queue(9S)

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 ∗/
ulong	q_count;	/∗ approximate size of message queue ∗/
ulong	q_flag;	/∗ status of queue ∗/
long	q_minpsz;	/∗ smallest packet accepted by QUEUE ∗/
long	q_maxpsz;	/∗ largest packet accepted by QUEUE ∗/
ulong	q_hiwat;	/∗ high water mark ∗/
ulong	q_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.

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