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Bug #4706 ยป 0004-Improve-logger-documentation.patch

davetron5000 (David Copeland), 05/16/2011 11:50 AM

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lib/logger.rb
# license; either the dual license version in 2003, or any later version.
# Revision:: $Id$
#
# See Logger for documentation.
# A simple system for logging messages. See Logger for more documentation.
require 'monitor'
......
# == Description
#
# The Logger class provides a simple but sophisticated logging utility that
# anyone can use because it's included in the Ruby 1.8.x standard library.
# you can use to output messages.
#
# The HOWTOs below give a code-based overview of Logger's usage, but the basic
# concept is as follows. You create a Logger object (output to a file or
# elsewhere), and use it to log messages. The messages will have varying
# levels (+info+, +error+, etc), reflecting their varying importance. The
# levels, and their meanings, are:
# The messages have associated
# levels, such as +INFO+ or +ERROR+ that indicate their importance.
# You can then give the Logger a level, and only messages at that
# level of higher will be printed.
#
# The levels are:
#
# +FATAL+:: an unhandleable error that results in a program crash
# +ERROR+:: a handleable error condition
......
# +INFO+:: generic (useful) information about system operation
# +DEBUG+:: low-level information for developers
#
# So each message has a level, and the Logger itself has a level, which acts
# as a filter, so you can control the amount of information emitted from the
# logger without having to remove actual messages.
#
# For instance, in a production system, you may have your logger(s) set to
# +INFO+ (or +WARN+ if you don't want the log files growing large with
# repetitive information). When you are developing it, though, you probably
# want to know about the program's internal state, and would set them to
# For instance, in a production system, you may have your Logger set to
# +INFO+ or even +WARN+
# When you are developing the system, however, you probably
# want to know about the program's internal state, and would set the Logger to
# +DEBUG+.
#
# **Note**: Logger does not escape or sanitize any messages passed to it.
# *Note*: Logger does not escape or sanitize any messages passed to it.
# Developers should be aware of when potentially malicious data (user-input)
# is passed to Logger, and manually escape the untrusted data:
#
# logger.info("User-input: #{input.dump}")
# logger.info("User-input: %p" % input)
#
# You can use Logger#formatter= for escaping all data.
# You can use #formatter= for escaping all data.
#
# original_formatter = Logger::Formatter.new
# logger.formatter = proc { |severity, datetime, progname, msg|
......
#
# === Example
#
# A simple example demonstrates the above explanation:
# This creates a logger to the standard output stream, with a level of +WARN+
#
# log = Logger.new(STDOUT)
# log.level = Logger::WARN
......
# === How to log a message
#
# Notice the different methods (+fatal+, +error+, +info+) being used to log
# messages of various levels. Other methods in this family are +warn+ and
# messages of various levels? Other methods in this family are +warn+ and
# +debug+. +add+ is used below to log a message of an arbitrary (perhaps
# dynamic) level.
#
......
# 4. With severity.
#
# logger.add(Logger::FATAL) { 'Fatal error!' }
#
# The block form allows you to create potentially complex log messages,
# but to delay their evaluation until and unless the message is
# logged. For example, if we have the following:
#
# logger.debug { "This is a " + potentially + " expensive operation" }
#
# If the logger's level is +INFO+ or higher, no debug messages will be logged,
# and the entire block will not even be evaluated. Compare to this:
#
# logger.debug("This is a " + potentially + " expensive operation")
#
# Here, the string concatenation is done every time, even if the log
# level is not set to show the debug message.
#
# === How to close a logger
#
......
