## nng_aio_wait Wait for asynchronous I/O operation. ### Synopsis ```c #include void nng_aio_wait(nng_aio *aio); ``` == DESCRIPTION The `nng_aio_wait` function waits for an asynchronous I/O operation to complete. If the operation has not been started, or has already completed, then it returns immediately. If a callback was set with _aio_ when it was allocated, then this function will not be called until the callback has completed. IMPORTANT: This function should never be called from a function that itself is a callback of an xref:nng_aio.adoc[`aio`], either this one or any other. Doing so may result in a deadlock. ### See ALso xref:nng_aio_abort.adoc[nng_aio_abort], xref:nng_aio_busy.adoc[nng_aio_busy]