QEMU coroutine implementation¶
The documentation for the header qemu/coroutine.h.
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coroutine_fn()¶
Parameters
Description
cooperative userspace threading. These functions provide a simple but useful flavor of coroutines that is suitable for writing sequential code, rather than callbacks, for operations that need to give up control while waiting for events to complete.
These functions are re-entrant and may be used outside the global mutex.
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typedef void coroutine_fn
CoroutineEntry(void * opaque)¶
Parameters
void * opaque- undescribed
Description
When the coroutine is entered for the first time, opaque is passed in as an argument.
When this function returns, the coroutine is destroyed automatically and execution continues in the caller who last entered the coroutine.
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Coroutine *
qemu_coroutine_create(CoroutineEntry * entry, void * opaque)¶
Parameters
CoroutineEntry * entry- undescribed
void * opaque- undescribed
Description
Use qemu_coroutine_enter() to actually transfer control to the coroutine. The opaque argument is passed as the argument to the entry point.
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void
qemu_coroutine_enter(Coroutine * coroutine)¶
Parameters
Coroutine * coroutine- undescribed
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void
qemu_coroutine_enter_if_inactive(Coroutine * co)¶
Parameters
Coroutine * co- undescribed
Description
stack of the running coroutine). Otherwise, do nothing.
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void
qemu_aio_coroutine_enter(AioContext * ctx, Coroutine * co)¶
Parameters
AioContext * ctx- undescribed
Coroutine * co- undescribed
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void coroutine_fn
qemu_coroutine_yield(void)¶
Parameters
void- no arguments
Description
This function does not return until the coroutine is re-entered using qemu_coroutine_enter().
Parameters
void- no arguments
Description
This can be used to write functions that work both when in coroutine context and when not in coroutine context. Note that such functions cannot use the coroutine_fn annotation since they work outside coroutine context.
Parameters
Coroutine * co- undescribed
Description
A coroutine is “entered” if it has not yielded from the current qemu_coroutine_enter() call used to run it. This does not mean that the coroutine is currently executing code since it may have transferred control to another coroutine using qemu_coroutine_enter().
When several coroutines enter each other there may be no way to know which ones have already been entered. In such situations this function can be used to avoid recursively entering coroutines.
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void
qemu_co_mutex_init(CoMutex * mutex)¶
Parameters
CoMutex * mutex- undescribed
Description
on the CoMutex.
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void coroutine_fn
qemu_co_mutex_lock(CoMutex * mutex)¶
Parameters
CoMutex * mutex- undescribed
Description
transferred to the caller of the current coroutine.
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void coroutine_fn
qemu_co_mutex_unlock(CoMutex * mutex)¶
Parameters
CoMutex * mutex- undescribed
Description
lock to be run.
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void
qemu_co_queue_init(CoQueue * queue)¶
Parameters
CoQueue * queue- undescribed
Description
on the CoQueue.
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qemu_co_queue_wait(queue, lock)¶
Parameters
queue- undescribed
lock- undescribed
Description
caller of the coroutine. The mutex is unlocked during the wait and locked again afterwards.
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bool coroutine_fn
qemu_co_queue_next(CoQueue * queue)¶
Parameters
CoQueue * queue- undescribed
Description
Returns true if a coroutine was removed, false if the queue is empty.
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void coroutine_fn
qemu_co_queue_restart_all(CoQueue * queue)¶
Parameters
CoQueue * queue- undescribed
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qemu_co_enter_next(queue, lock)¶
Parameters
queue- undescribed
lock- undescribed
Description
qemu_co_queue_next, this function releases the lock during aio_co_wake because it is meant to be used outside coroutine context; in that case, the coroutine is entered immediately, before qemu_co_enter_next returns.
If used in coroutine context, qemu_co_enter_next is equivalent to qemu_co_queue_next.
Parameters
CoQueue * queue- undescribed
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void
qemu_co_rwlock_init(CoRwlock * lock)¶
Parameters
CoRwlock * lock- undescribed
Description
is used on the CoRwlock
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void
qemu_co_rwlock_rdlock(CoRwlock * lock)¶
Parameters
CoRwlock * lock- undescribed
Description
of a parallel writer, control is transferred to the caller of the current coroutine.
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void
qemu_co_rwlock_upgrade(CoRwlock * lock)¶
Parameters
CoRwlock * lock- undescribed
Description
qemu_co_rwlock_unlock followed by a separate qemu_co_rwlock_wrlock. However, if the lock cannot be upgraded immediately, control is transferred to the caller of the current coroutine. Also, qemu_co_rwlock_upgrade only overrides CoRwlock fairness if there are no concurrent readers, so another writer might run while qemu_co_rwlock_upgrade blocks.
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void
qemu_co_rwlock_downgrade(CoRwlock * lock)¶ side critical section to a reader. Downgrading with qemu_co_rwlock_downgrade never blocks, unlike qemu_co_rwlock_unlock followed by qemu_co_rwlock_rdlock. This makes it more efficient, but may also sometimes be necessary for correctness.
Parameters
CoRwlock * lock- undescribed
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void
qemu_co_rwlock_wrlock(CoRwlock * lock)¶
Parameters
CoRwlock * lock- undescribed
Description
of a parallel reader, control is transferred to the caller of the current coroutine.
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void
qemu_co_rwlock_unlock(CoRwlock * lock)¶
Parameters
CoRwlock * lock- undescribed
Description
waiting for this lock to be run.
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void coroutine_fn
qemu_co_sleep_ns(QEMUClockType type, int64_t ns)¶
Parameters
QEMUClockType type- undescribed
int64_t ns- undescribed
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void coroutine_fn
yield_until_fd_readable(int fd)¶
Parameters
int fd- undescribed
Description
Note that this function clobbers the handlers for the file descriptor.