third_party/WebKit/public/platform/WebThread.h

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef WebThread_h
#define WebThread_h

#include "WebCommon.h"

#include <stdint.h>

namespace blink {
namespace scheduler {
class TaskTimeObserver;
}

class WebScheduler;
class WebTaskRunner;

// Always an integer value.
typedef uintptr_t PlatformThreadId;

// Provides an interface to an embedder-defined thread implementation.
//
// Deleting the thread blocks until all pending, non-delayed tasks have been
// run.
class BLINK_PLATFORM_EXPORT WebThread {
 public:
  // An IdleTask is passed a deadline in CLOCK_MONOTONIC seconds and is
  // expected to complete before this deadline.
  class IdleTask {
   public:
    virtual ~IdleTask() {}
    virtual void run(double deadlineSeconds) = 0;
  };

  class BLINK_PLATFORM_EXPORT TaskObserver {
   public:
    virtual ~TaskObserver() {}
    virtual void willProcessTask() = 0;
    virtual void didProcessTask() = 0;
  };

  // Returns a WebTaskRunner bound to the underlying scheduler's default task
  // queue.
  virtual WebTaskRunner* getWebTaskRunner() { return nullptr; }

  virtual bool isCurrentThread() const = 0;
  virtual PlatformThreadId threadId() const { return 0; }

  // TaskObserver is an object that receives task notifications from the
  // MessageLoop
  // NOTE: TaskObserver implementation should be extremely fast!
  // This API is performance sensitive. Use only if you have a compelling
  // reason.
  virtual void addTaskObserver(TaskObserver*) {}
  virtual void removeTaskObserver(TaskObserver*) {}

  // TaskTimeObserver is an object that receives notifications for
  // CPU time spent in each top-level MessageLoop task.
  // NOTE: TaskTimeObserver implementation should be extremely fast!
  // This API is performance sensitive. Use only if you have a compelling
  // reason.
  virtual void addTaskTimeObserver(scheduler::TaskTimeObserver*) {}
  virtual void removeTaskTimeObserver(scheduler::TaskTimeObserver*) {}

  // Returns the scheduler associated with the thread.
  virtual WebScheduler* scheduler() const = 0;

  virtual ~WebThread() {}
};

}  // namespace blink

#endif