/* * Copyright (C) 2007, 2008, 2015 Apple Inc. All rights reserved. * Copyright (C) 2009 Google Inc. All rights reserved. * Copyright (C) 2009 Torch Mobile, 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 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. */ /* * There are numerous academic and practical works on how to implement pthread_cond_wait/pthread_cond_signal/pthread_cond_broadcast * 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' * of modern attempts. There are several more or less proven implementations, one in Boost C++ library (http://www.boost.org) and another * in pthreads-win32 (http://sourceware.org/pthreads-win32/). * * The number of articles and discussions is the evidence of significant difficulties in implementing these primitives correctly. * The brief search of revisions, ChangeLog entries, discussions in comp.programming.threads and other places clearly documents * numerous pitfalls and performance problems the authors had to overcome to arrive to the suitable implementations. * Optimally, WebKit would use one of those supported/tested libraries directly. To roll out our own implementation is impractical, * if even for the lack of sufficient testing. However, a faithful reproduction of the code from one of the popular supported * libraries seems to be a good compromise. * * 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) * 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). * Current Boost uses yet another (although seemingly equivalent) algorithm which came from their 'thread rewrite' effort. * * This file includes timedWait/signal/broadcast implementations translated to WebKit coding style from the latest algorithm by * 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 * It replaces the implementation of their previous algorithm, also documented in the same source above. * The naming and comments are left very close to original to enable easy cross-check. * * The corresponding Pthreads-win32 License is included below, and CONTRIBUTORS file which it refers to is added to * source directory (as CONTRIBUTORS.pthreads-win32). */ /* * Pthreads-win32 - POSIX Threads Library for Win32 * Copyright(C) 1998 John E. Bossom * Copyright(C) 1999,2005 Pthreads-win32 contributors * * Contact Email: rpj@callisto.canberra.edu.au * * The current list of contributors is contained * in the file CONTRIBUTORS included with the source * code distribution. The list can also be seen at the * following World Wide Web location: * http://sources.redhat.com/pthreads-win32/contributors.html * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library in the file COPYING.LIB; * if not, write to the Free Software Foundation, Inc., * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA */ #include "config.h" #include <wtf/Threading.h> #include <errno.h> #include <process.h> #include <windows.h> #include <wtf/HashMap.h> #include <wtf/Lock.h> #include <wtf/MainThread.h> #include <wtf/MathExtras.h> #include <wtf/NeverDestroyed.h> #include <wtf/ThreadingPrimitives.h> namespace WTF { static Lock globalSuspendLock; Thread::~Thread() { // It is OK because FLSAlloc's callback will be called even before there are some open handles. // This easily ensures that all the thread resources are automatically closed. if (m_handle != INVALID_HANDLE_VALUE) CloseHandle(m_handle); } void Thread::initializeCurrentThreadEvenIfNonWTFCreated() { } // MS_VC_EXCEPTION, THREADNAME_INFO, and setThreadNameInternal all come from <http://msdn.microsoft.com/en-us/library/xcb2z8hs.aspx>. static const DWORD MS_VC_EXCEPTION = 0x406D1388; #pragma pack(push, 8) typedef struct tagTHREADNAME_INFO { DWORD dwType; // must be 0x1000 LPCSTR szName; // pointer to name (in user addr space) DWORD dwThreadID; // thread