--- /dev/null
+/*
+ * Win32 implementation for mutex/cond/thread functions
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Author:
+ * Paolo Bonzini <pbonzini@redhat.com>
+ *
+ * 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 "qemu/notify.h"
+#include <process.h>
+#include <assert.h>
+#include <limits.h>
+
+static bool name_threads;
+
+void qemu_thread_naming(bool enable)
+{
+ /* But note we don't actually name them on Windows yet */
+ name_threads = enable;
+
+ fprintf(stderr, "qemu: thread naming not supported on this host\n");
+}
+
+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__);
+ }
+}
+
+void qemu_event_init(QemuEvent *ev, bool init)
+{
+ /* Manual reset. */
+ ev->event = CreateEvent(NULL, TRUE, init, NULL);
+}
+
+void qemu_event_destroy(QemuEvent *ev)
+{
+ CloseHandle(ev->event);
+}
+
+void qemu_event_set(QemuEvent *ev)
+{
+ SetEvent(ev->event);
+}
+
+void qemu_event_reset(QemuEvent *ev)
+{
+ ResetEvent(ev->event);
+}
+
+void qemu_event_wait(QemuEvent *ev)
+{
+ WaitForSingleObject(ev->event, INFINITE);
+}
+
+struct QemuThreadData {
+ /* Passed to win32_start_routine. */
+ void *(*start_routine)(void *);
+ void *arg;
+ short mode;
+ NotifierList exit;
+
+ /* Only used for joinable threads. */
+ bool exited;
+ void *ret;
+ CRITICAL_SECTION cs;
+};
+
+static bool atexit_registered;
+static NotifierList main_thread_exit;
+
+static __thread QemuThreadData *qemu_thread_data;
+
+static void run_main_thread_exit(void)
+{
+ notifier_list_notify(&main_thread_exit, NULL);
+}
+
+void qemu_thread_atexit_add(Notifier *notifier)
+{
+ if (!qemu_thread_data) {
+ if (!atexit_registered) {
+ atexit_registered = true;
+ atexit(run_main_thread_exit);
+ }
+ notifier_list_add(&main_thread_exit, notifier);
+ } else {
+ notifier_list_add(&qemu_thread_data->exit, notifier);
+ }
+}
+
+void qemu_thread_atexit_remove(Notifier *notifier)
+{
+ notifier_remove(notifier);
+}
+
+static unsigned __stdcall win32_start_routine(void *arg)
+{
+ QemuThreadData *data = (QemuThreadData *) arg;
+ void *(*start_routine)(void *) = data->start_routine;
+ void *thread_arg = data->arg;
+
+ qemu_thread_data = data;
+ qemu_thread_exit(start_routine(thread_arg));
+ abort();
+}
+
+void qemu_thread_exit(void *arg)
+{
+ QemuThreadData *data = qemu_thread_data;
+
+ notifier_list_notify(&data->exit, NULL);
+ if (data->mode == QEMU_THREAD_JOINABLE) {
+ data->ret = arg;
+ EnterCriticalSection(&data->cs);
+ data->exited = true;
+ LeaveCriticalSection(&data->cs);
+ } else {
+ g_free(data);
+ }
+ _endthreadex(0);
+}
+
+void *qemu_thread_join(QemuThread *thread)
+{
+ QemuThreadData *data;
+ void *ret;
+ HANDLE handle;
+
+ data = thread->data;
+ if (data->mode == QEMU_THREAD_DETACHED) {
+ 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;
+ DeleteCriticalSection(&data->cs);
+ g_free(data);
+ return ret;
+}
+
+void qemu_thread_create(QemuThread *thread, const char *name,
+ 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;
+ notifier_list_init(&data->exit);
+
+ 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 = 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->mode == QEMU_THREAD_DETACHED) {
+ return NULL;
+ }
+
+ 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;
+}
Code Review / kvmfornfv.git / blobdiff