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* Problem: boilerplate when init msg from data copy Solution: Add zmq_msg_init_buffer to construct a message by copying memory from buffer.
91 lines
2.2 KiB
Plaintext
91 lines
2.2 KiB
Plaintext
zmq_msg_init_data(3)
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====================
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NAME
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----
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zmq_msg_init_data - initialise 0MQ message from a supplied buffer
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SYNOPSIS
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--------
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*typedef void (zmq_free_fn) (void '*data', void '*hint');*
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*int zmq_msg_init_data (zmq_msg_t '*msg', void '*data', size_t 'size', zmq_free_fn '*ffn', void '*hint');*
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DESCRIPTION
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-----------
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The _zmq_msg_init_data()_ function shall initialise the message object
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referenced by 'msg' to represent the content referenced by the buffer located
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at address 'data', 'size' bytes long. No copy of 'data' shall be performed and
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0MQ shall take ownership of the supplied buffer.
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If provided, the deallocation function 'ffn' shall be called once the data
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buffer is no longer required by 0MQ, with the 'data' and 'hint' arguments
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supplied to _zmq_msg_init_data()_.
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CAUTION: Never access 'zmq_msg_t' members directly, instead always use the
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_zmq_msg_ family of functions.
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CAUTION: The deallocation function 'ffn' needs to be thread-safe, since it
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will be called from an arbitrary thread.
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CAUTION: If the deallocation function is not provided, the allocated memory
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will not be freed, and this may cause a memory leak.
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CAUTION: The functions _zmq_msg_init()_, _zmq_msg_init_data()_,
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_zmq_msg_init_size()_ and _zmq_msg_init_buffer()_ are mutually exclusive.
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Never initialise the same 'zmq_msg_t' twice.
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RETURN VALUE
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------------
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The _zmq_msg_init_data()_ function shall return zero if successful. Otherwise
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it shall return `-1` and set 'errno' to one of the values defined below.
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ERRORS
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------
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*ENOMEM*::
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Insufficient storage space is available.
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EXAMPLE
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-------
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.Initialising a message from a supplied buffer
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----
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void my_free (void *data, void *hint)
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{
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free (data);
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}
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/* ... */
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void *data = malloc (6);
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assert (data);
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memcpy (data, "ABCDEF", 6);
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zmq_msg_t msg;
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rc = zmq_msg_init_data (&msg, data, 6, my_free, NULL);
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assert (rc == 0);
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----
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SEE ALSO
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--------
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linkzmq:zmq_msg_init_size[3]
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linkzmq:zmq_msg_init_buffer[3]
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linkzmq:zmq_msg_init[3]
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linkzmq:zmq_msg_close[3]
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linkzmq:zmq_msg_data[3]
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linkzmq:zmq_msg_size[3]
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linkzmq:zmq[7]
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AUTHORS
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-------
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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 <http://www.zeromq.org/docs:contributing>.
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