[Retry][SyncFS] Implement LargestKnownChangeID handling

BUG=240165
R=kinuko@chromium.org, nhiroki@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/62583003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235709 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 34 insertions, 9 deletions

diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database.cc b/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
index 7926452..a5f995f 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
@@ -500,17 +500,13 @@ int64 MetadataDatabase::GetSyncRootTrackerID() const {
 }
 
 int64 MetadataDatabase::GetLargestKnownChangeID() const {
-  // TODO(tzik): Implement:
-  //  - Add |largest_known_file_id| member to hold the value, that should
-  //    initially have the same value to |largest_change_id|.
-  //  - Change UpdateByFileResource and UpdateByChangeList not to overwrite
-  //    FileMetadata if the newer one.
-  //  - Change ListChangesTask to set UpdateLargestKnownChangeID.
-  return GetLargestFetchedChangeID();
+  DCHECK_LE(GetLargestFetchedChangeID(), largest_known_change_id_);
+  return largest_known_change_id_;
 }
 
 void MetadataDatabase::UpdateLargestKnownChangeID(int64 change_id) {
-  NOTIMPLEMENTED();
+  if (largest_known_change_id_ < change_id)
+    largest_known_change_id_ = change_id;
 }
 
 bool MetadataDatabase::HasSyncRoot() const {
@@ -528,6 +524,7 @@ void MetadataDatabase::PopulateInitialData(
 
   scoped_ptr<leveldb::WriteBatch> batch(new leveldb::WriteBatch);
   service_metadata_->set_largest_change_id(largest_change_id);
+  UpdateLargestKnownChangeID(largest_change_id);
 
   FileTracker* sync_root_tracker = NULL;
   int64 sync_root_tracker_id = 0;
@@ -761,6 +758,9 @@ void MetadataDatabase::UpdateByChangeList(
        itr != changes.end();
        ++itr) {
     const google_apis::ChangeResource& change = **itr;
+    if (HasNewerFileMetadata(change.file_id(), change.change_id()))
+      continue;
+
     scoped_ptr<FileMetadata> file(
         CreateFileMetadataFromChangeResource(change));
     std::string file_id = file->file_id();
@@ -779,6 +779,7 @@ void MetadataDatabase::UpdateByChangeList(
     }
   }
 
+  UpdateLargestKnownChangeID(largest_change_id);
   service_metadata_->set_largest_change_id(largest_change_id);
   PutServiceMetadataToBatch(*service_metadata_, batch.get());
   WriteToDatabase(batch.Pass(), callback);
@@ -793,6 +794,8 @@ void MetadataDatabase::UpdateByFileResource(
   scoped_ptr<FileMetadata> file(
       CreateFileMetadataFromFileResource(change_id, resource));
   std::string file_id = file->file_id();
+  if (HasNewerFileMetadata(file_id, change_id))
+    return;
 
   // TODO(tzik): Consolidate with UpdateByChangeList.
   MarkTrackersDirtyByFileID(file_id, batch.get());
@@ -961,7 +964,9 @@ bool MetadataDatabase::GetLowPriorityDirtyTracker(
 }
 
 MetadataDatabase::MetadataDatabase(base::SequencedTaskRunner* task_runner)
-    : task_runner_(task_runner), weak_ptr_factory_(this) {
+    : task_runner_(task_runner),
+      largest_known_change_id_(0),
+      weak_ptr_factory_(this) {
   DCHECK(task_runner);
 }
 
@@ -1055,6 +1060,7 @@ SyncStatusCode MetadataDatabase::InitializeOnTaskRunner(
 
 void MetadataDatabase::BuildIndexes(DatabaseContents* contents) {
   service_metadata_ = contents->service_metadata.Pass();
+  UpdateLargestKnownChangeID(service_metadata_->largest_change_id());
 
   for (ScopedVector<FileMetadata>::const_iterator itr =
            contents->file_metadata.begin();
@@ -1572,5 +1578,14 @@ void MetadataDatabase::GetRegisteredAppIDs(std::vector<std::string>* app_ids) {
   }
 }
 
+bool MetadataDatabase::HasNewerFileMetadata(const std::string& file_id,
+                                            int64 change_id) {
+  FileByID::const_iterator found = file_by_id_.find(file_id);
+  if (found == file_by_id_.end())
+    return false;
+  DCHECK(found->second->has_details());
+  return found->second->details().change_id() >= change_id;
+}
+
 }  // namespace drive_backend
 }  // namespace sync_file_system
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database.h b/chrome/browser/sync_file_system/drive_backend/metadata_database.h
index 0590712..04ece53 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.h
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.h
@@ -338,10 +338,13 @@ class MetadataDatabase {
   void WriteToDatabase(scoped_ptr<leveldb::WriteBatch> batch,
                        const SyncStatusCallback& callback);
 
+  bool HasNewerFileMetadata(const std::string& file_id, int64 change_id);
+
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
   scoped_ptr<leveldb::DB> db_;
 
   scoped_ptr<ServiceMetadata> service_metadata_;
+  int64 largest_known_change_id_;
 
   FileByID file_by_id_;  // Owned.
   TrackerByID tracker_by_id_;  // Owned.
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc b/chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc
index 27da3410..f9724b4 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database_unittest.cc
@@ -401,6 +401,10 @@ class MetadataDatabaseTest : public testing::Test {
     details->set_change_id(++current_change_id_);
   }
 
+  void ApplyNoopChangeToMetadata(FileMetadata* file) {
+    file->mutable_details()->set_change_id(++current_change_id_);
+  }
+
   void PushToChangeList(scoped_ptr<google_apis::ChangeResource> change,
                         ScopedVector<google_apis::ChangeResource>* changes) {
     changes->push_back(change.release());
@@ -749,6 +753,9 @@ TEST_F(MetadataDatabaseTest, UpdateByChangeListTest) {
                                   &reorganized_file.metadata);
   ApplyContentChangeToMetadata(&updated_file.metadata);
 
+  // Update change ID.
+  ApplyNoopChangeToMetadata(&noop_file.metadata);
+
   ScopedVector<google_apis::ChangeResource> changes;
   PushToChangeList(
       CreateChangeResourceFromMetadata(renamed_file.metadata), &changes);