barrier/lib/arch/CArchMultithreadWindows.cpp

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2002 Chris Schoeneman
 * 
 * This package is free software you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file COPYING that should have accompanied this file.
 * 
 * This package 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 General Public License for more details.
 */

#if !defined(_MT)
#	error multithreading compile option is required
#endif

#include "CArchMultithreadWindows.h"
#include "CArch.h"
#include "XArch.h"
#include <process.h>

//
// note -- implementation of condition variable taken from:
//   http://www.cs.wustl.edu/~schmidt/win32-cv-1.html
// titled "Strategies for Implementing POSIX Condition Variables
// on Win32."  it also provides an implementation that doesn't
// suffer from the incorrectness problem described in our
// corresponding header but it is slower, still unfair, and
// can cause busy waiting.
//

//
// CArchThreadImpl
//

class CArchThreadImpl {
public:
	CArchThreadImpl();
	~CArchThreadImpl();

public:
	int					m_refCount;
	HANDLE				m_thread;
	DWORD				m_id;
	IArchMultithread::ThreadFunc	m_func;
	void*				m_userData;
	HANDLE				m_cancel;
	bool				m_cancelling;
	HANDLE				m_exit;
	void*				m_result;
};

CArchThreadImpl::CArchThreadImpl() :
	m_refCount(1),
	m_thread(NULL),
	m_id(0),
	m_func(NULL),
	m_userData(NULL),
	m_cancelling(false),
	m_result(NULL)
{
	m_exit   = CreateEvent(NULL, TRUE, FALSE, NULL);
	m_cancel = CreateEvent(NULL, TRUE, FALSE, NULL);
}

CArchThreadImpl::~CArchThreadImpl()
{
	CloseHandle(m_exit);
	CloseHandle(m_cancel);
}


//
// CArchMultithreadWindows
//

CArchMultithreadWindows*	CArchMultithreadWindows::s_instance = NULL;

CArchMultithreadWindows::CArchMultithreadWindows()
{
	assert(s_instance == NULL);
	s_instance = this;

	// create mutex for thread list
	m_threadMutex = newMutex();

	// create thread for calling (main) thread and add it to our
	// list.  no need to lock the mutex since we're the only thread.
	CArchThreadImpl* mainThread = new CArchThreadImpl;
	mainThread->m_thread = NULL;
	mainThread->m_id     = GetCurrentThreadId();
	insert(mainThread);
}

CArchMultithreadWindows::~CArchMultithreadWindows()
{
	s_instance = NULL;
}

HANDLE
CArchMultithreadWindows::getCancelEventForCurrentThread()
{
	lockMutex(m_threadMutex);
	CArchThreadImpl* thread = findNoRef(GetCurrentThreadId());
	unlockMutex(m_threadMutex);
	return thread->m_cancel;
}

CArchMultithreadWindows*
CArchMultithreadWindows::getInstance()
{
	return s_instance;
}

CArchCond
CArchMultithreadWindows::newCondVar()
{
	CArchCondImpl* cond                       = new CArchCondImpl;
	cond->m_events[CArchCondImpl::kSignal]    = CreateEvent(NULL,
													FALSE, FALSE, NULL);
	cond->m_events[CArchCondImpl::kBroadcast] = CreateEvent(NULL,
													TRUE,  FALSE, NULL);
	cond->m_waitCountMutex                    = newMutex();
	cond->m_waitCount                         = 0;
	return cond;
}

void
CArchMultithreadWindows::closeCondVar(CArchCond cond)
{
	CloseHandle(cond->m_events[CArchCondImpl::kSignal]);
	CloseHandle(cond->m_events[CArchCondImpl::kBroadcast]);
	closeMutex(cond->m_waitCountMutex);
	delete cond;
}

void
CArchMultithreadWindows::signalCondVar(CArchCond cond)
{
	// is anybody waiting?
	lockMutex(cond->m_waitCountMutex);
	const bool hasWaiter = (cond->m_waitCount > 0);
	unlockMutex(cond->m_waitCountMutex);

	// wake one thread if anybody is waiting
	if (hasWaiter) {
		SetEvent(cond->m_events[CArchCondImpl::kSignal]);
	}
}

void
CArchMultithreadWindows::broadcastCondVar(CArchCond cond)
{
	// is anybody waiting?
	lockMutex(cond->m_waitCountMutex);
	const bool hasWaiter = (cond->m_waitCount > 0);
	unlockMutex(cond->m_waitCountMutex);

