Erlang style concurrency for CHICKEN Scheme, heavily inspired by termite.
This is a fork of hardwood with support for CHICKEN 5, plus additional changes for my own use.
All the Termite API is currently not implemented and probably never will. Also, some incompatibilities are to be expected.
The source code for this fork of hardwood is available in a git repository on Sourcehut.
You can clone it with:
git clone https://git.sr.ht/~nilium/hardwood
The original hardwood code is available in a git repository.
You can clone it with:
git clone git://upyum.com/hardwood
Adrien Ramos, heavily inspired by the Termite project of Guillaume Germain.
Hardwood processes are implemented as simple srfi-18 threads so they
behave in the same ways. The name
process was chosen as per
As a general rule, mutation should be avoided when using hardwood, especially inside messages themselves as there is no copy involved.
TIMEOUT in the following definitions can be (as per srfi-18) either
of the following:
DEFAULT is specified when
TIMEOUT is, it is returned in case
of timeout. Otherwise
timeout-condition is signaled.
Condition object raised when a timeout is reached.
[procedure] (monitor-ref? OBJ)
obj is a monitor reference or not.
[procedure] (pid? OBJ)
obj is a
pid object or not.
[procedure] (process-exist? PID)
pid is a running process or not.
[procedure] (timeout-condition? OBJ)
timeout-condition or not.
[procedure] (spawn PROC . ARGS)
Create a process running
(proc args ...) and returns its
Return the current process'
[procedure] (setup-thread [THREAD])
thread a hardwood process.
thread must be a srfi-18 thread. Otherwise, the current
thread is used.
Return a new
Tags are guaranteed to be universally unique.
[procedure] (monitor PID)
The calling process starts monitoring the
Return a monitor reference
If that process exits, either normally or not, the caller process will be informed with a message of the form:
('DOWN ref pid reason)
reason can be one of the following:
exited: the process exited normally
no-process: the process didn't exist
('condition c): the process exited because of condition
[procedure] (demonitor ref)
Stop the monitor associated with
[procedure] (! PID MSG)
msg to process
[procedure] (!! LIST MSG)
List must be a list of pids.
msg to all pids in
[syntax] (? [TIMEOUT [DEFAULT]])
Fetch the first message from the mailbox.
[procedure] (?? PRED [TIMEOUT [DEFAULT]])
Fetch the next message that matches
[procedure] (!? PID MSG [TIMEOUT [DEFAULT]])
msg to process
pid and wait for a reply.
The actual message sent to
pid is (list (self) tag
This procedure wait for a reply of the form (list tag
[syntax] (recv PAT [...] [(after TIMEOUT TMO-ACTION ...)])
Match incoming messages against
Each pattern must be a valid pattern for
This version of
recvis incompatible with the one defined in the Termite paper and implementation as it uses the syntax of the matchable egg.
(use hardwood srfi-18) (setup-thread)
This can be useful to communicate with other processes from the REPL, as in the following examples.
(use hardwood srfi-18) (setup-thread) (define pong-server (spawn (lambda () (let loop () (recv (((? pid? pid) 'ping) (! pid 'pong) (loop)) (else (loop)))) (! pong-server (list (self) 'ping)) (?) --> pong
(use hardwood srfi-18) (setup-thread) (! (self) 1) (! (self) 2) (! (self) 3) (?) --> 1 (?? odd?) --> 3 (?) --> 2
(use hardwood srfi-18) (setup-thread) (define rpc-server (spawn (lambda () (let loop () (recv ((from tag ('add a b)) (! from (list tag (+ a b))))) (loop))))) (!? rpc-server '(add 21 21)) ---> 42
(use hardwood srfi-18) (setup-thread) (define pid (spawn (lambda () (recv (x (/ 0))))))) (define ref (monitor pid)) (! pid 'msg) (?) --> ('DOWN ref pid ('condition exn))
0.5: setup-thread now uses the current-thread by default, macro helper procedures are not exported from the module anymore (thanks Evan for the patches!).
0.4: Bug fixes; tests now use the test egg; in-process call history is now more useful.
0.3: Bug fix;
!!function; spawn accepts procedure arguments; monitor references.
0.2: Implement process monitoring.
0.1: Initial release.
The license text can be found in the accompanying LICENSE.txt, and is also reproduced below:
Copyright (c) 2014, Adrien Ramos firstname.lastname@example.org All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.