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      1 // Copyright (c) 2012 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_SIMPLE_TASK_RUNNER_H_
      6 #define BASE_TEST_TEST_SIMPLE_TASK_RUNNER_H_
      7 
      8 #include <deque>
      9 
     10 #include "base/callback.h"
     11 #include "base/compiler_specific.h"
     12 #include "base/macros.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/platform_thread.h"
     17 
     18 namespace base {
     19 
     20 class TimeDelta;
     21 
     22 // TestSimpleTaskRunner is a simple TaskRunner implementation that can
     23 // be used for testing.  It implements SingleThreadTaskRunner as that
     24 // interface implements SequencedTaskRunner, which in turn implements
     25 // TaskRunner, so TestSimpleTaskRunner can be passed in to a function
     26 // that accepts any *TaskRunner object.
     27 //
     28 // TestSimpleTaskRunner has the following properties which make it simple:
     29 //
     30 //   - Tasks are simply stored in a queue in FIFO order, ignoring delay
     31 //     and nestability.
     32 //   - Tasks aren't guaranteed to be destroyed immediately after
     33 //     they're run.
     34 //
     35 // However, TestSimpleTaskRunner allows for reentrancy, in that it
     36 // handles the running of tasks that in turn call back into itself
     37 // (e.g., to post more tasks).
     38 //
     39 // Note that, like any TaskRunner, TestSimpleTaskRunner is
     40 // ref-counted.
     41 class TestSimpleTaskRunner : public SingleThreadTaskRunner {
     42  public:
     43   TestSimpleTaskRunner();
     44 
     45   // SingleThreadTaskRunner implementation.
     46   bool PostDelayedTask(const tracked_objects::Location& from_here,
     47                        OnceClosure task,
     48                        TimeDelta delay) override;
     49   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
     50                                   OnceClosure task,
     51                                   TimeDelta delay) override;
     52 
     53   bool RunsTasksOnCurrentThread() const override;
     54 
     55   std::deque<TestPendingTask> TakePendingTasks();
     56   size_t NumPendingTasks() const;
     57   bool HasPendingTask() const;
     58   base::TimeDelta NextPendingTaskDelay() const;
     59   base::TimeDelta FinalPendingTaskDelay() const;
     60 
     61   // Clears the queue of pending tasks without running them.
     62   void ClearPendingTasks();
     63 
     64   // Runs each current pending task in order and clears the queue. Tasks posted
     65   // by the tasks that run within this call do not run within this call. Can
     66   // only be called on the thread that created this TestSimpleTaskRunner.
     67   void RunPendingTasks();
     68 
     69   // Runs pending tasks until the queue is empty. Can only be called on the
     70   // thread that created this TestSimpleTaskRunner.
     71   void RunUntilIdle();
     72 
     73  protected:
     74   ~TestSimpleTaskRunner() override;
     75 
     76  private:
     77   // Thread on which this was instantiated.
     78   const PlatformThreadRef thread_ref_ = PlatformThread::CurrentRef();
     79 
     80   // Synchronizes access to |pending_tasks_|.
     81   mutable Lock lock_;
     82 
     83   std::deque<TestPendingTask> pending_tasks_;
     84 
     85   DISALLOW_COPY_AND_ASSIGN(TestSimpleTaskRunner);
     86 };
     87 
     88 }  // namespace base
     89 
     90 #endif  // BASE_TEST_TEST_SIMPLE_TASK_RUNNER_H_
     91