Repo created

TMessagesProj/jni/voip/webrtc/base/task/task_executor.h

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+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_TASK_TASK_EXECUTOR_H_
+#define BASE_TASK_TASK_EXECUTOR_H_
+
+#include <stdint.h>
+
+#include "base/base_export.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task/single_thread_task_runner_thread_mode.h"
+#include "base/task_runner.h"
+#include "build/build_config.h"
+
+namespace base {
+
+class Location;
+class TaskTraits;
+
+// A TaskExecutor can execute Tasks with a specific TaskTraits extension id. To
+// handle Tasks posted via the //base/task/post_task.h API, the TaskExecutor
+// should be registered by calling RegisterTaskExecutor().
+class BASE_EXPORT TaskExecutor {
+ public:
+  virtual ~TaskExecutor() = default;
+
+  // Posts |task| with a |delay| and specific |traits|. |delay| can be zero. For
+  // one off tasks that don't require a TaskRunner. Returns false if the task
+  // definitely won't run because of current shutdown state.
+  virtual bool PostDelayedTask(const Location& from_here,
+                               const TaskTraits& traits,
+                               OnceClosure task,
+                               TimeDelta delay) = 0;
+
+  // Returns a TaskRunner whose PostTask invocations result in scheduling tasks
+  // using |traits|. Tasks may run in any order and in parallel.
+  virtual scoped_refptr<TaskRunner> CreateTaskRunner(
+      const TaskTraits& traits) = 0;
+
+  // Returns a SequencedTaskRunner whose PostTask invocations result in
+  // scheduling tasks using |traits|. Tasks run one at a time in posting order.
+  virtual scoped_refptr<SequencedTaskRunner> CreateSequencedTaskRunner(
+      const TaskTraits& traits) = 0;
+
+  // Returns a SingleThreadTaskRunner whose PostTask invocations result in
+  // scheduling tasks using |traits|. Tasks run on a single thread in posting
+  // order. If |traits| identifies an existing thread,
+  // SingleThreadTaskRunnerThreadMode::SHARED must be used.
+  virtual scoped_refptr<SingleThreadTaskRunner> CreateSingleThreadTaskRunner(
+      const TaskTraits& traits,
+      SingleThreadTaskRunnerThreadMode thread_mode) = 0;
+
+#if defined(OS_WIN)
+  // Returns a SingleThreadTaskRunner whose PostTask invocations result in
+  // scheduling tasks using |traits| in a COM Single-Threaded Apartment. Tasks
+  // run in the same Single-Threaded Apartment in posting order for the returned
+  // SingleThreadTaskRunner. If |traits| identifies an existing thread,
+  // SingleThreadTaskRunnerThreadMode::SHARED must be used.
+  virtual scoped_refptr<SingleThreadTaskRunner> CreateCOMSTATaskRunner(
+      const TaskTraits& traits,
+      SingleThreadTaskRunnerThreadMode thread_mode) = 0;
+#endif  // defined(OS_WIN)
+};
+
+// Register a TaskExecutor with the //base/task/post_task.h API in the current
+// process for tasks subsequently posted with a TaskTraits extension with the
+// given |extension_id|. All executors need to be registered before any tasks
+// are posted with |extension_id|. Only one executor per |extension_id| is
+// supported.
+void BASE_EXPORT RegisterTaskExecutor(uint8_t extension_id,
+                                      TaskExecutor* task_executor);
+void BASE_EXPORT UnregisterTaskExecutorForTesting(uint8_t extension_id);
+
+// Stores the provided TaskExecutor in TLS for the current thread, to be used by
+// tasks with the CurrentThread() trait.
+void BASE_EXPORT SetTaskExecutorForCurrentThread(TaskExecutor* task_executor);
+
+// Returns the task executor registered for the current thread.
+BASE_EXPORT TaskExecutor* GetTaskExecutorForCurrentThread();
+
+// Determines whether a registered TaskExecutor will handle tasks with the given
+// |traits| and, if so, returns a pointer to it. Otherwise, returns |nullptr|.
+TaskExecutor* GetRegisteredTaskExecutorForTraits(const TaskTraits& traits);
+
+}  // namespace base
+
+#endif  // BASE_TASK_TASK_EXECUTOR_H_