Implementation of OnDiskAttachmentStore.

sync/internal_api/attachments/on_disk_attachment_store.cc

+// Copyright 2014 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 "sync/internal_api/public/attachments/on_disk_attachment_store.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/location.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/sequenced_task_runner.h"
+#include "sync/protocol/attachments.pb.h"
+#include "third_party/leveldatabase/src/include/leveldb/db.h"
+#include "third_party/leveldatabase/src/include/leveldb/options.h"
+#include "third_party/leveldatabase/src/include/leveldb/slice.h"
+#include "third_party/leveldatabase/src/include/leveldb/status.h"
+
+namespace syncer {
+
+namespace {
+
+// Prefix for records containing attachment data.
+const char kDataPrefix[] = "data-";
+
+const base::FilePath::CharType kLeveldbDirectory[] =
+    FILE_PATH_LITERAL("leveldb");
+}  // namespace
+
+OnDiskAttachmentStore::OnDiskAttachmentStore(
+    const scoped_refptr<base::SequencedTaskRunner>& callback_task_runner)
+    : callback_task_runner_(callback_task_runner) {
+}
+
+OnDiskAttachmentStore::~OnDiskAttachmentStore() {
+}
+
+void OnDiskAttachmentStore::Read(const AttachmentIdList& ids,
+                                 const ReadCallback& callback) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(db_);
+  scoped_ptr<AttachmentMap> result_map(new AttachmentMap());
+  scoped_ptr<AttachmentIdList> unavailable_attachments(new AttachmentIdList());
+
+  leveldb::ReadOptions read_options;
+  // Attachment content is typically large and only read once. Don't cache it on
+  // db level.
+  read_options.fill_cache = false;
+  read_options.verify_checksums = true;
+
+  AttachmentIdList::const_iterator iter = ids.begin();
+  const AttachmentIdList::const_iterator end = ids.end();
+  for (; iter != end; ++iter) {
+    std::string key = CreateDataKeyFromAttachmentId(*iter);

[maniscalco, 2014/10/17 00:00:19]

Opportunity for const.

[pavely, 2014/10/17 00:13:25]

Done.

+    std::string data_str;
+    leveldb::Status status = db_->Get(read_options, key, &data_str);
+    if (!status.ok()) {
+      DVLOG(1) << "DB::Get failed: status=" << status.ToString();
+      unavailable_attachments->push_back(*iter);
+      continue;
+    }
+    scoped_refptr<base::RefCountedMemory> data =
+        base::RefCountedString::TakeString(&data_str);
+    Attachment attachment = Attachment::CreateWithId(*iter, data);
+    result_map->insert(std::make_pair(*iter, attachment));
+  }
+
+  Result result_code =
+      unavailable_attachments->empty() ? SUCCESS : UNSPECIFIED_ERROR;
+  callback_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(callback,
+                 result_code,
+                 base::Passed(&result_map),
+                 base::Passed(&unavailable_attachments)));
+}
+
+void OnDiskAttachmentStore::Write(const AttachmentList& attachments,
+                                  const WriteCallback& callback) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(db_);
+  Result result_code = SUCCESS;
+
+  leveldb::ReadOptions read_options;
+  read_options.fill_cache = false;
+  read_options.verify_checksums = true;
+
+  leveldb::WriteOptions write_options;
+  write_options.sync = true;
+
+  AttachmentList::const_iterator iter = attachments.begin();
+  const AttachmentList::const_iterator end = attachments.end();
+  for (; iter != end; ++iter) {

[maniscalco, 2014/10/17 00:00:19]

Opportunity for const.  I often wish automatic variables were const by default
:)

[pavely, 2014/10/17 00:13:25]

Done.

+    std::string key = CreateDataKeyFromAttachmentId(iter->GetId());
+
+    std::string data_str;
+    // TODO(pavely): crbug/424304 This read is expensive. When I add metadata
+    // records this read will target metadata record instead of payload record.
+    leveldb::Status status = db_->Get(read_options, key, &data_str);
+    if (status.ok()) {
+      // Entry exists, don't overwrite.
+      continue;
+    } else if (!status.IsNotFound()) {
+      // Entry exists but failed to read.
+      DVLOG(1) << "DB::Get failed: status=" << status.ToString();
+      result_code = UNSPECIFIED_ERROR;
+      continue;
+    }
+    DCHECK(status.IsNotFound());
+
+    scoped_refptr<base::RefCountedMemory> data = iter->GetData();
+    leveldb::Slice data_slice(data->front_as<char>(), data->size());
+    status = db_->Put(write_options, key, data_slice);
+    if (!status.ok()) {
+      // Failed to write.
+      DVLOG(1) << "DB::Put failed: status=" << status.ToString();
+      result_code = UNSPECIFIED_ERROR;
+    }
+  }
+  callback_task_runner_->PostTask(FROM_HERE, base::Bind(callback, result_code));
+}
+
+void OnDiskAttachmentStore::Drop(const AttachmentIdList& ids,
+                                 const DropCallback& callback) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(db_);
+  Result result_code = SUCCESS;
+  leveldb::WriteOptions write_options;
+  write_options.sync = true;
+  AttachmentIdList::const_iterator iter = ids.begin();
+  const AttachmentIdList::const_iterator end = ids.end();
+  for (; iter != end; ++iter) {
+    std::string key = CreateDataKeyFromAttachmentId(*iter);
+    leveldb::Status status = db_->Delete(write_options, key);
+    if (!status.ok()) {
+      // DB::Delete doesn't check if record exists, it returns ok just like
+      // AttachmentStore::Drop should.
+      DVLOG(1) << "DB::Delete failed: status=" << status.ToString();
+      result_code = UNSPECIFIED_ERROR;
+    }
+  }
+  callback_task_runner_->PostTask(FROM_HERE, base::Bind(callback, result_code));
+}
+
+AttachmentStore::Result OnDiskAttachmentStore::OpenOrCreate(
+    const base::FilePath& path) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(!db_);
+  Result result_code = UNSPECIFIED_ERROR;
+  base::FilePath leveldb_path = path.Append(kLeveldbDirectory);
+
+  leveldb::DB* db;
+  leveldb::Options options;
+  options.create_if_missing = true;
+  // TODO(pavely): crbug/424287 Consider adding info_log, block_cache and
+  // filter_policy to options.
+  leveldb::Status status =
+      leveldb::DB::Open(options, leveldb_path.AsUTF8Unsafe(), &db);
+  if (!status.ok()) {
+    DVLOG(1) << "DB::Open failed: status=" << status.ToString()
+             << ", path=" << path.AsUTF8Unsafe();
+  } else {
+    db_.reset(db);
+    result_code = SUCCESS;
+  }
+  return result_code;
+}
+
+std::string OnDiskAttachmentStore::CreateDataKeyFromAttachmentId(
+    const AttachmentId& attachment_id) {
+  std::string key = kDataPrefix + attachment_id.GetProto().unique_id();
+  return key;
+}
+
+}  // namespace syncer