sync: Finish the SyncScheduler refactor

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>
 
 #include "base/callback.h"
 #include "base/cancelable_callback.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time.h"
 #include "base/timer.h"
 #include "sync/base/sync_export.h"
 #include "sync/engine/net/server_connection_manager.h"
 #include "sync/engine/nudge_source.h"
 #include "sync/engine/sync_scheduler.h"
-#include "sync/engine/sync_session_job.h"
 #include "sync/engine/syncer.h"
 #include "sync/internal_api/public/base/model_type_invalidation_map.h"
 #include "sync/internal_api/public/engine/polling_constants.h"
 #include "sync/internal_api/public/util/weak_handle.h"
+#include "sync/sessions/nudge_tracker.h"
 #include "sync/sessions/sync_session.h"
 #include "sync/sessions/sync_session_context.h"
 
 namespace syncer {
 
 class BackoffDelayProvider;
 
+namespace sessions {
+struct ModelNeutralState;
+}
+
 class SYNC_EXPORT_PRIVATE SyncSchedulerImpl
     : public SyncScheduler,
       public base::NonThreadSafe {
  public:
   // |name| is a display string to identify the syncer thread.  Takes
   // |ownership of |syncer| and |delay_provider|.
   SyncSchedulerImpl(const std::string& name,
                     BackoffDelayProvider* delay_provider,
                     sessions::SyncSessionContext* context,
                     Syncer* syncer);
@@ skipping 29 matching lines @@
       const base::TimeDelta& new_interval) OVERRIDE;
   virtual void OnReceivedLongPollIntervalUpdate(
       const base::TimeDelta& new_interval) OVERRIDE;
   virtual void OnReceivedSessionsCommitDelay(
       const base::TimeDelta& new_delay) OVERRIDE;
   virtual void OnShouldStopSyncingPermanently() OVERRIDE;
   virtual void OnSyncProtocolError(
       const sessions::SyncSessionSnapshot& snapshot) OVERRIDE;
 
  private:
-  enum JobProcessDecision {
-    // Indicates we should continue with the current job.
-    CONTINUE,
-    // Indicates that we should save it to be processed later.
-    SAVE,
-    // Indicates we should drop this job.
-    DROP,
-  };
-
   enum JobPriority {
     // Non-canary jobs respect exponential backoff.
     NORMAL_PRIORITY,
     // Canary jobs bypass exponential backoff, so use with extreme caution.
     CANARY_PRIORITY
   };
 
+  enum PollAdjustType {
+    // Restart the poll interval.
+    FORCE_RESET,
+    // Restart the poll interval only if its length has changed.
+    UPDATE_INTERVAL,
+  };
+
   friend class SyncSchedulerTest;
   friend class SyncSchedulerWhiteboxTest;
   friend class SyncerTest;
 
+  FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest, NoNudgesInConfigureMode);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest,
       DropNudgeWhileExponentialBackOff);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest, SaveNudge);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest,
                            SaveNudgeWhileTypeThrottled);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest, ContinueNudge);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest, ContinueConfiguration);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest,
                            SaveConfigurationWhileThrottled);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest,
@@ skipping 22 matching lines @@
     WaitInterval(Mode mode, base::TimeDelta length);
 
     static const char* GetModeString(Mode mode);
 
     Mode mode;
     base::TimeDelta length;
   };
 
   static const char* GetModeString(Mode mode);
 
-  static const char* GetDecisionString(JobProcessDecision decision);
-
-  // Invoke the syncer to perform a non-POLL job.
-  bool DoSyncSessionJobImpl(scoped_ptr<SyncSessionJob> job,
-                            JobPriority priority);
-
   // Invoke the syncer to perform a nudge job.
   void DoNudgeSyncSessionJob(JobPriority priority);
 
   // Invoke the syncer to perform a configuration job.
   bool DoConfigurationSyncSessionJob(JobPriority priority);
 
-  // Returns whether or not it's safe to run a poll job at this time.
-  bool ShouldPoll();
+  // Helper function for Do{Nudge,Configuration}SyncSessionJob.
+  void HandleFailure(
+      const sessions::ModelNeutralState& model_neutral_state);
 
   // Invoke the Syncer to perform a poll job.
   void DoPollSyncSessionJob();
 
-  // 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(SyncSessionJob* job,
-                            bool exited_prematurely,
-                            sessions::SyncSession* session);
-
-  // Helper to schedule retries of a failed configure or nudge job.
-  void ScheduleNextSync(scoped_ptr<SyncSessionJob> finished_job,
-                        sessions::SyncSession* session);
-
-  // Helper to configure polling intervals. Used by Start and ScheduleNextSync.
-  void AdjustPolling(const SyncSessionJob* old_job);
+  // Adjusts the poll timer to account for new poll interval, and possibly
+  // resets the poll interval, depedning on the flag's value.
+  void AdjustPolling(PollAdjustType type);
 
