1 /*
2 * Copyright (C) 2007, 2008 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 *
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 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
14 * its contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include "config.h"
30 #include "MainThread.h"
31
32 #include "StdLibExtras.h"
33 #include "CurrentTime.h"
34 #include "Deque.h"
35 #include "Threading.h"
36
37 namespace WTF {
38
39 struct FunctionWithContext {
40 MainThreadFunction* function;
41 void* context;
42 ThreadCondition* syncFlag;
43
FunctionWithContextWTF::FunctionWithContext44 FunctionWithContext(MainThreadFunction* function = 0, void* context = 0, ThreadCondition* syncFlag = 0)
45 : function(function)
46 , context(context)
47 , syncFlag(syncFlag)
48 {
49 }
50 };
51
52 typedef Deque<FunctionWithContext> FunctionQueue;
53
54 static bool callbacksPaused; // This global variable is only accessed from main thread.
55
mainThreadFunctionQueueMutex()56 Mutex& mainThreadFunctionQueueMutex()
57 {
58 DEFINE_STATIC_LOCAL(Mutex, staticMutex, ());
59 return staticMutex;
60 }
61
functionQueue()62 static FunctionQueue& functionQueue()
63 {
64 DEFINE_STATIC_LOCAL(FunctionQueue, staticFunctionQueue, ());
65 return staticFunctionQueue;
66 }
67
initializeMainThread()68 void initializeMainThread()
69 {
70 mainThreadFunctionQueueMutex();
71 initializeMainThreadPlatform();
72 }
73
74 // 0.1 sec delays in UI is approximate threshold when they become noticeable. Have a limit that's half of that.
75 static const double maxRunLoopSuspensionTime = 0.05;
76
dispatchFunctionsFromMainThread()77 void dispatchFunctionsFromMainThread()
78 {
79 ASSERT(isMainThread());
80
81 if (callbacksPaused)
82 return;
83
84 double startTime = currentTime();
85
86 FunctionWithContext invocation;
87 while (true) {
88 {
89 MutexLocker locker(mainThreadFunctionQueueMutex());
90 if (!functionQueue().size())
91 break;
92 invocation = functionQueue().first();
93 functionQueue().removeFirst();
94 }
95
96 invocation.function(invocation.context);
97 if (invocation.syncFlag)
98 invocation.syncFlag->signal();
99
100 // If we are running accumulated functions for too long so UI may become unresponsive, we need to
101 // yield so the user input can be processed. Otherwise user may not be able to even close the window.
102 // This code has effect only in case the scheduleDispatchFunctionsOnMainThread() is implemented in a way that
103 // allows input events to be processed before we are back here.
104 if (currentTime() - startTime > maxRunLoopSuspensionTime) {
105 scheduleDispatchFunctionsOnMainThread();
106 break;
107 }
108 }
109 }
110
callOnMainThread(MainThreadFunction * function,void * context)111 void callOnMainThread(MainThreadFunction* function, void* context)
112 {
113 ASSERT(function);
114 bool needToSchedule = false;
115 {
116 MutexLocker locker(mainThreadFunctionQueueMutex());
117 needToSchedule = functionQueue().size() == 0;
118 functionQueue().append(FunctionWithContext(function, context));
119 }
120 if (needToSchedule)
121 scheduleDispatchFunctionsOnMainThread();
122 }
123
callOnMainThreadAndWait(MainThreadFunction * function,void * context)124 void callOnMainThreadAndWait(MainThreadFunction* function, void* context)
125 {
126 ASSERT(function);
127
128 if (isMainThread()) {
129 function(context);
130 return;
131 }
132
133 ThreadCondition syncFlag;
134 Mutex& functionQueueMutex = mainThreadFunctionQueueMutex();
135 MutexLocker locker(functionQueueMutex);
136 functionQueue().append(FunctionWithContext(function, context, &syncFlag));
137 if (functionQueue().size() == 1)
138 scheduleDispatchFunctionsOnMainThread();
139 syncFlag.wait(functionQueueMutex);
140 }
141
setMainThreadCallbacksPaused(bool paused)142 void setMainThreadCallbacksPaused(bool paused)
143 {
144 ASSERT(isMainThread());
145
146 if (callbacksPaused == paused)
147 return;
148
149 callbacksPaused = paused;
150
151 if (!callbacksPaused)
152 scheduleDispatchFunctionsOnMainThread();
153 }
154
155 } // namespace WTF
156