diff options
Diffstat (limited to 'src/mongo/db/repl/task_runner.h')
| -rw-r--r-- | src/mongo/db/repl/task_runner.h | 240 |
1 files changed, 119 insertions, 121 deletions
diff --git a/src/mongo/db/repl/task_runner.h b/src/mongo/db/repl/task_runner.h index 33e879e08b8..f041174ffd9 100644 --- a/src/mongo/db/repl/task_runner.h +++ b/src/mongo/db/repl/task_runner.h @@ -37,129 +37,127 @@ namespace mongo { - class OperationContext; - class Status; - class OldThreadPool; +class OperationContext; +class Status; +class OldThreadPool; namespace repl { - class TaskRunner { - MONGO_DISALLOW_COPYING(TaskRunner); - public: - - /** - * Represents next steps of task runner. - */ - enum class NextAction { - kInvalid=0, - kDisposeOperationContext=1, - kKeepOperationContext=2, - kCancel=3, - }; - - using CreateOperationContextFn = stdx::function<OperationContext*()>; - using Task = stdx::function<NextAction (OperationContext*, const Status&)>; - - /** - * Creates a Task returning kCancel. This is useful in shutting down the task runner after - * running a series of tasks. - * - * Without a cancellation task, the client would need to coordinate the completion of the - * last task with calling cancel() on the task runner. - */ - static Task makeCancelTask(); - - TaskRunner(OldThreadPool* threadPool, - const CreateOperationContextFn& createOperationContext); - - virtual ~TaskRunner(); - - /** - * Returns diagnostic information. - */ - std::string getDiagnosticString() const; - - /** - * Returns true if there are any scheduled or actively running tasks. - */ - bool isActive() const; - - /** - * Schedules a task to be run by the task runner. Tasks are run in the same order that they - * are scheduled. - * - * This transitions the task runner to an active state. - * - * The task runner creates an operation context using '_createOperationContext' - * prior to running a scheduled task. Depending on the NextAction returned from the - * task, operation contexts may be shared between consecutive tasks invoked by the task - * runner. - * - * On completion, each task is expected to return a NextAction to the task runner. - * - * If the task returns kDisposeOperationContext, the task runner destroys the operation - * context. The next task to be invoked will receive a new operation context. - * - * If the task returns kKeepOperationContext, the task runner will retain the operation - * context to pass to the next task in the queue. - * - * If the task returns kCancel, the task runner will destroy the operation context and - * cancel the remaining tasks (each task will be invoked with a status containing the - * code ErrorCodes::CallbackCanceled). After all the tasks have been canceled, the task - * runner will become inactive. - * - * If the task returns kInvalid, this NextAction will be handled in the same way as - * kDisposeOperationContext. - * - * If the status passed to the task is not OK, the task should not proceed and return - * immediately. This is usually the case when the task runner is canceled. Accessing the - * operation context in the task will result in undefined behavior. - */ - void schedule(const Task& task); - - /** - * If there is a task that is already running, allows the task to run to completion. - * Cancels all scheduled tasks that have not been run. Canceled tasks will still be - * invoked with a status containing the code ErrorCodes::CallbackCanceled. - * After all active tasks have completed and unscheduled tasks have been canceled, the - * task runner will go into an inactive state. - * - * It is a no-op to call cancel() before scheduling any tasks. - */ - void cancel(); - - private: - - /** - * Runs tasks in a loop. - * Loop exits when any of the tasks returns a non-kContinue next action. - */ - void _runTasks(); - void _finishRunTasks_inlock(); - - /** - * Waits for next scheduled task to be added to queue. - * Returns null task when task runner is stopped. - */ - Task _waitForNextTask(); - - OldThreadPool* _threadPool; - CreateOperationContextFn _createOperationContext; - - // Protects member data of this TaskRunner. - mutable stdx::mutex _mutex; - - stdx::condition_variable _condition; - - // _active is true when there are scheduled tasks in the task queue or - // when a task is being run by the task runner. - bool _active; - - bool _cancelRequested; - - // FIFO queue of scheduled tasks - std::list<Task> _tasks; +class TaskRunner { + MONGO_DISALLOW_COPYING(TaskRunner); + +public: + /** + * Represents next steps of task runner. + */ + enum class NextAction { + kInvalid = 0, + kDisposeOperationContext = 1, + kKeepOperationContext = 2, + kCancel = 3, }; -} // namespace repl -} // namespace mongo + using CreateOperationContextFn = stdx::function<OperationContext*()>; + using Task = stdx::function<NextAction(OperationContext*, const Status&)>; + + /** + * Creates a Task returning kCancel. This is useful in shutting down the task runner after + * running a series of tasks. + * + * Without a cancellation task, the client would need to coordinate the completion of the + * last task with calling cancel() on the task runner. + */ + static Task makeCancelTask(); + + TaskRunner(OldThreadPool* threadPool, const CreateOperationContextFn& createOperationContext); + + virtual ~TaskRunner(); + + /** + * Returns diagnostic information. + */ + std::string getDiagnosticString() const; + + /** + * Returns true if there are any scheduled or actively running tasks. + */ + bool isActive() const; + + /** + * Schedules a task to be run by the task runner. Tasks are run in the same order that they + * are scheduled. + * + * This transitions the task runner to an active state. + * + * The task runner creates an operation context using '_createOperationContext' + * prior to running a scheduled task. Depending on the NextAction returned from the + * task, operation contexts may be shared between consecutive tasks invoked by the task + * runner. + * + * On completion, each task is expected to return a NextAction to the task runner. + * + * If the task returns kDisposeOperationContext, the task runner destroys the operation + * context. The next task to be invoked will receive a new operation context. + * + * If the task returns kKeepOperationContext, the task runner will retain the operation + * context to pass to the next task in the queue. + * + * If the task returns kCancel, the task runner will destroy the operation context and + * cancel the remaining tasks (each task will be invoked with a status containing the + * code ErrorCodes::CallbackCanceled). After all the tasks have been canceled, the task + * runner will become inactive. + * + * If the task returns kInvalid, this NextAction will be handled in the same way as + * kDisposeOperationContext. + * + * If the status passed to the task is not OK, the task should not proceed and return + * immediately. This is usually the case when the task runner is canceled. Accessing the + * operation context in the task will result in undefined behavior. + */ + void schedule(const Task& task); + + /** + * If there is a task that is already running, allows the task to run to completion. + * Cancels all scheduled tasks that have not been run. Canceled tasks will still be + * invoked with a status containing the code ErrorCodes::CallbackCanceled. + * After all active tasks have completed and unscheduled tasks have been canceled, the + * task runner will go into an inactive state. + * + * It is a no-op to call cancel() before scheduling any tasks. + */ + void cancel(); + +private: + /** + * Runs tasks in a loop. + * Loop exits when any of the tasks returns a non-kContinue next action. + */ + void _runTasks(); + void _finishRunTasks_inlock(); + + /** + * Waits for next scheduled task to be added to queue. + * Returns null task when task runner is stopped. + */ + Task _waitForNextTask(); + + OldThreadPool* _threadPool; + CreateOperationContextFn _createOperationContext; + + // Protects member data of this TaskRunner. + mutable stdx::mutex _mutex; + + stdx::condition_variable _condition; + + // _active is true when there are scheduled tasks in the task queue or + // when a task is being run by the task runner. + bool _active; + + bool _cancelRequested; + + // FIFO queue of scheduled tasks + std::list<Task> _tasks; +}; + +} // namespace repl +} // namespace mongo |