[qemu.git] / util / qemu-thread-win32.c

/*
 * Win32 implementation for mutex/cond/thread functions
 *
 * Copyright Red Hat, Inc. 2010
 *
 * Author:
 *  Paolo Bonzini <[email protected]>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 *
 */
#include "qemu-common.h"
#include "qemu/thread.h"
#include <process.h>
#include <assert.h>
#include <limits.h>

static void error_exit(int err, const char *msg)
{
    char *pstr;

    FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
                  NULL, err, 0, (LPTSTR)&pstr, 2, NULL);
    fprintf(stderr, "qemu: %s: %s\n", msg, pstr);
    LocalFree(pstr);
    abort();
}

void qemu_mutex_init(QemuMutex *mutex)
{
    mutex->owner = 0;
    InitializeCriticalSection(&mutex->lock);
}

void qemu_mutex_destroy(QemuMutex *mutex)
{
    assert(mutex->owner == 0);
    DeleteCriticalSection(&mutex->lock);
}

void qemu_mutex_lock(QemuMutex *mutex)
{
    EnterCriticalSection(&mutex->lock);

    /* Win32 CRITICAL_SECTIONs are recursive.  Assert that we're not
     * using them as such.
     */
    assert(mutex->owner == 0);
    mutex->owner = GetCurrentThreadId();
}

int qemu_mutex_trylock(QemuMutex *mutex)
{
    int owned;

    owned = TryEnterCriticalSection(&mutex->lock);
    if (owned) {
        assert(mutex->owner == 0);
        mutex->owner = GetCurrentThreadId();
    }
    return !owned;
}

void qemu_mutex_unlock(QemuMutex *mutex)
{
    assert(mutex->owner == GetCurrentThreadId());
    mutex->owner = 0;
    LeaveCriticalSection(&mutex->lock);
}

void qemu_cond_init(QemuCond *cond)
{
    memset(cond, 0, sizeof(*cond));

    cond->sema = CreateSemaphore(NULL, 0, LONG_MAX, NULL);
    if (!cond->sema) {
        error_exit(GetLastError(), __func__);
    }
    cond->continue_event = CreateEvent(NULL,    /* security */
                                       FALSE,   /* auto-reset */
                                       FALSE,   /* not signaled */
                                       NULL);   /* name */
    if (!cond->continue_event) {
        error_exit(GetLastError(), __func__);
    }
}

void qemu_cond_destroy(QemuCond *cond)
{
    BOOL result;
    result = CloseHandle(cond->continue_event);
    if (!result) {
        error_exit(GetLastError(), __func__);
    }
    cond->continue_event = 0;
    result = CloseHandle(cond->sema);
    if (!result) {
        error_exit(GetLastError(), __func__);
    }
    cond->sema = 0;
}

void qemu_cond_signal(QemuCond *cond)
{
    DWORD result;

    /*
     * Signal only when there are waiters.  cond->waiters is
     * incremented by pthread_cond_wait under the external lock,
     * so we are safe about that.
     */
    if (cond->waiters == 0) {
        return;
    }

    /*
     * Waiting threads decrement it outside the external lock, but
     * only if another thread is executing pthread_cond_broadcast and
     * has the mutex.  So, it also cannot be decremented concurrently
     * with this particular access.
     */
    cond->target = cond->waiters - 1;
    result = SignalObjectAndWait(cond->sema, cond->continue_event,
                                 INFINITE, FALSE);
    if (result == WAIT_ABANDONED || result == WAIT_FAILED) {
        error_exit(GetLastError(), __func__);
    }
}

void qemu_cond_broadcast(QemuCond *cond)
{
    BOOLEAN result;
    /*
     * As in pthread_cond_signal, access to cond->waiters and
     * cond->target is locked via the external mutex.
     */
    if (cond->waiters == 0) {
        return;
    }

    cond->target = 0;
    result = ReleaseSemaphore(cond->sema, cond->waiters, NULL);
    if (!result) {
        error_exit(GetLastError(), __func__);
    }

