posix man page for getq

getq(9F)						   Kernel Functions for Drivers 						  getq(9F)

NAME

       getq - get the next message from a queue

SYNOPSIS

       #include <sys/stream.h>

       mblk_t *getq(queue_t *q);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       q	Pointer to the queue from which the message is to be retrieved.

DESCRIPTION

       getq() is used by a service ( srv(9E)) routine to retrieve its enqueued messages.

       A  module  or driver may include a service routine to process enqueued messages. Once the STREAMS scheduler calls srv() it must process all
       enqueued messages, unless prevented by flow control. getq() obtains the next available message from the top of the queue pointed to  by	q.
       It should be called in a while loop that is exited only when there are no more messages or flow control prevents further processing.

       If  an attempt was made to write to the queue while it was blocked by flow control, getq() back-enables (restarts) the service routine once
       it falls below the low water mark.

RETURN VALUES

       If there is a message to retrieve, getq() returns a pointer to it. If no message is queued, getq() returns a NULL pointer.

CONTEXT

       getq() can be called from user or interrupt context.

EXAMPLES

       See dupb(9F).

SEE ALSO

       srv(9E), bcanput(9F), canput(9F), dupb(9F), putbq(9F), putq(9F), qenable(9F)

       Writing Device Drivers

       STREAMS Programming Guide

SunOS 5.10							    12 Nov 1992 							  getq(9F)