sync: Handle POLL jobs in separate a code path

sync/engine/sync_scheduler_impl.h

 // Copyright 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_SCHEDULER_IMPL_H_
 #define SYNC_ENGINE_SYNC_SCHEDULER_IMPL_H_
 
 #include <map>
 #include <string>
 
@@ skipping 151 matching lines @@
   // Helpers that log before posting to |sync_loop_|.  These will only post
   // the task in between calls to Start/Stop.
   void PostTask(const tracked_objects::Location& from_here,
                 const char* name,
                 const base::Closure& task);
   void PostDelayedTask(const tracked_objects::Location& from_here,
                        const char* name,
                        const base::Closure& task,
                        base::TimeDelta delay);
 
-  // Helper to assemble a job and post a delayed task to sync.
-  void ScheduleSyncSessionJob(const tracked_objects::Location& loc,
-                              scoped_ptr<SyncSessionJob> job);
-
-  // Invoke the Syncer to perform a sync.
+  // Invoke the Syncer to perform a non-poll job.
   bool DoSyncSessionJob(scoped_ptr<SyncSessionJob> job,
                         JobPriority priority);
 
+  // Returns whether or not it's safe to run a poll job at this time.
+  bool ShouldPoll();
+
+  // Invoke the Syncer to perform a poll job.
+  void DoPollSyncSessionJob(scoped_ptr<SyncSessionJob> job);
+
   // Called after the Syncer has performed the sync represented by |job|, to
   // reset our state.  |exited_prematurely| is true if the Syncer did not
   // cycle from job.start_step() to job.end_step(), likely because the
   // scheduler was forced to quit the job mid-way through.
-  bool FinishSyncSessionJob(scoped_ptr<SyncSessionJob> job,
+  bool FinishSyncSessionJob(SyncSessionJob* job,
                             bool exited_prematurely);
 
-  // Helper to FinishSyncSessionJob to schedule the next sync operation.
-  // |succeeded| carries the return value of |old_job|->Finish.
-  void ScheduleNextSync(scoped_ptr<SyncSessionJob> finished_job,
-                        bool succeeded);
+  // Helper to schedule retries of a failed configure or nudge job.
+  void ScheduleNextSync(scoped_ptr<SyncSessionJob> finished_job);
 
   // Helper to configure polling intervals. Used by Start and ScheduleNextSync.
   void AdjustPolling(const SyncSessionJob* old_job);
 
   // Helper to restart waiting with |wait_interval_|'s timer.
   void RestartWaiting(scoped_ptr<SyncSessionJob> job);
 
   // Helper to ScheduleNextSync in case of consecutive sync errors.
   void HandleContinuationError(scoped_ptr<SyncSessionJob> old_job);
 
   // Decide whether we should CONTINUE, SAVE or DROP the job.
   JobProcessDecision DecideOnJob(const SyncSessionJob& job,
                                  JobPriority priority);
 
   // If DecideOnJob decides that |job| should be SAVEd, this function will
   // carry out the task of actually "saving" (or coalescing) the job.
   void HandleSaveJobDecision(scoped_ptr<SyncSessionJob> job);
 
   // Decide on whether to CONTINUE, SAVE or DROP the job when we are in
   // backoff mode.
   JobProcessDecision DecideWhileInWaitInterval(const SyncSessionJob& job,
                                                JobPriority priority);
 
   // 'Impl' here refers to real implementation of public functions, running on
   // |thread_|.
   void StopImpl(const base::Closure& callback);
+
+  // If the scheduler's current state supports it, this will create a job based
+  // on the passed in parameters and coalesce it with any other pending jobs,
+  // then post a delayed task to run it.  It may also choose to drop the job or
+  // save it for later, depending on the scheduler's current state.
   void ScheduleNudgeImpl(
       const base::TimeDelta& delay,
       sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source,
       const ModelTypeInvalidationMap& invalidation_map,
       const tracked_objects::Location& nudge_location);
 
   // Returns true if the client is currently in exponential backoff.
   bool IsBackingOff() const;
 
   // Helper to signal all listeners registered with |session_context_|.
@@ skipping 109 matching lines @@
   // take place during a sync cycle. We call this out because such violations
   // could result in tight sync loops hitting sync servers.
   bool no_scheduling_allowed_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncSchedulerImpl);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_SYNC_SCHEDULER_IMPL_H_