	// wake all threads if anybody is waiting
	if (hasWaiter) {
		SetEvent(cond->m_events[CArchCondImpl::kBroadcast]);
	}
}

bool
CArchMultithreadWindows::waitCondVar(CArchCond cond,
							CArchMutex mutex, double timeout)
{
	// prepare to wait
	const DWORD winTimeout = (timeout < 0.0) ? INFINITE :
								static_cast<DWORD>(1000.0 * timeout);

	// make a list of the condition variable events and the cancel event
	// for the current thread.
	HANDLE handles[3];
	handles[0] = cond->m_events[CArchCondImpl::kSignal];
	handles[1] = cond->m_events[CArchCondImpl::kBroadcast];
	handles[2] = getCancelEventForCurrentThread();

	// update waiter count
	lockMutex(cond->m_waitCountMutex);
	++cond->m_waitCount;
	unlockMutex(cond->m_waitCountMutex);

	// release mutex.  this should be atomic with the wait so that it's
	// impossible for another thread to signal us between the unlock and
	// the wait, which would lead to a lost signal on broadcasts.
	// however, we're using a manual reset event for broadcasts which
	// stays set until we reset it, so we don't lose the broadcast.
	unlockMutex(mutex);

	// wait for a signal or broadcast
	DWORD result = WaitForMultipleObjects(3, handles, FALSE, winTimeout);

	// cancel takes priority
	if (result != WAIT_OBJECT_0 + 2 &&
		WaitForSingleObject(handles[2], 0) == WAIT_OBJECT_0) {
		result = WAIT_OBJECT_0 + 2;
	}

	// update the waiter count and check if we're the last waiter
	lockMutex(cond->m_waitCountMutex);
	--cond->m_waitCount;
	const bool last = (result == WAIT_OBJECT_0 + 1 && cond->m_waitCount == 0);
	unlockMutex(cond->m_waitCountMutex);

	// reset the broadcast event if we're the last waiter
	if (last) {
		ResetEvent(cond->m_events[CArchCondImpl::kBroadcast]);
	}

	// reacquire the mutex
	lockMutex(mutex);

	// cancel thread if necessary
	if (result == WAIT_OBJECT_0 + 2) {
		ARCH->testCancelThread();
	}

	// return success or failure
	return (result == WAIT_OBJECT_0 + 0 ||
			result == WAIT_OBJECT_0 + 1);
}

CArchMutex
CArchMultithreadWindows::newMutex()
{
	CArchMutexImpl* mutex = new CArchMutexImpl;
	InitializeCriticalSection(&mutex->m_mutex);
	return mutex;
}

void
CArchMultithreadWindows::closeMutex(CArchMutex mutex)
{
	DeleteCriticalSection(&mutex->m_mutex);
	delete mutex;
}

void
CArchMultithreadWindows::lockMutex(CArchMutex mutex)
{
	EnterCriticalSection(&mutex->m_mutex);
}

void
CArchMultithreadWindows::unlockMutex(CArchMutex mutex)
{
	LeaveCriticalSection(&mutex->m_mutex);
}

CArchThread
CArchMultithreadWindows::newThread(ThreadFunc func, void* data)
{
	lockMutex(m_threadMutex);

	// create thread impl for new thread
	CArchThreadImpl* thread = new CArchThreadImpl;
	thread->m_func          = func;
	thread->m_userData      = data;

	// create thread
	unsigned int id;
	thread->m_thread = reinterpret_cast<HANDLE>(_beginthreadex(NULL, 0,
								threadFunc, (void*)thread, 0, &id));
	thread->m_id     = static_cast<DWORD>(id);

	// check if thread was started
	if (thread->m_thread == 0) {
		// failed to start thread so clean up
		delete thread;
		thread = NULL;
	}
	else {
		// add thread to list
		insert(thread);

		// increment ref count to account for the thread itself
		refThread(thread);
	}

	// note that the child thread will wait until we release this mutex
	unlockMutex(m_threadMutex);

	return thread;
}

CArchThread
CArchMultithreadWindows::newCurrentThread()
{
	lockMutex(m_threadMutex);
	CArchThreadImpl* thread = find(GetCurrentThreadId());
	unlockMutex(m_threadMutex);
	assert(thread != NULL);
	return thread;
}

void
CArchMultithreadWindows::closeThread(CArchThread thread)
{
	assert(thread != NULL);

	// decrement ref count and clean up thread if no more references
	if (--thread->m_refCount == 0) {
		// close the handle (main thread has a NULL handle)
		if (thread->m_thread != NULL) {
			CloseHandle(thread->m_thread);
		}