    /*
     * At this point all waiters continue. Each one takes its
     * slice of the semaphore. Now it's our turn to wait: Since
     * the external mutex is held, no thread can leave cond_wait,
     * yet. For this reason, we can be sure that no thread gets
     * a chance to eat *more* than one slice. OTOH, it means
     * that the last waiter must send us a wake-up.
     */
    WaitForSingleObject(cond->continue_event, INFINITE);
}

void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
{
    /*
     * This access is protected under the mutex.
     */
    cond->waiters++;

    /*
     * Unlock external mutex and wait for signal.
     * NOTE: we've held mutex locked long enough to increment
     * waiters count above, so there's no problem with
     * leaving mutex unlocked before we wait on semaphore.
     */
    qemu_mutex_unlock(mutex);
    WaitForSingleObject(cond->sema, INFINITE);

    /* Now waiters must rendez-vous with the signaling thread and
     * let it continue.  For cond_broadcast this has heavy contention
     * and triggers thundering herd.  So goes life.
     *
     * Decrease waiters count.  The mutex is not taken, so we have
     * to do this atomically.
     *
     * All waiters contend for the mutex at the end of this function
     * until the signaling thread relinquishes it.  To ensure
     * each waiter consumes exactly one slice of the semaphore,
     * the signaling thread stops until it is told by the last
     * waiter that it can go on.
     */
    if (InterlockedDecrement(&cond->waiters) == cond->target) {
        SetEvent(cond->continue_event);
    }

    qemu_mutex_lock(mutex);
}

void qemu_sem_init(QemuSemaphore *sem, int init)
{
    /* Manual reset.  */
    sem->sema = CreateSemaphore(NULL, init, LONG_MAX, NULL);
}

void qemu_sem_destroy(QemuSemaphore *sem)
{
    CloseHandle(sem->sema);
}

void qemu_sem_post(QemuSemaphore *sem)
{
    ReleaseSemaphore(sem->sema, 1, NULL);
}

int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
{
    int rc = WaitForSingleObject(sem->sema, ms);
    if (rc == WAIT_OBJECT_0) {
        return 0;
    }
    if (rc != WAIT_TIMEOUT) {
        error_exit(GetLastError(), __func__);
    }
    return -1;
}

void qemu_sem_wait(QemuSemaphore *sem)
{
    if (WaitForSingleObject(sem->sema, INFINITE) != WAIT_OBJECT_0) {
        error_exit(GetLastError(), __func__);
    }
}

struct QemuThreadData {
    /* Passed to win32_start_routine.  */
    void             *(*start_routine)(void *);
    void             *arg;
    short             mode;

    /* Only used for joinable threads. */
    bool              exited;
    void             *ret;
    CRITICAL_SECTION  cs;
};

static __thread QemuThreadData *qemu_thread_data;

static unsigned __stdcall win32_start_routine(void *arg)
{
    QemuThreadData *data = (QemuThreadData *) arg;
    void *(*start_routine)(void *) = data->start_routine;
    void *thread_arg = data->arg;

    if (data->mode == QEMU_THREAD_DETACHED) {
        g_free(data);
        data = NULL;
    }
    qemu_thread_data = data;
    qemu_thread_exit(start_routine(thread_arg));
    abort();
}

void qemu_thread_exit(void *arg)
{
    QemuThreadData *data = qemu_thread_data;

    if (data) {
        assert(data->mode != QEMU_THREAD_DETACHED);
        data->ret = arg;
        EnterCriticalSection(&data->cs);
        data->exited = true;
        LeaveCriticalSection(&data->cs);
    }
    _endthreadex(0);
}

void *qemu_thread_join(QemuThread *thread)
{
    QemuThreadData *data;
    void *ret;
    HANDLE handle;

