*/
#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;
}
}
+/* Wrap a Win32 manual-reset event with a fast userspace path. The idea
+ * is to reset the Win32 event lazily, as part of a test-reset-test-wait
+ * sequence. Such a sequence is, indeed, how QemuEvents are used by
+ * RCU and other subsystems!
+ *
+ * Valid transitions:
+ * - free->set, when setting the event
+ * - busy->set, when setting the event, followed by futex_wake
+ * - set->free, when resetting the event
+ * - free->busy, when waiting
+ *
+ * set->busy does not happen (it can be observed from the outside but
+ * it really is set->free->busy).
+ *
+ * busy->free provably cannot happen; to enforce it, the set->free transition
+ * is done with an OR, which becomes a no-op if the event has concurrently
+ * transitioned to free or busy (and is faster than cmpxchg).
+ */
+
+#define EV_SET 0
+#define EV_FREE 1
+#define EV_BUSY -1
+
void qemu_event_init(QemuEvent *ev, bool init)
{
/* Manual reset. */
- ev->event = CreateEvent(NULL, TRUE, init, NULL);
+ ev->event = CreateEvent(NULL, TRUE, TRUE, NULL);
+ ev->value = (init ? EV_SET : EV_FREE);
}
void qemu_event_destroy(QemuEvent *ev)
void qemu_event_set(QemuEvent *ev)
{
- SetEvent(ev->event);
+ if (atomic_mb_read(&ev->value) != EV_SET) {
+ if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
+ /* There were waiters, wake them up. */
+ SetEvent(ev->event);
+ }
+ }
}
void qemu_event_reset(QemuEvent *ev)
{
- ResetEvent(ev->event);
+ if (atomic_mb_read(&ev->value) == EV_SET) {
+ /* If there was a concurrent reset (or even reset+wait),
+ * do nothing. Otherwise change EV_SET->EV_FREE.
+ */
+ atomic_or(&ev->value, EV_FREE);
+ }
}
void qemu_event_wait(QemuEvent *ev)
{
- WaitForSingleObject(ev->event, INFINITE);
+ unsigned value;
+
+ value = atomic_mb_read(&ev->value);
+ if (value != EV_SET) {
+ if (value == EV_FREE) {
+ /* qemu_event_set is not yet going to call SetEvent, but we are
+ * going to do another check for EV_SET below when setting EV_BUSY.
+ * At that point it is safe to call WaitForSingleObject.
+ */
+ ResetEvent(ev->event);
+
+ /* Tell qemu_event_set that there are waiters. No need to retry
+ * because there cannot be a concurent busy->free transition.
+ * After the CAS, the event will be either set or busy.
+ */
+ if (atomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
+ value = EV_SET;
+ } else {
+ value = EV_BUSY;
+ }
+ }
+ if (value == EV_BUSY) {
+ WaitForSingleObject(ev->event, INFINITE);
+ }
+ }
}
struct QemuThreadData {
void *(*start_routine)(void *);
void *arg;
short mode;
+ NotifierList exit;
/* Only used for joinable threads. */
bool exited;
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;
- if (data->mode == QEMU_THREAD_DETACHED) {
- g_free(data);
- data = NULL;
- }
qemu_thread_data = data;
qemu_thread_exit(start_routine(thread_arg));
abort();
{
QemuThreadData *data = qemu_thread_data;
- if (data) {
- assert(data->mode != QEMU_THREAD_DETACHED);
+ 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);
}
HANDLE handle;
data = thread->data;
- if (!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
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 qemu_thread_create(QemuThread *thread, const char *name,
void *(*start_routine)(void *),
void *arg, int mode)
{
data->arg = arg;
data->mode = mode;
data->exited = false;
+ notifier_list_init(&data->exit);
if (data->mode != QEMU_THREAD_DETACHED) {
InitializeCriticalSection(&data->cs);
error_exit(GetLastError(), __func__);
}
CloseHandle(hThread);
- thread->data = (mode == QEMU_THREAD_DETACHED) ? NULL : data;
+ thread->data = data;
}
void qemu_thread_get_self(QemuThread *thread)
HANDLE handle;
data = thread->data;
- if (!data) {
+ if (data->mode == QEMU_THREAD_DETACHED) {
return NULL;
}
- assert(data->mode != QEMU_THREAD_DETACHED);
EnterCriticalSection(&data->cs);
if (!data->exited) {
handle = OpenThread(SYNCHRONIZE | THREAD_SUSPEND_RESUME, FALSE,
projects / qemu.git / blobdiff