@ -44,7 +41,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
-import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -54,14 +50,14 @@ public class ReceiveCommitsAdvertiseRefsHook implements AdvertiseRefsHook {
       .getLogger(ReceiveCommitsAdvertiseRefsHook.class);
 
   private final ReviewDb db;
-  private final Provider<QueryProcessor> queryProcessor;
+  private final Provider<InternalChangeQuery> queryProvider;
   private final Project.NameKey projectName;
 
   public ReceiveCommitsAdvertiseRefsHook(ReviewDb db,
-      Provider<QueryProcessor> queryProcessor,
+      Provider<InternalChangeQuery> queryProvider,
       Project.NameKey projectName) {
     this.db = db;
-    this.queryProcessor = queryProcessor;
+    this.queryProvider = queryProvider;
     this.projectName = projectName;
   }
 
@@ -105,7 +101,8 @@ public class ReceiveCommitsAdvertiseRefsHook implements AdvertiseRefsHook {
     final int limit = 32;
     try {
       Set<PatchSet.Id> toGet = Sets.newHashSetWithExpectedSize(limit);
-      for (ChangeData cd : queryRecentChanges(limit)) {
+      for (ChangeData cd :
+          queryProvider.get().setLimit(limit).byProjectOpen(projectName)) {
         PatchSet.Id id = cd.change().currentPatchSetId();
         if (id != null) {
           toGet.add(id);
@@ -174,20 +171,6 @@ public class ReceiveCommitsAdvertiseRefsHook implements AdvertiseRefsHook {
     return toInclude;
   }
 
-  private List<ChangeData> queryRecentChanges(int limit)
-      throws OrmException {
-    QueryProcessor qp = queryProcessor.get();
-    qp.setLimit(limit);
-    ChangeQueryBuilder qb = qp.getQueryBuilder();
-    Predicate<ChangeData> p =
-        Predicate.and(qb.project(projectName.get()), qb.status_open());
-    try {
-      return qp.queryChanges(p).changes();
-    } catch (QueryParseException e) {
-      throw new OrmException(e);
-    }
-  }
-
   private static boolean skip(String name) {
     return name.startsWith(RefNames.REFS_CHANGES)
         || name.startsWith(RefNames.REFS_CACHE_AUTOMERGE)

gerrit-server/src/main/java/com/google/gerrit/server/query/change/InternalChangeQuery.java

@@ -0,0 +1,55 @@
+// Copyright (C) 2014 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.server.query.change;
+
+import static com.google.gerrit.server.query.Predicate.and;
+
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.query.Predicate;
+import com.google.gerrit.server.query.QueryParseException;
+import com.google.gwtorm.server.OrmException;
+import com.google.inject.Inject;
+
+import java.util.List;
+
+/** Execute a single query over changes, for use by Gerrit internals. */
+public class InternalChangeQuery {
+  private final QueryProcessor qp;
+  private final ChangeQueryBuilder qb;
+
+  @Inject
+  InternalChangeQuery(QueryProcessor queryProcessor) {
+    qp = queryProcessor;
+    qb = qp.getQueryBuilder();
+  }
+
+  public InternalChangeQuery setLimit(int n) {
+    qp.setLimit(n);
+    return this;
+  }
+
+  public List<ChangeData> byProjectOpen(Project.NameKey project)
+      throws OrmException {
+    return query(and(qb.project(project.get()), qb.status_open()));
+  }
+
+  private List<ChangeData> query(Predicate<ChangeData> p) throws OrmException {
+    try {
+      return qp.queryChanges(p).changes();
+    } catch (QueryParseException e) {
+      throw new OrmException(e);
+    }
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/query/change/QueryProcessor.java

@@ -53,12 +53,14 @@ public class QueryProcessor {
     return queryBuilder;
   }
 
-  public void setLimit(int n) {
+  public QueryProcessor setLimit(int n) {
     limitFromCaller = n;
+    return this;
   }
 
-  public void setStart(int n) {
+  public QueryProcessor setStart(int n) {
     start = n;
+    return this;
   }
 
   /**