chrome/browser/safe_browsing/incident_reporting/delayed_callback_runner.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 CHROME_BROWSER_SAFE_BROWSING_INCIDENT_REPORTING_DELAYED_CALLBACK_RUNNER_H_
   6 #define CHROME_BROWSER_SAFE_BROWSING_INCIDENT_REPORTING_DELAYED_CALLBACK_RUNNER_H_
   7
   8 #include <list>
   9
  10 #include "base/callback_forward.h"
  11 #include "base/macros.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/task_runner.h"
  14 #include "base/threading/thread_checker.h"
  15 #include "base/time/time.h"
  16 #include "base/timer/timer.h"
  17
  18 namespace safe_browsing {
  19
  20 // Runs callbacks on a given task runner, waiting a certain amount of time
  21 // between each. The delay also applies to running the first callback (i.e.,
  22 // the first callback will be run some time after Start() is invoked). Callbacks
  23 // are deleted after they are run. Start() is idempotent: calling it while the
  24 // runner is doing its job has no effect.
  25 class DelayedCallbackRunner {
  26  public:
  27   // Constructs an instance that runs tasks on |callback_runner|, waiting for
  28   // |delay| time to pass before and between each callback.
  29   DelayedCallbackRunner(base::TimeDelta delay,
  30                         const scoped_refptr<base::TaskRunner>& task_runner);
  31   ~DelayedCallbackRunner();
  32
  33   // Registers |callback| with the runner. A copy of |callback| is held until it
  34   // is run.
  35   void RegisterCallback(const base::Closure& callback);
  36
  37   // Starts running the callbacks after the delay.
  38   void Start();
  39
  40  private:
  41   typedef std::list<base::Closure> CallbackList;
  42
  43   // A callback invoked by the timer to run the next callback. The timer is
  44   // restarted to process the next callback if there is one.
  45   void OnTimer();
  46
  47   base::ThreadChecker thread_checker_;
  48
  49   // The runner on which callbacks are to be run.
  50   scoped_refptr<base::TaskRunner> task_runner_;
  51
  52   // The list of callbacks to run. Callbacks are removed when run.
  53   CallbackList callbacks_;
  54
  55   // callbacks_.end() when no work is being done. Any other value otherwise.
  56   CallbackList::iterator next_callback_;
  57
  58   // A timer upon the firing of which the next callback will be run.
  59   base::DelayTimer<DelayedCallbackRunner> timer_;
  60
  61   DISALLOW_COPY_AND_ASSIGN(DelayedCallbackRunner);
  62 };
  63
  64 }  // namespace safe_browsing
  65
  66 #endif  // CHROME_BROWSER_SAFE_BROWSING_INCIDENT_REPORTING_DELAYED_CALLBACK_RUNNER_H_