sync_session.h revision 4e180b6a0b4720a9b8e9e959a882386f690f08ff 
1// Copyright 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// A class representing an attempt to synchronize the local syncable data
6// store with a sync server. A SyncSession instance is passed as a stateful
7// bundle to and from various SyncerCommands with the goal of converging the
8// client view of data with that of the server. The commands twiddle with
9// session status in response to events and hiccups along the way, set and
10// query session progress with regards to conflict resolution and applying
11// server updates, and access the SyncSessionContext for the current session
12// via SyncSession instances.
13
14#ifndef SYNC_SESSIONS_SYNC_SESSION_H_
15#define SYNC_SESSIONS_SYNC_SESSION_H_
16
17#include <map>
18#include <set>
19#include <string>
20#include <utility>
21#include <vector>
22
23#include "base/basictypes.h"
24#include "base/memory/scoped_ptr.h"
25#include "base/time/time.h"
26#include "sync/base/sync_export.h"
27#include "sync/internal_api/public/base/model_type.h"
28#include "sync/internal_api/public/engine/model_safe_worker.h"
29#include "sync/internal_api/public/sessions/sync_session_snapshot.h"
30#include "sync/sessions/status_controller.h"
31#include "sync/sessions/sync_session_context.h"
32
33namespace syncer {
34class ModelSafeWorker;
35
36namespace sessions {
37
38class NudgeTracker;
39
40class SYNC_EXPORT_PRIVATE SyncSession {
41 public:
42  // The Delegate services events that occur during the session requiring an
43  // explicit (and session-global) action, as opposed to events that are simply
44  // recorded in per-session state.
45  class SYNC_EXPORT_PRIVATE Delegate {
46   public:
47    // The client was throttled and should cease-and-desist syncing activity
48    // until the specified time.
49    virtual void OnThrottled(const base::TimeDelta& throttle_duration) = 0;
50
51    // Some of the client's types were throttled.
52    virtual void OnTypesThrottled(
53        ModelTypeSet types,
54        const base::TimeDelta& throttle_duration) = 0;
55
56    // Silenced intervals can be out of phase with individual sessions, so the
57    // delegate is the only thing that can give an authoritative answer for
58    // "is syncing silenced right now". This shouldn't be necessary very often
59    // as the delegate ensures no session is started if syncing is silenced.
60    // ** Note **  This will return true if silencing commenced during this
61    // session and the interval has not yet elapsed, but the contract here is
62    // solely based on absolute time values. So, this cannot be used to infer
63    // that any given session _instance_ is silenced.  An example of reasonable
64    // use is for UI reporting.
65    virtual bool IsCurrentlyThrottled() = 0;
66
67    // The client has been instructed to change its short poll interval.
68    virtual void OnReceivedShortPollIntervalUpdate(
69        const base::TimeDelta& new_interval) = 0;
70
71    // The client has been instructed to change its long poll interval.
72    virtual void OnReceivedLongPollIntervalUpdate(
73        const base::TimeDelta& new_interval) = 0;
74
75    // The client has been instructed to change its sessions commit
76    // delay.
77    virtual void OnReceivedSessionsCommitDelay(
78        const base::TimeDelta& new_delay) = 0;
79
80    // The client needs to cease and desist syncing at once.  This occurs when
81    // the Syncer detects that the backend store has fundamentally changed or
82    // is a different instance altogether (e.g. swapping from a test instance
83    // to production, or a global stop syncing operation has wiped the store).
84    // TODO(lipalani) : Replace this function with the one below. This function
85    // stops the current sync cycle and purges the client. In the new model
86    // the former would be done by the |SyncProtocolError| and
87    // the latter(which is an action) would be done in ProfileSyncService
88    // along with the rest of the actions.
89    virtual void OnShouldStopSyncingPermanently() = 0;
90
91    // Called for the syncer to respond to the error sent by the server.
92    virtual void OnSyncProtocolError(
93        const sessions::SyncSessionSnapshot& snapshot) = 0;
94
95    // Called when the server wants to change the number of hints the client
96    // will buffer locally.
97    virtual void OnReceivedClientInvalidationHintBufferSize(int size) = 0;
98
99   protected:
100    virtual ~Delegate() {}
101  };
102
103  // Build a session without a nudge tracker.  Used for poll or configure type
104  // sync cycles.
105  static SyncSession* Build(SyncSessionContext* context,
106                            Delegate* delegate);
107  ~SyncSession();
108
109  // Builds a thread-safe and read-only copy of the current session state.
110  SyncSessionSnapshot TakeSnapshot() const;
111  SyncSessionSnapshot TakeSnapshotWithSource(
112      sync_pb::GetUpdatesCallerInfo::GetUpdatesSource legacy_updates_source)
113      const;
114
115  // Builds and sends a snapshot to the session context's listeners.
116  void SendSyncCycleEndEventNotification(
117      sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source);
118  void SendEventNotification(SyncEngineEvent::EventCause cause);
119
120  // TODO(akalin): Split this into context() and mutable_context().
121  SyncSessionContext* context() const { return context_; }
122  Delegate* delegate() const { return delegate_; }
123  const StatusController& status_controller() const {
124    return *status_controller_.get();
125  }
126  StatusController* mutable_status_controller() {
127    return status_controller_.get();
128  }
129
130 private:
131  SyncSession(SyncSessionContext* context, Delegate* delegate);
132
133  // The context for this session, guaranteed to outlive |this|.
134  SyncSessionContext* const context_;
135
136  // The delegate for this session, must never be NULL.
137  Delegate* const delegate_;
138
139  // Our controller for various status and error counters.
140  scoped_ptr<StatusController> status_controller_;
141
142  DISALLOW_COPY_AND_ASSIGN(SyncSession);
143};
144
145}  // namespace sessions
146}  // namespace syncer
147
148#endif  // SYNC_SESSIONS_SYNC_SESSION_H_
149