root/Source/wtf/ThreadingWin.cpp

DEFINITIONS

1. initializeCurrentThreadInternal
2. lockAtomicallyInitializedStaticMutex
3. unlockAtomicallyInitializedStaticMutex
4. threadMapMutex
5. initializeThreading
6. threadMap
7. storeThreadHandleByIdentifier
8. threadHandleForIdentifier
9. clearThreadHandleForIdentifier
10. wtfThreadEntryPoint
11. createThreadInternal
12. waitForThreadCompletion
13. detachThread
14. yield
15. currentThread
16. lock
17. tryLock
18. unlock
19. timedWait
20. signal
21. wait
22. timedWait
23. signal
24. broadcast
25. absoluteTimeToWaitTimeoutInterval

/*
 * Copyright (C) 2007, 2008 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 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.
 */

/*
 * 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 "Threading.h"

#if OS(WIN)

#include "wtf/CurrentTime.h"
#include "wtf/DateMath.h"
#include "wtf/HashMap.h"
#include "wtf/MainThread.h"
#include "wtf/MathExtras.h"
#include "wtf/OwnPtr.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/ThreadFunctionInvocation.h"
#include "wtf/ThreadSpecific.h"
#include "wtf/ThreadingPrimitives.h"
#include "wtf/WTFThreadData.h"
#include "wtf/dtoa.h"
#include "wtf/dtoa/cached-powers.h"
#include <errno.h>
#include <process.h>
#include <windows.h>

namespace WTF {

// 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 initializeCurrentThreadInternal(const char* szThreadName)
{
    THREADNAME_INFO info;
    info.dwType = 0x1000;
    info.szName = 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) {
    }
}

static Mutex* atomicallyInitializedStaticMutex;

void lockAtomicallyInitializedStaticMutex()
{
    ASSERT(atomicallyInitializedStaticMutex);
    atomicallyInitializedStaticMutex->lock();
}

void unlockAtomicallyInitializedStaticMutex()
{
    atomicallyInitializedStaticMutex->unlock();
}

static Mutex& threadMapMutex()
{
    static Mutex mutex;
    return mutex;
}

void initializeThreading()
{
    // This should only be called once.
    ASSERT(!atomicallyInitializedStaticMutex);

    // StringImpl::empty() does not construct its static string in a threadsafe fashion,
    // so ensure it has been initialized from here.
    StringImpl::empty();
    atomicallyInitializedStaticMutex = new Mutex;
    threadMapMutex();
    wtfThreadData();
    s_dtoaP5Mutex = new Mutex;
    initializeDates();
}

static HashMap<DWORD, HANDLE>& threadMap()
{
    static HashMap<DWORD, HANDLE>* gMap;
    if (!gMap)
        gMap = new HashMap<DWORD, HANDLE>();
    return *gMap;
}

static void storeThreadHandleByIdentifier(DWORD threadID, HANDLE threadHandle)
{
    MutexLocker locker(threadMapMutex());
    ASSERT(!threadMap().contains(threadID));
    threadMap().add(threadID, threadHandle);
}

static HANDLE threadHandleForIdentifier(ThreadIdentifier id)
{
    MutexLocker locker(threadMapMutex());
    return threadMap().get(id);
}

static void clearThreadHandleForIdentifier(ThreadIdentifier id)
{
    MutexLocker locker(threadMapMutex());
    ASSERT(threadMap().contains(id));
    threadMap().remove(id);
}

static unsigned __stdcall wtfThreadEntryPoint(void* param)
{
    OwnPtr<ThreadFunctionInvocation> invocation = adoptPtr(static_cast<ThreadFunctionInvocation*>(param));
    invocation->function(invocation->data);

    // Do the TLS cleanup.
    ThreadSpecificThreadExit();

    return 0;
}

ThreadIdentifier createThreadInternal(ThreadFunction entryPoint, void* data, const char* threadName)
{
    unsigned threadIdentifier = 0;
    ThreadIdentifier threadID = 0;
    OwnPtr<ThreadFunctionInvocation> invocation = adoptPtr(new ThreadFunctionInvocation(entryPoint, data));
    HANDLE threadHandle = reinterpret_cast<HANDLE>(_beginthreadex(0, 0, wtfThreadEntryPoint, invocation.get(), 0, &threadIdentifier));
    if (!threadHandle) {
        WTF_LOG_ERROR("Failed to create thread at entry point %p with data %p: %ld", entryPoint, data, errno);
        return 0;
    }

