Materialize IdentifiedUser deps in BatchUpdate

When executing BatchUpdates from a receive commit, materialise the user
dependent objects so that it can be passed over to other threads
for delayed execution outside the current scope.

P.S. This fixes Gerrit master breakages caused by OutOfScopeException.

Change-Id: Ic463ddaeb5d9c90573a3a4639523f214125aaaad

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

@@ -424,6 +424,28 @@ public class IdentifiedUser extends CurrentUser {
     }
   }
 
+  /**
+   * Returns a materialized copy of the user with all dependencies.
+   *
+   * Invoke all providers and factories of dependent objects and store the
+   * references to a copy of the current identified user.
+   *
+   * @return copy of the identified user
+   */
+  public IdentifiedUser materializedCopy() {
+    final CapabilityControl capabilities = getCapabilities();
+    return new IdentifiedUser(new CapabilityControl.Factory() {
+
+      @Override
+      public CapabilityControl create(CurrentUser user) {
+        return capabilities;
+      }
+    }, authConfig, realm, anonymousCowardName,
+        Providers.of(canonicalUrl.get()), accountCache, groupBackend,
+        disableReverseDnsLookup, Providers.of(remotePeerProvider.get()), state,
+        realUser);
+  }
+
   private String getHost(final InetAddress in) {
     if (Boolean.FALSE.equals(disableReverseDnsLookup)) {
       return in.getCanonicalHostName();

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

@@ -825,8 +825,9 @@ public class ReceiveCommits {
       return;
     }
 
-    try (BatchUpdate bu = batchUpdateFactory.create(db,
-          magicBranch.dest.getParentKey(), user, TimeUtil.nowTs());
+    try (BatchUpdate bu =
+        batchUpdateFactory.create(db, magicBranch.dest.getParentKey(),
+            user.materializedCopy(), TimeUtil.nowTs());
         ObjectInserter ins = repo.newObjectInserter()) {
       bu.setRepository(repo, rp.getRevWalk(), ins)
           .updateChangesInParallel();