Asynchronous Input/Output

  select-stream stream-list timeout [function]

• finds a list of streams which are ready for input operation, in stream-list. NIL is returned if timeout seconds have expired before any streams become ready. Select-stream is useful when you choose active streams out of a list of input-streams on which input operation becomes possible asynchronously. Timeout specifies the time when the select operation is aborted. It can be a float number. If no timeout is specified, select-stream blocks until input arrives at least one stream. If timeout is specified and no input appears on any streams, select-stream aborts and returns NIL.

  def-async stream function [macro]

• defines function to be called when data arrives at stream. stream is either a file-stream or a socket-port. When data comes to the file-stream or a connection request appears on the socket-port, function is invoked with the stream as its argument. This macro installs a SIGIO handler that dispatches to user supplied function which is expected to perform actual input operation, and uses unix:fcntl on stream to issue SIGIO asynchronously when stream becomes ready to be read.