    data = thread->data;
    if (!data) {
        return NULL;
    }
    /*
     * Because multiple copies of the QemuThread can exist via
     * qemu_thread_get_self, we need to store a value that cannot
     * leak there.  The simplest, non racy way is to store the TID,
     * discard the handle that _beginthreadex gives back, and
     * get another copy of the handle here.
     */
    handle = qemu_thread_get_handle(thread);
    if (handle) {
        WaitForSingleObject(handle, INFINITE);
        CloseHandle(handle);
    }
    ret = data->ret;
    assert(data->mode != QEMU_THREAD_DETACHED);
    DeleteCriticalSection(&data->cs);
    g_free(data);
    return ret;
}

void qemu_thread_create(QemuThread *thread,
                       void *(*start_routine)(void *),
                       void *arg, int mode)
{
    HANDLE hThread;
    struct QemuThreadData *data;

    data = g_malloc(sizeof *data);
    data->start_routine = start_routine;
    data->arg = arg;
    data->mode = mode;
    data->exited = false;

    if (data->mode != QEMU_THREAD_DETACHED) {
        InitializeCriticalSection(&data->cs);
    }

    hThread = (HANDLE) _beginthreadex(NULL, 0, win32_start_routine,
                                      data, 0, &thread->tid);
    if (!hThread) {
        error_exit(GetLastError(), __func__);
    }
    CloseHandle(hThread);
    thread->data = (mode == QEMU_THREAD_DETACHED) ? NULL : data;
}

void qemu_thread_get_self(QemuThread *thread)
{
    thread->data = qemu_thread_data;
    thread->tid = GetCurrentThreadId();
}

HANDLE qemu_thread_get_handle(QemuThread *thread)
{
    QemuThreadData *data;
    HANDLE handle;

    data = thread->data;
    if (!data) {
        return NULL;
    }

    assert(data->mode != QEMU_THREAD_DETACHED);
    EnterCriticalSection(&data->cs);
    if (!data->exited) {
        handle = OpenThread(SYNCHRONIZE | THREAD_SUSPEND_RESUME, FALSE,
                            thread->tid);
    } else {
        handle = NULL;
    }
    LeaveCriticalSection(&data->cs);
    return handle;
}