    // The thread will take ownership of invocation.
    ThreadFunctionInvocation* ALLOW_UNUSED leakedInvocation = invocation.leakPtr();

    threadID = static_cast<ThreadIdentifier>(threadIdentifier);
    storeThreadHandleByIdentifier(threadIdentifier, threadHandle);

    return threadID;
}

int waitForThreadCompletion(ThreadIdentifier threadID)
{
    ASSERT(threadID);

    HANDLE threadHandle = threadHandleForIdentifier(threadID);
    if (!threadHandle)
        WTF_LOG_ERROR("ThreadIdentifier %u did not correspond to an active thread when trying to quit", threadID);

    DWORD joinResult = WaitForSingleObject(threadHandle, INFINITE);
    if (joinResult == WAIT_FAILED)
        WTF_LOG_ERROR("ThreadIdentifier %u was found to be deadlocked trying to quit", threadID);

    CloseHandle(threadHandle);
    clearThreadHandleForIdentifier(threadID);

    return joinResult;
}

void detachThread(ThreadIdentifier threadID)
{
    ASSERT(threadID);

    HANDLE threadHandle = threadHandleForIdentifier(threadID);
    if (threadHandle)
        CloseHandle(threadHandle);
    clearThreadHandleForIdentifier(threadID);
}

void yield()
{
    ::Sleep(1);
}

ThreadIdentifier currentThread()
{
    return static_cast<ThreadIdentifier>(GetCurrentThreadId());
}

Mutex::Mutex()
{
    m_mutex.m_recursionCount = 0;
    InitializeCriticalSection(&m_mutex.m_internalMutex);
}

Mutex::~Mutex()
{
    DeleteCriticalSection(&m_mutex.m_internalMutex);
}

void Mutex::lock()
{
    EnterCriticalSection(&m_mutex.m_internalMutex);
    ++m_mutex.m_recursionCount;
}

bool Mutex::tryLock()
{
    // This method is modeled after the behavior of pthread_mutex_trylock,
    // which will return an error if the lock is already owned by the
    // current thread.  Since the primitive Win32 'TryEnterCriticalSection'
    // treats this as a successful case, it changes the behavior of several
    // tests in WebKit that check to see if the current thread already
    // owned this mutex (see e.g., IconDatabase::getOrCreateIconRecord)
    DWORD result = TryEnterCriticalSection(&m_mutex.m_internalMutex);

    if (result != 0) {       // We got the lock
        // If this thread already had the lock, we must unlock and
        // return false so that we mimic the behavior of POSIX's
        // pthread_mutex_trylock:
        if (m_mutex.m_recursionCount > 0) {
            LeaveCriticalSection(&m_mutex.m_internalMutex);
            return false;
        }

        ++m_mutex.m_recursionCount;
        return true;
    }

    return false;
}

void Mutex::unlock()
{
    ASSERT(m_mutex.m_recursionCount);
    --m_mutex.m_recursionCount;
    LeaveCriticalSection(&m_mutex.m_internalMutex);
}

bool PlatformCondition::timedWait(PlatformMutex& mutex, DWORD durationMilliseconds)
{
    // Enter the wait state.
    DWORD res = WaitForSingleObject(m_blockLock, INFINITE);
    ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
    ++m_waitersBlocked;
    res = ReleaseSemaphore(m_blockLock, 1, 0);
    ASSERT_UNUSED(res, res);

    --mutex.m_recursionCount;
    LeaveCriticalSection(&mutex.m_internalMutex);

    // Main wait - use timeout.
    bool timedOut = (WaitForSingleObject(m_blockQueue, durationMilliseconds) == WAIT_TIMEOUT);

    res = WaitForSingleObject(m_unblockLock, INFINITE);
    ASSERT_UNUSED(res, res == WAIT_OBJECT_0);

    int signalsLeft = m_waitersToUnblock;

    if (m_waitersToUnblock)
        --m_waitersToUnblock;
    else if (++m_waitersGone == (INT_MAX / 2)) { // timeout/canceled or spurious semaphore
        // timeout or spurious wakeup occured, normalize the m_waitersGone count
        // this may occur if many calls to wait with a timeout are made and
        // no call to notify_* is made
        res = WaitForSingleObject(m_blockLock, INFINITE);
        ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
        m_waitersBlocked -= m_waitersGone;
        res = ReleaseSemaphore(m_blockLock, 1, 0);
        ASSERT_UNUSED(res, res);
        m_waitersGone = 0;
    }

    res = ReleaseMutex(m_unblockLock);
    ASSERT_UNUSED(res, res);

    if (signalsLeft == 1) {
        res = ReleaseSemaphore(m_blockLock, 1, 0); // Open the gate.
        ASSERT_UNUSED(res, res);
    }

