nanonext (version 0.13.2)

call_aio: Call the Value of an Asynchronous Aio Operation

Description

call_aio retrieves the value of an asynchronous Aio operation, waiting for the operation to complete if still in progress.

call_aio_ is a variant that allows user interrupts, suitable for interactive use.

Usage

call_aio(aio)
call_aio_(aio)

Value

The passed object (invisibly).

Arguments

aio

an Aio (object of class 'sendAio', 'recvAio' or 'ncurlAio').

Alternatively

Aio values may be accessed directly at $result for a 'sendAio', and $data for a 'recvAio'. If the Aio operation is yet to complete, an 'unresolved' logical NA will be returned. Once complete, the resolved value will be returned instead.

unresolved may also be used, which returns TRUE only if an Aio or Aio value has yet to resolve and FALSE otherwise. This is suitable for use in control flow statements such as while or if.

Details

For a 'recvAio', the received value may be retrieved at $data.

For a 'sendAio', the send result may be retrieved at $result. This will be zero on success, or else an integer error code.

To access the values directly, use for example on a 'recvAio' x: call_aio(x)$data.

For a 'recvAio', if an error occurred in unserialization or conversion of the message data to the specified mode, a raw vector will be returned instead to allow recovery (accompanied by a warning).

Once the value has been successfully retrieved, the Aio is deallocated and only the value is stored in the Aio object.

Note this function operates silently and does not error even if 'aio' is not an active Aio, always returning invisibly the passed object.

Examples

s1 <- socket("pair", listen = "inproc://nanonext")
s2 <- socket("pair", dial = "inproc://nanonext")

res <- send_aio(s1, data.frame(a = 1, b = 2), timeout = 100)
res
call_aio(res)
res$result

msg <- recv_aio(s2, timeout = 100)
msg
call_aio_(msg)$data

close(s1)
close(s2)