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Name

queue - STREAMS queue structure

Synopsis

#include <sys/stream.h>

Interface Level

Architecture independent level 1 (DDI/DKI).

Description

A STREAMS driver or module consists of two queue structures, one for upstream processing (read) and one for downstream processing (write). This structure is the major building block of a stream. It contains pointers to the processing procedures, pointers to the next and previous queues in the stream, flow control parameters, and a pointer defining the position of its messages on the STREAMS scheduler list.

The queue structure is defined as type queue_t.

Structure Members

struct qinit*q_qinfo;/* module or driver entry points */
struct msgb*q_first;/* first message in queue */
struct msgb*q_last;/* last message in queue */
struct queue*q_next;/* next queue in stream */
struct queue*q_link;/*to next queue for scheduling*/
void*q_ptr;/* pointer to private data structure */
ulongq_count;/* approximate size of message queue */
ulongq_flag;/* status of queue */
longq_minpsz;/* smallest packet accepted by QUEUE */
longq_maxpsz;/* largest packet accepted by QUEUE */
ulongq_hiwat;/* high water mark */
ulongq_lowat;/* low water mark */

Valid flags are as follows:

QENAB
queue is already enabled to run.
QWANTR
someone wants to read queue.
QWANTW
someone wants to write to queue.
QFULL
queue is considered full.
QREADR
this is the reader (first) queue.
QUSE
this queue in use (allocation).
QNOENB
do not enable queue via putq.

See Also

strqget(9F) , strqset(9F) , module_info(9S) , msgb(9S) , qinit(9S) , streamtab(9S)

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