hmp: add NBD server commands
[qemu/opensuse.git] / qemu-thread-win32.c
blob4b3db60f5cd2f4661c0c410dce527cd409d13374
1 /*
2 * Win32 implementation for mutex/cond/thread functions
4 * Copyright Red Hat, Inc. 2010
6 * Author:
7 * Paolo Bonzini <pbonzini@redhat.com>
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.
13 #include "qemu-common.h"
14 #include "qemu-thread.h"
15 #include <process.h>
16 #include <assert.h>
17 #include <limits.h>
19 static void error_exit(int err, const char *msg)
21 char *pstr;
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);
27 abort();
30 void qemu_mutex_init(QemuMutex *mutex)
32 mutex->owner = 0;
33 InitializeCriticalSection(&mutex->lock);
36 void qemu_mutex_destroy(QemuMutex *mutex)
38 assert(mutex->owner == 0);
39 DeleteCriticalSection(&mutex->lock);
42 void qemu_mutex_lock(QemuMutex *mutex)
44 EnterCriticalSection(&mutex->lock);
46 /* Win32 CRITICAL_SECTIONs are recursive. Assert that we're not
47 * using them as such.
49 assert(mutex->owner == 0);
50 mutex->owner = GetCurrentThreadId();
53 int qemu_mutex_trylock(QemuMutex *mutex)
55 int owned;
57 owned = TryEnterCriticalSection(&mutex->lock);
58 if (owned) {
59 assert(mutex->owner == 0);
60 mutex->owner = GetCurrentThreadId();
62 return !owned;
65 void qemu_mutex_unlock(QemuMutex *mutex)
67 assert(mutex->owner == GetCurrentThreadId());
68 mutex->owner = 0;
69 LeaveCriticalSection(&mutex->lock);
72 void qemu_cond_init(QemuCond *cond)
74 memset(cond, 0, sizeof(*cond));
76 cond->sema = CreateSemaphore(NULL, 0, LONG_MAX, NULL);
77 if (!cond->sema) {
78 error_exit(GetLastError(), __func__);
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__);
89 void qemu_cond_destroy(QemuCond *cond)
91 BOOL result;
92 result = CloseHandle(cond->continue_event);
93 if (!result) {
94 error_exit(GetLastError(), __func__);
96 cond->continue_event = 0;
97 result = CloseHandle(cond->sema);
98 if (!result) {
99 error_exit(GetLastError(), __func__);
101 cond->sema = 0;
104 void qemu_cond_signal(QemuCond *cond)
106 DWORD result;
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.
113 if (cond->waiters == 0) {
114 return;
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.
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__);
131 void qemu_cond_broadcast(QemuCond *cond)
133 BOOLEAN result;
135 * As in pthread_cond_signal, access to cond->waiters and
136 * cond->target is locked via the external mutex.
138 if (cond->waiters == 0) {
139 return;
142 cond->target = 0;
143 result = ReleaseSemaphore(cond->sema, cond->waiters, NULL);
144 if (!result) {
145 error_exit(GetLastError(), __func__);
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.
156 WaitForSingleObject(cond->continue_event, INFINITE);
159 void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
162 * This access is protected under the mutex.
164 cond->waiters++;
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.
172 qemu_mutex_unlock(mutex);
173 WaitForSingleObject(cond->sema, INFINITE);
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.
179 * Decrease waiters count. The mutex is not taken, so we have
180 * to do this atomically.
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.
