Revert 164565 - sync: make scheduling logic and job ownership more obvious.

sync/engine/sync_session_job.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SYNC_ENGINE_SYNC_SESSION_JOB_H_
-#define SYNC_ENGINE_SYNC_SESSION_JOB_H_
-
-#include "base/memory/scoped_ptr.h"
-#include "base/time.h"
-#include "base/tracked_objects.h"
-#include "sync/engine/sync_scheduler.h"
-#include "sync/engine/syncer.h"
-#include "sync/sessions/sync_session.h"
-
-namespace syncer {
-
-class SyncSessionJob {
- public:
-  enum Purpose {
-    // Uninitialized state, should never be hit in practice.
-    UNKNOWN = -1,
-    // Our poll timer schedules POLL jobs periodically based on a server
-    // assigned poll interval.
-    POLL,
-    // A nudge task can come from a variety of components needing to force
-    // a sync.  The source is inferable from |session.source()|.
-    NUDGE,
-    // Typically used for fetching updates for a subset of the enabled types
-    // during initial sync or reconfiguration.
-    CONFIGURATION,
-  };
-
-  SyncSessionJob(Purpose purpose,
-                 base::TimeTicks start,
-                 scoped_ptr<sessions::SyncSession> session,
-                 const ConfigurationParams& config_params,
-                 const tracked_objects::Location& nudge_location);
-  ~SyncSessionJob();
-
-  // Returns a new clone of the job, with a cloned SyncSession ready to be
-  // retried / rescheduled.  The returned job will *never* be a canary,
-  // regardless of |this|. A job can only be cloned once it has finished,
-  // to prevent bugs where multiple jobs are scheduled with the same session.
-  // Use CloneAndAbandon if you want to clone before finishing.
-  scoped_ptr<SyncSessionJob> Clone() const;
-  scoped_ptr<SyncSessionJob> CloneFromLocation(
-      const tracked_objects::Location& from_here) const;
-
-  // Same as Clone() above, but also ejects the SyncSession from this job,
-  // preventing it from ever being used for a sync cycle.
-  scoped_ptr<SyncSessionJob> CloneAndAbandon();
-
-  // Record that the scheduler has deemed the job as finished and give it a
-  // chance to perform any remaining cleanup and/or notification completion
-  // callback invocations.
-  // |early_exit| specifies whether the job 1) cycled through all the
-  // SyncerSteps it needed, or 2) was pre-empted by the scheduler.
-  // Returns true if we completely ran the session without errors.
-  // There are many errors that could prevent a sync cycle from succeeding,
-  // such as invalid local state, inability to contact the server, inability
-  // to authenticate with the server, and server errors.  What they have in
-  // common is that the we either need to take some action and then retry the
-  // sync cycle or, in the case of transient errors, retry after some backoff
-  // timer has expired.  Most importantly, the SyncScheduler should not assume
-  // that the original action that triggered the sync cycle (ie. a nudge or a
-  // notification) has been properly serviced.
-  bool Finish(bool early_exit);
-
-  // Causes is_canary() to return true. Use with caution.
-  void GrantCanaryPrivilege();
-
-  static const char* GetPurposeString(Purpose purpose);
-  static void GetSyncerStepsForPurpose(Purpose purpose,
-                                       SyncerStep* start,
-                                       SyncerStep* end);
-
-  bool is_canary() const;
-  Purpose purpose() const;
-  base::TimeTicks scheduled_start() const;
-  void set_scheduled_start(base::TimeTicks start);
-  const sessions::SyncSession* session() const;
-  sessions::SyncSession* mutable_session();
-  const tracked_objects::Location& from_location() const;
-  SyncerStep start_step() const;
-  SyncerStep end_step() const;
-  ConfigurationParams config_params() const;
-
- private:
-  // A SyncSessionJob can be in one of these three states, controlled by the
-  // Finish() function, see method comments.
-  enum FinishedState {
-    NOT_FINISHED,  // Finish has not been called.
-    EARLY_EXIT,    // Finish was called but the job was "preempted",
-    FINISHED       // Indicates a "clean" finish operation.
-  };
-
-  scoped_ptr<sessions::SyncSession> CloneSession() const;
-
-  const Purpose purpose_;
-
-  base::TimeTicks scheduled_start_;
-  scoped_ptr<sessions::SyncSession> session_;
-  bool is_canary_;
-
-  // Only used for purpose_ == CONFIGURATION.  This, and different Finish() and
-  // Succeeded() behavior may be arguments to subclass in the future.
-  const ConfigurationParams config_params_;
-
-  // Set to true if Finish() was called, false otherwise. True implies that
-  // a SyncShare operation took place with |session_| and it cycled through
-  // all requisite steps given |purpose_| without being preempted.
-  FinishedState finished_;
-
-  // This is the location the job came from.  Used for debugging.
-  // In case of multiple nudges getting coalesced this stores the
-  // first location that came in.
-  tracked_objects::Location from_location_;
-
-  DISALLOW_COPY_AND_ASSIGN(SyncSessionJob);
-};
-
-}  // namespace syncer
-
-#endif  // SYNC_ENGINE_SYNC_SESSION_JOB_H_