		// remove thread from list
		lockMutex(m_threadMutex);
		assert(findNoRef(thread->m_id) == thread);
		erase(thread);
		unlockMutex(m_threadMutex);

		// done with thread
		delete thread;
	}
}

CArchThread
CArchMultithreadWindows::copyThread(CArchThread thread)
{
	refThread(thread);
	return thread;
}

void
CArchMultithreadWindows::cancelThread(CArchThread thread)
{
	assert(thread != NULL);

	// set cancel flag
	SetEvent(thread->m_cancel);
}

void
CArchMultithreadWindows::setPriorityOfThread(CArchThread thread, int n)
{
	assert(thread != NULL);

	DWORD pClass = NORMAL_PRIORITY_CLASS;
	if (n < 0) {
		switch (-n) {
		case 1:  n = THREAD_PRIORITY_ABOVE_NORMAL; break;
		case 2:  n = THREAD_PRIORITY_HIGHEST; break;
		default:
			pClass = HIGH_PRIORITY_CLASS;
			switch (-n - 3) {
			case 0:  n = THREAD_PRIORITY_LOWEST; break;
			case 1:  n = THREAD_PRIORITY_BELOW_NORMAL; break;
			case 2:  n = THREAD_PRIORITY_NORMAL; break;
			case 3:  n = THREAD_PRIORITY_ABOVE_NORMAL; break;
			default: n = THREAD_PRIORITY_HIGHEST; break;
			}
			break;
		}
	}
	else {
		switch (n) {
		case 0:  n = THREAD_PRIORITY_NORMAL; break;
		case 1:  n = THREAD_PRIORITY_BELOW_NORMAL; break;
		case 2:  n = THREAD_PRIORITY_LOWEST; break;
		default: n = THREAD_PRIORITY_IDLE; break;
		}
	}
	SetPriorityClass(thread->m_thread, pClass);
	SetThreadPriority(thread->m_thread, n);
}

void
CArchMultithreadWindows::testCancelThread()
{
	// find current thread
	lockMutex(m_threadMutex);
	CArchThreadImpl* thread = findNoRef(GetCurrentThreadId());
	unlockMutex(m_threadMutex);

	// test cancel on thread
	testCancelThreadImpl(thread);
}

bool
CArchMultithreadWindows::wait(CArchThread target, double timeout)
{
	assert(target != NULL);

	lockMutex(m_threadMutex);

	// find current thread
	CArchThreadImpl* self = findNoRef(GetCurrentThreadId());

	// ignore wait if trying to wait on ourself
	if (target == self) {
		unlockMutex(m_threadMutex);
		return false;
	}

	// ref the target so it can't go away while we're watching it
	refThread(target);

	unlockMutex(m_threadMutex);

	// convert timeout
	DWORD t;
	if (timeout < 0.0) {
		t = INFINITE;
	}
	else {
		t = (DWORD)(1000.0 * timeout);
	}

	// wait for this thread to be cancelled or for the target thread to
	// terminate.
	HANDLE handles[2];
	handles[0] = target->m_exit;
	handles[1] = self->m_cancel;
	DWORD result = WaitForMultipleObjects(2, handles, FALSE, t);

	// cancel takes priority
	if (result != WAIT_OBJECT_0 + 1 &&
		WaitForSingleObject(handles[1], 0) == WAIT_OBJECT_0) {
		result = WAIT_OBJECT_0 + 1;
	}

	// release target
	closeThread(target);

	// handle result
	switch (result) {
	case WAIT_OBJECT_0 + 0:
		// target thread terminated
		return true;

	case WAIT_OBJECT_0 + 1:
		// this thread was cancelled.  does not return.
		testCancelThreadImpl(self);

	default:
		// timeout or error
		return false;
	}
}

bool
CArchMultithreadWindows::waitForEvent(double timeout)
{
	// check if messages are available first.  if we don't do this then
	// MsgWaitForMultipleObjects() will block even if the queue isn't
	// empty if the messages in the queue were there before the last
	// call to GetMessage()/PeekMessage().
	if (HIWORD(GetQueueStatus(QS_ALLINPUT)) != 0) {
		return true;
	}

	// find current thread
	lockMutex(m_threadMutex);
	CArchThreadImpl* self = findNoRef(GetCurrentThreadId());
	unlockMutex(m_threadMutex);
	assert(self != NULL);

