2 * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
3 * Copyright (C) 2009 Google Inc. All rights reserved.
4 * Copyright (C) 2009 Torch Mobile, Inc. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
16 * its contributors may be used to endorse or promote products derived
17 * from this software without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
20 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
21 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
22 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
23 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
26 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 * There are numerous academic and practical works on how to implement pthread_cond_wait/pthread_cond_signal/pthread_cond_broadcast
33 * functions on Win32. Here is one example: http://www.cs.wustl.edu/~schmidt/win32-cv-1.html which is widely credited as a 'starting point'
34 * of modern attempts. There are several more or less proven implementations, one in Boost C++ library (http://www.boost.org) and another
35 * in pthreads-win32 (http://sourceware.org/pthreads-win32/).
37 * The number of articles and discussions is the evidence of significant difficulties in implementing these primitives correctly.
38 * The brief search of revisions, ChangeLog entries, discussions in comp.programming.threads and other places clearly documents
39 * numerous pitfalls and performance problems the authors had to overcome to arrive to the suitable implementations.
40 * Optimally, WebKit would use one of those supported/tested libraries directly. To roll out our own implementation is impractical,
41 * if even for the lack of sufficient testing. However, a faithful reproduction of the code from one of the popular supported
42 * libraries seems to be a good compromise.
44 * The early Boost implementation (http://www.boxbackup.org/trac/browser/box/nick/win/lib/win32/boost_1_32_0/libs/thread/src/condition.cpp?rev=30)
45 * is identical to pthreads-win32 (http://sourceware.org/cgi-bin/cvsweb.cgi/pthreads/pthread_cond_wait.c?rev=1.10&content-type=text/x-cvsweb-markup&cvsroot=pthreads-win32).
46 * Current Boost uses yet another (although seemingly equivalent) algorithm which came from their 'thread rewrite' effort.
48 * This file includes timedWait/signal/broadcast implementations translated to WebKit coding style from the latest algorithm by
49 * Alexander Terekhov and Louis Thomas, as captured here: http://sourceware.org/cgi-bin/cvsweb.cgi/pthreads/pthread_cond_wait.c?rev=1.10&content-type=text/x-cvsweb-markup&cvsroot=pthreads-win32
50 * It replaces the implementation of their previous algorithm, also documented in the same source above.
51 * The naming and comments are left very close to original to enable easy cross-check.
53 * The corresponding Pthreads-win32 License is included below, and CONTRIBUTORS file which it refers to is added to
54 * source directory (as CONTRIBUTORS.pthreads-win32).
58 * Pthreads-win32 - POSIX Threads Library for Win32
59 * Copyright(C) 1998 John E. Bossom
60 * Copyright(C) 1999,2005 Pthreads-win32 contributors
62 * Contact Email: rpj@callisto.canberra.edu.au
64 * The current list of contributors is contained
65 * in the file CONTRIBUTORS included with the source
66 * code distribution. The list can also be seen at the
67 * following World Wide Web location:
68 * http://sources.redhat.com/pthreads-win32/contributors.html
70 * This library is free software; you can redistribute it and/or
71 * modify it under the terms of the GNU Lesser General Public
72 * License as published by the Free Software Foundation; either
73 * version 2 of the License, or (at your option) any later version.
75 * This library is distributed in the hope that it will be useful,
76 * but WITHOUT ANY WARRANTY; without even the implied warranty of
77 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
78 * Lesser General Public License for more details.
80 * You should have received a copy of the GNU Lesser General Public
81 * License along with this library in the file COPYING.LIB;
82 * if not, write to the Free Software Foundation, Inc.,
83 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
87 #include "Threading.h"
91 #include "wtf/CurrentTime.h"
92 #include "wtf/DateMath.h"
93 #include "wtf/HashMap.h"
94 #include "wtf/MainThread.h"
95 #include "wtf/MathExtras.h"
96 #include "wtf/OwnPtr.h"
97 #include "wtf/PassOwnPtr.h"
98 #include "wtf/ThreadFunctionInvocation.h"
99 #include "wtf/ThreadSpecific.h"
100 #include "wtf/ThreadingPrimitives.h"
101 #include "wtf/WTFThreadData.h"
102 #include "wtf/dtoa.h"
103 #include "wtf/dtoa/cached-powers.h"
110 // MS_VC_EXCEPTION, THREADNAME_INFO, and setThreadNameInternal all come from <http://msdn.microsoft.com/en-us/library/xcb2z8hs.aspx>.
