basis/concurrency/exchangers/exchangers.factor

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