c7c4d063f5
This emulates Win32 manual-reset events using futexes or conditional
variables. Typical ways to use them are with multi-producer,
single-consumer data structures, to test for a complex condition whose
elements come from different threads:
for (;;) {
qemu_event_reset(ev);
... test complex condition ...
if (condition is true) {
break;
}
qemu_event_wait(ev);
}
Or more efficiently (but with some duplication):
... evaluate condition ...
while (!condition) {
qemu_event_reset(ev);
... evaluate condition ...
if (!condition) {
qemu_event_wait(ev);
... evaluate condition ...
}
}
QemuEvent provides a very fast userspace path in the common case when
no other thread is waiting, or the event is not changing state.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
64 lines
1.9 KiB
C
64 lines
1.9 KiB
C
#ifndef __QEMU_THREAD_H
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#define __QEMU_THREAD_H 1
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#include <inttypes.h>
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#include <stdbool.h>
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typedef struct QemuMutex QemuMutex;
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typedef struct QemuCond QemuCond;
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typedef struct QemuSemaphore QemuSemaphore;
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typedef struct QemuEvent QemuEvent;
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typedef struct QemuThread QemuThread;
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#ifdef _WIN32
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#include "qemu/thread-win32.h"
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#else
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#include "qemu/thread-posix.h"
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#endif
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#define QEMU_THREAD_JOINABLE 0
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#define QEMU_THREAD_DETACHED 1
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void qemu_mutex_init(QemuMutex *mutex);
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void qemu_mutex_destroy(QemuMutex *mutex);
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void qemu_mutex_lock(QemuMutex *mutex);
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int qemu_mutex_trylock(QemuMutex *mutex);
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void qemu_mutex_unlock(QemuMutex *mutex);
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#define rcu_read_lock() do { } while (0)
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#define rcu_read_unlock() do { } while (0)
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void qemu_cond_init(QemuCond *cond);
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void qemu_cond_destroy(QemuCond *cond);
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/*
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* IMPORTANT: The implementation does not guarantee that pthread_cond_signal
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* and pthread_cond_broadcast can be called except while the same mutex is
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* held as in the corresponding pthread_cond_wait calls!
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*/
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void qemu_cond_signal(QemuCond *cond);
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void qemu_cond_broadcast(QemuCond *cond);
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void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex);
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void qemu_sem_init(QemuSemaphore *sem, int init);
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void qemu_sem_post(QemuSemaphore *sem);
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void qemu_sem_wait(QemuSemaphore *sem);
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int qemu_sem_timedwait(QemuSemaphore *sem, int ms);
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void qemu_sem_destroy(QemuSemaphore *sem);
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void qemu_event_init(QemuEvent *ev, bool init);
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void qemu_event_set(QemuEvent *ev);
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void qemu_event_reset(QemuEvent *ev);
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void qemu_event_wait(QemuEvent *ev);
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void qemu_event_destroy(QemuEvent *ev);
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void qemu_thread_create(QemuThread *thread,
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void *(*start_routine)(void *),
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void *arg, int mode);
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void *qemu_thread_join(QemuThread *thread);
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void qemu_thread_get_self(QemuThread *thread);
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bool qemu_thread_is_self(QemuThread *thread);
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void qemu_thread_exit(void *retval);
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#endif
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