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Article contents:== Outdated egg! This is an egg for CHICKEN 4, the unsupported old release. You're almost certainly looking for [[/eggref/5/pigeon-hole|the CHICKEN 5 version of this egg]], if it exists. If it does not exist, there may be equivalent functionality provided by another egg; have a look at the [[https://wiki.call-cc.org/chicken-projects/egg-index-5.html|egg index]]. Otherwise, please consider porting this egg to the current version of CHICKEN. == pigeon-hole A mailbox constrained by capacity. * API similar to mailbox. * No timeouts we love our pigeons too much. * Flow control. {{send/blocking!}} blocks if capacity is exceeded. A second module [[pigeonry]] - currently unstable in API and undocumented - provides a threadpool. This is only slightly faster than creating a fresh thread, catching exceptions and run job it does while still obeying the capacity limit. This module {{NYD}} (not yet documented) at all. == API <procedure>(isa? *) -> boolean</procedure> Test predicate for {{PIGEON-HOLE}}. <procedure>(: make (&optional NAME #!key (capacity: 0) -> {{PIGEON-HOLE}}))</procedure> Return a {{PIGEON-HOLE}} constrained by capacity. <procedure>(size PIGEON-HOLE) -> fixnum</procedure> Return number of pigeons in {{PIGEON-HOLE}}. <procedure>(empty? PIGEON-HOLE) -> boolean</procedure> Test {{PIGEON-HOLE}} to be empty. <procedure>(count PIGEON-HOLE) -> fixnum</procedure> Return number of waiters on {{PIGEON-HOLE}}. <procedure>(send! PIGEON-HOLE VALUE) -> boolean</procedure> Immediately send {{VALUE}} to {{PIGEON-HOLE}}. Does *not* respect capacity limits! <procedure>(send/blocking! PIGEON-HOLE VALUE [BLOCK]) -> boolean</procedure> Send {{VALUE}} to {{PIGEON-HOLE}}, blocks if capacity is reached. {{BLOCK}} is either a boolean or a procedure taking the queue as argument and returning a boolean. If it is a procedure it is call in tail position when the call would block. If {{#f}} does not block but return #f. Default if {{#t}}: block for capacity. Return: {{#t}} if value was send. <procedure>(receive! PIGEON-HOLE) -> *</procedure> Receive value from {{PIGEON-HOLE}}, block if none available. === Unstable API <procedure>(send-list/anyway!! PIGEON-HOLE LIST [NUM LAST]) -> undefined</procedure> Append all values from {{LIST}} to {{PIGEON-HOLE}}. It is an error to access {{LIST}} after this call. Optional {{NUM}} and {{LAST}} may be given for optimization. Must be the length of the {{LIST}} and the last pair of it. All bets are off otherwise. <procedure>(receive-all! PIGEON-HOLE) -> LIST</procedure> Receive list of all currently available values from {{PIGEON-HOLE}}. == Examples (module test (test-run) (import scheme chicken srfi-18 extras) (import (prefix pigeon-hole mailbox-)) (define mb (mailbox-make 'm0 capacity: 10)) ;; ;;(define active-mailbox-send! mailbox-send!) (define active-mailbox-send! mailbox-send/blocking!) ;; (cond-expand (compiling (define turns 1000000)) (else (define turns 1000))) ;; (define tw (make-thread (lambda () (do ((i 0 (add1 i))) ((= i turns)) (active-mailbox-send! mb i))) 'w)) ;; (define tr (make-thread (lambda () (do ((i 0 (add1 i))) ((= i turns)) (mailbox-receive! mb) )) 'r)) ;; (define (test-run) (thread-start! tr) (define t0 (current-milliseconds)) (thread-start! tw) (thread-join! tr) (define t1 (current-milliseconds)) (format #t "~a message passings in ~a (~a per ms)\n " turns (- t1 t0) (/ turns (- t1 t0))) ) ) (import test) (test-run) == About this egg === Source code Maintained at github [[https://github.com/0-8-15/pigeon-hole|pigeon-hole]]. === Author Jörg F. Wittenberger === License BSD Description of your changes:

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