'\" te
.\" Copyright (c) 2006, Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 1989 AT&T
.TH getq 9F "16 Jan 2006" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
getq \- get the next message from a queue
.SH SYNOPSIS
.LP
.nf
#include <sys/stream.h>

\fBmblk_t *\fR\fBgetq\fR(\fBqueue_t *\fR\fIq\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Architecture independent level 1 (DDI/DKI).
.SH PARAMETERS
.sp
.ne 2
.mk
.na
\fB\fIq\fR\fR
.ad
.RS 5n
.rt  
Pointer to the queue from which the message is to be retrieved.
.RE

.SH DESCRIPTION
.sp
.LP
The \fBgetq()\fR function is used by a service ( \fBsrv\fR(9E)) routine to retrieve its enqueued messages.
.sp
.LP
A module or driver may include a service routine to process enqueued messages. Once the \fBSTREAMS \fRscheduler calls \fBsrv()\fR it must process all enqueued messages, unless prevented by flow control. \fBgetq()\fR obtains the next available message from the top of the queue pointed to by \fIq\fR. It should be called in a \fBwhile\fR loop that is exited only when there are no more messages or flow control prevents further processing.
.sp
.LP
If an attempt was made to write to the queue while it was blocked by flow control, \fBgetq()\fR back-enables (restarts) the service routine once it falls below the low water mark.
.SH RETURN VALUES
.sp
.LP
If there is a message to retrieve, \fBgetq()\fR returns a pointer to it. If no message is queued, \fBgetq()\fR returns a \fBNULL\fR pointer.
.SH CONTEXT
.sp
.LP
The \fBgetq()\fR function can be called from user, interrupt, or kernel context.
.SH EXAMPLES
.sp
.LP
See \fBdupb\fR(9F).
.SH SEE ALSO
.sp
.LP
\fBsrv\fR(9E), \fBbcanput\fR(9F), \fBcanput\fR(9F), \fBdupb\fR(9F), \fBputbq\fR(9F), \fBputq\fR(9F), \fBqenable\fR(9F)
.sp
.LP
\fIWriting Device Drivers for Oracle Solaris 11.2\fR
.sp
.LP
\fISTREAMS Programming Guide\fR