sync/api/attachments/attachment_store.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_
   6 #define SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "sync/api/attachments/attachment.h"
  12 #include "sync/api/attachments/attachment_id.h"
  13 #include "sync/api/attachments/attachment_metadata.h"
  14 #include "sync/base/sync_export.h"
  15
  16 namespace base {
  17 class FilePath;
  18 class RefCountedMemory;
  19 class SequencedTaskRunner;
  20 }  // namespace base
  21
  22 namespace syncer {
  23
  24 class Attachment;
  25 class AttachmentId;
  26
  27 // A place to locally store and access Attachments.
  28 //
  29 // Destroying this object does not necessarily cancel outstanding async
  30 // operations. If you need cancel like semantics, use WeakPtr in the callbacks.
  31 class SYNC_EXPORT AttachmentStoreBase {
  32  public:
  33   // TODO(maniscalco): Consider udpating Read and Write methods to support
  34   // resumable transfers (bug 353292).
  35
  36   // The result status of an attachment store operation.
  37   // Do not re-order or delete these entries; they are used in a UMA histogram.
  38   enum Result {
  39     SUCCESS = 0,            // No error, all completed successfully.
  40     UNSPECIFIED_ERROR = 1,  // An unspecified error occurred for >= 1 item.
  41     STORE_INITIALIZATION_FAILED = 2,  // AttachmentStore initialization failed.
  42     // When adding a value here, you must increment RESULT_SIZE below.
  43   };
  44   const int RESULT_SIZE = 10; // Size of the Result enum; used for histograms.
  45
  46   typedef base::Callback<void(const Result&)> InitCallback;
  47   typedef base::Callback<void(const Result&,
  48                               scoped_ptr<AttachmentMap>,
  49                               scoped_ptr<AttachmentIdList>)> ReadCallback;
  50   typedef base::Callback<void(const Result&)> WriteCallback;
  51   typedef base::Callback<void(const Result&)> DropCallback;
  52   typedef base::Callback<void(const Result&,
  53                               scoped_ptr<AttachmentMetadataList>)>
  54       ReadMetadataCallback;
  55
  56   AttachmentStoreBase();
  57   virtual ~AttachmentStoreBase();
  58
  59   // Asynchronously initializes attachment store.
  60   //
  61   // This method should not be called by consumer of this interface. It is
  62   // called by factory methods in AttachmentStore class. When initialization is
  63   // complete |callback| is invoked with result, in case of failure result is
  64   // UNSPECIFIED_ERROR.
  65   virtual void Init(const InitCallback& callback) = 0;
  66
  67   // Asynchronously reads the attachments identified by |ids|.
  68   //
  69   // |callback| will be invoked when finished. AttachmentStore will attempt to
  70   // read all attachments specified in ids. If any of the attachments do not
  71   // exist or could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
  72   // Callback's AttachmentMap will contain all attachments that were
  73   // successfully read, AttachmentIdList will contain attachment ids of
  74   // attachments that are unavailable in attachment store, these need to be
  75   // downloaded from server.
  76   //
  77   // Reads on individual attachments are treated atomically; |callback| will not
  78   // read only part of an attachment.
  79   virtual void Read(const AttachmentIdList& ids,
  80                     const ReadCallback& callback) = 0;
  81
  82   // Asynchronously writes |attachments| to the store.
  83   //
  84   // Will not overwrite stored attachments. Attempting to overwrite an
  85   // attachment that already exists is not an error.
  86   //
  87   // |callback| will be invoked when finished. If any of the attachments could
  88   // not be written |callback|'s Result will be UNSPECIFIED_ERROR. When this
  89   // happens, some or none of the attachments may have been written
  90   // successfully.
  91   virtual void Write(const AttachmentList& attachments,
  92                      const WriteCallback& callback) = 0;
  93
  94   // Asynchronously drops |attchments| from this store.
  95   //
  96   // This does not remove attachments from the server.
  97   //
  98   // |callback| will be invoked when finished. Attempting to drop an attachment
  99   // that does not exist is not an error. If any of the existing attachment
 100   // could not be dropped, |callback|'s Result will be UNSPECIFIED_ERROR. When
 101   // this happens, some or none of the attachments may have been dropped
 102   // successfully.
 103   virtual void Drop(const AttachmentIdList& ids,
 104                     const DropCallback& callback) = 0;
 105
 106   // Asynchronously reads metadata for the attachments identified by |ids|.
 107   //
 108   // |callback| will be invoked when finished. AttachmentStore will attempt to
 109   // read metadata for all attachments specified in ids. If any of the
 110   // metadata entries do not exist or could not be read, |callback|'s Result
 111   // will be UNSPECIFIED_ERROR.
 112   virtual void ReadMetadata(const AttachmentIdList& ids,
 113                             const ReadMetadataCallback& callback) = 0;
 114
 115   // Asynchronously reads metadata for all attachments in the store.
 116   //
 117   // |callback| will be invoked when finished. If any of the metadata entries
 118   // could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
 119   virtual void ReadAllMetadata(const ReadMetadataCallback& callback) = 0;
 120 };
 121
 122 // AttachmentStore is an interface exposed to data type and AttachmentService
 123 // code. Also contains factory methods for default implementations.
 124 class SYNC_EXPORT AttachmentStore
 125     : public AttachmentStoreBase,
 126       public base::RefCountedThreadSafe<AttachmentStore> {
 127  public:
 128   AttachmentStore();
 129
 130   // Creates an AttachmentStoreHandle backed by in-memory implementation of
 131   // attachment store. For now frontend lives on the same thread as backend.
 132   static scoped_refptr<AttachmentStore> CreateInMemoryStore();
 133
 134   // Creates an AttachmentStoreHandle backed by on-disk implementation of
 135   // attachment store. Opens corresponding leveldb database located at |path|.
 136   // All backend operations are scheduled to |backend_task_runner|. Opening
 137   // attachment store is asynchronous, once it finishes |callback| will be
 138   // called on the thread that called CreateOnDiskStore. Calling Read/Write/Drop
 139   // before initialization completed is allowed.  Later if initialization fails
 140   // these operations will fail with STORE_INITIALIZATION_FAILED error.
 141   static scoped_refptr<AttachmentStore> CreateOnDiskStore(
 142       const base::FilePath& path,
 143       const scoped_refptr<base::SequencedTaskRunner>& backend_task_runner,
 144       const InitCallback& callback);
 145
 146  protected:
 147   friend class base::RefCountedThreadSafe<AttachmentStore>;
 148   ~AttachmentStore() override;
 149 };
 150
 151 }  // namespace syncer
 152
 153 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_