[SyncFS] Retry initialization of MetadataDatabase on failure of loading ServiceMetadata

chrome/browser/sync_file_system/drive_backend/metadata_database.cc

Index: chrome/browser/sync_file_system/drive_backend/metadata_database.cc
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 5456f52593ce52a28506f67bb25842de016b11d9..e53f562bfff4f25e160923eb156b3c5b77072aa4 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
@@ -1424,11 +1424,22 @@ void MetadataDatabase::CreateOnWorkerTaskRunner(
       new MetadataDatabase(create_param->worker_task_runner,
                            create_param->database_path,
                            create_param->env_override));
+
   SyncStatusCode status = metadata_database->Initialize();
+  // Retry to initialize database, if the initialization fails.
+  for (int i = 0; i < kMaxRetry && status != SYNC_STATUS_OK; ++i) {

[tzik, 2014/09/03 04:47:37]

I think 2 is enough for the number of retry.

Can you add metadata_database.reset() here to avoid creating multiple instance
of leveldb::DB?

[peria, 2014/09/03 09:24:21]

Done.

+    metadata_database.reset(
+        new MetadataDatabase(create_param->worker_task_runner,
+                             create_param->database_path,
+                             create_param->env_override));
+    status = metadata_database->Initialize();
+  }
+
   if (status != SYNC_STATUS_OK)
     metadata_database.reset();
 
-  metadata_database->DetachFromSequence();
+  if (metadata_database)
+    metadata_database->DetachFromSequence();
   create_param->worker_task_runner->PostTask(
       FROM_HERE,
       base::Bind(
@@ -1460,6 +1471,16 @@ SyncStatusCode MetadataDatabase::Initialize() {
   } else {
     index_ = MetadataDatabaseIndex::Create(db_.get());
   }
+  if (!index_) {
+    // Delete all entries in |db_| to reset it.
+    // TODO(peria): Make LevelDBWrapper::DestroyDB() to avoid a full scan.
+    scoped_ptr<LevelDBWrapper::Iterator> itr = db_->NewIterator();
+    for (itr->SeekToFirst(); itr->Valid();)
+      itr->Delete();
+    db_->Commit();
+
+    return SYNC_DATABASE_ERROR_FAILED;
+  }
 
   status = LevelDBStatusToSyncStatusCode(db_->Commit());
   if (status != SYNC_STATUS_OK)