bool qemu_thread_is_self(QemuThread *thread)
{
    return GetCurrentThreadId() == thread->tid;
}
Commit	Line	Data
9257d46d PB	1	/*
	2	* Win32 implementation for mutex/cond/thread functions
	3	*
	4	* Copyright Red Hat, Inc. 2010
	5	*
	6	* Author:
	7	* Paolo Bonzini <[email protected]>
	8	*
	9	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	10	* See the COPYING file in the top-level directory.
	11	*
	12	*/
	13	#include "qemu-common.h"
1de7afc9	14	#include "qemu/thread.h"
9257d46d PB	15	#include <process.h>
	16	#include <assert.h>
	17	#include <limits.h>
	18
	19	static void error_exit(int err, const char *msg)
	20	{
	21	char *pstr;
	22
	23	FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM \| FORMAT_MESSAGE_ALLOCATE_BUFFER,
	24	NULL, err, 0, (LPTSTR)&pstr, 2, NULL);
	25	fprintf(stderr, "qemu: %s: %s\n", msg, pstr);
	26	LocalFree(pstr);
53380ac3	27	abort();
9257d46d PB	28	}
	29
	30	void qemu_mutex_init(QemuMutex *mutex)
	31	{
	32	mutex->owner = 0;
	33	InitializeCriticalSection(&mutex->lock);
	34	}
	35
1a290aea SW	36	void qemu_mutex_destroy(QemuMutex *mutex)
	37	{
	38	assert(mutex->owner == 0);
	39	DeleteCriticalSection(&mutex->lock);
	40	}
	41
9257d46d PB	42	void qemu_mutex_lock(QemuMutex *mutex)
	43	{
	44	EnterCriticalSection(&mutex->lock);
	45
	46	/* Win32 CRITICAL_SECTIONs are recursive. Assert that we're not
	47	* using them as such.
	48	*/
	49	assert(mutex->owner == 0);
	50	mutex->owner = GetCurrentThreadId();
	51	}
	52
	53	int qemu_mutex_trylock(QemuMutex *mutex)
	54	{
	55	int owned;
	56
	57	owned = TryEnterCriticalSection(&mutex->lock);
	58	if (owned) {
	59	assert(mutex->owner == 0);
	60	mutex->owner = GetCurrentThreadId();
	61	}
	62	return !owned;
	63	}
	64
	65	void qemu_mutex_unlock(QemuMutex *mutex)
	66	{
	67	assert(mutex->owner == GetCurrentThreadId());
	68	mutex->owner = 0;
	69	LeaveCriticalSection(&mutex->lock);
	70	}
	71
	72	void qemu_cond_init(QemuCond *cond)
	73	{
	74	memset(cond, 0, sizeof(*cond));
	75
	76	cond->sema = CreateSemaphore(NULL, 0, LONG_MAX, NULL);
	77	if (!cond->sema) {
	78	error_exit(GetLastError(), __func__);
	79	}
	80	cond->continue_event = CreateEvent(NULL, /* security */
	81	FALSE, /* auto-reset */
	82	FALSE, /* not signaled */
	83	NULL); /* name */
	84	if (!cond->continue_event) {
	85	error_exit(GetLastError(), __func__);
	86	}
	87	}
	88
1a290aea SW	89	void qemu_cond_destroy(QemuCond *cond)
	90	{
	91	BOOL result;
	92	result = CloseHandle(cond->continue_event);
	93	if (!result) {
	94	error_exit(GetLastError(), __func__);
	95	}
	96	cond->continue_event = 0;
	97	result = CloseHandle(cond->sema);
	98	if (!result) {
	99	error_exit(GetLastError(), __func__);
	100	}
	101	cond->sema = 0;
	102	}
	103
9257d46d PB	104	void qemu_cond_signal(QemuCond *cond)
	105	{
	106	DWORD result;
	107
	108	/*
	109	* Signal only when there are waiters. cond->waiters is
	110	* incremented by pthread_cond_wait under the external lock,
	111	* so we are safe about that.
	112	*/
	113	if (cond->waiters == 0) {
	114	return;
	115	}
	116
	117	/*
	118	* Waiting threads decrement it outside the external lock, but
	119	* only if another thread is executing pthread_cond_broadcast and
	120	* has the mutex. So, it also cannot be decremented concurrently
	121	* with this particular access.
	122	*/
	123	cond->target = cond->waiters - 1;
	124	result = SignalObjectAndWait(cond->sema, cond->continue_event,
	125	INFINITE, FALSE);
	126	if (result == WAIT_ABANDONED \|\| result == WAIT_FAILED) {
