sync: Implement per-type GetCommitIds

sync/engine/get_commit_ids.h

Index: sync/engine/get_commit_ids.h
diff --git a/sync/engine/get_commit_ids.h b/sync/engine/get_commit_ids.h
new file mode 100644
index 0000000000000000000000000000000000000000..2d60bb5c10f7711daf5f2832b1e201c50c4425a7
--- /dev/null
+++ b/sync/engine/get_commit_ids.h
@@ -0,0 +1,75 @@
+// Copyright 2012 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_GET_COMMIT_IDS_H_
+#define SYNC_ENGINE_GET_COMMIT_IDS_H_
+
+#include <vector>
+
+#include "sync/base/sync_export.h"
+#include "sync/internal_api/public/base/model_type.h"
+#include "sync/syncable/directory.h"
+
+using std::vector;
+
+namespace syncer {
+
+namespace sessions {
+class OrderedCommitSet;
+}
+
+namespace syncable {
+class BaseTransaction;
+}
+
+// Filters |unsynced_handles| to remove all entries that do not belong to the
+// specified |requested_types|, or are not eligible for a commit at this time.
+SYNC_EXPORT_PRIVATE void FilterUnreadyEntries(
+    syncable::BaseTransaction* trans,
+    ModelTypeSet requested_types,
+    ModelTypeSet encrypted_types,
+    bool passphrase_missing,
+    const syncable::Directory::Metahandles& unsynced_handles,
+    std::set<int64>* ready_unsynced_set);
+
+// Returns up to |max_entries| metahandles of entries that belong to the
+// specified |type| and are ready for commit.  The returned handles will be
+// sorted for commit.
+SYNC_EXPORT_PRIVATE void GetCommitIdsForType(
+    syncable::BaseTransaction* trans,
+    ModelType type,
+    const size_t max_entries,

[Nicolas Zea, 2013/09/05 23:55:37]

no need for const on size_t (here and below)

[rlarocque, 2013/09/06 18:58:26]

Done.

+    std::vector<int64>* out);
+
+// Given a set of commit metahandles that are ready for commit
+// (|ready_unsynced_set|), sorts these into commit order and places up to
+// |max_entries| of them in the output parameter |out|.
+//
+// In "commit order", the metahandles are ordered so that parents are before
+// children, and predecessors are before successors.  Deletions are always
+// placed last.
+//
+// Since the implementation of UniquePositions, it is probably no longer
+// necessary to put predecessors before successors.  That functionality may be
+// removed in the future.
+SYNC_EXPORT_PRIVATE void OrderCommitIds(
+    syncable::BaseTransaction* trans,
+    size_t max_entries,
+    const std::set<int64>& ready_unsynced_set,
+    std::vector<int64>* out);
+
+// Fills the specified |ordered_commit_set| with up to |commit_batch_size|
+// metahandles that belong to the set of types |requested_types| and are ready
+// for commit.
+//
+// The list will be sorted for commit.
+SYNC_EXPORT_PRIVATE void GetCommitIds(

[Nicolas Zea, 2013/09/05 23:55:37]

Are any of the other methods beyond this one used outside of the cc file? Do we
need to declare them in the header?

[rlarocque, 2013/09/06 18:58:26]

No, but I would like to keep their implementations ordered in the .cc file in a
way that preservers history and makes for readable diffs, and that requires
forward declaring these functions somewhere.

As per offline discussion, I moved these forward declarations to the .cc file.

I left the declaration for GetCommitIdsForType() in the header because I intend
to make use of it soon.

+    syncable::BaseTransaction* trans,
+    ModelTypeSet requested_types,
+    const size_t commit_batch_size,
+    sessions::OrderedCommitSet* ordered_commit_set);
+
+}  // namespace syncer
+
+#endif  // SYNC_ENGINE_GET_COMMIT_IDS_H_