1/*
2 * Copyright (C) 2011 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1.  Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 * 2.  Redistributions in binary form must reproduce the above copyright
11 *     notice, this list of conditions and the following disclaimer in the
12 *     documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
18 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
21 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25#ifndef WebThread_h
26#define WebThread_h
27
28#include "WebCommon.h"
29#include <stdint.h>
30
31namespace blink {
32
33// Always an integer value.
34typedef uintptr_t PlatformThreadId;
35
36// Provides an interface to an embedder-defined thread implementation.
37//
38// Deleting the thread blocks until all pending, non-delayed tasks have been
39// run.
40class BLINK_PLATFORM_EXPORT WebThread {
41public:
42    class Task {
43    public:
44        virtual ~Task() { }
45        virtual void run() = 0;
46    };
47
48    class BLINK_PLATFORM_EXPORT TaskObserver {
49    public:
50        virtual ~TaskObserver() { }
51        virtual void willProcessTask() = 0;
52        virtual void didProcessTask() = 0;
53    };
54
55    // postTask() and postDelayedTask() take ownership of the passed Task
56    // object. It is safe to invoke postTask() and postDelayedTask() from any
57    // thread.
58    virtual void postTask(Task*) = 0;
59    virtual void postDelayedTask(Task*, long long delayMs) = 0;
60
61    virtual bool isCurrentThread() const = 0;
62    virtual PlatformThreadId threadId() const { return 0; }
63
64    virtual void addTaskObserver(TaskObserver*) { }
65    virtual void removeTaskObserver(TaskObserver*) { }
66
67    // enterRunLoop() processes tasks posted to this WebThread. This call does not return until some task calls exitRunLoop().
68    // WebThread does not support nesting, meaning that once the run loop is entered for a given WebThread it is not valid to
69    // call enterRunLoop() again.
70    virtual void enterRunLoop() = 0;
71
72    // exitRunLoop() runs tasks until there are no tasks available to run, then returns control to the caller of enterRunLoop().
73    // Must be called when the WebThread is running.
74    virtual void exitRunLoop() = 0;
75
76    virtual ~WebThread() { }
77};
78
79} // namespace blink
80
81#endif
82