coroutine: add test-coroutine --benchmark-lifecycle
[qemu/stefanha.git] / qemu-thread-win32.c
blob2d2d5abe39fa134cdc3cce83c3019822c9351cd4
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 exit(1);
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 struct QemuThreadData {
196 QemuThread *thread;
197 void *(*start_routine)(void *);
198 void *arg;
201 static int qemu_thread_tls_index = TLS_OUT_OF_INDEXES;
203 static unsigned __stdcall win32_start_routine(void *arg)
205 struct QemuThreadData data = *(struct QemuThreadData *) arg;
206 QemuThread *thread = data.thread;
208 free(arg);
209 TlsSetValue(qemu_thread_tls_index, thread);
212 * Use DuplicateHandle instead of assigning thread->thread in the
213 * creating thread to avoid races. It's simpler this way than with
214 * synchronization.
216 DuplicateHandle(GetCurrentProcess(), GetCurrentThread(),
217 GetCurrentProcess(), &thread->thread,
218 0, FALSE, DUPLICATE_SAME_ACCESS);
220 qemu_thread_exit(data.start_routine(data.arg));
221 abort();
224 void qemu_thread_exit(void *arg)
226 QemuThread *thread = TlsGetValue(qemu_thread_tls_index);
227 thread->ret = arg;
228 CloseHandle(thread->thread);
229 thread->thread = NULL;
230 ExitThread(0);
233 static inline void qemu_thread_init(void)
235 if (qemu_thread_tls_index == TLS_OUT_OF_INDEXES) {
236 qemu_thread_tls_index = TlsAlloc();
237 if (qemu_thread_tls_index == TLS_OUT_OF_INDEXES) {
238 error_exit(ERROR_NO_SYSTEM_RESOURCES, __func__);
244 void qemu_thread_create(QemuThread *thread,
245 void *(*start_routine)(void *),
246 void *arg)
248 HANDLE hThread;
250 struct QemuThreadData *data;
251 qemu_thread_init();
252 data = qemu_malloc(sizeof *data);
253 data->thread = thread;
254 data->start_routine = start_routine;
255 data->arg = arg;
257 hThread = (HANDLE) _beginthreadex(NULL, 0, win32_start_routine,
258 data, 0, NULL);
259 if (!hThread) {
260 error_exit(GetLastError(), __func__);
262 CloseHandle(hThread);
265 void qemu_thread_get_self(QemuThread *thread)
267 if (!thread->thread) {
268 /* In the main thread of the process. Initialize the QemuThread
269 pointer in TLS, and use the dummy GetCurrentThread handle as
270 the identifier for qemu_thread_is_self. */
271 qemu_thread_init();
272 TlsSetValue(qemu_thread_tls_index, thread);
273 thread->thread = GetCurrentThread();
277 int qemu_thread_is_self(QemuThread *thread)
279 QemuThread *this_thread = TlsGetValue(qemu_thread_tls_index);
280 return this_thread->thread == thread->thread;