= nng_aio_alloc(3) :doctype: manpage :manmanual: nng :mansource: nng :manvolnum: 3 :copyright: Copyright 2018 mailto:info@staysail.tech[Staysail Systems, Inc.] + \ Copyright 2018 mailto:info@capitar.com[Capitar IT Group BV] + \ {blank} + \ This document is supplied under the terms of the \ https://opensource.org/licenses/MIT[MIT License]. == NAME nng_aio_alloc - allocate asynchronous I/O handle == SYNOPSIS [source, c] ----------- #include int nng_aio_alloc(nng_aio **aiop, void (*callb)(void *), void *arg); ----------- == DESCRIPTION The `nng_aio_alloc()` function allocates a handle for asynchronous I/O operations, and stores a pointer to it in __aiop__. The handle is initialized with a completion callback of _callb_, which will be executed when an associated asynchronous operation finishes. It will be called with the argument _arg_. Asynchronous I/O operations all take an "aio" handle such as allocated by this function. Such operations are usually started by a function that returns immediately. The operation is then run asynchronously, and completes sometime later. When that operation is complete, the callback supplied here is called, and that callback is able to determine the result of the operation using <>, <>, and <>. It is possible to wait synchronously for an otherwise asynchronous operation by using the function <>. In that case, it is permissible for _callb_ and _arg_ to both be `NULL`. Note that if these are `NULL`, then it will not be possible to determine when the operation is complete except by calling the aforementioned <>. == RETURN VALUES This function returns 0 on success, and non-zero otherwise. == ERRORS `NNG_ENOMEM`:: Insufficient free memory to perform the operation. == SEE ALSO <>, <>, <>, <>, <>, <>, <>, <>, <>, <>, <>, <>, <>, <>, <>, <> == COPYRIGHT {copyright}