typed-racket/typed-racket-lib/unstable/logging.rkt
2015-07-23 11:48:39 -05:00

63 lines
2.1 KiB
Racket

#lang racket/base
(require racket/contract/base
racket/logging)
;; re-exported from racket/logging, for backwards compatibility
(provide with-intercepted-logging
with-logging-to-port)
;; helper used below
(define (receiver-thread receiver stop-chan intercept)
(thread
(lambda ()
(define (clear-events)
(let ([l (sync/timeout 0 receiver)])
(when l ; still something to read
(intercept l) ; interceptor gets the whole vector
(clear-events))))
(let loop ()
(let ([l (sync receiver stop-chan)])
(cond [(eq? l 'stop)
;; we received all the events we were supposed
;; to get, read them all (w/o waiting), then
;; stop
(clear-events)]
[else ; keep going
(intercept l)
(loop)]))))))
(struct listener (stop-chan
;; ugly, but the thread and the listener need to know each
;; other
[thread #:mutable]
[rev-messages #:mutable]
[done? #:mutable]))
;; [level] -> listener
(define (start-recording . log-spec)
(let* ([receiver (apply make-log-receiver (current-logger) log-spec)]
[stop-chan (make-channel)]
[cur-listener (listener stop-chan #f '() #f)]
[t (receiver-thread
receiver stop-chan
(lambda (l)
(set-listener-rev-messages!
cur-listener
(cons l (listener-rev-messages cur-listener)))))])
(set-listener-thread! cur-listener t)
cur-listener))
;; listener -> listof messages
(define (stop-recording cur-listener)
(unless (listener-done? cur-listener)
(channel-put (listener-stop-chan cur-listener)
'stop) ; stop the receiver thread
(thread-wait (listener-thread cur-listener))
(set-listener-done?! cur-listener #t))
(reverse (listener-rev-messages cur-listener)))
(provide/contract
[start-recording (->* () #:rest (listof (or/c symbol? #f)) listener?)]
[stop-recording (-> listener? (listof log-message/c))])