   // Helper to restart waiting with |wait_interval_|'s timer.
   void RestartWaiting();
 
-  // Helper to ScheduleNextSync in case of consecutive sync errors.
-  void HandleContinuationError(scoped_ptr<SyncSessionJob> old_job,
-                               sessions::SyncSession* session);
+  // Helper to adjust our wait interval when we expereince a transient failure.
+  void UpdateExponentialBackoff(
+      const sessions::ModelNeutralState& model_neutral_state);
 
-  // Decide whether we should CONTINUE, SAVE or DROP the job.
-  JobProcessDecision DecideOnJob(const SyncSessionJob& job,
-                                 JobPriority priority);
+  // Determines if we're allowed to contact the server right now.
+  bool CanRunJobNow(JobPriority priority);
 
-  // Decide on whether to CONTINUE, SAVE or DROP the job when we are in
-  // backoff mode.
-  JobProcessDecision DecideWhileInWaitInterval(const SyncSessionJob& job,
-                                               JobPriority priority);
+  // Determines if we're allowed to contact the server right now.
+  bool CanRunNudgeJobNow(JobPriority priority);
 
-  // 'Impl' here refers to real implementation of public functions, running on
-  // |thread_|.
+  // 'Impl' here refers to real implementation of public functions.
   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,
@@ skipping 14 matching lines @@
 
   // Transitions out of the THROTTLED WaitInterval then calls TryCanaryJob().
   void Unthrottle();
 
   // Called when the root cause of the current connection error is fixed.
   void OnServerConnectionErrorFixed();
 
   // Creates a session for a poll and performs the sync.
   void PollTimerCallback();
 
-  // Called once the first time thread_ is started to broadcast an initial
-  // session snapshot containing data like initial_sync_ended.  Important when
-  // the client starts up and does not need to perform an initial sync.
+  // Called as we are started to broadcast an initial session snapshot
+  // containing data like initial_sync_ended.  Important when the client starts
+  // up and does not need to perform an initial sync.
   void SendInitialSnapshot();
 
   // This is used for histogramming and analysis of ScheduleNudge* APIs.
   // SyncScheduler is the ultimate choke-point for all such invocations (with
   // and without InvalidationState variants, all NudgeSources, etc) and as such
   // is the most flexible place to do this bookkeeping.
   void UpdateNudgeTimeRecords(const sessions::SyncSourceInfo& info);
 
   virtual void OnActionableError(const sessions::SyncSessionSnapshot& snapshot);
 
@@ skipping 27 matching lines @@
   Mode mode_;
 
   // Current wait state.  Null if we're not in backoff and not throttled.
   scoped_ptr<WaitInterval> wait_interval_;
 
   scoped_ptr<BackoffDelayProvider> delay_provider_;
 
   // The event that will wake us up.
   base::OneShotTimer<SyncSchedulerImpl> pending_wakeup_timer_;
 
-  // Pending configure job storage.  Note that
-  // (mode_ != CONFIGURATION_MODE) \implies !pending_configure_job_.
-  scoped_ptr<SyncSessionJob> pending_configure_job_;
+  // Storage for variables related to an in-progress configure request.  Note
+  // that (mode_ != CONFIGURATION_MODE) \implies !pending_configure_params_.
+  scoped_ptr<ConfigurationParams> pending_configure_params_;
 
-  // Pending nudge job storage.  These jobs can exist in CONFIGURATION_MODE, but
-  // they will be run only in NORMAL_MODE.
-  scoped_ptr<SyncSessionJob> pending_nudge_job_;
+  // If we have a nudge pending to run soon, it will be listed here.
+  base::TimeTicks scheduled_nudge_time_;
+
+  // Keeps track of work that the syncer needs to handle.
+  sessions::NudgeTracker nudge_tracker_;
 
   // Invoked to run through the sync cycle.
   scoped_ptr<Syncer> syncer_;
 
   sessions::SyncSessionContext* session_context_;
 
   // A map tracking LOCAL NudgeSource invocations of ScheduleNudge* APIs,
   // organized by datatype. Each datatype that was part of the types requested
   // in the call will have its TimeTicks value updated.
   typedef std::map<ModelType, base::TimeTicks> ModelTypeTimeMap;
   ModelTypeTimeMap last_local_nudges_by_model_type_;
 
   // Used as an "anti-reentrancy defensive assertion".
   // While true, it is illegal for any new scheduling activity to take place.
   // Ensures that higher layers don't break this law in response to events that
   // 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_