sync: Implement per-type commit interface

sync/engine/sync_directory_commit_contribution.h

Index: sync/engine/sync_directory_commit_contribution.h
diff --git a/sync/engine/sync_directory_commit_contribution.h b/sync/engine/sync_directory_commit_contribution.h
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+++ b/sync/engine/sync_directory_commit_contribution.h
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+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SYNC_ENGINE_SYNC_DIRECTORY_COMMIT_CONTRIBUTION_H_
+#define SYNC_ENGINE_SYNC_DIRECTORY_COMMIT_CONTRIBUTION_H_
+
+#include <vector>
+
+#include "base/gtest_prod_util.h"
+#include "sync/base/sync_export.h"
+#include "sync/internal_api/public/base/model_type.h"
+#include "sync/internal_api/public/util/syncer_error.h"
+#include "sync/protocol/sync.pb.h"
+#include "sync/sessions/status_controller.h"
+
+namespace syncer {
+
+namespace sessions {
+class StatusController;
+}  // namespace sessions
+
+namespace syncable {
+class Directory;
+}  // namespace syncable
+
+// This class represents a set of items belonging to a particular data type that
+// have been selected from the syncable Directory and prepared for commit.
+//
+// This class handles the bookkeeping related to the commit of these items,
+// including processing the commit response message and setting and unsetting
+// the SYNCING bits.
+class SYNC_EXPORT_PRIVATE SyncDirectoryCommitContribution {
+ public:
+  // This destructor will DCHECK if UnsetSyncingBits() has not been called yet.
+  ~SyncDirectoryCommitContribution();
+
+  // Build a CommitContribution from the IS_UNSYNCED items in |dir| with the
+  // given |type|.  The contribution will include at most |max_items| entries.
+  //
+  // This function may return NULL if this type has no items ready for and
+  // requiring commit.  This function may make model neutral changes to the
+  // directory.
+  static SyncDirectoryCommitContribution* Build(
+      syncable::Directory* dir,
+      ModelType type,
+      size_t max_items);
+
+  // Serialize this contribution's entries to the given commit request |msg|.
+  //
+  // This function is not const.  It will update some state in this contribution
+  // that will be used when processing the associated commit response.  This
+  // function should not be called more than once.
+  void AddToCommitMessage(sync_pb::ClientToServerMessage* msg);
+
+  // Updates this contribution's contents in accordance with the provided
+  // |response|.
+  //
+  // This function may make model-neutral changes to the directory.  It is not
+  // valid to call this function unless AddToCommitMessage() was called earlier.
+  // This function should not be called more than once.
+  SyncerError ProcessCommitResponse(
+      const sync_pb::ClientToServerResponse& response,
+      sessions::StatusController* status);
+
+  // Cleans up any temproary state associated with the commit.  Must be called
+  // before destruction.
+  void CleanUp();
+
+  // Returns the number of entries included in this contribution.
+  size_t GetNumEntries() const;
+
+ private:
+  class SyncDirectoryCommitContributionTest;
+  FRIEND_TEST_ALL_PREFIXES(SyncDirectoryCommitContributionTest, GatherByTypes);
+  FRIEND_TEST_ALL_PREFIXES(SyncDirectoryCommitContributionTest,
+                           GatherAndTruncate);
+
+  SyncDirectoryCommitContribution(
+      const std::vector<int64>& metahandles,
+      const google::protobuf::RepeatedPtrField<sync_pb::SyncEntity>& entities,
+      syncable::Directory* directory);
+
+  void UnsetSyncingBits();
+
+  syncable::Directory* dir_;
+  const std::vector<int64> metahandles_;
+  const google::protobuf::RepeatedPtrField<sync_pb::SyncEntity> entities_;
+  size_t entries_start_index_;
+
+  // This flag is tracks whether or not the directory entries associated with
+  // this commit still have their SYNCING bits set.  These bits will be set when
+  // the CommitContribution is created with Build() and unset when CleanUp() is
+  // called.  This flag must be unset by the time our destructor is called.
+  bool syncing_bits_set_;
+
+  DISALLOW_COPY_AND_ASSIGN(SyncDirectoryCommitContribution);
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_ENGINE_SYNC_DIRECTORY_COMMIT_CONTRIBUTION_H_