# Log sample:
# I, [Wed Mar 03 02:34:24 JST 1999 895701 #19074] INFO -- Main: info.
#
# You may change the date and time format in this manner:
# You may change the date and time format via #datetime_format=
#
# logger.datetime_format = "%Y-%m-%d %H:%M:%S"
# # e.g. "2004-01-03 00:54:26"
#
# You may change the overall format with Logger#formatter= method.
# Or, you may change the overall format with #formatter= method.
#
# logger.formatter = proc { |severity, datetime, progname, msg|
# logger.formatter = proc do |severity, datetime, progname, msg|
# "#{datetime}: #{msg}\n"
# }
# # e.g. "Thu Sep 22 08:51:08 GMT+9:00 2005: hello world"
# end
# # e.g. "Thu Sep 22 08:51:08 GMT+9:00 2005: hello world"
#
class Logger
VERSION = "1.2.7"
_, name, rev = %w$Id$
......
rev ||= "v#{VERSION}"
ProgName = "#{name}/#{rev}"
class Error < RuntimeError; end
class ShiftingError < Error; end # not used after 1.2.7. just for compat.
class Error < RuntimeError # :nodoc:
end
# not used after 1.2.7. just for compat.
class ShiftingError < Error # :nodoc:
end
# Logging severity.
module Severity
# Low-level information, mostly for developers
DEBUG = 0
# generic, useful information about system operation
INFO = 1
# a warning
WARN = 2
# a handleable error condition
ERROR = 3
# an unhandleable error that results in a program crash
FATAL = 4
# an unknown message that should always be logged
UNKNOWN = 5
end
include Severity
......
# Logging severity threshold (e.g. <tt>Logger::INFO</tt>).
attr_accessor :level
# Logging program name.
# program name to include in log messages.
attr_accessor :progname
# Logging date-time format (string passed to +strftime+).
# Set date-time format.
#
# +datetime_format+:: A string suitable for passing to +strftime+.
def datetime_format=(datetime_format)
@default_formatter.datetime_format = datetime_format
end
# Returns the date format (string passed to +strftime+) being used (it's set
# using datetime_format=)
# Returns the date format being used. See #datetime_format=
def datetime_format
@default_formatter.datetime_format
end
# Logging formatter. formatter#call is invoked with 4 arguments; severity,
# time, progname and msg for each log. Bear in mind that time is a Time and
# msg is an Object that user passed and it could not be a String. It is
# expected to return a logdev#write-able Object. Default formatter is used
# when no formatter is set.
# Logging formatter, as a +Proc+ that will take four arguments and
# return the formatted message. The arguments are:
#
# +severity+:: The Severity of the log message
# +time+:: A Time instance representing when the message was logged
# +progname+:: The #progname configured, or passed to the logger method
# +msg+:: The _Object_ the user passed to the log message; not necessarily a String.
#
# The block should return an Object that can be written to the logging device via +write+. The
# default formatter is used when no formatter is set.
attr_accessor :formatter
alias sev_threshold level
......
#
# * Logfile is not locked.
# * Append open does not need to lock file.
# * But on the OS which supports multi I/O, records possibly be mixed.
# * If the OS which supports multi I/O, records possibly be mixed.
#
def add(severity, message = nil, progname = nil, &block)
severity ||= UNKNOWN
......
end
#
# :call-seq:
# info(message)
# info(progname,&block)
#
# Log an +INFO+ message.
#
# The message can come either from the +progname+ argument or the +block+. If
# both are provided, then the +block+ is used as the message, and +progname+
# is used as the program name.
# +message+:: the message to log; does not need to be a String
# +progname+:: in the block form, this is the #progname to use in the
# the log message. The default can be set with #progname=
# <tt>&block</tt>:: evaluates to the message to log. This is not evaluated
# unless the logger's level is sufficient
# to log the message. This allows you to create
# potentially expensive logging messages that are
# only called when the logger is configured to show them.
#
# === Examples
#
......
# logger.info { "User typed #{input}" }
#
# You'll probably stick to the second form above, unless you want to provide a
# program name (which you can do with <tt>Logger#progname=</tt> as well).
# program name (which you can do with #progname= as well).
#
# === Return
#
......
end
#
# Log an +UNKNOWN+ message. This will be printed no matter what the logger
# Log an +UNKNOWN+ message. This will be printed no matter what the logger's
# level.
#
# See #info for more information.
......
end
# Default formatter for log messages
class Formatter
Format = "%s, [%s#%d] %5s -- %s: %s\n"
......
end
# Device used for logging messages.
class LogDevice
attr_reader :dev
attr_reader :filename
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