basis/concurrency/exchangers/exchangers.factor

   1 ! Copyright (C) 2008, 2010 Slava Pestov.
   2 ! See http://factorcode.org/license.txt for BSD license.
   3 USING: kernel threads boxes accessors fry ;
   4 IN: concurrency.exchangers
   5
   6 ! Motivated by
   7 ! http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/Exchanger.html
   8
   9 TUPLE: exchanger thread object ;
  10
  11 : <exchanger> ( -- exchanger )
  12     <box> <box> exchanger boa ;
  13
  14 : exchange ( obj exchanger -- newobj )
  15     dup thread>> occupied>> [
  16         dup object>> box>
  17         [ thread>> box> resume-with ] dip
  18     ] [
  19         [ object>> >box ] keep
  20         [ self ] dip thread>> >box
  21         "exchange" suspend
  22     ] if ;