111 static const DWORD MS_VC_EXCEPTION = 0x406D1388;
113 #pragma pack(push, 8)
114 typedef struct tagTHREADNAME_INFO {
115 DWORD dwType; // must be 0x1000
116 LPCSTR szName; // pointer to name (in user addr space)
117 DWORD dwThreadID; // thread ID (-1=caller thread)
118 DWORD dwFlags; // reserved for future use, must be zero
122 static Mutex* atomicallyInitializedStaticMutex;
124 void lockAtomicallyInitializedStaticMutex()
126 ASSERT(atomicallyInitializedStaticMutex);
127 atomicallyInitializedStaticMutex->lock();
130 void unlockAtomicallyInitializedStaticMutex()
132 atomicallyInitializedStaticMutex->unlock();
135 void initializeThreading()
137 // This should only be called once.
138 ASSERT(!atomicallyInitializedStaticMutex);
140 // StringImpl::empty() does not construct its static string in a threadsafe fashion,
141 // so ensure it has been initialized from here.
143 atomicallyInitializedStaticMutex = new Mutex;
145 s_dtoaP5Mutex = new Mutex;
149 ThreadIdentifier currentThread()
151 return static_cast<ThreadIdentifier>(GetCurrentThreadId());
154 MutexBase::MutexBase(bool recursive)
156 m_mutex.m_recursionCount = 0;
157 InitializeCriticalSection(&m_mutex.m_internalMutex);
160 MutexBase::~MutexBase()
162 DeleteCriticalSection(&m_mutex.m_internalMutex);
165 void MutexBase::lock()
167 EnterCriticalSection(&m_mutex.m_internalMutex);
168 ++m_mutex.m_recursionCount;
171 void MutexBase::unlock()
173 ASSERT(m_mutex.m_recursionCount);
174 --m_mutex.m_recursionCount;
175 LeaveCriticalSection(&m_mutex.m_internalMutex);
178 bool Mutex::tryLock()
180 // This method is modeled after the behavior of pthread_mutex_trylock,
181 // which will return an error if the lock is already owned by the
182 // current thread. Since the primitive Win32 'TryEnterCriticalSection'
183 // treats this as a successful case, it changes the behavior of several
184 // tests in WebKit that check to see if the current thread already
185 // owned this mutex (see e.g., IconDatabase::getOrCreateIconRecord)
186 DWORD result = TryEnterCriticalSection(&m_mutex.m_internalMutex);
188 if (result != 0) { // We got the lock
189 // If this thread already had the lock, we must unlock and return
190 // false since this is a non-recursive mutex. This is to mimic the
191 // behavior of POSIX's pthread_mutex_trylock. We don't do this
192 // check in the lock method (presumably due to performance?). This
193 // means lock() will succeed even if the current thread has already
194 // entered the critical section.
195 if (m_mutex.m_recursionCount > 0) {
196 LeaveCriticalSection(&m_mutex.m_internalMutex);
199 ++m_mutex.m_recursionCount;
206 bool RecursiveMutex::tryLock()
208 // CRITICAL_SECTION is recursive/reentrant so TryEnterCriticalSection will
209 // succeed if the current thread is already in the critical section.
210 DWORD result = TryEnterCriticalSection(&m_mutex.m_internalMutex);
211 if (result == 0) { // We didn't get the lock.
214 ++m_mutex.m_recursionCount;
218 bool PlatformCondition::timedWait(PlatformMutex& mutex, DWORD durationMilliseconds)
220 // Enter the wait state.
221 DWORD res = WaitForSingleObject(m_blockLock, INFINITE);
222 ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
224 res = ReleaseSemaphore(m_blockLock, 1, 0);
225 ASSERT_UNUSED(res, res);
227 --mutex.m_recursionCount;
228 LeaveCriticalSection(&mutex.m_internalMutex);
230 // Main wait - use timeout.
231 bool timedOut = (WaitForSingleObject(m_blockQueue, durationMilliseconds) == WAIT_TIMEOUT);
233 res = WaitForSingleObject(m_unblockLock, INFINITE);
234 ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
236 int signalsLeft = m_waitersToUnblock;
238 if (m_waitersToUnblock)
239 --m_waitersToUnblock;
240 else if (++m_waitersGone == (INT_MAX / 2)) { // timeout/canceled or spurious semaphore
241 // timeout or spurious wakeup occured, normalize the m_waitersGone count
242 // this may occur if many calls to wait with a timeout are made and
243 // no call to notify_* is made
244 res = WaitForSingleObject(m_blockLock, INFINITE);
245 ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
246 m_waitersBlocked -= m_waitersGone;
247 res = ReleaseSemaphore(m_blockLock, 1, 0);
248 ASSERT_UNUSED(res, res);
252 res = ReleaseMutex(m_unblockLock);
253 ASSERT_UNUSED(res, res);
255 if (signalsLeft == 1) {
256 res = ReleaseSemaphore(m_blockLock, 1, 0); // Open the gate.
