import

qemu/util/qemu-thread-win32.c

@@ -0,0 +1,386 @@
+/*
+ * 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 <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__);
+    }
+}
+
+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;
+
+    /* 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, 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;
+
+    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;
+}