[SyncFS] Implement MetadataDatabase initialization

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 6e52b5110d23e289cfa98ec38ddb45462efbf08a..4815b65c3271684cd645c43ae43caea05c04e7c4 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
@@ -4,26 +4,299 @@
 
 #include "chrome/browser/sync_file_system/drive_backend/metadata_database.h"
 
+#include <stack>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "base/location.h"
+#include "base/memory/scoped_vector.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/sequenced_task_runner.h"
+#include "base/stl_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
+#include "base/task_runner_util.h"
+#include "base/threading/thread_restrictions.h"
 #include "chrome/browser/google_apis/drive_api_parser.h"
+#include "chrome/browser/sync_file_system/drive_backend/metadata_database.pb.h"
+#include "chrome/browser/sync_file_system/drive_backend/metadata_db_migration_util.h"
+#include "chrome/browser/sync_file_system/logger.h"
+#include "third_party/leveldatabase/src/include/leveldb/db.h"
+#include "third_party/leveldatabase/src/include/leveldb/write_batch.h"
+#include "webkit/browser/fileapi/syncable/syncable_file_system_util.h"
+#include "webkit/common/fileapi/file_system_util.h"
 
 namespace sync_file_system {
 namespace drive_backend {
 
-MetadataDatabase::MetadataDatabase(base::SequencedTaskRunner* task_runner) {
-  NOTIMPLEMENTED();
+typedef MetadataDatabase::FileByAppID FileByAppID;
+typedef MetadataDatabase::FileByFileID FileByFileID;
+typedef MetadataDatabase::FileByParentAndTitle FileByParentAndTitle;
+typedef MetadataDatabase::FileSet FileSet;
+typedef MetadataDatabase::FilesByParent FilesByParent;
+
+const char kDatabaseVersionKey[] = "VERSION";
+const int64 kCurrentDatabaseVersion = 3;
+const char kServiceMetadataKey[] = "SERVICE";
+const char kFileMetadataKeyPrefix[] = "FILE: ";
+
+struct DatabaseContents {
+  scoped_ptr<ServiceMetadata> service_metadata;
+  ScopedVector<DriveFileMetadata> file_metadata;
+};
+
+namespace {
+
+std::string RemovePrefix(const std::string& str, const std::string& prefix) {
+  if (StartsWithASCII(str, prefix, true))
+    return str.substr(prefix.size());
+  return str;
 }
 
-MetadataDatabase::~MetadataDatabase() {
+void AdaptLevelDBStatusToSyncStatusCode(const SyncStatusCallback& callback,
+                                        const leveldb::Status& status) {
+  callback.Run(LevelDBStatusToSyncStatusCode(status));
 }
 
