components/domain_reliability/scheduler.h

   1 // Copyright 2014 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 COMPONENTS_DOMAIN_RELIABILITY_SCHEDULER_H_
   6 #define COMPONENTS_DOMAIN_RELIABILITY_SCHEDULER_H_
   7
   8 #include <vector>
   9
  10 #include "base/callback.h"
  11 #include "base/time/time.h"
  12 #include "components/domain_reliability/domain_reliability_export.h"
  13
  14 namespace domain_reliability {
  15
  16 class DomainReliabilityConfig;
  17 class MockableTime;
  18
  19 // Determines when an upload should be scheduled. A domain's config will
  20 // specify minimum and maximum upload delays; the minimum upload delay ensures
  21 // that Chrome will not send too many upload requests to a site by waiting at
  22 // least that long after the first beacon, while the maximum upload delay makes
  23 // sure the server receives the reports while they are still fresh.
  24 //
  25 // When everything is working fine, the scheduler will return precisely that
  26 // interval. If all uploaders have failed, then the beginning or ending points
  27 // of the interval may be pushed later to accomodate the retry with exponential
  28 // backoff.
  29 //
  30 // See dispatcher.h for an explanation of what happens with the scheduled
  31 // interval.
  32 class DOMAIN_RELIABILITY_EXPORT DomainReliabilityScheduler {
  33  public:
  34   typedef base::Callback<void(base::TimeDelta, base::TimeDelta)>
  35       ScheduleUploadCallback;
  36
  37   struct Params {
  38    public:
  39     base::TimeDelta minimum_upload_delay;
  40     base::TimeDelta maximum_upload_delay;
  41     base::TimeDelta upload_retry_interval;
  42
  43     static Params GetFromFieldTrialsOrDefaults();
  44   };
  45
  46   DomainReliabilityScheduler(MockableTime* time,
  47                              size_t num_collectors,
  48                              const Params& params,
  49                              const ScheduleUploadCallback& callback);
  50   ~DomainReliabilityScheduler();
  51
  52   // If there is no upload pending, schedules an upload based on the provided
  53   // parameters (some time between the minimum and maximum delay from now).
  54   // May call the ScheduleUploadCallback.
  55   void OnBeaconAdded();
  56
  57   // Returns which collector to use for an upload that is about to start. Must
  58   // be called exactly once during or after the ScheduleUploadCallback but
  59   // before OnUploadComplete is called. (Also records the upload start time for
  60   // future retries, if the upload ends up failing.)
  61   size_t OnUploadStart();
  62
  63   // Updates the scheduler state based on the result of an upload. Must be
  64   // called exactly once after |OnUploadStart|. |success| should be true if the
  65   // upload was successful, and false otherwise.
  66   void OnUploadComplete(bool success);
  67
  68  private:
  69   struct CollectorState {
  70     CollectorState();
  71
  72     // The number of consecutive failures to upload to this collector, or 0 if
  73     // the most recent upload succeeded.
  74     unsigned failures;
  75     base::TimeTicks next_upload;
  76   };
  77
  78   void MaybeScheduleUpload();
  79
  80   void GetNextUploadTimeAndCollector(base::TimeTicks now,
  81                                      base::TimeTicks* upload_time_out,
  82                                      size_t* collector_index_out);
  83
  84   base::TimeDelta GetUploadRetryInterval(unsigned failures);
  85
  86   MockableTime* time_;
  87   std::vector<CollectorState> collectors_;
  88   Params params_;
  89   ScheduleUploadCallback callback_;
  90
  91   // Whether there are beacons that have not yet been uploaded. Set when a
  92   // beacon arrives or an upload fails, and cleared when an upload starts.
  93   bool upload_pending_;
  94
  95   // Whether the scheduler has called the ScheduleUploadCallback to schedule
  96   // the next upload. Set when an upload is scheduled and cleared when the
  97   // upload starts.
  98   bool upload_scheduled_;
  99
 100   // Whether the last scheduled upload is in progress. Set when the upload
 101   // starts and cleared when the upload completes (successfully or not).
 102   bool upload_running_;
 103
 104   // Index of the collector selected for the next upload.  (Set in
 105   // |OnUploadStart| and cleared in |OnUploadComplete|.)
 106   size_t collector_index_;
 107
 108   // Time of the first beacon that was not included in the last successful
 109   // upload.
 110   base::TimeTicks first_beacon_time_;
 111
 112   // first_beacon_time_ saved during uploads.  Restored if upload fails.
 113   base::TimeTicks old_first_beacon_time_;
 114 };
 115
 116 }  // namespace domain_reliability
 117
 118 #endif  // COMPONENTS_DOMAIN_RELIABILITY_SCHEDULER_H_