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      1 // Copyright 2013 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 to track the outstanding work required to bring the client back into
      6 // sync with the server.
      7 #ifndef SYNC_SESSIONS_NUDGE_TRACKER_H_
      8 #define SYNC_SESSIONS_NUDGE_TRACKER_H_
      9 
     10 #include <list>
     11 #include <map>
     12 
     13 #include "base/compiler_specific.h"
     14 #include "sync/base/sync_export.h"
     15 #include "sync/internal_api/public/base/model_type.h"
     16 #include "sync/protocol/sync.pb.h"
     17 #include "sync/sessions/data_type_tracker.h"
     18 
     19 namespace syncer {
     20 
     21 class ObjectIdInvalidationMap;
     22 
     23 namespace sessions {
     24 
     25 class SYNC_EXPORT_PRIVATE NudgeTracker {
     26  public:
     27   static size_t kDefaultMaxPayloadsPerType;
     28 
     29   NudgeTracker();
     30   ~NudgeTracker();
     31 
     32   // Returns true if there is a good reason for performing a sync cycle.
     33   // This does not take into account whether or not this is a good *time* to
     34   // perform a sync cycle; that's the scheduler's job.
     35   bool IsSyncRequired() const;
     36 
     37   // Returns true if there is a good reason for performing a get updates
     38   // request as part of the next sync cycle.
     39   bool IsGetUpdatesRequired() const;
     40 
     41   // Tells this class that all required update fetching and committing has
     42   // completed successfully.
     43   void RecordSuccessfulSyncCycle();
     44 
     45   // Takes note of a local change.
     46   void RecordLocalChange(ModelTypeSet types);
     47 
     48   // Takes note of a locally issued request to refresh a data type.
     49   void RecordLocalRefreshRequest(ModelTypeSet types);
     50 
     51   // Takes note of the receipt of an invalidation notice from the server.
     52   void RecordRemoteInvalidation(
     53       const ObjectIdInvalidationMap& invalidation_map);
     54 
     55   // These functions should be called to keep this class informed of the status
     56   // of the connection to the invalidations server.
     57   void OnInvalidationsEnabled();
     58   void OnInvalidationsDisabled();
     59 
     60   // Marks |types| as being throttled from |now| until |now| + |length|.
     61   void SetTypesThrottledUntil(ModelTypeSet types,
     62                               base::TimeDelta length,
     63                               base::TimeTicks now);
     64 
     65   // Removes any throttling that have expired by time |now|.
     66   void UpdateTypeThrottlingState(base::TimeTicks now);
     67 
     68   // Returns the time of the next type unthrottling, relative to
     69   // the input |now| value.
     70   base::TimeDelta GetTimeUntilNextUnthrottle(base::TimeTicks now) const;
     71 
     72   // Returns true if any type is currenlty throttled.
     73   bool IsAnyTypeThrottled() const;
     74 
     75   // Returns true if |type| is currently throttled.
     76   bool IsTypeThrottled(ModelType type) const;
     77 
     78   // Returns the set of currently throttled types.
     79   ModelTypeSet GetThrottledTypes() const;
     80 
     81   // Returns the 'source' of the GetUpdate request.
     82   //
     83   // This flag is deprecated, but still used by the server.  There can be more
     84   // than one reason to perform a particular sync cycle.  The GetUpdatesTrigger
     85   // message will contain more reliable information about the reasons for
     86   // performing a sync.
     87   //
     88   // See the implementation for important information about the coalesce logic.
     89   sync_pb::GetUpdatesCallerInfo::GetUpdatesSource updates_source() const;
     90 
     91   // Fills a GetUpdatesTrigger message for the next GetUpdates request.  This is
     92   // used by the DownloadUpdatesCommand to dump lots of useful per-type state
     93   // information into the GetUpdate request before sending it off to the server.
     94   void FillProtoMessage(
     95       ModelType type,
     96       sync_pb::GetUpdateTriggers* msg) const;
     97 
     98   // Fills a ProgressMarker with single legacy notification hint expected by the
     99   // sync server.  Newer servers will rely on the data set by FillProtoMessage()
    100   // instead of this.
    101   void SetLegacyNotificationHint(
    102       ModelType type,
    103       sync_pb::DataTypeProgressMarker* progress) const;
    104 
    105   // Adjusts the number of hints that can be stored locally.
    106   void SetHintBufferSize(size_t size);
    107 
    108  private:
    109   typedef std::map<ModelType, DataTypeTracker> TypeTrackerMap;
    110 
    111   TypeTrackerMap type_trackers_;
    112 
    113   // Merged updates source.  This should be obsolete, but the server still
    114   // relies on it for some heuristics.
    115   sync_pb::GetUpdatesCallerInfo::GetUpdatesSource updates_source_;
    116 
    117   // Tracks whether or not invalidations are currently enabled.
    118   bool invalidations_enabled_;
    119 
    120   // This flag is set if suspect that some technical malfunction or known bug
    121   // may have left us with some unserviced invalidations.
    122   //
    123   // Keeps track of whether or not we're fully in sync with the invalidation
    124   // server.  This can be false even if invalidations are enabled and working
    125   // correctly.  For example, until we get ack-tracking working properly, we
    126   // won't persist invalidations between restarts, so we may be out of sync when
    127   // we restart.  The only way to get back into sync is to have invalidations
    128   // enabled, then complete a sync cycle to make sure we're fully up to date.
    129   bool invalidations_out_of_sync_;
    130 
    131   size_t num_payloads_per_type_;
    132 
    133   DISALLOW_COPY_AND_ASSIGN(NudgeTracker);
    134 };
    135 
    136 }  // namespace sessions
    137 }  // namespace syncer
    138 
    139 #endif  // SYNC_SESSIONS_NUDGE_TRACKER_H_
    140