1 /* 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. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 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. 18 * 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. 29 */ 30 31 /* 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/). 36 * 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. 43 * 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. 47 * 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. 52 * 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). 55 */ 56 57 /* 58 * Pthreads-win32 - POSIX Threads Library for Win32 59 * Copyright(C) 1998 John E. Bossom 60 * Copyright(C) 1999,2005 Pthreads-win32 contributors 61 * 62 * Contact Email: rpj (at) callisto.canberra.edu.au 63 * 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 69 * 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. 74 * 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. 79 * 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 84 */ 85 86 #include "config.h" 87 #include "Threading.h" 88 89 #if OS(WIN) 90 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" 104 #include <errno.h> 105 #include <process.h> 106 #include <windows.h> 107 108 namespace WTF { 109 110 // 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; 112 113 #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 119 } THREADNAME_INFO; 120 #pragma pack(pop) 121 122 static Mutex* atomicallyInitializedStaticMutex; 123 124 void lockAtomicallyInitializedStaticMutex() 125 { 126 ASSERT(atomicallyInitializedStaticMutex); 127 atomicallyInitializedStaticMutex->lock(); 128 } 129 130 void unlockAtomicallyInitializedStaticMutex() 131 { 132 atomicallyInitializedStaticMutex->unlock(); 133 } 134 135 void initializeThreading() 136 { 137 // This should only be called once. 138 ASSERT(!atomicallyInitializedStaticMutex); 139 140 // StringImpl::empty() does not construct its static string in a threadsafe fashion, 141 // so ensure it has been initialized from here. 142 StringImpl::empty(); 143 StringImpl::empty16Bit(); 144 atomicallyInitializedStaticMutex = new Mutex; 145 wtfThreadData(); 146 s_dtoaP5Mutex = new Mutex; 147 initializeDates(); 148 // Force initialization of static DoubleToStringConverter converter variable 149 // inside EcmaScriptConverter function while we are in single thread mode. 150 double_conversion::DoubleToStringConverter::EcmaScriptConverter(); 151 } 152 153 ThreadIdentifier currentThread() 154 { 155 return static_cast<ThreadIdentifier>(GetCurrentThreadId()); 156 } 157 158 MutexBase::MutexBase(bool recursive) 159 { 160 m_mutex.m_recursionCount = 0; 161 InitializeCriticalSection(&m_mutex.m_internalMutex); 162 } 163 164 MutexBase::~MutexBase() 165 { 166 DeleteCriticalSection(&m_mutex.m_internalMutex); 167 } 168 169 void MutexBase::lock() 170 { 171 EnterCriticalSection(&m_mutex.m_internalMutex); 172 ++m_mutex.m_recursionCount; 173 } 174 175 void MutexBase::unlock() 176 { 177 ASSERT(m_mutex.m_recursionCount); 178 --m_mutex.m_recursionCount; 179 LeaveCriticalSection(&m_mutex.m_internalMutex); 180 } 181 182 bool Mutex::tryLock() 183 { 184 // This method is modeled after the behavior of pthread_mutex_trylock, 185 // which will return an error if the lock is already owned by the 186 // current thread. Since the primitive Win32 'TryEnterCriticalSection' 187 // treats this as a successful case, it changes the behavior of several 188 // tests in WebKit that check to see if the current thread already 189 // owned this mutex (see e.g., IconDatabase::getOrCreateIconRecord) 190 DWORD result = TryEnterCriticalSection(&m_mutex.m_internalMutex); 191 192 if (result != 0) { // We got the lock 193 // If this thread already had the lock, we must unlock and return 194 // false since this is a non-recursive mutex. This is to mimic the 195 // behavior of POSIX's pthread_mutex_trylock. We don't do this 196 // check in the lock method (presumably due to performance?). This 197 // means lock() will succeed even if the current thread has already 198 // entered the critical section. 199 if (m_mutex.m_recursionCount > 0) { 200 LeaveCriticalSection(&m_mutex.m_internalMutex); 201 return false; 202 } 203 ++m_mutex.m_recursionCount; 204 return true; 205 } 206 207 return false; 208 } 209 210 bool RecursiveMutex::tryLock() 211 { 212 // CRITICAL_SECTION is recursive/reentrant so TryEnterCriticalSection will 213 // succeed if the current thread is already in the critical section. 214 DWORD result = TryEnterCriticalSection(&m_mutex.m_internalMutex); 215 if (result == 0) { // We didn't get the lock. 216 return false; 217 } 218 ++m_mutex.m_recursionCount; 219 return true; 220 } 221 222 bool PlatformCondition::timedWait(PlatformMutex& mutex, DWORD durationMilliseconds) 223 { 224 // Enter the wait state. 225 DWORD res = WaitForSingleObject(m_blockLock, INFINITE); 226 ASSERT_UNUSED(res, res == WAIT_OBJECT_0); 227 ++m_waitersBlocked; 228 res = ReleaseSemaphore(m_blockLock, 1, 0); 229 ASSERT_UNUSED(res, res); 230 231 --mutex.m_recursionCount; 232 LeaveCriticalSection(&mutex.m_internalMutex); 233 234 // Main wait - use timeout. 