-void MetadataDatabase::Initialize(const base::FilePath& database_dir,
-                                  const SyncStatusCallback& callback) {
-  NOTIMPLEMENTED();
+// Returns true if |db| has no content.
+bool IsDatabaseEmpty(leveldb::DB* db) {
+  DCHECK(db);
+  scoped_ptr<leveldb::Iterator> itr(db->NewIterator(leveldb::ReadOptions()));
+  itr->SeekToFirst();
+  return !itr->Valid();
+}
+
+SyncStatusCode OpenDatabase(const base::FilePath& path,
+                            scoped_ptr<leveldb::DB>* db_out,
+                            bool* created) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  DCHECK(db_out);
+  DCHECK(created);
+
+  leveldb::Options options;
+  options.create_if_missing = true;
+  leveldb::DB* db = NULL;
+  leveldb::Status db_status =
+      leveldb::DB::Open(options, path.AsUTF8Unsafe(), &db);
+  SyncStatusCode status = LevelDBStatusToSyncStatusCode(db_status);
+  if (status != SYNC_STATUS_OK) {
+    delete db;
+    return status;
+  }
+
+  *created = IsDatabaseEmpty(db);
+  db_out->reset(db);
+  return status;
+}
+
+SyncStatusCode MigrateDatabaseIfNeeded(leveldb::DB* db) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  DCHECK(db);
+  std::string value;
+  leveldb::Status status =
+      db->Get(leveldb::ReadOptions(), kDatabaseVersionKey, &value);
+  int64 version = 0;
+  if (status.ok()) {
+    if (!base::StringToInt64(value, &version))
+      return SYNC_DATABASE_ERROR_FAILED;
+  } else {
+    if (!status.IsNotFound())
+      return SYNC_DATABASE_ERROR_FAILED;
+  }
+
+  switch (version) {
+    case 0:
+      drive_backend::MigrateDatabaseFromV0ToV1(db);
+      // fall-through
+    case 1:
+      drive_backend::MigrateDatabaseFromV1ToV2(db);
+      // fall-through
+    case 2:
+      // TODO(tzik): Migrate database from version 2 to 3.
+      //   * Add sync-root folder as active, dirty and needs_folder_listing
+      //     folder.
+      //   * Add app-root folders for each origins.  Each app-root folder for
+      //     an enabled origin should be a active, dirty and
+      //     needs_folder_listing folder.  And Each app-root folder for a
+      //     disabled origin should be an inactive, dirty and
+      //     non-needs_folder_listing folder.
+      //   * Add a file metadata for each file in previous version.
+      NOTIMPLEMENTED();
+      return SYNC_DATABASE_ERROR_FAILED;
+      // fall-through
+    case 3:
+      DCHECK_EQ(3, kCurrentDatabaseVersion);
+      return SYNC_STATUS_OK;
+    default:
+      return SYNC_DATABASE_ERROR_FAILED;
+  }
+}
+
+SyncStatusCode WriteVersionInfo(leveldb::DB* db) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  DCHECK(db);
+  return LevelDBStatusToSyncStatusCode(
+      db->Put(leveldb::WriteOptions(),
+              kDatabaseVersionKey,
+              base::Int64ToString(kCurrentDatabaseVersion)));
+}
+
+SyncStatusCode ReadDatabaseContents(leveldb::DB* db,
+                                    DatabaseContents* contents) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  DCHECK(db);
+  DCHECK(contents);
+
+  scoped_ptr<leveldb::Iterator> itr(db->NewIterator(leveldb::ReadOptions()));
+  for (itr->SeekToFirst(); itr->Valid(); itr->Next()) {
+    std::string key = itr->key().ToString();
+    std::string value = itr->value().ToString();
+    if (key == kServiceMetadataKey) {
+      scoped_ptr<ServiceMetadata> service_metadata(new ServiceMetadata);
+      if (!service_metadata->ParseFromString(value)) {
+        util::Log(logging::LOG_WARNING, FROM_HERE,
+                  "Failed to parse SyncServiceMetadata");
+        continue;
+      }
+
+      contents->service_metadata = service_metadata.Pass();
+      continue;
+    }
+
+    if (StartsWithASCII(key, kFileMetadataKeyPrefix, true)) {
+      std::string file_id = RemovePrefix(key, kFileMetadataKeyPrefix);
+
+      scoped_ptr<DriveFileMetadata> metadata(new DriveFileMetadata);
+      if (!metadata->ParseFromString(itr->value().ToString())) {
+        util::Log(logging::LOG_WARNING, FROM_HERE,
+                  "Failed to parse a Metadata");
+        continue;
+      }
+
+      contents->file_metadata.push_back(metadata.release());
+      continue;
+    }
+  }
+
+  return SYNC_STATUS_OK;
+}
+
+SyncStatusCode InitializeServiceMetadata(DatabaseContents* contents,
+                                         leveldb::WriteBatch* batch) {
+
+  if (!contents->service_metadata) {
+    contents->service_metadata.reset(new ServiceMetadata);
+
+    std::string value;
+    contents->service_metadata->SerializeToString(&value);
+    batch->Put(kServiceMetadataKey, value);
+  }
+  return SYNC_STATUS_OK;
+}
+
+SyncStatusCode RemoveUnreachableFiles(DatabaseContents* contents,
+                                      leveldb::WriteBatch* batch) {
+  FileByFileID unvisited_files;
+  FilesByParent files_by_parent;
+
+  for (ScopedVector<DriveFileMetadata>::iterator itr =
+           contents->file_metadata.begin();
+       itr != contents->file_metadata.end();
+       ++itr) {
+    DriveFileMetadata* metadata = *itr;
+    DCHECK(!ContainsKey(unvisited_files, metadata->file_id()));
+    unvisited_files[metadata->file_id()] = metadata;
+    files_by_parent[metadata->parent_folder_id()].insert(metadata);
+  }
+
+  // Traverse synced metadata tree. Take only active items and their children.
+  // Drop unreachable items.
+  ScopedVector<DriveFileMetadata> reachable_files;
+  std::stack<std::string> pending;
+  if (!contents->service_metadata->sync_root_folder_id().empty())
+    pending.push(contents->service_metadata->sync_root_folder_id());
+
+  while (!pending.empty()) {
+    std::string file_id = pending.top();
+    pending.pop();
+
+    {
+      FileByFileID::iterator found = unvisited_files.find(file_id);
+      if (found == unvisited_files.end())
+        continue;
+
+      DriveFileMetadata* metadata = found->second;
+      unvisited_files.erase(found);
+      reachable_files.push_back(metadata);
+
+      if (!metadata->active())
+        continue;
+    }
+
+    FilesByParent::iterator found = files_by_parent.find(file_id);
+    if (found == files_by_parent.end())
+      continue;
+
+    for (FileSet::const_iterator itr = found->second.begin();
+         itr != found->second.end();
+         ++itr)
+      pending.push((*itr)->file_id());
+  }
+
+  for (FileByFileID::iterator itr = unvisited_files.begin();
+       itr != unvisited_files.end();
+       ++itr) {
+    DriveFileMetadata* metadata = itr->second;
+    batch->Delete(metadata->file_id());
+    delete metadata;
+  }
+  unvisited_files.clear();
+
+  // |reachable_files| contains all files/folders reachable from sync-root
+  // folder via active folders.
+  contents->file_metadata.weak_clear();
+  contents->file_metadata.swap(reachable_files);
+
+  return SYNC_STATUS_OK;
+}
+
+template <typename Container, typename Key, typename Value>
+bool FindItem(const Container& container, const Key& key, Value* value) {
+  typename Container::const_iterator found = container.find(key);
+  if (found == container.end())
+    return false;
+  if (value)
+    *value = *found->second;
+  return true;
+}
+
+}  // namespace
+
+bool MetadataDatabase::FileIDComparator::operator()(DriveFileMetadata* left,
+                                                    DriveFileMetadata* right) {
+  return left->file_id() < right->file_id();
+}
+
+MetadataDatabase::MetadataDatabase(base::SequencedTaskRunner* task_runner)
+    : task_runner_(task_runner), weak_ptr_factory_(this) {
+  DCHECK(task_runner);
+}
+
+// static
+void MetadataDatabase::Create(base::SequencedTaskRunner* task_runner,
+                              const base::FilePath& database_path,
+                              const CreateCallback& callback) {
+  task_runner->PostTask(FROM_HERE, base::Bind(
+      &CreateOnTaskRunner,
+      base::MessageLoopProxy::current(),
+      make_scoped_refptr(task_runner),
+      database_path, callback));
 }
 
