1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
/*
* Copyright (C) 2007, 2008 Apple 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.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* 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.
*/
#include "config.h"
#include "MainThread.h"
#include "CurrentTime.h"
#include "Deque.h"
#include "StdLibExtras.h"
#include "Threading.h"
#if PLATFORM(CHROMIUM)
#error Chromium uses a different main thread implementation
#endif
namespace WTF {
struct FunctionWithContext {
MainThreadFunction* function;
void* context;
ThreadCondition* syncFlag;
FunctionWithContext(MainThreadFunction* function = 0, void* context = 0, ThreadCondition* syncFlag = 0)
: function(function)
, context(context)
, syncFlag(syncFlag)
{
}
bool operator == (const FunctionWithContext& o)
{
return function == o.function
&& context == o.context
&& syncFlag == o.syncFlag;
}
};
class FunctionWithContextFinder {
public:
FunctionWithContextFinder(const FunctionWithContext& m) : m(m) {}
bool operator() (FunctionWithContext& o) { return o == m; }
FunctionWithContext m;
};
typedef Deque<FunctionWithContext> FunctionQueue;
static bool callbacksPaused; // This global variable is only accessed from main thread.
#if !PLATFORM(MAC) && !PLATFORM(QT)
static ThreadIdentifier mainThreadIdentifier;
#endif
static Mutex& mainThreadFunctionQueueMutex()
{
DEFINE_STATIC_LOCAL(Mutex, staticMutex, ());
return staticMutex;
}
static FunctionQueue& functionQueue()
{
DEFINE_STATIC_LOCAL(FunctionQueue, staticFunctionQueue, ());
return staticFunctionQueue;
}
#if !PLATFORM(MAC)
void initializeMainThread()
{
static bool initializedMainThread;
if (initializedMainThread)
return;
initializedMainThread = true;
#if !PLATFORM(QT)
mainThreadIdentifier = currentThread();
#endif
mainThreadFunctionQueueMutex();
initializeMainThreadPlatform();
}
#else
static pthread_once_t initializeMainThreadKeyOnce = PTHREAD_ONCE_INIT;
static void initializeMainThreadOnce()
{
mainThreadFunctionQueueMutex();
initializeMainThreadPlatform();
}
void initializeMainThread()
{
pthread_once(&initializeMainThreadKeyOnce, initializeMainThreadOnce);
}
static void initializeMainThreadToProcessMainThreadOnce()
{
mainThreadFunctionQueueMutex();
initializeMainThreadToProcessMainThreadPlatform();
}
void initializeMainThreadToProcessMainThread()
{
pthread_once(&initializeMainThreadKeyOnce, initializeMainThreadToProcessMainThreadOnce);
}
#endif
// 0.1 sec delays in UI is approximate threshold when they become noticeable. Have a limit that's half of that.
static const double maxRunLoopSuspensionTime = 0.05;
void dispatchFunctionsFromMainThread()
{
ASSERT(isMainThread());
if (callbacksPaused)
return;
double startTime = currentTime();
FunctionWithContext invocation;
while (true) {
{
MutexLocker locker(mainThreadFunctionQueueMutex());
if (!functionQueue().size())
break;
invocation = functionQueue().takeFirst();
}
invocation.function(invocation.context);
if (invocation.syncFlag)
invocation.syncFlag->signal();
// If we are running accumulated functions for too long so UI may become unresponsive, we need to
// yield so the user input can be processed. Otherwise user may not be able to even close the window.
// This code has effect only in case the scheduleDispatchFunctionsOnMainThread() is implemented in a way that
// allows input events to be processed before we are back here.
if (currentTime() - startTime > maxRunLoopSuspensionTime) {
scheduleDispatchFunctionsOnMainThread();
break;
}
}
}
void callOnMainThread(MainThreadFunction* function, void* context)
{
ASSERT(function);
bool needToSchedule = false;
{
MutexLocker locker(mainThreadFunctionQueueMutex());
needToSchedule = functionQueue().size() == 0;
functionQueue().append(FunctionWithContext(function, context));
}
if (needToSchedule)
scheduleDispatchFunctionsOnMainThread();
}
void callOnMainThreadAndWait(MainThreadFunction* function, void* context)
{
ASSERT(function);
if (isMainThread()) {
function(context);
return;
}
ThreadCondition syncFlag;
Mutex& functionQueueMutex = mainThreadFunctionQueueMutex();
MutexLocker locker(functionQueueMutex);
functionQueue().append(FunctionWithContext(function, context, &syncFlag));
if (functionQueue().size() == 1)
scheduleDispatchFunctionsOnMainThread();
syncFlag.wait(functionQueueMutex);
}
void cancelCallOnMainThread(MainThreadFunction* function, void* context)
{
ASSERT(function);
MutexLocker locker(mainThreadFunctionQueueMutex());
FunctionWithContextFinder pred(FunctionWithContext(function, context));
while (true) {
// We must redefine 'i' each pass, because the itererator's operator=
// requires 'this' to be valid, and remove() invalidates all iterators
FunctionQueue::iterator i(functionQueue().findIf(pred));
if (i == functionQueue().end())
break;
functionQueue().remove(i);
}
}
void setMainThreadCallbacksPaused(bool paused)
{
ASSERT(isMainThread());
if (callbacksPaused == paused)
return;
callbacksPaused = paused;
if (!callbacksPaused)
scheduleDispatchFunctionsOnMainThread();
}
#if !PLATFORM(MAC) && !PLATFORM(QT) && !PLATFORM(BREWMP)
bool isMainThread()
{
return currentThread() == mainThreadIdentifier;
}
#endif
} // namespace WTF
|
