[SyncFS] Rollback function from version 4 to version 3.

chrome/browser/sync_file_system/drive_backend/metadata_db_migration_util_unittest.cc

Index: chrome/browser/sync_file_system/drive_backend/metadata_db_migration_util_unittest.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_db_migration_util_unittest.cc b/chrome/browser/sync_file_system/drive_backend/metadata_db_migration_util_unittest.cc
index 4ab2f1c03fcbd3a81e47f63ef8b03e45b57524dd..db62e1ba4620145849b575f72e1b6036af0f1369 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_db_migration_util_unittest.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_db_migration_util_unittest.cc
@@ -45,6 +45,24 @@ bool CreateV0SerializedSyncableFileSystemURL(
   return true;
 }
 
+void VerifyKeyAndValue(const std::string& key,
+                       const std::string& expect_val,
+                       leveldb::DB* db) {
+  scoped_ptr<leveldb::Iterator> itr(db->NewIterator(leveldb::ReadOptions()));
+
+  itr->Seek(key);
+  EXPECT_TRUE(itr->Valid());
+  EXPECT_EQ(expect_val, itr->value().ToString());
+}
+
+void VerifyNotExist(const std::string& key, leveldb::DB* db) {
+  scoped_ptr<leveldb::Iterator> itr(db->NewIterator(leveldb::ReadOptions()));
+
+  itr->Seek(key);
+  EXPECT_TRUE(!itr->Valid() ||
+              !StartsWithASCII(itr->key().ToString(), key, true));
+}
+
 }  // namespace
 
 TEST(DriveMetadataDBMigrationUtilTest, ParseV0FormatFileSystemURL) {
@@ -309,5 +327,83 @@ TEST(DriveMetadataDBMigrationUtilTest, MigrationFromV1) {
   EXPECT_EQ(RemoveWapiIdPrefix(kResourceId3), itr->value().ToString());
 }
 
+TEST(DriveMetadataDBMigrationUtilTest, RollbackFromV4ToV3) {
+  // Rollback from version 4 to version 3.
+  // Please see metadata_database_index.cc for version 3 format, and
+  // metadata_database_index_on_disk.cc for version 4 format.
+
+  const char kDatabaseVersionKey[] = "VERSION";
+  const char kServiceMetadataKey[] = "SERVICE";
+  const char kFileMetadataKeyPrefix[] = "FILE: ";
+  const char kFileTrackerKeyPrefix[] = "TRACKER: ";
+
+  // Key prefixes used in version 4.
+  const char kAppRootIDByAppIDKeyPrefix[] = "APP_ROOT: ";
+  const char kActiveTrackerIDByFileIDKeyPrefix[] = "ACTIVE_FILE: ";
+  const char kTrackerIDByFileIDKeyPrefix[] = "TRACKER_FILE: ";
+  const char kMultiTrackerByFileIDKeyPrefix[] = "MULTI_FILE: ";
+  const char kActiveTrackerIDByParentAndTitleKeyPrefix[] = "ACTIVE_PATH: ";
+  const char kTrackerIDByParentAndTitleKeyPrefix[] = "TRACKER_PATH: ";
+  const char kMultiBackingParentAndTitleKeyPrefix[] = "MULTI_PATH: ";
+  const char kDirtyIDKeyPrefix[] = "DIRTY: ";
+  const char kDemotedDirtyIDKeyPrefix[] = "DEMOTED_DIRTY: ";

[nhiroki, 2014/08/07 06:26:39]

I'd prefer not to spread these constants across production code, migration
helper and tests. How about wrapping these constants with any namespace and
reusing it? For example...

class DBConstantsV4 {
  ...  // defined constants only used for V4.
};

Wdyt?

+
+  // Set up environment.
+  leveldb::DB* db_ptr = NULL;
+  {
+    base::ScopedTempDir base_dir;
+    ASSERT_TRUE(base_dir.CreateUniqueTempDir());
+
+    leveldb::Options options;
+    options.create_if_missing = true;
+    std::string db_dir = fileapi::FilePathToString(
+        base_dir.path().Append(DriveMetadataStore::kDatabaseName));
+    leveldb::Status status = leveldb::DB::Open(options, db_dir, &db_ptr);
+    ASSERT_TRUE(status.ok());
+  }
+  scoped_ptr<leveldb::DB> db(db_ptr);
+
+  // Setup the database with the schema version 4, without IDs.
+  leveldb::WriteBatch batch;
+  batch.Put(kDatabaseVersionKey, "4");
+  batch.Put(kServiceMetadataKey, "service_metadata");
+  batch.Put(kFileMetadataKeyPrefix, "file_metadata");
+  batch.Put(kFileTrackerKeyPrefix, "file_tracker");
+  batch.Put(kAppRootIDByAppIDKeyPrefix, "app_root_id");
+  batch.Put(kActiveTrackerIDByFileIDKeyPrefix, "active_id_by_file");
+  batch.Put(kTrackerIDByFileIDKeyPrefix, "tracker_id_by_file");
+  batch.Put(kMultiTrackerByFileIDKeyPrefix, "multi_tracker_by_file");
+  batch.Put(kActiveTrackerIDByParentAndTitleKeyPrefix, "active_id_by_path");
+  batch.Put(kTrackerIDByParentAndTitleKeyPrefix, "tracker_id_by_path");
+  batch.Put(kMultiBackingParentAndTitleKeyPrefix, "multi_tracker_by_path");
+  batch.Put(kDirtyIDKeyPrefix, "dirty");
+  batch.Put(kDemotedDirtyIDKeyPrefix, "demoted_dirty");
+
+  leveldb::Status status = db->Write(leveldb::WriteOptions(), &batch);
+  EXPECT_EQ(SYNC_STATUS_OK, LevelDBStatusToSyncStatusCode(status));
+
+  // Migrate the database.
+  MigrateDatabaseFromV4ToV3(db.get());
+
+  // Verify DB schema verison
+  VerifyKeyAndValue(kDatabaseVersionKey, "3", db.get());
+
+  // Verify remained entries.
+  VerifyKeyAndValue(kServiceMetadataKey, "service_metadata", db.get());
+  VerifyKeyAndValue(kFileMetadataKeyPrefix, "file_metadata", db.get());
+  VerifyKeyAndValue(kFileTrackerKeyPrefix, "file_tracker", db.get());
+
+  // Verify
+  VerifyNotExist(kAppRootIDByAppIDKeyPrefix, db.get());
+  VerifyNotExist(kActiveTrackerIDByFileIDKeyPrefix, db.get());
+  VerifyNotExist(kTrackerIDByFileIDKeyPrefix, db.get());
+  VerifyNotExist(kMultiTrackerByFileIDKeyPrefix, db.get());
+  VerifyNotExist(kActiveTrackerIDByParentAndTitleKeyPrefix, db.get());
+  VerifyNotExist(kTrackerIDByParentAndTitleKeyPrefix, db.get());
+  VerifyNotExist(kMultiBackingParentAndTitleKeyPrefix, db.get());
+  VerifyNotExist(kDirtyIDKeyPrefix, db.get());
+  VerifyNotExist(kDemotedDirtyIDKeyPrefix, db.get());
+}
+
 }  // namespace drive_backend
 }  // namespace sync_file_system