    EnterCriticalSection (&mutex.m_internalMutex);
    ++mutex.m_recursionCount;

    return !timedOut;
}

void PlatformCondition::signal(bool unblockAll)
{
    unsigned signalsToIssue = 0;

    DWORD res = WaitForSingleObject(m_unblockLock, INFINITE);
    ASSERT_UNUSED(res, res == WAIT_OBJECT_0);

    if (m_waitersToUnblock) { // the gate is already closed
        if (!m_waitersBlocked) { // no-op
            res = ReleaseMutex(m_unblockLock);
            ASSERT_UNUSED(res, res);
            return;
        }

        if (unblockAll) {
            signalsToIssue = m_waitersBlocked;
            m_waitersToUnblock += m_waitersBlocked;
            m_waitersBlocked = 0;
        } else {
            signalsToIssue = 1;
            ++m_waitersToUnblock;
            --m_waitersBlocked;
        }
    } else if (m_waitersBlocked > m_waitersGone) {
        res = WaitForSingleObject(m_blockLock, INFINITE); // Close the gate.
        ASSERT_UNUSED(res, res == WAIT_OBJECT_0);
        if (m_waitersGone != 0) {
            m_waitersBlocked -= m_waitersGone;
            m_waitersGone = 0;
        }
        if (unblockAll) {
            signalsToIssue = m_waitersBlocked;
            m_waitersToUnblock = m_waitersBlocked;
            m_waitersBlocked = 0;
        } else {
            signalsToIssue = 1;
            m_waitersToUnblock = 1;
            --m_waitersBlocked;
        }
    } else { // No-op.
        res = ReleaseMutex(m_unblockLock);
        ASSERT_UNUSED(res, res);
        return;
    }

    res = ReleaseMutex(m_unblockLock);
    ASSERT_UNUSED(res, res);

    if (signalsToIssue) {
        res = ReleaseSemaphore(m_blockQueue, signalsToIssue, 0);
        ASSERT_UNUSED(res, res);
    }
}

static const long MaxSemaphoreCount = static_cast<long>(~0UL >> 1);

ThreadCondition::ThreadCondition()
{
    m_condition.m_waitersGone = 0;
    m_condition.m_waitersBlocked = 0;
    m_condition.m_waitersToUnblock = 0;
    m_condition.m_blockLock = CreateSemaphore(0, 1, 1, 0);
    m_condition.m_blockQueue = CreateSemaphore(0, 0, MaxSemaphoreCount, 0);
    m_condition.m_unblockLock = CreateMutex(0, 0, 0);

    if (!m_condition.m_blockLock || !m_condition.m_blockQueue || !m_condition.m_unblockLock) {
        if (m_condition.m_blockLock)
            CloseHandle(m_condition.m_blockLock);
        if (m_condition.m_blockQueue)
            CloseHandle(m_condition.m_blockQueue);
        if (m_condition.m_unblockLock)
            CloseHandle(m_condition.m_unblockLock);
    }
}

ThreadCondition::~ThreadCondition()
{
    CloseHandle(m_condition.m_blockLock);
    CloseHandle(m_condition.m_blockQueue);
    CloseHandle(m_condition.m_unblockLock);
}

void ThreadCondition::wait(Mutex& mutex)
{
    m_condition.timedWait(mutex.impl(), INFINITE);
}

bool ThreadCondition::timedWait(Mutex& mutex, double absoluteTime)
{
    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;
    }

    return m_condition.timedWait(mutex.impl(), interval);
}

void ThreadCondition::signal()
{
    m_condition.signal(false); // Unblock only 1 thread.
}

void ThreadCondition::broadcast()
{
    m_condition.signal(true); // Unblock all threads.
}

DWORD absoluteTimeToWaitTimeoutInterval(double absoluteTime)
{
    double currentTime = WTF::currentTime();

    // 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 > static_cast<double>(INT_MAX) / 1000.0)
        return INFINITE;

    return static_cast<DWORD>((absoluteTime - currentTime) * 1000.0);
}

} // namespace WTF

#endif // OS(WIN)