log.lisp

   1 ;;; -*- Mode: LISP; Syntax: COMMON-LISP; Package: HUNCHENTOOT; Base: 10 -*-
   2
   3 ;;; Copyright (c) 2004-2010, Dr. Edmund Weitz.  All rights reserved.
   4
   5 ;;; Redistribution and use in source and binary forms, with or without
   6 ;;; modification, are permitted provided that the following conditions
   7 ;;; are met:
   8
   9 ;;;   * Redistributions of source code must retain the above copyright
  10 ;;;     notice, this list of conditions and the following disclaimer.
  11
  12 ;;;   * Redistributions in binary form must reproduce the above
  13 ;;;     copyright notice, this list of conditions and the following
  14 ;;;     disclaimer in the documentation and/or other materials
  15 ;;;     provided with the distribution.
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  17 ;;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS' AND ANY EXPRESSED
  18 ;;; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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  28
  29 (in-package :hunchentoot)
  30
  31 (defmacro with-log-stream ((stream-var destination lock) &body body)
  32   "Helper macro to write log entries.  STREAM-VAR is a symbol that
  33 will be bound to the logging stream during the execution of BODY.
  34 DESTINATION is the logging destination, which can be either a pathname
  35 designator of the log file, a symbol designating an open stream or NIL
  36 if no logging should be done.  LOCK refers to the lock that should be
  37 held during the logging operation.  If DESTINATION is a pathname, a
  38 flexi stream with UTF-8 encoding will be created and bound to
  39 STREAM-VAR.  If an error occurs while writing to the log file, that
  40 error will be logged to *ERROR-OUTPUT*.
  41
  42 Note that logging to a file involves opening and closing the log file
  43 for every logging operation, which is overall costly.  Web servers
  44 with high throughput demands should make use of a specialized logging
  45 function rather than relying on Hunchentoot's default logging
  46 facility."
  47   (with-unique-names (binary-stream)
  48     (with-rebinding (destination)
  49       (let ((body body))
  50         `(when ,destination
  51            (with-lock-held (,lock)
  52              (etypecase ,destination
  53                ((or string pathname)
  54                 (with-open-file (,binary-stream ,destination
  55                                                 :direction :output
  56                                                 :element-type 'octet
  57                                                 :if-does-not-exist :create
  58                                                 :if-exists :append
  59                                                 #+:openmcl :sharing #+:openmcl :lock)
  60                   (let ((,stream-var (make-flexi-stream ,binary-stream :external-format +utf-8+)))
  61                     ,@body)))
  62                (stream
  63                 (let ((,stream-var ,destination))
  64                   (prog1 (progn ,@body)
  65                     (finish-output ,destination)))))))))))
  66