 int64 MetadataDatabase::GetLargestChangeID() const {
-  NOTIMPLEMENTED();
-  return 0;
+  return service_metadata_->largest_change_id();
 }
 
 void MetadataDatabase::RegisterApp(const std::string& app_id,
@@ -49,14 +322,12 @@ void MetadataDatabase::UnregisterApp(const std::string& app_id,
 
 bool MetadataDatabase::FindAppRootFolder(const std::string& app_id,
                                          DriveFileMetadata* folder) const {
-  NOTIMPLEMENTED();
-  return false;
+  return FindItem(app_root_by_app_id_, app_id, folder);
 }
 
 bool MetadataDatabase::FindFileByFileID(const std::string& file_id,
                                         DriveFileMetadata* metadata) const {
-  NOTIMPLEMENTED();
-  return false;
+  return FindItem(file_by_file_id_, file_id, metadata);
 }
 
 size_t MetadataDatabase::FindFilesByParentAndTitle(
@@ -71,19 +342,38 @@ bool MetadataDatabase::FindActiveFileByParentAndTitle(
     const std::string& folder_id,
     const std::string& title,
     DriveFileMetadata* file) const {
-  NOTIMPLEMENTED();
-  return false;
+  return FindItem(active_file_by_parent_and_title_,
+                  std::make_pair(folder_id, title),
+                  file);
 }
 
 bool MetadataDatabase::FindActiveFileByPath(const std::string& app_id,
                                             const base::FilePath& path,
                                             DriveFileMetadata* file) const {
-  NOTIMPLEMENTED();
-  return false;
+  DriveFileMetadata current;
+  if (!FindAppRootFolder(app_id, &current))
+    return false;
+
+  std::vector<base::FilePath::StringType> components;
+  path.GetComponents(&components);
+
+  std::string parent_folder_id = current.file_id();
+  for (std::vector<base::FilePath::StringType>::iterator itr =
+           components.begin();
+       itr != components.end();
+       ++itr) {
+    std::string current_folder_id = current.file_id();
+    if (!FindActiveFileByParentAndTitle(
+            current_folder_id, base::FilePath(*itr).AsUTF8Unsafe(), &current))
+      return false;
+  }
+  if (file)
+    *file = current;
+  return true;
 }
 
