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 COMPUTER, 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#if USE(ACCELERATED_COMPOSITING)
30
31#include "AbstractCACFLayerTreeHost.h"
32#include "StructuredExceptionHandlerSuppressor.h"
33#include <wtf/StdLibExtras.h>
34#include <wtf/Vector.h>
35
36namespace WebCore {
37
38LayerChangesFlusher& LayerChangesFlusher::shared()
39{
40    DEFINE_STATIC_LOCAL(LayerChangesFlusher, flusher, ());
41    return flusher;
42}
43
44LayerChangesFlusher::LayerChangesFlusher()
45    : m_hook(0)
46    , m_isCallingHosts(false)
47{
48}
49
50void LayerChangesFlusher::flushPendingLayerChangesSoon(AbstractCACFLayerTreeHost* host)
51{
52    if (!m_hostsWithChangesToFlush.add(host).isNewEntry || m_hook)
53        return;
54
55    setHook();
56}
57
58void LayerChangesFlusher::cancelPendingFlush(AbstractCACFLayerTreeHost* host)
59{
60    m_hostsWithChangesToFlush.remove(host);
61
62    if (!m_hostsWithChangesToFlush.isEmpty() || !m_hook)
63        return;
64
65    // We handle removing the hook when we finish calling out to the hosts, so we shouldn't
66    // mess with it while we're in the process of calling them.
67    if (m_isCallingHosts)
68        return;
69
70    removeHook();
71}
72
73LRESULT LayerChangesFlusher::hookCallback(int code, WPARAM wParam, LPARAM lParam)
74{
75    // Supress the exception handler Windows puts around all hook calls so we can
76    // crash for debugging purposes if an exception is hit.
77    ExceptionRegistration registrationStruct; // Note: must be stack allocated.
78    StructuredExceptionHandlerSuppressor supressor(registrationStruct);
79    return shared().hookFired(code, wParam, lParam);
80}
81
82LRESULT LayerChangesFlusher::hookFired(int code, WPARAM wParam, LPARAM lParam)
83{
84    ASSERT(m_hook);
85
86    // Calling out to the hosts can cause m_hostsWithChangesToFlush to be modified, so we copy it
87    // into a Vector first.
88    Vector<AbstractCACFLayerTreeHost*> hosts;
89    copyToVector(m_hostsWithChangesToFlush, hosts);
90    m_hostsWithChangesToFlush.clear();
91
92    m_isCallingHosts = true;
93    for (size_t i = 0; i < hosts.size(); ++i)
94        hosts[i]->flushPendingLayerChangesNow();
95    m_isCallingHosts = false;
96
97    LRESULT result = ::CallNextHookEx(m_hook, code, wParam, lParam);
98
99    if (m_hook && m_hostsWithChangesToFlush.isEmpty()) {
100        // We won't have any work to do next time around, so just remove our hook.
101        removeHook();
102    }
103
104    return result;
105}
106
107void LayerChangesFlusher::setHook()
108{
109    ASSERT(!m_hook);
110    ASSERT(!m_isCallingHosts);
111
112    DWORD threadID = ::GetCurrentThreadId();
113
114    m_hook = ::SetWindowsHookExW(WH_GETMESSAGE, hookCallback, 0, threadID);
115    ASSERT_WITH_MESSAGE(m_hook, "::SetWindowsHookExW failed with error %lu", ::GetLastError());
116
117    // Post a message to the message queue to prevent ::GetMessage from blocking, which will ensure
118    // our hook is called soon.
119    ::PostThreadMessageW(threadID, WM_NULL, 0, 0);
120}
121
122void LayerChangesFlusher::removeHook()
123{
124    ASSERT(m_hook);
125    ASSERT(!m_isCallingHosts);
126
127    if (!::UnhookWindowsHookEx(m_hook))
128        ASSERT_WITH_MESSAGE(false, "::UnhookWindowsHookEx failed with error %lu", ::GetLastError());
129
130    m_hook = 0;
131}
132
133} // namespace WebCore
134
135#endif // USE(ACCELERATED_COMPOSITING)
136