	// convert timeout
	DWORD t;
	if (timeout < 0.0) {
		t = INFINITE;
	}
	else {
		t = (DWORD)(1000.0 * timeout);
	}

	// wait for this thread to be cancelled or for a message
	HANDLE handles[1];
	handles[0] = self->m_cancel;
	DWORD result = MsgWaitForMultipleObjects(1, handles, FALSE, t, QS_ALLINPUT);

	// handle result
	switch (result) {
	case WAIT_OBJECT_0 + 1:
		// message is available
		return true;

	case WAIT_OBJECT_0 + 0:
		// this thread was cancelled.  does not return.
		testCancelThreadImpl(self);

	default:
		// timeout or error
		return false;
	}
}

bool
CArchMultithreadWindows::isSameThread(CArchThread thread1, CArchThread thread2)
{
	return (thread1 == thread2);
}

bool
CArchMultithreadWindows::isExitedThread(CArchThread thread)
{
	// poll exit event
	return (WaitForSingleObject(thread->m_exit, 0) == WAIT_OBJECT_0);
}

void*
CArchMultithreadWindows::getResultOfThread(CArchThread thread)
{
	lockMutex(m_threadMutex);
	void* result = thread->m_result;
	unlockMutex(m_threadMutex);
	return result;
}

IArchMultithread::ThreadID
CArchMultithreadWindows::getIDOfThread(CArchThread thread)
{
	return static_cast<ThreadID>(thread->m_id);
}

CArchThreadImpl*
CArchMultithreadWindows::find(DWORD id)
{
	CArchThreadImpl* impl = findNoRef(id);
	if (impl != NULL) {
		refThread(impl);
	}
	return impl;
}

CArchThreadImpl*
CArchMultithreadWindows::findNoRef(DWORD id)
{
	// linear search
	for (CThreadList::const_iterator index  = m_threadList.begin();
									 index != m_threadList.end(); ++index) {
		if ((*index)->m_id == id) {
			return *index;
		}
	}
	return NULL;
}

void
CArchMultithreadWindows::insert(CArchThreadImpl* thread)
{
	assert(thread != NULL);

	// thread shouldn't already be on the list
	assert(findNoRef(thread->m_id) == NULL);

	// append to list
	m_threadList.push_back(thread);
}

void
CArchMultithreadWindows::erase(CArchThreadImpl* thread)
{
	for (CThreadList::iterator index  = m_threadList.begin();
							   index != m_threadList.end(); ++index) {
		if (*index == thread) {
			m_threadList.erase(index);
			break;
		}
	}
}

void
CArchMultithreadWindows::refThread(CArchThreadImpl* thread)
{
	assert(thread != NULL);
	assert(findNoRef(thread->m_id) != NULL);
	++thread->m_refCount;
}

void
CArchMultithreadWindows::testCancelThreadImpl(CArchThread thread)
{
	assert(thread != NULL);

	// poll cancel event.  return if not set.
	const DWORD result = WaitForSingleObject(thread->m_cancel, 0);
	if (result != WAIT_OBJECT_0) {
		return;
	}

	// update cancel state
	lockMutex(m_threadMutex);
	bool cancel          = !thread->m_cancelling;
	thread->m_cancelling = true;
	ResetEvent(thread->m_cancel);
	unlockMutex(m_threadMutex);

	// unwind thread's stack if cancelling
	if (cancel) {
		throw XThreadCancel();
	}
}

unsigned int __stdcall
CArchMultithreadWindows::threadFunc(void* vrep)
{
	// get the thread
	CArchThreadImpl* thread = reinterpret_cast<CArchThreadImpl*>(vrep);

	// run thread
	s_instance->doThreadFunc(thread);

	// terminate the thread
	return 0;
}

void
CArchMultithreadWindows::doThreadFunc(CArchThread thread)
{
	// default priority is slightly below normal
	setPriorityOfThread(thread, 1);

	// wait for parent to initialize this object
	lockMutex(m_threadMutex);
	unlockMutex(m_threadMutex);

	void* result = NULL;
	try {
		// go
		result = (*thread->m_func)(thread->m_userData);
	}

	catch (XThreadCancel&) {
		// client called cancel()
	}
	catch (...) {
		// note -- don't catch (...) to avoid masking bugs
		SetEvent(thread->m_exit);
		closeThread(thread);
		throw;
	}

	// thread has exited
	lockMutex(m_threadMutex);
	thread->m_result = result;
	unlockMutex(m_threadMutex);
	SetEvent(thread->m_exit);

	// done with thread
	closeThread(thread);
}