1 // Copyright 2016 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_TASK_SCHEDULER_TASK_H_ 6 #define BASE_TASK_SCHEDULER_TASK_H_ 7 8 #include "base/base_export.h" 9 #include "base/callback_forward.h" 10 #include "base/location.h" 11 #include "base/macros.h" 12 #include "base/memory/ref_counted.h" 13 #include "base/pending_task.h" 14 #include "base/sequenced_task_runner.h" 15 #include "base/single_thread_task_runner.h" 16 #include "base/task_scheduler/task_traits.h" 17 #include "base/time/time.h" 18 19 namespace base { 20 namespace internal { 21 22 // A task is a unit of work inside the task scheduler. Support for tracing and 23 // profiling inherited from PendingTask. 24 struct BASE_EXPORT Task : public PendingTask { 25 // |posted_from| is the site the task was posted from. |task| is the closure 26 // to run. |traits| is metadata about the task. |delay| is a delay that must 27 // expire before the Task runs. 28 Task(const tracked_objects::Location& posted_from, 29 const Closure& task, 30 const TaskTraits& traits, 31 const TimeDelta& delay); 32 ~Task(); 33 34 // The TaskTraits of this task. 35 const TaskTraits traits; 36 37 // The time at which the task was inserted in its sequence. For an undelayed 38 // task, this happens at post time. For a delayed task, this happens some 39 // time after the task's delay has expired. If the task hasn't been inserted 40 // in a sequence yet, this defaults to a null TimeTicks. 41 TimeTicks sequenced_time; 42 43 // A reference to the SequencedTaskRunner or SingleThreadTaskRunner that 44 // posted this task, if any. Used to set ThreadTaskRunnerHandle and/or 45 // SequencedTaskRunnerHandle while the task is running. 46 // Note: this creates an ownership cycle 47 // Sequence -> Task -> TaskRunner -> Sequence -> ... 48 // but that's okay as it's broken when the Task is popped from its Sequence 49 // after being executed which means this cycle forces the TaskRunner to stick 50 // around until all its tasks have been executed which is a requirement to 51 // support TaskRunnerHandles. 52 scoped_refptr<SequencedTaskRunner> sequenced_task_runner_ref; 53 scoped_refptr<SingleThreadTaskRunner> single_thread_task_runner_ref; 54 55 private: 56 // Disallow copies to make sure no unnecessary ref-bumps are incurred. Making 57 // it move-only would be an option, but isn't necessary for now. 58 DISALLOW_COPY_AND_ASSIGN(Task); 59 }; 60 61 } // namespace internal 62 } // namespace base 63 64 #endif // BASE_TASK_SCHEDULER_TASK_H_ 65
