SyncFS: Convert WAPI ResourceID to DriveAPI FileID

chrome/browser/sync_file_system/drive/metadata_db_migration_util.cc

+// 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.
+
+#include "chrome/browser/sync_file_system/drive/metadata_db_migration_util.h"
+
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/string_util.h"
+#include "googleurl/src/gurl.h"
+#include "third_party/leveldatabase/src/include/leveldb/write_batch.h"
+
+namespace sync_file_system {
+namespace drive {
+
+namespace {
+const char kWapiFileIdPrefix[] = "file:";
+const char kWapiFolderIdPrefix[] = "folder:";
+}
+
+std::string AddWapiFilePrefix(const std::string& resource_id) {
+  if (resource_id.empty() ||
+      StartsWithASCII(resource_id, kWapiFileIdPrefix, true) ||
+      StartsWithASCII(resource_id, kWapiFolderIdPrefix, true))

[kinuko, 2013/05/28 15:09:20]

Is this ok?  Does this mean we get 'folder:xxxx' resource Id while expecting a
file?

[nhiroki, 2013/05/29 04:10:18]

Yes, I mean it. Do you prefer to return empty string or something else?

[kinuko, 2013/05/29 04:44:36]

When does this happen? If your answer to my first question is yes (i.e. it's
totally ok and it doesn't mean anything wrong/error) this code's fine for me
too.

[nhiroki, 2013/05/29 06:31:03]

For example:

a) metadata.type() == TYPE_FILE, but metadata.resource_id() == "folder:xxx"
b) origin_root_resource_id == "file:yyy"

This never happen as long as all stored metadata are consistent. And probably
this conditional branch is not necessary since |resource_id| must be stripped
and not empty in an actual situation. Even if happens, WAPI API could just be
failed (e.g. UpdateExistingFile with folder resource id).

[kinuko, 2013/05/29 06:41:13]

Thanks for the details.
If it never happens or it's not expected can we have a stricter debug-only check
(e.g. DCHECK)?  This code confused me.

[nhiroki, 2013/05/29 07:49:16]

Sorry, empty resource id is valid here since to-be-fetched change does not have
resource id. Anyway added DCHECKs.

+    return resource_id;
+  return kWapiFileIdPrefix + resource_id;
+}
+
+std::string AddWapiFolderPrefix(const std::string& resource_id) {
+  if (resource_id.empty() ||
+      StartsWithASCII(resource_id, kWapiFileIdPrefix, true) ||
+      StartsWithASCII(resource_id, kWapiFolderIdPrefix, true))
+    return resource_id;
+  return kWapiFolderIdPrefix + resource_id;
+}
+
+std::string AddWapiIdPrefix(const std::string& resource_id,
+                            DriveMetadata_ResourceType type) {
+  switch (type) {
+    case DriveMetadata_ResourceType_RESOURCE_TYPE_FILE:
+      return AddWapiFilePrefix(resource_id);
+    case DriveMetadata_ResourceType_RESOURCE_TYPE_FOLDER:
+      return AddWapiFolderPrefix(resource_id);
+    default:
+      NOTREACHED();
+      return resource_id;
+  }
+}
+
+std::string RemoveWapiIdPrefix(const std::string& resource_id) {
+  if (StartsWithASCII(resource_id, kWapiFileIdPrefix, true))
+    return std::string(resource_id.begin() + arraysize(kWapiFileIdPrefix) - 1,
+                       resource_id.end());
+  if (StartsWithASCII(resource_id, kWapiFolderIdPrefix, true))
+    return std::string(resource_id.begin() + arraysize(kWapiFolderIdPrefix) - 1,
+                       resource_id.end());

[kinuko, 2013/05/28 15:09:20]

nit: please put { } if body spans multiple line (for both if blocks)

nit: can we make these patterns a local (template) function like 
RemovePrefix(string, prefix) and use it here and for all leveldb strip-prefix
operations?

[nhiroki, 2013/05/29 04:10:18]

Done.

