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Side by Side Diff: sync/engine/sync_session_job.h

Issue 10917234: sync: make scheduling logic and job ownership more obvious. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: address review Created 8 years, 1 month ago
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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_SYNC_SESSION_JOB_H_
6 #define SYNC_ENGINE_SYNC_SESSION_JOB_H_
7
8 #include "base/memory/scoped_ptr.h"
9 #include "base/time.h"
10 #include "base/tracked_objects.h"
11 #include "sync/engine/sync_scheduler.h"
12 #include "sync/engine/syncer.h"
13 #include "sync/sessions/sync_session.h"
14
15 namespace syncer {
16
17 class SyncSessionJob {
18 public:
19 enum Purpose {
20 // Uninitialized state, should never be hit in practice.
21 UNKNOWN = -1,
22 // Our poll timer schedules POLL jobs periodically based on a server
23 // assigned poll interval.
24 POLL,
25 // A nudge task can come from a variety of components needing to force
26 // a sync. The source is inferable from |session.source()|.
27 NUDGE,
28 // Typically used for fetching updates for a subset of the enabled types
29 // during initial sync or reconfiguration.
30 CONFIGURATION,
31 };
32
33 SyncSessionJob(Purpose purpose,
34 base::TimeTicks start,
35 scoped_ptr<sessions::SyncSession> session,
36 const ConfigurationParams& config_params,
37 const tracked_objects::Location& nudge_location);
38 ~SyncSessionJob();
39
40 // Returns a new clone of the job, with a cloned SyncSession ready to be
41 // retried / rescheduled. The returned job will *never* be a canary,
42 // regardless of |this|. A job can only be cloned once it has finished,
43 // to prevent bugs where multiple jobs are scheduled with the same session.
44 // Use CloneAndAbandon if you want to clone before finishing.
45 scoped_ptr<SyncSessionJob> Clone() const;
46 scoped_ptr<SyncSessionJob> CloneFromLocation(
47 const tracked_objects::Location& from_here) const;
48
49 // Same as Clone() above, but also ejects the SyncSession from this job,
50 // preventing it from ever being used for a sync cycle.
51 scoped_ptr<SyncSessionJob> CloneAndAbandon();
52
53 // Record that the scheduler has deemed the job as finished and give it a
54 // chance to perform any remaining cleanup and/or notification completion
55 // callback invocations.
56 // |early_exit| specifies whether the job 1) cycled through all the
57 // SyncerSteps it needed, or 2) was pre-empted by the scheduler.
58 // Returns true if we completely ran the session without errors.
59 // There are many errors that could prevent a sync cycle from succeeding,
60 // such as invalid local state, inability to contact the server, inability
61 // to authenticate with the server, and server errors. What they have in
62 // common is that the we either need to take some action and then retry the
63 // sync cycle or, in the case of transient errors, retry after some backoff
64 // timer has expired. Most importantly, the SyncScheduler should not assume
65 // that the original action that triggered the sync cycle (ie. a nudge or a
66 // notification) has been properly serviced.
67 bool Finish(bool early_exit);
68
69 // Causes is_canary() to return true. Use with caution.
70 void GrantCanaryPrivilege();
71
72 static const char* GetPurposeString(Purpose purpose);
73 static void GetSyncerStepsForPurpose(Purpose purpose,
74 SyncerStep* start,
75 SyncerStep* end);
76
77 bool is_canary() const;
78 Purpose purpose() const;
79 base::TimeTicks scheduled_start() const;
80 void set_scheduled_start(base::TimeTicks start);
81 const sessions::SyncSession* session() const;
82 sessions::SyncSession* mutable_session();
83 const tracked_objects::Location& from_location() const;
84 SyncerStep start_step() const;
85 SyncerStep end_step() const;
86 ConfigurationParams config_params() const;
87
88 private:
89 // A SyncSessionJob can be in one of these three states, controlled by the
90 // Finish() function, see method comments.
91 enum FinishedState {
92 NOT_FINISHED, // Finish has not been called.
93 EARLY_EXIT, // Finish was called but the job was "preempted",
94 FINISHED // Indicates a "clean" finish operation.
95 };
96
97 scoped_ptr<sessions::SyncSession> CloneSession() const;
98
99 const Purpose purpose_;
100
101 base::TimeTicks scheduled_start_;
102 scoped_ptr<sessions::SyncSession> session_;
103 bool is_canary_;
104
105 // Only used for purpose_ == CONFIGURATION. This, and different Finish() and
106 // Succeeded() behavior may be arguments to subclass in the future.
107 const ConfigurationParams config_params_;
108
109 // Set to true if Finish() was called, false otherwise. True implies that
110 // a SyncShare operation took place with |session_| and it cycled through
111 // all requisite steps given |purpose_| without being preempted.
112 FinishedState finished_;
113
114 // This is the location the job came from. Used for debugging.
115 // In case of multiple nudges getting coalesced this stores the
116 // first location that came in.
117 tracked_objects::Location from_location_;
118
119 DISALLOW_COPY_AND_ASSIGN(SyncSessionJob);
120 };
121
122 } // namespace syncer
123
124 #endif // SYNC_ENGINE_SYNC_SESSION_JOB_H_
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