Device (Async)

Create an asynchronous device: a zero-copy forwarder that relays raw messages between two Sockets. This is the building block for brokers and proxies, such as a publisher/subscriber relay or a pair-to-pair bridge.

Usage

device_aio(s1, s2 = s1)

Arguments

s1

a Socket, in raw mode.

s2

a Socket, in raw mode, using the complementary protocol to s1. If not supplied, defaults to s1 to create a reflector.

Value

A 'sendAio' (object of class 'sendAio') (invisibly).

Details

A device runs on background threads and relays messages until it is stopped or an error occurs. The returned 'sendAio' resolves only at that point: its $result is an 'unresolved' logical NA while the device is running, and otherwise the integer exit code (usually the error that caused it to stop, such as a Socket being closed).

Both Sockets must be opened in raw mode (see socket()) and use complementary protocols, that is the peer protocol of each must be the protocol of the other (for example two 'pair' Sockets, or a 'pub' and a 'sub' Socket). The same Socket may be supplied for both arguments to create a reflector.

To stop the device, use stop_aio(), or close either of the Sockets. To block and wait for the device to stop, use call_aio().

See also

send_aio() for the structure of the returned 'sendAio'.

Examples

s1 <- socket("pair", listen = "inproc://device1", raw = TRUE)
s2 <- socket("pair", listen = "inproc://device2", raw = TRUE)

dev <- device_aio(s1, s2)
dev$result
#> 'unresolved' logi NA

stop_aio(dev)
dev$result
#> 'errorValue' int 20 | Operation canceled
close(s1)
close(s2)