ID (-1=caller thread) DWORD dwFlags; // reserved for future use, must be zero } THREADNAME_INFO; #pragma pack(pop) void Thread::initializeCurrentThreadInternal(const char* szThreadName) { #if COMPILER(MINGW) // FIXME: Implement thread name setting with MingW. UNUSED_PARAM(szThreadName); #else THREADNAME_INFO info; info.dwType = 0x1000; info.szName = Thread::normalizeThreadName(szThreadName); info.dwThreadID = GetCurrentThreadId(); info.dwFlags = 0; __try { RaiseException(MS_VC_EXCEPTION, 0, sizeof(info) / sizeof(ULONG_PTR), reinterpret_cast<ULONG_PTR*>(&info)); } __except(EXCEPTION_CONTINUE_EXECUTION) { } #endif initializeCurrentThreadEvenIfNonWTFCreated(); } void Thread::initializePlatformThreading() { } static unsigned __stdcall wtfThreadEntryPoint(void* data) { Thread::entryPoint(reinterpret_cast<Thread::NewThreadContext*>(data)); return 0; } bool Thread::establishHandle(NewThreadContext* data, Optional<size_t> stackSize) { unsigned threadIdentifier = 0; unsigned initFlag = stackSize ? STACK_SIZE_PARAM_IS_A_RESERVATION : 0; HANDLE threadHandle = reinterpret_cast<HANDLE>(_beginthreadex(nullptr, stackSize.valueOr(0), wtfThreadEntryPoint, data, initFlag, &threadIdentifier)); if (!threadHandle) { LOG_ERROR("Failed to create thread at entry point %p with data %p: %ld", wtfThreadEntryPoint, data, errno); return false; } establishPlatformSpecificHandle(threadHandle, threadIdentifier); return true; } void Thread::changePriority(int delta) { auto locker = holdLock(m_mutex); SetThreadPriority(m_handle, THREAD_PRIORITY_NORMAL + delta); } int Thread::waitForCompletion() { HANDLE handle; { auto locker = holdLock(m_mutex); handle = m_handle; } DWORD joinResult = WaitForSingleObject(handle, INFINITE); if (joinResult == WAIT_FAILED) LOG_ERROR("Thread %p was found to be deadlocked trying to quit", this); auto locker = holdLock(m_mutex); ASSERT(joinableState() == Joinable); // The thread has already exited, do nothing. // The thread hasn't exited yet, so don't clean anything up. Just signal that we've already joined on it so that it will clean up after itself. if (!hasExited()) didJoin(); return joinResult; } void Thread::detach() { // We follow the pthread semantics: even after the detach is called, // we can still perform various operations onto the thread. For example, // we can do pthread_kill for the detached thread. The problem in Windows // is that closing HANDLE loses the way to do such operations. // To do so, we do nothing here in Windows. Original detach's purpose, // releasing thread resource when the thread exits, will be achieved by // FlsCallback automatically. FlsCallback will call CloseHandle to clean up // resource. So in this function, we just mark the thread as detached to // avoid calling waitForCompletion for this thread. auto locker = holdLock(m_mutex); if (!hasExited()) didBecomeDetached(); } auto Thread::suspend() -> Expected<void, PlatformSuspendError> { RELEASE_ASSERT_WITH_MESSAGE(this != &Thread::current(), "We do not support suspending the current thread itself."); LockHolder locker(globalSuspendLock); DWORD result = SuspendThread(m_handle); if (result != (DWORD)-1) return { }; return makeUnexpected(result); } // During resume, suspend or resume should not be executed from the other threads. void Thread::resume() { LockHolder locker(globalSuspendLock); ResumeThread(m_handle); } size_t Thread::getRegisters(PlatformRegisters& registers) { LockHolder locker(globalSuspendLock); registers.ContextFlags = CONTEXT_INTEGER | CONTEXT_CONTROL; GetThreadContext(m_handle, ®isters); return sizeof(CONTEXT); } Thread& Thread::initializeCurrentTLS() { // Not a WTF-created thread, ThreadIdentifier is not established yet. Ref<Thread> thread = adoptRef(*new Thread()); HANDLE handle; bool isSuccessful = DuplicateHandle(GetCurrentProcess(), GetCurrentThread(), GetCurrentProcess(), &handle, 0, FALSE, DUPLICATE_SAME_ACCESS); RELEASE_ASSERT(isSuccessful); thread->establishPlatformSpecificHandle(handle, currentID()); thread->initializeInThread(); initializeCurrentThreadEvenIfNonWTFCreated(); return initializeTLS(WTFMove(thread)); } ThreadIdentifier Thread::currentID() { return static_cast<ThreadIdentifier>(GetCurrentThreadId()); } void Thread::establishPlatformSpecificHandle(HANDLE handle, ThreadIdentifier threadID) { auto locker = holdLock(m_mutex); m_handle = handle; m_id = threadID; } struct Thread::ThreadHolder { ~ThreadHolder() { // The thread_local object of the main thread is destructed // after Windows terminates other threads. If the terminated // thread was holding a mutex, trying to lock the mutex causes // deadlock. if (isMainThread()) return; if (thread) { thread->specificStorage().destroySlots(); thread->didExit(); } } RefPtr<Thread> thread; }; thread_local static Thread::ThreadHolder s_threadHolder; Thread* Thread::currentMayBeNull() { return s_threadHolder.thread.get(); } Thread& Thread::initializeTLS(Ref<Thread>&& thread) { s_threadHolder.thread = WTFMove(thread); return *s_threadHolder.thread; } Atomic<int> Thread::SpecificStorage::s_numberOfKeys; std::array<Atomic<Thread::SpecificStorage::DestroyFunction>, Thread::SpecificStorage::s_maxKeys> Thread::SpecificStorage::s_destroyFunctions; bool Thread::SpecificStorage::allocateKey(int& key, DestroyFunction destroy) { int k = s_numberOfKeys.exchangeAdd(1); if (k >= s_maxKeys) { s_numberOfKeys.exchangeSub(1); return false; } key = k; s_destroyFunctions[key].store(destroy); return true; } void* Thread::SpecificStorage::get(int key) { return m_slots[key]; } void Thread::SpecificStorage::set(int key, void* value) { m_slots[key] = value; } void Thread::SpecificStorage::destroySlots() { auto numberOfKeys = s_numberOfKeys.load(); for (size_t i = 0; i < numberOfKeys; i++) { auto destroy = s_destroyFunctions[i].load(); if (destroy && m_slots[i]) { destroy(m_slots[i]); m_slots[i] = nullptr; } } } Mutex::~Mutex() { } void Mutex::lock() { AcquireSRWLockExclusive(&m_mutex); } bool Mutex::tryLock() { return TryAcquireSRWLockExclusive(&m_mutex); } void Mutex::unlock() { ReleaseSRWLockExclusive(&m_mutex); } // Returns an interval in milliseconds suitable for passing to one of the Win32 wait functions (e.g., ::WaitForSingleObject). static DWORD absoluteTimeToWaitTimeoutInterval(WallTime absoluteTime) { WallTime currentTime = WallTime::now(); // Time is in the past - return immediately. if (absoluteTime < currentTime) return 0; // Time is too far in the future (and would overflow unsigned long) - wait forever. if ((absoluteTime - currentTime) > Seconds::fromMilliseconds(INT_MAX)) return INFINITE; return static_cast<DWORD>((absoluteTime - currentTime).milliseconds()); } ThreadCondition::~ThreadCondition() { } void ThreadCondition::wait(Mutex& mutex) { SleepConditionVariableSRW(&m_condition, &mutex.impl(), INFINITE, 0); } bool ThreadCondition::timedWait(Mutex& mutex, WallTime absoluteTime) { // https://msdn.microsoft.com/en-us/library/windows/desktop/ms686304(v=vs.85).aspx DWORD interval = absoluteTimeToWaitTimeoutInterval(absoluteTime); if (!interval) { // Consider the wait to have timed out, even if our condition has already been signaled, to // match the pthreads implementation. return false; } if (SleepConditionVariableSRW(&m_condition, &mutex.impl(), interval, 0)) return true; ASSERT(GetLastError() == ERROR_TIMEOUT); return false; } void ThreadCondition::signal() { WakeConditionVariable(&m_condition); } void ThreadCondition::broadcast() { WakeAllConditionVariable(&m_condition); } void Thread::yield() { SwitchToThread(); } } // namespace WTF