files: Implement {set,clear,wait}_fds_event()

The idea is symilar to kernel's wake_up() and wait_event().
One task needs some event. It checks the event has not
happened yet (fle hasn't received, unix peer hasn't bound, etc)
and calls get_fds_event(). Other task makes the event
(sends a fle, binds the peer to a name, etc) and calls set_fds_event().

So, while there is no an event, the first task is sleeping,
and the second wakes it up later:

Task A:      clear_fds_event();
             if (!socket_bound)
                     wait_fds_event(); /* sleep */

Task B:      bind_socket();
             set_fds_event();         /* wake up */

For the details of using see next patches.

v5: Use bit operations.
    Split clear_fds_event from wait function.

v2: Do not wait for foreign transport sock is ready,
as it's guarantied by we create it before CR_STATE_FORKING.

travis-ci: success for Rework file opening scheme to make it asynchronous (rev5)
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/common/lock.h b/include/common/lock.h
index cb48ea602..f68045cfe 100644
--- a/include/common/lock.h
+++ b/include/common/lock.h
@@ -79,6 +79,12 @@ static inline void futex_set_and_wake(futex_t *f, uint32_t v)
 	LOCK_BUG_ON(sys_futex((uint32_t *)&f->raw.counter, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
 }
 
+/* Wake up all futex @f waiters */
+static inline void futex_wake(futex_t *f)
+{
+	LOCK_BUG_ON(sys_futex((uint32_t *)&f->raw.counter, FUTEX_WAKE, INT_MAX, NULL, NULL, 0) < 0);
+}
+
 /* Mark futex @f as wait abort needed and wake up all waiters */
 static inline void futex_abort_and_wake(futex_t *f)
 {