sync/engine/syncer.h

   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 class CancelationSignal;
  25 class CommitProcessor;
  26 class GetUpdatesProcessor;
  27
  28 // A Syncer provides a control interface for driving the sync cycle.  These
  29 // cycles consist of downloading updates, parsing the response (aka. process
  30 // updates), applying updates while resolving conflicts, and committing local
  31 // changes.  Some of these steps may be skipped if they're deemed to be
  32 // unnecessary.
  33 //
  34 // A Syncer instance expects to run on a dedicated thread.  Calls to SyncShare()
  35 // may take an unbounded amount of time because it may block on network I/O, on
  36 // lock contention, or on tasks posted to other threads.
  37 class SYNC_EXPORT_PRIVATE Syncer {
  38  public:
  39   typedef std::vector<int64> UnsyncedMetaHandles;
  40
  41   Syncer(CancelationSignal* cancelation_signal);
  42   virtual ~Syncer();
  43
  44   // Whether an early exist was requested due to a cancelation signal.
  45   bool ExitRequested();
  46
  47   // Whether the syncer is in the middle of a sync cycle.
  48   bool IsSyncing() const;
  49
  50   // Fetches and applies updates, resolves conflicts and commits local changes
  51   // for |request_types| as necessary until client and server states are in
  52   // sync.  The |nudge_tracker| contains state that describes why the client is
  53   // out of sync and what must be done to bring it back into sync.
  54   // Returns: false if an error occurred and retries should backoff, true
  55   // otherwise.
  56   virtual bool NormalSyncShare(ModelTypeSet request_types,
  57                                sessions::NudgeTracker* nudge_tracker,
  58                                sessions::SyncSession* session);
  59
  60   // Performs an initial download for the |request_types|.  It is assumed that
  61   // the specified types have no local state, and that their associated change
  62   // processors are in "passive" mode, so none of the downloaded updates will be
  63   // applied to the model.  The |source| is sent up to the server for debug
  64   // purposes.  It describes the reson for performing this initial download.
  65   // Returns: false if an error occurred and retries should backoff, true
  66   // otherwise.
  67   virtual bool ConfigureSyncShare(
  68       ModelTypeSet request_types,
  69       sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source,
  70       sessions::SyncSession* session);
  71
  72   // Requests to download updates for the |request_types|.  For a well-behaved
  73   // client with a working connection to the invalidations server, this should
  74   // be unnecessary.  It may be invoked periodically to try to keep the client
  75   // in sync despite bugs or transient failures.
  76   // Returns: false if an error occurred and retries should backoff, true
  77   // otherwise.
  78   virtual bool PollSyncShare(ModelTypeSet request_types,
  79                              sessions::SyncSession* session);
  80
  81   // Posts a ClearServerData command.
  82   // Returns: false if an error occurred and retries should backoff, true
  83   // otherwise.
  84   virtual bool PostClearServerData(sessions::SyncSession* session);
  85
  86  private:
  87   friend class SyncerTest;
  88   FRIEND_TEST_ALL_PREFIXES(SyncerTest, NameClashWithResolver);
  89   FRIEND_TEST_ALL_PREFIXES(SyncerTest, IllegalAndLegalUpdates);
  90   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestCommitListOrderingAndNewParent);
  91   FRIEND_TEST_ALL_PREFIXES(SyncerTest,
  92                            TestCommitListOrderingAndNewParentAndChild);
  93   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestCommitListOrderingCounterexample);
  94   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestCommitListOrderingWithNesting);
  95   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestCommitListOrderingWithNewItems);
  96   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestGetUnsyncedAndSimpleCommit);
  97   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestPurgeWhileUnsynced);
  98   FRIEND_TEST_ALL_PREFIXES(SyncerTest, TestPurgeWhileUnapplied);
  99   FRIEND_TEST_ALL_PREFIXES(SyncerTest, UnappliedUpdateDuringCommit);
 100   FRIEND_TEST_ALL_PREFIXES(SyncerTest, DeletingEntryInFolder);
 101   FRIEND_TEST_ALL_PREFIXES(SyncerTest,
 102                            LongChangelistCreatesFakeOrphanedEntries);
 103   FRIEND_TEST_ALL_PREFIXES(SyncerTest, QuicklyMergeDualCreatedHierarchy);
 104   FRIEND_TEST_ALL_PREFIXES(SyncerTest, LongChangelistWithApplicationConflict);
 105   FRIEND_TEST_ALL_PREFIXES(SyncerTest, DeletingEntryWithLocalEdits);
 106   FRIEND_TEST_ALL_PREFIXES(EntryCreatedInNewFolderTest,
 107                            EntryCreatedInNewFolderMidSync);
 108
 109   bool DownloadAndApplyUpdates(
 110       ModelTypeSet* request_types,
 111       sessions::SyncSession* session,
 112       GetUpdatesProcessor* get_updates_processor,
 113       bool create_mobile_bookmarks_folder);
 114
 115   // This function will commit batches of unsynced items to the server until the
 116   // number of unsynced and ready to commit items reaches zero or an error is
 117   // encountered.  A request to exit early will be treated as an error and will
 118   // abort any blocking operations.
 119   SyncerError BuildAndPostCommits(ModelTypeSet request_types,
 120                                   sessions::NudgeTracker* nudge_tracker,
 121                                   sessions::SyncSession* session,
 122                                   CommitProcessor* commit_processor);
 123
 124   void HandleCycleBegin(sessions::SyncSession* session);
 125   bool HandleCycleEnd(
 126       sessions::SyncSession* session,
 127       sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source);
 128
 129   syncer::CancelationSignal* const cancelation_signal_;
 130
 131   // Whether the syncer is in the middle of a sync attempt.
 132   bool is_syncing_;
 133
 134   DISALLOW_COPY_AND_ASSIGN(Syncer);
 135 };
 136
 137 }  // namespace syncer
 138
 139 #endif  // SYNC_ENGINE_SYNCER_H_