Wake one thread waiting on a futex, and requeue more waiters to another futex wait queue.


#include <zircon/syscalls.h>

zx_status_t zx_futex_requeue_single_owner(const zx_futex_t* value_ptr,
                                          zx_futex_t current_value,
                                          const zx_futex_t* requeue_ptr,
                                          uint32_t requeue_count,
                                          zx_handle_t new_requeue_owner);


Wake one thread waiting on value_ptr and assign ownership of value_ptr to the thread that was woken. If there are no threads waiting on value_ptr then the ownership of value_ptr is set to none.

Then move up to requeue_count threads that are still waiting on value_ptr from the value_ptr futex to the requeue_ptr futex.

zx_futex_requeue_single_owner is similar to zx_futex_requeue with a wake_count of 1, except that zx_futex_requeue_single_owner changes the ownership of value_ptr to the woken thread. See zx_futex_requeue() for a full description.



Return value

zx_futex_requeue_single_owner() returns ZX_OK on success.


ZX_ERR_INVALID_ARGS One of the following is true:

  • Either value_ptr or requeue_ptr is not a valid userspace pointer
  • Either value_ptr or requeue_ptr is not aligned to a sizeof(zx_futex_t) boundary.
  • value_ptr is the same futex as requeue_ptr
  • new_requeue_owner is currently a member of the waiters for either value_ptr or requeue_ptr

ZX_ERR_BAD_HANDLE new_requeue_owner is not ZX_HANDLE_INVALID, and not a valid handle.

ZX_ERR_WRONG_TYPE new_requeue_owner is a valid handle, but is not a handle to a thread.

ZX_ERR_BAD_STATE current_value does not match the value at value_ptr.

See also