	127	error_exit(GetLastError(), __func__);
	128	}
	129	}
	130
	131	void qemu_cond_broadcast(QemuCond *cond)
	132	{
	133	BOOLEAN result;
	134	/*
	135	* As in pthread_cond_signal, access to cond->waiters and
	136	* cond->target is locked via the external mutex.
	137	*/
	138	if (cond->waiters == 0) {
	139	return;
	140	}
	141
	142	cond->target = 0;
	143	result = ReleaseSemaphore(cond->sema, cond->waiters, NULL);
	144	if (!result) {
	145	error_exit(GetLastError(), __func__);
	146	}
	147
	148	/*
	149	* At this point all waiters continue. Each one takes its
	150	* slice of the semaphore. Now it's our turn to wait: Since
	151	* the external mutex is held, no thread can leave cond_wait,
	152	* yet. For this reason, we can be sure that no thread gets
	153	* a chance to eat more than one slice. OTOH, it means
	154	* that the last waiter must send us a wake-up.
	155	*/
	156	WaitForSingleObject(cond->continue_event, INFINITE);
	157	}
	158
	159	void qemu_cond_wait(QemuCond cond, QemuMutex mutex)
	160	{
	161	/*
	162	* This access is protected under the mutex.
	163	*/
	164	cond->waiters++;
	165
	166	/*
	167	* Unlock external mutex and wait for signal.
168	* NOTE: we've held mutex locked long enough to increment
169	* waiters count above, so there's no problem with
170	* leaving mutex unlocked before we wait on semaphore.
171	*/
172	qemu_mutex_unlock(mutex);
173	WaitForSingleObject(cond->sema, INFINITE);
174
175	/* Now waiters must rendez-vous with the signaling thread and
176	* let it continue. For cond_broadcast this has heavy contention
177	* and triggers thundering herd. So goes life.
178	*
179	* Decrease waiters count. The mutex is not taken, so we have
180	* to do this atomically.
181	*
182	* All waiters contend for the mutex at the end of this function
183	* until the signaling thread relinquishes it. To ensure
184	* each waiter consumes exactly one slice of the semaphore,
185	* the signaling thread stops until it is told by the last
186	* waiter that it can go on.
187	*/
188	if (InterlockedDecrement(&cond->waiters) == cond->target) {
189	SetEvent(cond->continue_event);
190	}
191
192	qemu_mutex_lock(mutex);
193	}
194
38b14db3 PB	195	void qemu_sem_init(QemuSemaphore *sem, int init)
	196	{
	197	/* Manual reset. */
	198	sem->sema = CreateSemaphore(NULL, init, LONG_MAX, NULL);
	199	}
	200
	201	void qemu_sem_destroy(QemuSemaphore *sem)
	202	{
	203	CloseHandle(sem->sema);
	204	}
	205
	206	void qemu_sem_post(QemuSemaphore *sem)
	207	{
	208	ReleaseSemaphore(sem->sema, 1, NULL);
	209	}
	210
	211	int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
	212	{
	213	int rc = WaitForSingleObject(sem->sema, ms);
	214	if (rc == WAIT_OBJECT_0) {
	215	return 0;
	216	}
	217	if (rc != WAIT_TIMEOUT) {
	218	error_exit(GetLastError(), __func__);
	219	}
	220	return -1;
	221	}
	222
	223	void qemu_sem_wait(QemuSemaphore *sem)
	224	{
	225	if (WaitForSingleObject(sem->sema, INFINITE) != WAIT_OBJECT_0) {
	226	error_exit(GetLastError(), __func__);
	227	}
	228	}
	229
9257d46d	230	struct QemuThreadData {
403e6331 PB	231	/* Passed to win32_start_routine. */
	232	void (start_routine)(void *);
	233	void *arg;
	234	short mode;
	235
	236	/* Only used for joinable threads. */
	237	bool exited;
	238	void *ret;
	239	CRITICAL_SECTION cs;
9257d46d PB	240	};
9257d46d PB	241
6265e4ff	242	static __thread QemuThreadData *qemu_thread_data;
9257d46d PB	243
	244	static unsigned __stdcall win32_start_routine(void *arg)
	245	{
