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      1 // Copyright (c) 2012 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_ENGINE_SYNCER_H_
      6 #define SYNC_ENGINE_SYNCER_H_
      7 
      8 #include <utility>
      9 #include <vector>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/callback.h"
     13 #include "base/gtest_prod_util.h"
     14 #include "base/synchronization/lock.h"
     15 #include "sync/base/sync_export.h"
     16 #include "sync/engine/conflict_resolver.h"
     17 #include "sync/engine/syncer_types.h"
     18 #include "sync/internal_api/public/base/model_type.h"
     19 #include "sync/sessions/sync_session.h"
     20 #include "sync/util/extensions_activity.h"
     21 
     22 namespace syncer {
     23 
     24 // A Syncer provides a control interface for driving the individual steps
     25 // of the sync cycle.  Each cycle (hopefully) moves the client into closer
     26 // synchronization with the server.  The individual steps are modeled
     27 // as SyncerCommands, and the ordering of the steps is expressed using
     28 // the SyncerStep enum.
     29 //
     30 // A Syncer instance expects to run on a dedicated thread.  Calls
     31 // to SyncShare() may take an unbounded amount of time, as SyncerCommands
     32 // may block on network i/o, on lock contention, or on tasks posted to
     33 // other threads.
     34 class SYNC_EXPORT_PRIVATE Syncer {
     35  public:
     36   typedef std::vector<int64> UnsyncedMetaHandles;
     37 
     38   Syncer();
     39   virtual ~Syncer();
     40 
     41   // Called by other threads to tell the syncer to stop what it's doing
     42   // and return early from SyncShare, if possible.
     43   bool ExitRequested();
     44   void RequestEarlyExit();
     45 
     46   // Fetches and applies updates, resolves conflicts and commits local changes
     47   // for |request_types| as necessary until client and server states are in
     48   // sync.  The |nudge_tracker| contains state that describes why the client is
     49   // out of sync and what must be done to bring it back into sync.
     50   virtual bool NormalSyncShare(ModelTypeSet request_types,
     51                                const sessions::NudgeTracker& nudge_tracker,
     52                                sessions::SyncSession* session);
     53 
     54   // Performs an initial download for the |request_types|.  It is assumed that
     55   // the specified types have no local state, and that their associated change
     56   // processors are in "passive" mode, so none of the downloaded updates will be
     57   // applied to the model.  The |source| is sent up to the server for debug
     58   // purposes.  It describes the reson for performing this initial download.
     59   virtual bool ConfigureSyncShare(
     60       ModelTypeSet request_types,
     61       sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source,
     62       sessions::SyncSession* session);
     63 
     64   // Requests to download updates for the |request_types|.  For a well-behaved
     65   // client with a working connection to the invalidations server, this should
     66   // be unnecessary.  It may be invoked periodically to try to keep the client
     67   // in sync despite bugs or transient failures.
     68   virtual bool PollSyncShare(ModelTypeSet request_types,
     69                              sessions::SyncSession* session);
     70 
     71  private:
     72   void ApplyUpdates(sessions::SyncSession* session);
     73   bool DownloadAndApplyUpdates(
     74       sessions::SyncSession* session,
     75       base::Callback<SyncerError(void)> download_fn);
     76 
     77   void HandleCycleBegin(sessions::SyncSession* session);
     78   bool HandleCycleEnd(
     79       sessions::SyncSession* session,
     80       sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source);
     81 
     82   bool early_exit_requested_;
     83   base::Lock early_exit_requested_lock_;
     84 
     85   friend class SyncerTest;
     86   FRIEND_TEST_ALL_PREFIXES(SyncerTest, NameClashWithResolver);
     87   FRIEND_TEST_ALL_PREFIXES(SyncerTest, IllegalAndLegalUpdates);
     88   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestCommitListOrderingAndNewParent);
     89   FRIEND_TEST_ALL_PREFIXES(SyncerTest,
     90                            TestCommitListOrderingAndNewParentAndChild);
     91   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestCommitListOrderingCounterexample);
     92   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestCommitListOrderingWithNesting);
     93   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestCommitListOrderingWithNewItems);
     94   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestGetUnsyncedAndSimpleCommit);
     95   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestPurgeWhileUnsynced);
     96   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestPurgeWhileUnapplied);
     97   FRIEND_TEST_ALL_PREFIXES(SyncerTest, UnappliedUpdateDuringCommit);
     98   FRIEND_TEST_ALL_PREFIXES(SyncerTest, DeletingEntryInFolder);
     99   FRIEND_TEST_ALL_PREFIXES(SyncerTest,
    100                            LongChangelistCreatesFakeOrphanedEntries);
    101   FRIEND_TEST_ALL_PREFIXES(SyncerTest, QuicklyMergeDualCreatedHierarchy);
    102   FRIEND_TEST_ALL_PREFIXES(SyncerTest, LongChangelistWithApplicationConflict);
    103   FRIEND_TEST_ALL_PREFIXES(SyncerTest, DeletingEntryWithLocalEdits);
    104   FRIEND_TEST_ALL_PREFIXES(EntryCreatedInNewFolderTest,
    105                            EntryCreatedInNewFolderMidSync);
    106 
    107   DISALLOW_COPY_AND_ASSIGN(Syncer);
    108 };
    109 
    110 }  // namespace syncer
    111 
    112 #endif  // SYNC_ENGINE_SYNCER_H_
    113