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guix-cuirass/src/cuirass/logging.scm
Ludovic Courtès 23fecf8f3d cuirass: Log resource usage statistics regularly.
* src/cuirass/logging.scm (log-monitoring-stats): New procedure.
* bin/cuirass.in (main): Add a fiber that calls it regularly.
2018-01-29 18:06:47 +01:00

76 lines
2.7 KiB
Scheme

;;; logging.scm -- Event logging.
;;; Copyright © 2018 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of Cuirass.
;;;
;;; Cuirass is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published by
;;; the Free Software Foundation, either version 3 of the License, or
;;; (at your option) any later version.
;;;
;;; Cuirass is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with Cuirass. If not, see <http://www.gnu.org/licenses/>.
(define-module (cuirass logging)
#:use-module (srfi srfi-19)
#:use-module (ice-9 format)
#:use-module (ice-9 threads)
#:use-module (ice-9 ftw)
#:export (current-logging-port
current-logging-procedure
log-message
with-time-logging
log-monitoring-stats))
(define current-logging-port
(make-parameter (current-error-port)))
(define (log-to-port port str)
(define now
(current-time time-utc))
(define date
(date->string (time-utc->date now) "~5"))
(display (string-append date " " str "\n")
port))
(define current-logging-procedure
;; The logging procedure. This could be 'syslog', for instance.
(make-parameter (lambda (str)
(log-to-port (current-logging-port) str))))
(define-syntax-rule (log-message fmt args ...)
"Log the given message as one line."
;; Note: Use '@' to make sure -Wformat detects this use of 'format'.
((current-logging-procedure)
((@ (ice-9 format) format) #f fmt args ...)))
(define (call-with-time-logging name thunk)
(let* ((start (current-time time-utc))
(result (thunk))
(end (current-time time-utc))
(elapsed (time-difference end start)))
(log-message "~a took ~a seconds" name
(+ (time-second elapsed)
(/ (time-nanosecond elapsed) 1e9)))
result))
(define-syntax-rule (with-time-logging name exp ...)
"Log under NAME the time taken to evaluate EXP."
(call-with-time-logging name (lambda () exp ...)))
(define (log-monitoring-stats)
"Log info about useful metrics: heap size, number of threads, etc."
(log-message "heap: ~,2f MiB; threads: ~a; file descriptors: ~a"
(/ (assoc-ref (gc-stats) 'heap-size) (expt 2. 20))
(length (all-threads))
(length
(scandir "/proc/self/fd"
(lambda (file)
(not (member file '("." ".."))))))))