188 if (InterlockedDecrement(&cond->waiters) == cond->target) {
189 SetEvent(cond->continue_event);
192 qemu_mutex_lock(mutex);
195 void qemu_sem_init(QemuSemaphore *sem, int init)
197 /* Manual reset. */
198 sem->sema = CreateSemaphore(NULL, init, LONG_MAX, NULL);
201 void qemu_sem_destroy(QemuSemaphore *sem)
203 CloseHandle(sem->sema);
206 void qemu_sem_post(QemuSemaphore *sem)
208 ReleaseSemaphore(sem->sema, 1, NULL);
211 int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
213 int rc = WaitForSingleObject(sem->sema, ms);
214 if (rc == WAIT_OBJECT_0) {
215 return 0;
217 if (rc != WAIT_TIMEOUT) {
218 error_exit(GetLastError(), __func__);
220 return -1;
223 void qemu_sem_wait(QemuSemaphore *sem)
225 if (WaitForSingleObject(sem->sema, INFINITE) != WAIT_OBJECT_0) {
226 error_exit(GetLastError(), __func__);
230 struct QemuThreadData {
231 /* Passed to win32_start_routine. */
232 void *(*start_routine)(void *);
233 void *arg;
234 short mode;
236 /* Only used for joinable threads. */
237 bool exited;
238 void *ret;
239 CRITICAL_SECTION cs;
242 static int qemu_thread_tls_index = TLS_OUT_OF_INDEXES;
244 static unsigned __stdcall win32_start_routine(void *arg)
246 QemuThreadData *data = (QemuThreadData *) arg;
247 void *(*start_routine)(void *) = data->start_routine;
248 void *thread_arg = data->arg;
250 if (data->mode == QEMU_THREAD_DETACHED) {
251 g_free(data);
252 data = NULL;
254 TlsSetValue(qemu_thread_tls_index, data);
255 qemu_thread_exit(start_routine(thread_arg));
256 abort();
259 void qemu_thread_exit(void *arg)
261 QemuThreadData *data = TlsGetValue(qemu_thread_tls_index);
262 if (data) {
263 assert(data->mode != QEMU_THREAD_DETACHED);
264 data->ret = arg;
265 EnterCriticalSection(&data->cs);
266 data->exited = true;
267 LeaveCriticalSection(&data->cs);
269 _endthreadex(0);
272 void *qemu_thread_join(QemuThread *thread)
274 QemuThreadData *data;
275 void *ret;
276 HANDLE handle;
278 data = thread->data;
279 if (!data) {
280 return NULL;
283 * Because multiple copies of the QemuThread can exist via
284 * qemu_thread_get_self, we need to store a value that cannot
285 * leak there. The simplest, non racy way is to store the TID,
286 * discard the handle that _beginthreadex gives back, and
287 * get another copy of the handle here.
289 handle = qemu_thread_get_handle(thread);
290 if (handle) {
291 WaitForSingleObject(handle, INFINITE);
292 CloseHandle(handle);
294 ret = data->ret;
295 assert(data->mode != QEMU_THREAD_DETACHED);
296 DeleteCriticalSection(&data->cs);
297 g_free(data);
298 return ret;
301 static inline void qemu_thread_init(void)
303 if (qemu_thread_tls_index == TLS_OUT_OF_INDEXES) {
304 qemu_thread_tls_index = TlsAlloc();
305 if (qemu_thread_tls_index == TLS_OUT_OF_INDEXES) {
306 error_exit(ERROR_NO_SYSTEM_RESOURCES, __func__);
312 void qemu_thread_create(QemuThread *thread,
313 void *(*start_routine)(void *),
314 void *arg, int mode)
316 HANDLE hThread;
318 struct QemuThreadData *data;
319 qemu_thread_init();
320 data = g_malloc(sizeof *data);
321 data->start_routine = start_routine;
322 data->arg = arg;
323 data->mode = mode;
324 data->exited = false;
326 if (data->mode != QEMU_THREAD_DETACHED) {
327 InitializeCriticalSection(&data->cs);
330 hThread = (HANDLE) _beginthreadex(NULL, 0, win32_start_routine,
331 data, 0, &thread->tid);
332 if (!hThread) {
333 error_exit(GetLastError(), __func__);
335 CloseHandle(hThread);
336 thread->data = (mode == QEMU_THREAD_DETACHED) ? NULL : data;
339 void qemu_thread_get_self(QemuThread *thread)
341 qemu_thread_init();
342 thread->data = TlsGetValue(qemu_thread_tls_index);
343 thread->tid = GetCurrentThreadId();
346 HANDLE qemu_thread_get_handle(QemuThread *thread)
348 QemuThreadData *data;
349 HANDLE handle;
351 data = thread->data;
352 if (!data) {
353 return NULL;
356 assert(data->mode != QEMU_THREAD_DETACHED);
357 EnterCriticalSection(&data->cs);
358 if (!data->exited) {
359 handle = OpenThread(SYNCHRONIZE | THREAD_SUSPEND_RESUME, FALSE,
360 thread->tid);
361 } else {
362 handle = NULL;
364 LeaveCriticalSection(&data->cs);
365 return handle;
368 bool qemu_thread_is_self(QemuThread *thread)
370 return GetCurrentThreadId() == thread->tid;