-bool MetadataDatabase::ConstructPathForFile(const std::string& file_id,
-                                            base::FilePath* path) const {
+bool MetadataDatabase::BuildPathForFile(const std::string& file_id,
+                                        base::FilePath* path) const {
   NOTIMPLEMENTED();
   return false;
 }
@@ -101,5 +391,108 @@ void MetadataDatabase::PopulateFolder(
   NOTIMPLEMENTED();
 }
 
+void MetadataDatabase::BuildIndexes(DatabaseContents* contents) {
+  for (ScopedVector<DriveFileMetadata>::iterator itr =
+           contents->file_metadata.begin();
+       itr != contents->file_metadata.end();
+       ++itr) {
+    DriveFileMetadata* file = *itr;
+    file_by_file_id_[file->file_id()] = file;
+
+    if (file->is_app_root())
+      app_root_by_app_id_[file->app_id()] = file;
+
+    if (file->active() && file->has_synced_details()) {
+      FileByParentAndTitle::key_type key =
+          std::make_pair(file->parent_folder_id(),
+                         file->synced_details().title());
+      active_file_by_parent_and_title_[key] = file;
+    }
+
+    if (!file->parent_folder_id().empty())
+      files_by_parent_[file->parent_folder_id()].insert(file);
+  }
+
+  contents->file_metadata.weak_clear();
+}
+
+void MetadataDatabase::CreateOnTaskRunner(
+    base::SingleThreadTaskRunner* callback_runner,
+    base::SequencedTaskRunner* task_runner,
+    const base::FilePath& database_path,
+    const CreateCallback& callback) {
+  scoped_ptr<MetadataDatabase> metadata_database(
+      new MetadataDatabase(task_runner));
+  SyncStatusCode status =
+      metadata_database->InitializeOnTaskRunner(database_path);
+  if (status != SYNC_STATUS_OK)
+    metadata_database.reset();
+
+  callback_runner->PostTask(FROM_HERE, base::Bind(
+      callback, status, base::Passed(&metadata_database)));
+}
+
+SyncStatusCode MetadataDatabase::InitializeOnTaskRunner(
+    const base::FilePath& database_path) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  DCHECK(task_runner_->RunsTasksOnCurrentThread());
+
+  SyncStatusCode status = SYNC_STATUS_UNKNOWN;
+  bool created = false;
+  status = OpenDatabase(database_path, &db_, &created);
+  if (status != SYNC_STATUS_OK)
+    return status;
+
+  if (created) {
+    status = WriteVersionInfo(db_.get());
+    if (status != SYNC_STATUS_OK)
+      return status;
+  } else {
+    status = MigrateDatabaseIfNeeded(db_.get());
+    if (status != SYNC_STATUS_OK)
+      return status;
+  }
+
+  DatabaseContents contents;
+  status = ReadDatabaseContents(db_.get(), &contents);
+  if (status != SYNC_STATUS_OK)
+    return status;
+
+  leveldb::WriteBatch batch;
+  status = InitializeServiceMetadata(&contents, &batch);
+  if (status != SYNC_STATUS_OK)
+    return status;
+
+  status = RemoveUnreachableFiles(&contents, &batch);
+  if (status != SYNC_STATUS_OK)
+    return status;
+
+  status = LevelDBStatusToSyncStatusCode(
+      db_->Write(leveldb::WriteOptions(), &batch));
+  if (status != SYNC_STATUS_OK)
+    return status;
+
+  BuildIndexes(&contents);
+  return status;
+}
+
+MetadataDatabase::~MetadataDatabase() {
+  task_runner_->DeleteSoon(FROM_HERE, db_.release());
+  STLDeleteContainerPairSecondPointers(
+      file_by_file_id_.begin(), file_by_file_id_.end());
+}
+
+void MetadataDatabase::WriteToDatabase(scoped_ptr<leveldb::WriteBatch> batch,
+                                       const SyncStatusCallback& callback) {
+  base::PostTaskAndReplyWithResult(
+      task_runner_.get(),
+      FROM_HERE,
+      base::Bind(&leveldb::DB::Write,
+                 base::Unretained(db_.get()),
+                 leveldb::WriteOptions(),
+                 base::Owned(batch.release())),
+      base::Bind(&AdaptLevelDBStatusToSyncStatusCode, callback));
+}
+
 }  // namespace drive_backend
 }  // namespace sync_file_system