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// 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.
#ifndef SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_
#define SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_
#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "sync/api/attachments/attachment.h"
#include "sync/api/attachments/attachment_id.h"
#include "sync/api/attachments/attachment_metadata.h"
#include "sync/base/sync_export.h"
namespace base {
class FilePath;
class SequencedTaskRunner;
} // namespace base
namespace syncer {
class AttachmentStoreBackend;
class AttachmentStoreForSync;
class AttachmentStoreFrontend;
// AttachmentStore is a place to locally store and access Attachments.
//
// AttachmentStore class is an interface exposed to data type and
// AttachmentService code.
// It also contains factory methods for default attachment store
// implementations.
// Destroying this object does not necessarily cancel outstanding async
// operations. If you need cancel like semantics, use WeakPtr in the callbacks.
class SYNC_EXPORT AttachmentStore {
public:
// TODO(maniscalco): Consider udpating Read and Write methods to support
// resumable transfers (bug 353292).
// The result status of an attachment store operation.
// Do not re-order or delete these entries; they are used in a UMA histogram.
enum Result {
SUCCESS = 0, // No error, all completed successfully.
UNSPECIFIED_ERROR = 1, // An unspecified error occurred for >= 1 item.
STORE_INITIALIZATION_FAILED = 2, // AttachmentStore initialization failed.
// When adding a value here, you must increment RESULT_SIZE below.
};
static const int RESULT_SIZE =
10; // Size of the Result enum; used for histograms.
// Each attachment can have references from sync or model type. Tracking these
// references is needed for lifetime management of attachment, it can only be
// deleted from the store when it doesn't have references.
enum Component {
MODEL_TYPE,
SYNC,
};
typedef base::Callback<void(const Result&)> InitCallback;
typedef base::Callback<void(const Result&,
scoped_ptr<AttachmentMap>,
scoped_ptr<AttachmentIdList>)> ReadCallback;
typedef base::Callback<void(const Result&)> WriteCallback;
typedef base::Callback<void(const Result&)> DropCallback;
typedef base::Callback<void(const Result&,
scoped_ptr<AttachmentMetadataList>)>
ReadMetadataCallback;
~AttachmentStore();
// Asynchronously reads the attachments identified by |ids|.
//
// |callback| will be invoked when finished. AttachmentStore will attempt to
// read all attachments specified in ids. If any of the attachments do not
// exist or could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
// Callback's AttachmentMap will contain all attachments that were
// successfully read, AttachmentIdList will contain attachment ids of
// attachments that are unavailable in attachment store, these need to be
// downloaded from server.
//
// Reads on individual attachments are treated atomically; |callback| will not
// read only part of an attachment.
void Read(const AttachmentIdList& ids, const ReadCallback& callback);
// Asynchronously writes |attachments| to the store.
//
// Will not overwrite stored attachments. Attempting to overwrite an
// attachment that already exists is not an error.
//
// |callback| will be invoked when finished. If any of the attachments could
// not be written |callback|'s Result will be UNSPECIFIED_ERROR. When this
// happens, some or none of the attachments may have been written
// successfully.
void Write(const AttachmentList& attachments, const WriteCallback& callback);
// Asynchronously drops |attchments| from this store.
//
// This does not remove attachments from the server.
//
// |callback| will be invoked when finished. Attempting to drop an attachment
// that does not exist is not an error. If any of the existing attachment
// could not be dropped, |callback|'s Result will be UNSPECIFIED_ERROR. When
// this happens, some or none of the attachments may have been dropped
// successfully.
void Drop(const AttachmentIdList& ids, const DropCallback& callback);
// Asynchronously reads metadata for the attachments identified by |ids|.
//
// |callback| will be invoked when finished. AttachmentStore will attempt to
// read metadata for all attachments specified in ids. If any of the
// metadata entries do not exist or could not be read, |callback|'s Result
// will be UNSPECIFIED_ERROR.
void ReadMetadataById(const AttachmentIdList& ids,
const ReadMetadataCallback& callback);
// Asynchronously reads metadata for all attachments with |component_|
// reference in the store.
//
// |callback| will be invoked when finished. If any of the metadata entries
// could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
void ReadMetadata(const ReadMetadataCallback& callback);
// Given current AttachmentStore (this) creates separate AttachmentStore that
// will be used by sync components (AttachmentService). Resulting
// AttachmentStore is backed by the same frontend/backend.
scoped_ptr<AttachmentStoreForSync> CreateAttachmentStoreForSync() const;
// Creates an AttachmentStore backed by in-memory implementation of attachment
// store. For now frontend lives on the same thread as backend.
static scoped_ptr<AttachmentStore> CreateInMemoryStore();
// Creates an AttachmentStore backed by on-disk implementation of attachment
// store. Opens corresponding leveldb database located at |path|. All backend
// operations are scheduled to |backend_task_runner|. Opening attachment store
// is asynchronous, once it finishes |callback| will be called on the thread
// that called CreateOnDiskStore. Calling Read/Write/Drop before
// initialization completed is allowed. Later if initialization fails these
// operations will fail with STORE_INITIALIZATION_FAILED error.
static scoped_ptr<AttachmentStore> CreateOnDiskStore(
const base::FilePath& path,
const scoped_refptr<base::SequencedTaskRunner>& backend_task_runner,
const InitCallback& callback);
// Creates set of AttachmentStore/AttachmentStoreFrontend instances for tests
// that provide their own implementation of AttachmentstoreBackend for
// mocking.
static scoped_ptr<AttachmentStore> CreateMockStoreForTest(
scoped_ptr<AttachmentStoreBackend> backend);
protected:
AttachmentStore(const scoped_refptr<AttachmentStoreFrontend>& frontend,
Component component);
const scoped_refptr<AttachmentStoreFrontend>& frontend() { return frontend_; }
Component component() const { return component_; }
private:
scoped_refptr<AttachmentStoreFrontend> frontend_;
// Modification operations with attachment store will be performed on behalf
// of |component_|.
const Component component_;
DISALLOW_COPY_AND_ASSIGN(AttachmentStore);
};
// AttachmentStoreForSync extends AttachmentStore and provides additional
// functions necessary for AttachmentService. These are needed when
// AttachmentService writes attachment on behalf of model type after download
// and takes reference on attachment for the duration of upload.
// Model type implementation shouldn't use this interface.
class SYNC_EXPORT_PRIVATE AttachmentStoreForSync : public AttachmentStore {
public:
~AttachmentStoreForSync();
// Asynchronously adds reference from sync to attachments.
void SetSyncReference(const AttachmentIdList& ids);
// Asynchronously adds reference from model type to attachments.
// Needed in GetOrDownloadAttachments when attachment is in local store but
// doesn't have model type reference.
void SetModelTypeReference(const AttachmentIdList& ids);
// Asynchronously drops sync reference from attachments.
void DropSyncReference(const AttachmentIdList& ids);
// Asynchronously reads metadata for all attachments with |sync_component_|
// reference in the store.
//
// |callback| will be invoked when finished. If any of the metadata entries
// could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
void ReadMetadataForSync(const ReadMetadataCallback& callback);
private:
friend class AttachmentStore;
AttachmentStoreForSync(const scoped_refptr<AttachmentStoreFrontend>& frontend,
Component consumer_component,
Component sync_component);
// |sync_component_| is passed to frontend when sync related operations are
// perfromed.
const Component sync_component_;
DISALLOW_COPY_AND_ASSIGN(AttachmentStoreForSync);
};
} // namespace syncer
#endif // SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_