ZMQ_CTX_GET - Online Linux Manual Page

Section : 3
Updated : 01/21/2023
Source : 0MQ 4.3.4
Note : 0MQ Manual

NAME

zmq_ctx_get − get context options

SYNOPSIS

int zmq_ctx_get (void

*context

, int

option_name

);

DESCRIPTION

The zmq_ctx_get(

)

function shall return the option specified by the

option_name

argument. The

zmq_ctx_get(

)

function accepts the following option names:

ZMQ_IO_THREADS: Get number of I/O threads

The ZMQ_IO_THREADS

argument returns the size of the 0MQ thread pool for this context.

ZMQ_MAX_SOCKETS: Get maximum number of sockets

The ZMQ_MAX_SOCKETS

argument returns the maximum number of sockets allowed for this context.

ZMQ_MAX_MSGSZ: Get maximum message size

The ZMQ_MAX_MSGSZ

argument returns the maximum size of a message allowed for this context. Default value is INT_MAX.

ZMQ_ZERO_COPY_RECV: Get message decoding strategy

The ZMQ_ZERO_COPY_RECV

argument return whether message decoder uses a zero copy strategy when receiving messages. Default value is 1. NOTE: in DRAFT state, not yet available in stable releases.

ZMQ_SOCKET_LIMIT: Get largest configurable number of sockets

The ZMQ_SOCKET_LIMIT

argument returns the largest number of sockets that

zmq_ctx_set

(3) will accept.

ZMQ_IPV6: Set IPv6 option

The ZMQ_IPV6

argument returns the IPv6 option for the context.

ZMQ_BLOCKY: Get blocky setting

The ZMQ_BLOCKY

argument returns 1 if the context will block on terminate, zero if the "block forever on context termination" gambit was disabled by setting ZMQ_BLOCKY to false on all new contexts.

ZMQ_THREAD_SCHED_POLICY: Get scheduling policy for I/O threads

The ZMQ_THREAD_SCHED_POLICY

argument returns the scheduling policy for internal context’s thread pool.

ZMQ_THREAD_NAME_PREFIX: Get name prefix for I/O threads

The ZMQ_THREAD_NAME_PREFIX

argument gets the numeric prefix of each thread created for the internal context’s thread pool.

ZMQ_MSG_T_SIZE: Get the zmq_msg_t size at runtime

The ZMQ_MSG_T_SIZE

argument returns the size of the zmq_msg_t structure at runtime, as defined in the include/zmq.h public header. This is useful for example for FFI bindings that can’t simply do a sizeof().

RETURN VALUE

The zmq_ctx_get(

)

function returns a value of 0 or greater if successful. Otherwise it returns −1 and sets

errno

to one of the values defined below.

ERRORS

EINVAL

The requested option option_name

is unknown.

EFAULT

The provided context

is invalid.

EXAMPLE

Setting a limit on the number of sockets

void *context = zmq_ctx_new (); zmq_ctx_set (context, ZMQ_MAX_SOCKETS, 256); int max_sockets = zmq_ctx_get (context, ZMQ_MAX_SOCKETS); assert (max_sockets == 256);

Switching off the context deadlock gambit

zmq_ctx_set (ctx, ZMQ_BLOCKY, false);