235 bool timedOut = (WaitForSingleObject(m_blockQueue, durationMilliseconds) == WAIT_TIMEOUT); 236 237 res = WaitForSingleObject(m_unblockLock, INFINITE); 238 ASSERT_UNUSED(res, res == WAIT_OBJECT_0); 239 240 int signalsLeft = m_waitersToUnblock; 241 242 if (m_waitersToUnblock) 243 --m_waitersToUnblock; 244 else if (++m_waitersGone == (INT_MAX / 2)) { // timeout/canceled or spurious semaphore 245 // timeout or spurious wakeup occured, normalize the m_waitersGone count 246 // this may occur if many calls to wait with a timeout are made and 247 // no call to notify_* is made 248 res = WaitForSingleObject(m_blockLock, INFINITE); 249 ASSERT_UNUSED(res, res == WAIT_OBJECT_0); 250 m_waitersBlocked -= m_waitersGone; 251 res = ReleaseSemaphore(m_blockLock, 1, 0); 252 ASSERT_UNUSED(res, res); 253 m_waitersGone = 0; 254 } 255 256 res = ReleaseMutex(m_unblockLock); 257 ASSERT_UNUSED(res, res); 258 259 if (signalsLeft == 1) { 260 res = ReleaseSemaphore(m_blockLock, 1, 0); // Open the gate. 261 ASSERT_UNUSED(res, res); 262 } 263 264 EnterCriticalSection (&mutex.m_internalMutex); 265 ++mutex.m_recursionCount; 266 267 return !timedOut; 268 } 269 270 void PlatformCondition::signal(bool unblockAll) 271 { 272 unsigned signalsToIssue = 0; 273 274 DWORD res = WaitForSingleObject(m_unblockLock, INFINITE); 275 ASSERT_UNUSED(res, res == WAIT_OBJECT_0); 276 277 if (m_waitersToUnblock) { // the gate is already closed 278 if (!m_waitersBlocked) { // no-op 279 res = ReleaseMutex(m_unblockLock); 280 ASSERT_UNUSED(res, res); 281 return; 282 } 283 284 if (unblockAll) { 285 signalsToIssue = m_waitersBlocked; 286 m_waitersToUnblock += m_waitersBlocked; 287 m_waitersBlocked = 0; 288 } else { 289 signalsToIssue = 1; 290 ++m_waitersToUnblock; 291 --m_waitersBlocked; 292 } 293 } else if (m_waitersBlocked > m_waitersGone) { 294 res = WaitForSingleObject(m_blockLock, INFINITE); // Close the gate. 295 ASSERT_UNUSED(res, res == WAIT_OBJECT_0); 296 if (m_waitersGone != 0) { 297 m_waitersBlocked -= m_waitersGone; 298 m_waitersGone = 0; 299 } 300 if (unblockAll) { 301 signalsToIssue = m_waitersBlocked; 302 m_waitersToUnblock = m_waitersBlocked; 303 m_waitersBlocked = 0; 304 } else { 305 signalsToIssue = 1; 306 m_waitersToUnblock = 1; 307 --m_waitersBlocked; 308 } 309 } else { // No-op. 310 res = ReleaseMutex(m_unblockLock); 311 ASSERT_UNUSED(res, res); 312 return; 313 } 314 315 res = ReleaseMutex(m_unblockLock); 316 ASSERT_UNUSED(res, res); 317 318 if (signalsToIssue) { 319 res = ReleaseSemaphore(m_blockQueue, signalsToIssue, 0); 320 ASSERT_UNUSED(res, res); 321 } 322 } 323 324 static const long MaxSemaphoreCount = static_cast<long>(~0UL >> 1); 325 326 ThreadCondition::ThreadCondition() 327 { 328 m_condition.m_waitersGone = 0; 329 m_condition.m_waitersBlocked = 0; 330 m_condition.m_waitersToUnblock = 0; 331 m_condition.m_blockLock = CreateSemaphore(0, 1, 1, 0); 332 m_condition.m_blockQueue = CreateSemaphore(0, 0, MaxSemaphoreCount, 0); 333 m_condition.m_unblockLock = CreateMutex(0, 0, 0); 334 335 if (!m_condition.m_blockLock || !m_condition.m_blockQueue || !m_condition.m_unblockLock) { 336 if (m_condition.m_blockLock) 337 CloseHandle(m_condition.m_blockLock); 338 if (m_condition.m_blockQueue) 339 CloseHandle(m_condition.m_blockQueue); 340 if (m_condition.m_unblockLock) 341 CloseHandle(m_condition.m_unblockLock); 342 } 343 } 344 345 ThreadCondition::~ThreadCondition() 346 { 347 CloseHandle(m_condition.m_blockLock); 348 CloseHandle(m_condition.m_blockQueue); 349 CloseHandle(m_condition.m_unblockLock); 350 } 351 352 void ThreadCondition::wait(MutexBase& mutex) 353 { 354 m_condition.timedWait(mutex.impl(), INFINITE); 355 } 356 357 bool ThreadCondition::timedWait(MutexBase& mutex, double absoluteTime) 358 { 359 DWORD interval = absoluteTimeToWaitTimeoutInterval(absoluteTime); 360 361 if (!interval) { 362 // Consider the wait to have timed out, even if our condition has already been signaled, to 363 // match the pthreads implementation. 364 return false; 365 } 366 367 return m_condition.timedWait(mutex.impl(), interval); 368 } 369 370 void ThreadCondition::signal() 371 { 372 m_condition.signal(false); // Unblock only 1 thread. 373 } 374 375 void ThreadCondition::broadcast() 376 { 377 m_condition.signal(true); // Unblock all threads. 378 } 379 380 DWORD absoluteTimeToWaitTimeoutInterval(double absoluteTime) 381 { 382 double currentTime = WTF::currentTime(); 383 384 // Time is in the past - return immediately. 385 if (absoluteTime < currentTime) 386 return 0; 387 388 // Time is too far in the future (and would overflow unsigned long) - wait forever. 389 if (absoluteTime - currentTime > static_cast<double>(INT_MAX) / 1000.0) 390 return INFINITE; 391 392 return static_cast<DWORD>((absoluteTime - currentTime) * 1000.0); 393 } 394 395 } // namespace WTF 396 397 #endif // OS(WIN) 398