403e6331 PB	246	QemuThreadData data = (QemuThreadData ) arg;
	247	void (start_routine)(void *) = data->start_routine;
	248	void *thread_arg = data->arg;
	249
	250	if (data->mode == QEMU_THREAD_DETACHED) {
	251	g_free(data);
	252	data = NULL;
403e6331	253	}
6265e4ff	254	qemu_thread_data = data;
403e6331	255	qemu_thread_exit(start_routine(thread_arg));
9257d46d PB	256	abort();
	257	}
	258
	259	void qemu_thread_exit(void *arg)
	260	{
6265e4ff JK	261	QemuThreadData *data = qemu_thread_data;
6265e4ff JK	262
403e6331	263	if (data) {
edc1de97	264	assert(data->mode != QEMU_THREAD_DETACHED);
403e6331 PB	265	data->ret = arg;
	266	EnterCriticalSection(&data->cs);
	267	data->exited = true;
	268	LeaveCriticalSection(&data->cs);
	269	}
	270	_endthreadex(0);
	271	}
	272
	273	void qemu_thread_join(QemuThread thread)
	274	{
	275	QemuThreadData *data;
	276	void *ret;
	277	HANDLE handle;
	278
	279	data = thread->data;
	280	if (!data) {
	281	return NULL;
	282	}
	283	/*
	284	* Because multiple copies of the QemuThread can exist via
	285	* qemu_thread_get_self, we need to store a value that cannot
	286	* leak there. The simplest, non racy way is to store the TID,
	287	* discard the handle that _beginthreadex gives back, and
	288	* get another copy of the handle here.
	289	*/
1ecf47bf PB	290	handle = qemu_thread_get_handle(thread);
1ecf47bf PB	291	if (handle) {
403e6331 PB	292	WaitForSingleObject(handle, INFINITE);
403e6331 PB	293	CloseHandle(handle);
403e6331 PB	294	}
403e6331 PB	295	ret = data->ret;
edc1de97	296	assert(data->mode != QEMU_THREAD_DETACHED);
403e6331 PB	297	DeleteCriticalSection(&data->cs);
	298	g_free(data);
	299	return ret;
9257d46d PB	300	}
9257d46d PB	301
9257d46d PB	302	void qemu_thread_create(QemuThread *thread,
9257d46d PB	303	void (start_routine)(void *),
cf218714	304	void *arg, int mode)
9257d46d PB	305	{
9257d46d PB	306	HANDLE hThread;
9257d46d	307	struct QemuThreadData *data;
6265e4ff	308
7267c094	309	data = g_malloc(sizeof *data);
9257d46d PB	310	data->start_routine = start_routine;
9257d46d PB	311	data->arg = arg;
403e6331 PB	312	data->mode = mode;
403e6331 PB	313	data->exited = false;
9257d46d	314
edc1de97 SW	315	if (data->mode != QEMU_THREAD_DETACHED) {
	316	InitializeCriticalSection(&data->cs);
	317	}
	318
9257d46d	319	hThread = (HANDLE) _beginthreadex(NULL, 0, win32_start_routine,
403e6331	320	data, 0, &thread->tid);
9257d46d PB	321	if (!hThread) {
	322	error_exit(GetLastError(), __func__);
	323	}
	324	CloseHandle(hThread);
403e6331	325	thread->data = (mode == QEMU_THREAD_DETACHED) ? NULL : data;
9257d46d PB	326	}
	327
	328	void qemu_thread_get_self(QemuThread *thread)
	329	{
6265e4ff	330	thread->data = qemu_thread_data;
403e6331	331	thread->tid = GetCurrentThreadId();
9257d46d PB	332	}
9257d46d PB	333
1ecf47bf PB	334	HANDLE qemu_thread_get_handle(QemuThread *thread)
	335	{
	336	QemuThreadData *data;
	337	HANDLE handle;
	338
	339	data = thread->data;
	340	if (!data) {
	341	return NULL;
	342	}
	343
edc1de97	344	assert(data->mode != QEMU_THREAD_DETACHED);
1ecf47bf PB	345	EnterCriticalSection(&data->cs);
	346	if (!data->exited) {
	347	handle = OpenThread(SYNCHRONIZE \| THREAD_SUSPEND_RESUME, FALSE,
	348	thread->tid);
	349	} else {
	350	handle = NULL;
	351	}
	352	LeaveCriticalSection(&data->cs);
	353	return handle;
	354	}
	355
2d797b65	356	bool qemu_thread_is_self(QemuThread *thread)
9257d46d	357	{
403e6331	358	return GetCurrentThreadId() == thread->tid;
9257d46d	359	}