mojave 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)