'\" t .\" Title: xs_sendmsg .\" Author: [see the "AUTHORS" section] .\" Generator: DocBook XSL Stylesheets v1.75.2 .\" Date: 06/13/2012 .\" Manual: Crossroads I/O Manual .\" Source: Crossroads I/O 1.2.0 .\" Language: English .\" .TH "XS_SENDMSG" "3" "06/13/2012" "Crossroads I/O 1\&.2\&.0" "Crossroads I/O Manual" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .\" http://bugs.debian.org/507673 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" xs_sendmsg \- send a message part on a socket (zero\-copy) .SH "SYNOPSIS" .sp \fBint xs_sendmsg (void \fR\fB\fI*socket\fR\fR\fB, xs_msg_t \fR\fB\fI*msg\fR\fR\fB, int \fR\fB\fIflags\fR\fR\fB);\fR .SH "DESCRIPTION" .sp The \fIxs_sendmsg()\fR function shall queue the message referenced by the \fImsg\fR argument to be sent to the socket referenced by the \fIsocket\fR argument\&. The \fIflags\fR argument is a combination of the flags defined below: .PP \fBXS_DONTWAIT\fR .RS 4 Specifies that the operation should be performed in non\-blocking mode\&. If the message cannot be queued on the \fIsocket\fR, the \fIxs_sendmsg()\fR function shall fail with \fIerrno\fR set to EAGAIN\&. .RE .PP \fBXS_SNDMORE\fR .RS 4 Specifies that the message being sent is a multi\-part message, and that further message parts are to follow\&. Refer to the section regarding multi\-part messages below for a detailed description\&. .RE .sp The \fIxs_msg_t\fR structure passed to \fIxs_sendmsg()\fR is nullified during the call\&. If you want to send the same message to multiple sockets you have to copy it using (e\&.g\&. using \fIxs_msg_copy()\fR)\&. .if n \{\ .sp .\} .RS 4 .it 1 an-trap .nr an-no-space-flag 1 .nr an-break-flag 1 .br .ps +1 \fBNote\fR .ps -1 .br .sp A successful invocation of \fIxs_sendmsg()\fR does not indicate that the message has been transmitted to the network, only that it has been queued on the \fIsocket\fR and Crossroads have assumed responsibility for the message\&. .sp .5v .RE .SS "Multi\-part messages" .sp A Crossroads message is composed of 1 or more message parts\&. Each message part is an independent \fIxs_msg_t\fR in its own right\&. Crossroads ensure atomic delivery of messages; peers shall receive either all \fImessage parts\fR of a message or none at all\&. The total number of message parts is unlimited except by available memory\&. .sp An application that sends multipart messages must use the \fIXS_SNDMORE\fR flag when sending each data part except the final one\&. .SH "RETURN VALUE" .sp The \fIxs_sendmsg()\fR function shall return number of bytes in the message if successful\&. Otherwise it shall return \-1 and set \fIerrno\fR to one of the values defined below\&. .SH "ERRORS" .PP \fBEAGAIN\fR .RS 4 Non\-blocking mode was requested and the message cannot be sent at the moment\&. .RE .PP \fBENOTSUP\fR .RS 4 The \fIxs_sendmsg()\fR operation is not supported by this socket type\&. .RE .PP \fBEFSM\fR .RS 4 The \fIxs_sendmsg()\fR operation cannot be performed on this socket at the moment due to the socket not being in the appropriate state\&. This error may occur with socket types that switch between several states, such as XS_REP\&. See the \fImessaging patterns\fR section of \fBxs_socket\fR(3) for more information\&. .RE .PP \fBETERM\fR .RS 4 The \fIcontext\fR associated with the specified \fIsocket\fR was terminated\&. .RE .PP \fBENOTSOCK\fR .RS 4 The provided \fIsocket\fR was invalid\&. .RE .PP \fBEINTR\fR .RS 4 The operation was interrupted by delivery of a signal before the message was sent\&. .RE .PP \fBEFAULT\fR .RS 4 Invalid message\&. .RE .SH "EXAMPLE" .PP \fBFilling in a message and sending it to a socket\fR. .sp .if n \{\ .RS 4 .\} .nf /* Create a new message, allocating 6 bytes for message content */ xs_msg_t msg; int rc = xs_msg_init_size (&msg, 6); assert (rc == 0); /* Fill in message content with \*(AqAAAAAA\*(Aq */ memset (xs_msg_data (&msg), \*(AqA\*(Aq, 6); /* Send the message to the socket */ rc = xs_sendmsg (socket, &msg, 0); assert (rc == 6); .fi .if n \{\ .RE .\} .PP \fBSending a multi-part message\fR. .sp .if n \{\ .RS 4 .\} .nf /* Send a multi\-part message consisting of three parts to socket */ rc = xs_sendmsg (socket, &part1, XS_SNDMORE); rc = xs_sendmsg (socket, &part2, XS_SNDMORE); /* Final part; no more parts to follow */ rc = xs_sendmsg (socket, &part3, 0); .fi .if n \{\ .RE .\} .sp .SH "SEE ALSO" .sp Applications that do not require zero\-copy messaging can use the simpler \fBxs_send\fR(3) instead of \fIxs_sendmsg()\fR\&. .sp \fBxs_recvmsg\fR(3) \fBxs_socket\fR(7) \fBxs\fR(7) .SH "AUTHORS" .sp This man page was written by Martin Sustrik <\m[blue]\fBsustrik@250bpm\&.com\fR\m[]\&\s-2\u[1]\d\s+2>, Martin Lucina <\m[blue]\fBmartin@lucina\&.net\fR\m[]\&\s-2\u[2]\d\s+2> and Pieter Hintjens <\m[blue]\fBph@imatix\&.com\fR\m[]\&\s-2\u[3]\d\s+2>\&. .SH "NOTES" .IP " 1." 4 sustrik@250bpm.com .RS 4 \%mailto:sustrik@250bpm.com .RE .IP " 2." 4 martin@lucina.net .RS 4 \%mailto:martin@lucina.net .RE .IP " 3." 4 ph@imatix.com .RS 4 \%mailto:ph@imatix.com .RE