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80 lines
2.5 KiB
Plaintext
80 lines
2.5 KiB
Plaintext
= zmq_ctx_set_ext(3)
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== NAME
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zmq_ctx_set_ext - set extended context options
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== SYNOPSIS
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*int zmq_ctx_set_ext (void '*context', int 'option_name', const void '*option_value', size_t 'option_len');*
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== DESCRIPTION
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The _zmq_ctx_set_ext()_ function shall set the option specified by the
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'option_name' argument to the value pointed to by the 'option_value' argument
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for the 0MQ context pointed to by the 'context' argument. The 'option_len'
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argument is the size of the option value in bytes. For options taking a value of
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type "character string", the provided byte data should either contain no zero
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bytes, or end in a single zero byte (terminating ASCII NUL character).
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The _zmq_ctx_set_ext()_ function accepts all the option names accepted by
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_zmq_ctx_set()_.
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Options that make most sense to set using _zmq_ctx_set_ext()_ instead of
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_zmq_ctx_set()_ are the following options:
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ZMQ_THREAD_NAME_PREFIX: Set name prefix for I/O threads
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_THREAD_NAME_PREFIX' argument sets a string prefix to each thread
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created for the internal context's thread pool. This option is only supported on Linux.
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This option is useful to help debugging done via "top -H" or "gdb"; in case
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multiple processes on the system are using ZeroMQ it is useful to provide through
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this context option an application-specific prefix to distinguish ZeroMQ background
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threads that belong to different processes.
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This option only applies before creating any sockets on the context.
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[horizontal]
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Option value type:: character string
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Option value unit:: N/A
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Default value:: empty string
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== RETURN VALUE
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The _zmq_ctx_set_ext()_ function returns zero if successful. Otherwise it
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returns `-1` and sets 'errno' to one of the values defined below.
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== ERRORS
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*EINVAL*::
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The requested option _option_name_ is unknown.
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*EFAULT*::
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The provided 'context' is invalid.
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== EXAMPLE
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.Setting a prefix on internal ZMQ thread names:
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----
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void *context = zmq_ctx_new ();
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const char prefix[] = "MyApp";
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size_t prefixLen = sizeof(prefix);
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zmq_ctx_set (context, ZMQ_THREAD_NAME_PREFIX, &prefix, &prefixLen);
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char buff[256];
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size_t buffLen = sizeof(buff);
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int rc = zmq_ctx_get (context, ZMQ_THREAD_NAME_PREFIX, &buff, &buffLen);
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assert (rc == 0);
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assert (buffLen == prefixLen);
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----
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== SEE ALSO
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* xref:zmq_ctx_set.adoc[zmq_ctx_set]
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* xref:zmq.adoc[zmq]
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== AUTHORS
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This page was written by the 0MQ community. To make a change please
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read the 0MQ Contribution Policy at <https://zeromq.org/how-to-contribute/>.
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