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termite

Erlang style concurrency for chicken scheme

Documentation

Fundamental Operations

spawn

[procedure] (spawn FUN)

Create a process running fun and returns its pid.

!

[procedure] (! PID MSG)

Send msg to process pid.

?

[procedure] (? [TIMEOUT [DEFAULT]])

Fetch a message from the mailbox. timeout is in seconds.

??

[procedure] (?? PRED)

Fetches next message that matches pred.

!?

[procedure] (!? PID MSG [TIMEOUT [DEFAULT]])

Send msg to process pid and wait for a reply.

[procedure] (spawn-link FUN)

Create a process running fun and returns its pid and link to it. When either process dies, and exception is raised in the other process.

recv

[procedure] (recv ((PAT VAR ACTION) [...]) [(after TIMEOUT TMO-ACTION)])

Receive a message, when it matches pat put it in var and take action (there can be many of these). Optionally, do tmo-action after timeout.

Distributed Operations

make-node

[procedure] (make-node HOST PORT)

Creates a node object for host:port and returns the node object.

node-init

[procedure] (node-init NODE)

Primary setup for creating a node to accept processes.

remote-spawn

[procedure] (remote-spawn NODE FUN)

Run fun on node, returns pid. Node needs to have done a node-init.

[procedure] (remote-spawn-link NODE FUN)

Run fun on node and link to it, returns pid.

Error Handling

with-exception-catcher

[procedure] (with-exception-catcher HANDLER BODY)

Installs a dynamically scoped exception handler handler for the duration of body. Resumes execution a the point where the handler was installed.

with-exception-handler

[procedure] (with-exception-handler HANDLER BODY)

Installs a dynamically scoped exception handler handler for the duration of body. Resumes execution a the point where the exception was raised.

raise

[procedure] (raise EXCEPTION)

Raises exception.

catch

[procedure] (catch HANDLER BODY)

Catches an exception with handler during execution of body.

Examples

Making a "server" process

 
(define pong-server
  (spawn
    (lambda ()
      (let loop ()
        (let ((msg (?)))
          (if (and (list? msg)
                   (= (length msg) 2)
                   (pid? (car msg))
                   (eq? (cadr msg) 'ping))
            (let ((from (car msg)))
              (! from 'pong)
              (loop))
            (loop)))))))

(! pong-server (list (self) 'ping))

(?)                     --> pong

Selective message retrieval

 
(! (self) 1)
(! (self) 2)
(! (self) 3)

(?)                 --> 1
(?? odd?)           --> 3
(?)                 --> 2

Notes

There's a paper about Termite.

Requirements

s11n mailbox mailbox-threads defstruct

Bugs and Limitations

Author

Gulliaume Germain, ported to chicken by Christian Kellermann

Version History

License

Copyright (c) 2005-2008, Guillaume Germain<br> Termite is licensed under the same terms as Gambit-C (LGPL and Apache v.2)<br> It comes with absolutely no warranty of any kind.<br> LGPL 2.1