NAME

       ck_ring_dequeue_spmc — dequeue pointer from bounded FIFO

LIBRARY

       Concurrency Kit (libck, -lck)

SYNOPSIS

       #include <ck_ring.h>

       bool
       ck_ring_dequeue_spmc(ck_ring_t *ring, ck_ring_buffer_t *buffer, void *result);

DESCRIPTION

       The  ck_ring_dequeue_spmc(3)  function  dequeues  a pointer from the bounded buffer pointed to by ring in
       FIFO fashion. The pointer is stored in the pointer pointed to by result.  The buffer pointed to by buffer
       must be unique to ring.  The decoupling of the ring from the buffer serves to address use-cases involving
       multiple address spaces and DMA, among others.  If you are on non-POSIX  platforms  or  wish  for  strict
       compliance with C, then it is recommended to pass a pointer of type void ** for result.  This function is
       safe  to  call  without  locking  for  UINT_MAX  concurrent  invocations  of  ck_ring_dequeue_spmc(3)  or
       ck_ring_trydequeue_spmc(3) and up to one concurrent ck_ring_enqueue_spmc(3) or ck_ring_tryenqueue_spmc(3)
       invocation. This function provides lock-free progress guarantees.

EXAMPLE

             #include <ck_ring.h>

             /* This ring was previously initialized with ck_ring_init. */
             ck_ring_t ring;

             /* The ring was initialized for 1023 elements. */
             ck_ring_buffer_t buffer[1024];

             void
             dequeue(void)
             {
                     void *result;

                     /* Dequeue from ring until it is empty. */
                     while (ck_ring_dequeue_spmc(&ring, &buffer, &result) == true) {
                             /*
                              * Results contains the oldest pointer in ring
                              * since the dequeue operation returned true.
                              */
                             operation(result);
                     }

                     /* An empty ring was encountered, leave. */
                     return;
             }

RETURN VALUES

       The function returns true if the buffer was non-empty.  The result of the dequeue operation is stored  in
       the  value pointed to by result.  The function will return false if the buffer was empty and the value in
       result will be undefined.

SEE ALSO

       ck_ring_init(3),   ck_ring_trydequeue_spmc(3),   ck_ring_enqueue_spmc(3),   ck_ring_enqueue_spmc_size(3),
       ck_ring_dequeue_spsc(3),   ck_ring_enqueue_spsc(3),   ck_ring_enqueue_spsc_size(3),  ck_ring_capacity(3),
       ck_ring_size(3)

       Additional information available at http://concurrencykit.org/

                                                 April 20, 2013                          CK_RING_DEQUEUE_SPMC(3)