257 ASSERT_UNUSED(res, res);
260 EnterCriticalSection (&mutex.m_internalMutex);
261 ++mutex.m_recursionCount;
266 void PlatformCondition::signal(bool unblockAll)
268 unsigned signalsToIssue = 0;
270 DWORD res = WaitForSingleObject(m_unblockLock, INFINITE);
271 ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
273 if (m_waitersToUnblock) { // the gate is already closed
274 if (!m_waitersBlocked) { // no-op
275 res = ReleaseMutex(m_unblockLock);
276 ASSERT_UNUSED(res, res);
281 signalsToIssue = m_waitersBlocked;
282 m_waitersToUnblock += m_waitersBlocked;
283 m_waitersBlocked = 0;
286 ++m_waitersToUnblock;
289 } else if (m_waitersBlocked > m_waitersGone) {
290 res = WaitForSingleObject(m_blockLock, INFINITE); // Close the gate.
291 ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
292 if (m_waitersGone != 0) {
293 m_waitersBlocked -= m_waitersGone;
297 signalsToIssue = m_waitersBlocked;
298 m_waitersToUnblock = m_waitersBlocked;
299 m_waitersBlocked = 0;
302 m_waitersToUnblock = 1;
306 res = ReleaseMutex(m_unblockLock);
307 ASSERT_UNUSED(res, res);
311 res = ReleaseMutex(m_unblockLock);
312 ASSERT_UNUSED(res, res);
314 if (signalsToIssue) {
315 res = ReleaseSemaphore(m_blockQueue, signalsToIssue, 0);
316 ASSERT_UNUSED(res, res);
320 static const long MaxSemaphoreCount = static_cast<long>(~0UL >> 1);
322 ThreadCondition::ThreadCondition()
324 m_condition.m_waitersGone = 0;
325 m_condition.m_waitersBlocked = 0;
326 m_condition.m_waitersToUnblock = 0;
327 m_condition.m_blockLock = CreateSemaphore(0, 1, 1, 0);
328 m_condition.m_blockQueue = CreateSemaphore(0, 0, MaxSemaphoreCount, 0);
329 m_condition.m_unblockLock = CreateMutex(0, 0, 0);
331 if (!m_condition.m_blockLock || !m_condition.m_blockQueue || !m_condition.m_unblockLock) {
332 if (m_condition.m_blockLock)
333 CloseHandle(m_condition.m_blockLock);
334 if (m_condition.m_blockQueue)
335 CloseHandle(m_condition.m_blockQueue);
336 if (m_condition.m_unblockLock)
337 CloseHandle(m_condition.m_unblockLock);
341 ThreadCondition::~ThreadCondition()
343 CloseHandle(m_condition.m_blockLock);
344 CloseHandle(m_condition.m_blockQueue);
345 CloseHandle(m_condition.m_unblockLock);
348 void ThreadCondition::wait(MutexBase& mutex)
350 m_condition.timedWait(mutex.impl(), INFINITE);
353 bool ThreadCondition::timedWait(MutexBase& mutex, double absoluteTime)
355 DWORD interval = absoluteTimeToWaitTimeoutInterval(absoluteTime);
358 // Consider the wait to have timed out, even if our condition has already been signaled, to
359 // match the pthreads implementation.
363 return m_condition.timedWait(mutex.impl(), interval);
366 void ThreadCondition::signal()
368 m_condition.signal(false); // Unblock only 1 thread.
371 void ThreadCondition::broadcast()
373 m_condition.signal(true); // Unblock all threads.
376 DWORD absoluteTimeToWaitTimeoutInterval(double absoluteTime)
378 double currentTime = WTF::currentTime();
380 // Time is in the past - return immediately.
381 if (absoluteTime < currentTime)
384 // Time is too far in the future (and would overflow unsigned long) - wait forever.
385 if (absoluteTime - currentTime > static_cast<double>(INT_MAX) / 1000.0)
388 return static_cast<DWORD>((absoluteTime - currentTime) * 1000.0);