1/*
2 * Copyright (C) 2011, 2013 Apple 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 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "LayerChangesFlusher.h"
28
29#include "AbstractCACFLayerTreeHost.h"
30#include "StructuredExceptionHandlerSuppressor.h"
31#include <wtf/StdLibExtras.h>
32#include <wtf/Vector.h>
33
34namespace WebCore {
35
36LayerChangesFlusher& LayerChangesFlusher::shared()
37{
38    DEPRECATED_DEFINE_STATIC_LOCAL(LayerChangesFlusher, flusher, ());
39    return flusher;
40}
41
42LayerChangesFlusher::LayerChangesFlusher()
43    : m_hook(0)
44    , m_isCallingHosts(false)
45{
46}
47
48void LayerChangesFlusher::flushPendingLayerChangesSoon(AbstractCACFLayerTreeHost* host)
49{
50    if (!m_hostsWithChangesToFlush.add(host).isNewEntry || m_hook)
51        return;
52
53    setHook();
54}
55
56void LayerChangesFlusher::cancelPendingFlush(AbstractCACFLayerTreeHost* host)
57{
58    m_hostsWithChangesToFlush.remove(host);
59
60    if (!m_hostsWithChangesToFlush.isEmpty() || !m_hook)
61        return;
62
63    // We handle removing the hook when we finish calling out to the hosts, so we shouldn't
64    // mess with it while we're in the process of calling them.
65    if (m_isCallingHosts)
66        return;
67
68    removeHook();
69}
70
71LRESULT LayerChangesFlusher::hookCallback(int code, WPARAM wParam, LPARAM lParam)
72{
73    // Supress the exception handler Windows puts around all hook calls so we can
74    // crash for debugging purposes if an exception is hit.
75    ExceptionRegistration registrationStruct; // Note: must be stack allocated.
76    StructuredExceptionHandlerSuppressor supressor(registrationStruct);
77    return shared().hookFired(code, wParam, lParam);
78}
79
80LRESULT LayerChangesFlusher::hookFired(int code, WPARAM wParam, LPARAM lParam)
81{
82    ASSERT(m_hook);
83
84    // Calling out to the hosts can cause m_hostsWithChangesToFlush to be modified, so we copy it
85    // into a Vector first.
86    Vector<AbstractCACFLayerTreeHost*> hosts;
87    copyToVector(m_hostsWithChangesToFlush, hosts);
88    m_hostsWithChangesToFlush.clear();
89
90    m_isCallingHosts = true;
91    for (size_t i = 0; i < hosts.size(); ++i)
92        hosts[i]->flushPendingLayerChangesNow();
93    m_isCallingHosts = false;
94
95    LRESULT result = ::CallNextHookEx(m_hook, code, wParam, lParam);
96
97    if (m_hook && m_hostsWithChangesToFlush.isEmpty()) {
98        // We won't have any work to do next time around, so just remove our hook.
99        removeHook();
100    }
101
102    return result;
103}
104
105void LayerChangesFlusher::setHook()
106{
107    ASSERT(!m_hook);
108    ASSERT(!m_isCallingHosts);
109
110    DWORD threadID = ::GetCurrentThreadId();
111
112    m_hook = ::SetWindowsHookExW(WH_GETMESSAGE, hookCallback, 0, threadID);
113    ASSERT_WITH_MESSAGE(m_hook, "::SetWindowsHookExW failed with error %lu", ::GetLastError());
114
115    // Post a message to the message queue to prevent ::GetMessage from blocking, which will ensure
116    // our hook is called soon.
117    ::PostThreadMessageW(threadID, WM_NULL, 0, 0);
118}
119
120void LayerChangesFlusher::removeHook()
121{
122    ASSERT(m_hook);
123    ASSERT(!m_isCallingHosts);
124
125    if (!::UnhookWindowsHookEx(m_hook))
126        ASSERT_WITH_MESSAGE(false, "::UnhookWindowsHookEx failed with error %lu", ::GetLastError());
127
128    m_hook = 0;
129}
130
131} // namespace WebCore
132