base/test/test_mock_time_task_runner.h

   1 // Copyright 2015 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 BASE_TEST_TEST_MOCK_TIME_TASK_RUNNER_H_
   6 #define BASE_TEST_TEST_MOCK_TIME_TASK_RUNNER_H_
   7
   8 #include <queue>
   9 #include <vector>
  10
  11 #include "base/macros.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/single_thread_task_runner.h"
  14 #include "base/synchronization/lock.h"
  15 #include "base/test/test_pending_task.h"
  16 #include "base/threading/thread_checker.h"
  17 #include "base/time/tick_clock.h"
  18 #include "base/time/time.h"
  19
  20 namespace base {
  21
  22 // Runs pending tasks in the order of the tasks' post time + delay, and keeps
  23 // track of a mock (virtual) tick clock time that can be fast-forwarded.
  24 //
  25 // TestMockTimeTaskRunner has the following properties:
  26 //
  27 //   - Methods RunsTasksOnCurrentThread() and Post[Delayed]Task() can be called
  28 //     from any thread, but the rest of the methods must be called on the same
  29 //     thread the TaskRunner was created on.
  30 //   - It allows for reentrancy, in that it handles the running of tasks that in
  31 //     turn call back into it (e.g., to post more tasks).
  32 //   - Tasks are stored in a priority queue, and executed in the increasing
  33 //     order of post time + delay.
  34 //   - Non-nestable tasks are not supported.
  35 //   - Tasks aren't guaranteed to be destroyed immediately after they're run.
  36 //
  37 // This is a slightly more sophisticated version of TestSimpleTaskRunner, in
  38 // that it supports running delayed tasks in the correct temporal order.
  39 class TestMockTimeTaskRunner : public base::SingleThreadTaskRunner {
  40  public:
  41   TestMockTimeTaskRunner();
  42
  43   // Fast-forwards virtual time by |delta|, causing all tasks with a remaining
  44   // delay less than or equal to |delta| to be executed.
  45   void FastForwardBy(base::TimeDelta delta);
  46
  47   // Fast-forwards virtual time just until all tasks are executed.
  48   void FastForwardUntilNoTasksRemain();
  49
  50   // Executes all tasks that have no remaining delay. Tasks with a remaining
  51   // delay greater than zero will remain enqueued, and no virtual time will
  52   // elapse.
  53   void RunUntilIdle();
  54
  55   // Returns the current virtual time.
  56   TimeTicks GetCurrentMockTime() const;
  57
  58   // Returns a TickClock that uses the mock time of |this| as its time source.
  59   // The returned TickClock will hold a reference to |this|.
  60   scoped_ptr<TickClock> GetMockTickClock() const;
  61
  62   bool HasPendingTask() const;
  63   TimeDelta NextPendingTaskDelay() const;
  64
  65   // SingleThreadTaskRunner:
  66   bool RunsTasksOnCurrentThread() const override;
  67   bool PostDelayedTask(const tracked_objects::Location& from_here,
  68                                const base::Closure& task,
  69                                TimeDelta delay) override;
  70   bool PostNonNestableDelayedTask(
  71       const tracked_objects::Location& from_here,
  72       const base::Closure& task,
  73       TimeDelta delay) override;
  74
  75  protected:
  76   ~TestMockTimeTaskRunner() override;
  77
  78   // Called before the next task to run is selected, so that subclasses have a
  79   // last chance to make sure all tasks are posted.
  80   virtual void OnBeforeSelectingTask();
  81
  82   // Called after the current mock time has been incremented so that subclasses
  83   // can react to the passing of time.
  84   virtual void OnAfterTimePassed();
  85
  86   // Called after each task is run so that subclasses may perform additional
  87   // activities, e.g., pump additional task runners.
  88   virtual void OnAfterTaskRun();
  89
  90  private:
  91   // Predicate that defines a strict weak temporal ordering of tasks.
  92   class TemporalOrder {
  93    public:
  94     bool operator()(const TestPendingTask& first_task,
  95                     const TestPendingTask& second_task) const;
  96   };
  97
  98   typedef std::priority_queue<TestPendingTask,
  99                               std::vector<TestPendingTask>,
 100                               TemporalOrder> TaskPriorityQueue;
 101
 102   // Returns the |next_task| to run if there is any with a running time that is
 103   // at most |reference| + |max_delta|. This additional complexity is required
 104   // so that |max_delta| == TimeDelta::Max() can be supported.
 105   bool DequeueNextTask(const base::TimeTicks& reference,
 106                        const base::TimeDelta& max_delta,
 107                        TestPendingTask* next_task);
 108
 109   base::ThreadChecker thread_checker_;
 110   base::TimeTicks now_;
 111
 112   // Temporally ordered heap of pending tasks. Must only be accessed while the
 113   // |tasks_lock_| is held.
 114   TaskPriorityQueue tasks_;
 115   base::Lock tasks_lock_;
 116
 117   DISALLOW_COPY_AND_ASSIGN(TestMockTimeTaskRunner);
 118 };
 119
 120 }  // namespace base
 121
 122 #endif  // BASE_TEST_TEST_MOCK_TIME_TASK_RUNNER_H_