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_THREADING_WORKER_POOL_H_ 6 #define BASE_THREADING_WORKER_POOL_H_ 7 8 #include "base/base_export.h" 9 #include "base/callback_forward.h" 10 #include "base/memory/ref_counted.h" 11 12 class Task; 13 14 namespace tracked_objects { 15 class Location; 16 } // namespace tracked_objects 17 18 namespace base { 19 20 class TaskRunner; 21 22 // This is a facility that runs tasks that don't require a specific thread or 23 // a message loop. 24 // 25 // WARNING: This shouldn't be used unless absolutely necessary. We don't wait 26 // for the worker pool threads to finish on shutdown, so the tasks running 27 // inside the pool must be extremely careful about other objects they access 28 // (MessageLoops, Singletons, etc). During shutdown these object may no longer 29 // exist. 30 class BASE_EXPORT WorkerPool { 31 public: 32 // This function posts |task| to run on a worker thread. |task_is_slow| 33 // should be used for tasks that will take a long time to execute. Returns 34 // false if |task| could not be posted to a worker thread. Regardless of 35 // return value, ownership of |task| is transferred to the worker pool. 36 static bool PostTask(const tracked_objects::Location& from_here, 37 const base::Closure& task, bool task_is_slow); 38 39 // Just like TaskRunner::PostTaskAndReply, except the destination 40 // for |task| is a worker thread and you can specify |task_is_slow| just 41 // like you can for PostTask above. 42 static bool PostTaskAndReply(const tracked_objects::Location& from_here, 43 const Closure& task, 44 const Closure& reply, 45 bool task_is_slow); 46 47 // Return true if the current thread is one that this WorkerPool runs tasks 48 // on. (Note that if the Windows worker pool is used without going through 49 // this WorkerPool interface, RunsTasksOnCurrentThread would return false on 50 // those threads.) 51 static bool RunsTasksOnCurrentThread(); 52 53 // Get a TaskRunner wrapper which posts to the WorkerPool using the given 54 // |task_is_slow| behavior. 55 static const scoped_refptr<TaskRunner>& GetTaskRunner(bool task_is_slow); 56 }; 57 58 } // namespace base 59 60 #endif // BASE_THREADING_WORKER_POOL_H_ 61