+  return resource_id;
+}
+
+SyncStatusCode MigrateDatabaseFromV1ToV2(leveldb::DB* db) {
+  // Strips prefix of WAPI resource ID.
+  // (i.e. "file:xxxx" => "xxxx", "folder:yyyy" => "yyyy")
+  //
+  // Version 2 database format (changed keys/fields are marked with '*'):
+  //   key: "VERSION"
+  // * value: 2
+  //
+  //   key: "CHANGE_STAMP"
+  //   value: <Largest Changestamp>
+  //
+  //   key: "SYNC_ROOT_DIR"
+  // * value: <Resource ID of the sync root directory> (striped)
+  //
+  //   key: "METADATA: " + <Origin and URL>
+  // * value: <Serialized DriveMetadata> (striped)
+  //
+  //   key: "ISYNC_ORIGIN: " + <URL string of a incremental sync origin>
+  // * value: <Resource ID of the drive directory for the origin> (striped)
+  //
+  //   key: "DISABLED_ORIGIN: " + <URL string of a disabled origin>
+  // * value: <Resource ID of the drive directory for the origin> (striped)
+
+  const char kDatabaseVersionKey[] = "VERSION";
+  const char kSyncRootDirectoryKey[] = "SYNC_ROOT_DIR";
+  const char kDriveMetadataKeyPrefix[] = "METADATA: ";
+  const char kDriveIncrementalSyncOriginKeyPrefix[] = "ISYNC_ORIGIN: ";
+  const char kDriveDisabledOriginKeyPrefix[] = "DISABLED_ORIGIN: ";
+
+  leveldb::WriteBatch write_batch;
+  write_batch.Put(kDatabaseVersionKey, "2");
+
+  // Strip resource id for the sync root directory.
+  std::string sync_root_resource_id;
+  leveldb::Status status = db->Get(
+      leveldb::ReadOptions(), kSyncRootDirectoryKey, &sync_root_resource_id);
+  write_batch.Put(kSyncRootDirectoryKey,
+                  RemoveWapiIdPrefix(sync_root_resource_id));
+
+  // Strip resource ids in the drive metadata.
+  scoped_ptr<leveldb::Iterator> itr(db->NewIterator(leveldb::ReadOptions()));
+  for (itr->Seek(kDriveMetadataKeyPrefix); itr->Valid(); itr->Next()) {
+    std::string key = itr->key().ToString();
+    if (!StartsWithASCII(key, kDriveMetadataKeyPrefix, true))
+      break;
+
+    DriveMetadata metadata;
+    bool success = metadata.ParseFromString(itr->value().ToString());
+    DCHECK(success);
+
+    metadata.set_resource_id(RemoveWapiIdPrefix(metadata.resource_id()));
+    std::string metadata_string;
+    metadata.SerializeToString(&metadata_string);
+
+    write_batch.Put(key, metadata_string);
+  }
+
+  // Strip resource ids of the incremental sync origins.
+  for (itr->Seek(kDriveIncrementalSyncOriginKeyPrefix);
+       itr->Valid(); itr->Next()) {
+    std::string key = itr->key().ToString();
+    if (!StartsWithASCII(key, kDriveIncrementalSyncOriginKeyPrefix, true))
+      break;
+
+    GURL origin(std::string(
+        key.begin() + arraysize(kDriveIncrementalSyncOriginKeyPrefix) - 1,
+        key.end()));
+    DCHECK(origin.is_valid());
+
+    write_batch.Put(kDriveIncrementalSyncOriginKeyPrefix + origin.spec(),
+                    RemoveWapiIdPrefix(itr->value().ToString()));
+  }
+
+  // Strip resource ids of the disabled sync origins.
+  for (itr->Seek(kDriveDisabledOriginKeyPrefix);
+       itr->Valid(); itr->Next()) {
+    std::string key = itr->key().ToString();
+    if (!StartsWithASCII(key, kDriveDisabledOriginKeyPrefix, true))
+      break;
+
+    GURL origin(std::string(
+        key.begin() + arraysize(kDriveDisabledOriginKeyPrefix) - 1,
+        key.end()));
+    DCHECK(origin.is_valid());
+
+    write_batch.Put(kDriveDisabledOriginKeyPrefix + origin.spec(),
+                    RemoveWapiIdPrefix(itr->value().ToString()));
+  }
+
+  return LevelDBStatusToSyncStatusCode(
+      db->Write(leveldb::WriteOptions(), &write_batch));
+}
+
+}  // namespace drive
+}  // namespace sync_file_system