'\" t
.\"     Title: zmq_ctx_set_ext
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 10/23/2023
.\"    Manual: 0MQ Manual
.\"    Source: 0MQ 4.3.5
.\"  Language: English
.\"
.TH "ZMQ_CTX_SET_EXT" "3" "10/23/2023" "0MQ 4\&.3\&.5" "0MQ Manual"
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.SH "NAME"
zmq_ctx_set_ext \- set extended context options
.SH "SYNOPSIS"
.sp
\fBint zmq_ctx_set_ext (void \fR\fB\fI*context\fR\fR\fB, int \fR\fB\fIoption_name\fR\fR\fB, const void \fR\fB\fI*option_value\fR\fR\fB, size_t \fR\fB\fIoption_len\fR\fR\fB);\fR
.SH "DESCRIPTION"
.sp
The \fIzmq_ctx_set_ext()\fR function shall set the option specified by the \fIoption_name\fR argument to the value pointed to by the \fIoption_value\fR argument for the 0MQ context pointed to by the \fIcontext\fR argument\&. The \fIoption_len\fR argument is the size of the option value in bytes\&. For options taking a value of type "character string", the provided byte data should either contain no zero bytes, or end in a single zero byte (terminating ASCII NUL character)\&.
.sp
The \fIzmq_ctx_set_ext()\fR function accepts all the option names accepted by \fIzmq_ctx_set()\fR\&. Options that make most sense to set using \fIzmq_ctx_set_ext()\fR instead of \fIzmq_ctx_set()\fR are the following options:
.SS "ZMQ_THREAD_NAME_PREFIX: Set name prefix for I/O threads"
.sp
The \fIZMQ_THREAD_NAME_PREFIX\fR argument sets a string prefix to each thread created for the internal context\(cqs thread pool\&. This option is only supported on Linux\&. This option is useful to help debugging done via "top \-H" or "gdb"; in case multiple processes on the system are using ZeroMQ it is useful to provide through this context option an application\-specific prefix to distinguish ZeroMQ background threads that belong to different processes\&. This option only applies before creating any sockets on the context\&.
.TS
tab(:);
lt lt
lt lt
lt lt.
T{
.sp
Option value type
T}:T{
.sp
character string
T}
T{
.sp
Option value unit
T}:T{
.sp
N/A
T}
T{
.sp
Default value
T}:T{
.sp
empty string
T}
.TE
.sp 1
.SH "RETURN VALUE"
.sp
The \fIzmq_ctx_set_ext()\fR function returns zero if successful\&. Otherwise it returns \-1 and sets \fIerrno\fR to one of the values defined below\&.
.SH "ERRORS"
.PP
\fBEINVAL\fR
.RS 4
The requested option
\fIoption_name\fR
is unknown\&.
.RE
.PP
\fBEFAULT\fR
.RS 4
The provided
\fIcontext\fR
is invalid\&.
.RE
.SH "EXAMPLE"
.PP
\fBSetting a prefix on internal ZMQ thread names:\fR. 
.sp
.if n \{\
.RS 4
.\}
.nf
void *context = zmq_ctx_new ();
const char prefix[] = "MyApp";
size_t prefixLen = sizeof(prefix);
zmq_ctx_set (context, ZMQ_THREAD_NAME_PREFIX, &prefix, &prefixLen);

char buff[256];
size_t buffLen = sizeof(buff);
int rc = zmq_ctx_get (context, ZMQ_THREAD_NAME_PREFIX, &buff, &buffLen);
assert (rc == 0);
assert (buffLen == prefixLen);
.fi
.if n \{\
.RE
.\}
.sp
.SH "SEE ALSO"
.sp
\fBzmq_ctx_set\fR(3) \fBzmq\fR(7)
.SH "AUTHORS"
.sp
This page was written by the 0MQ community\&. To make a change please read the 0MQ Contribution Policy at \m[blue]\fBhttp://www\&.zeromq\&.org/docs:contributing\fR\m[]\&.