PCQ(9) | Kernel Developer's Manual | PCQ(9) |
pcq
—
#include <sys/pcq.h>
pcq_t *
pcq_create
(size_t
maxlen, km_flags_t
kmflags);
void
pcq_destroy
(pcq_t
*pcq);
void *
pcq_get
(pcq_t
*pcq);
size_t
pcq_maxitems
(pcq_t
*pcq);
void *
pcq_peek
(pcq_t
*pcq);
bool
pcq_put
(pcq_t
*pcq, void
*item);
pcq
interface provides lockless
producer/consumer queues. A queue (pcq_t) allows
multiple writers (producers), but only a single reader (consumer). The
consumer is expected to be protected by a lock that covers the structure that
the pcq_t is embedded into (e.g., socket lock, ifnet
hwlock). These queues operate in a first-in, first-out (FIFO) manner. The act
of inserting or removing an item from a pcq_t does not
modify the item in any way. pcq
does not prevent an
item from being inserted multiple times into a single
pcq_t.
pcq_create
(maxlen,
kmflags)KM_SLEEP
, if pcq_create
()
is allowed to sleep until resources are available, or
KM_NOSLEEP
if it should return
NULL
immediately, if resources are
unavailable.pcq_destroy
(pcq)pcq_get
(pcq)NULL
. The caller must
prevent concurrent gets from occurring.pcq_maxitems
(pcq)pcq_peek
(pcq)NULL
.pcq_put
(pcq,
item)false
; otherwise, return
true
. The item must not have the value of
NULL
.pcq
interface is implemented within the file
sys/kern/subr_pcq.c.
pcq
interface first appeared in
NetBSD 6.0.
January 22, 2012 | NetBSD 9.0 |