Bug #4706 ยป 0004-Improve-logger-documentation.patch
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# license; either the dual license version in 2003, or any later version.
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# Revision:: $Id$
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#
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# See Logger for documentation.
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# A simple system for logging messages. See Logger for more documentation.
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require 'monitor'
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| ... | ... | |
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# == Description
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#
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# The Logger class provides a simple but sophisticated logging utility that
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# anyone can use because it's included in the Ruby 1.8.x standard library.
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# you can use to output messages.
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#
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# The HOWTOs below give a code-based overview of Logger's usage, but the basic
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# concept is as follows. You create a Logger object (output to a file or
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# elsewhere), and use it to log messages. The messages will have varying
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# levels (+info+, +error+, etc), reflecting their varying importance. The
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# levels, and their meanings, are:
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# The messages have associated
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# levels, such as +INFO+ or +ERROR+ that indicate their importance.
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# You can then give the Logger a level, and only messages at that
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# level of higher will be printed.
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#
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# The levels are:
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#
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# +FATAL+:: an unhandleable error that results in a program crash
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# +ERROR+:: a handleable error condition
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| ... | ... | |
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# +INFO+:: generic (useful) information about system operation
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# +DEBUG+:: low-level information for developers
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#
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# So each message has a level, and the Logger itself has a level, which acts
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# as a filter, so you can control the amount of information emitted from the
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# logger without having to remove actual messages.
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#
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# For instance, in a production system, you may have your logger(s) set to
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# +INFO+ (or +WARN+ if you don't want the log files growing large with
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# repetitive information). When you are developing it, though, you probably
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# want to know about the program's internal state, and would set them to
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# For instance, in a production system, you may have your Logger set to
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# +INFO+ or even +WARN+
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# When you are developing the system, however, you probably
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# want to know about the program's internal state, and would set the Logger to
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# +DEBUG+.
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#
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# **Note**: Logger does not escape or sanitize any messages passed to it.
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# *Note*: Logger does not escape or sanitize any messages passed to it.
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# Developers should be aware of when potentially malicious data (user-input)
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# is passed to Logger, and manually escape the untrusted data:
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#
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# logger.info("User-input: #{input.dump}")
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# logger.info("User-input: %p" % input)
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#
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# You can use Logger#formatter= for escaping all data.
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# You can use #formatter= for escaping all data.
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#
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# original_formatter = Logger::Formatter.new
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# logger.formatter = proc { |severity, datetime, progname, msg|
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| ... | ... | |
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#
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# === Example
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#
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# A simple example demonstrates the above explanation:
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# This creates a logger to the standard output stream, with a level of +WARN+
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#
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# log = Logger.new(STDOUT)
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# log.level = Logger::WARN
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| ... | ... | |
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# === How to log a message
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#
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# Notice the different methods (+fatal+, +error+, +info+) being used to log
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# messages of various levels. Other methods in this family are +warn+ and
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# messages of various levels? Other methods in this family are +warn+ and
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# +debug+. +add+ is used below to log a message of an arbitrary (perhaps
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# dynamic) level.
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#
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| ... | ... | |
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# 4. With severity.
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#
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# logger.add(Logger::FATAL) { 'Fatal error!' }
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#
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# The block form allows you to create potentially complex log messages,
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# but to delay their evaluation until and unless the message is
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# logged. For example, if we have the following:
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#
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# logger.debug { "This is a " + potentially + " expensive operation" }
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#
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# If the logger's level is +INFO+ or higher, no debug messages will be logged,
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# and the entire block will not even be evaluated. Compare to this:
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#
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# logger.debug("This is a " + potentially + " expensive operation")
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#
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# Here, the string concatenation is done every time, even if the log
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# level is not set to show the debug message.
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#
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# === How to close a logger
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#
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| ... | ... | |
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# Log sample:
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# I, [Wed Mar 03 02:34:24 JST 1999 895701 #19074] INFO -- Main: info.
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#
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# You may change the date and time format in this manner:
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# You may change the date and time format via #datetime_format=
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#
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# logger.datetime_format = "%Y-%m-%d %H:%M:%S"
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# # e.g. "2004-01-03 00:54:26"
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#
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# You may change the overall format with Logger#formatter= method.
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# Or, you may change the overall format with #formatter= method.
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#
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# logger.formatter = proc { |severity, datetime, progname, msg|
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# logger.formatter = proc do |severity, datetime, progname, msg|
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# "#{datetime}: #{msg}\n"
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# }
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# # e.g. "Thu Sep 22 08:51:08 GMT+9:00 2005: hello world"
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# end
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# # e.g. "Thu Sep 22 08:51:08 GMT+9:00 2005: hello world"
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#
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class Logger
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VERSION = "1.2.7"
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_, name, rev = %w$Id$
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| ... | ... | |
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rev ||= "v#{VERSION}"
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ProgName = "#{name}/#{rev}"
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class Error < RuntimeError; end
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class ShiftingError < Error; end # not used after 1.2.7. just for compat.
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class Error < RuntimeError # :nodoc:
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end
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# not used after 1.2.7. just for compat.
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class ShiftingError < Error # :nodoc:
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end
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# Logging severity.
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module Severity
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# Low-level information, mostly for developers
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DEBUG = 0
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# generic, useful information about system operation
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INFO = 1
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# a warning
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WARN = 2
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# a handleable error condition
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ERROR = 3
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# an unhandleable error that results in a program crash
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FATAL = 4
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# an unknown message that should always be logged
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UNKNOWN = 5
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end
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include Severity
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| ... | ... | |
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# Logging severity threshold (e.g. <tt>Logger::INFO</tt>).
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attr_accessor :level
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# Logging program name.
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# program name to include in log messages.
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attr_accessor :progname
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# Logging date-time format (string passed to +strftime+).
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# Set date-time format.
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#
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# +datetime_format+:: A string suitable for passing to +strftime+.
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def datetime_format=(datetime_format)
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@default_formatter.datetime_format = datetime_format
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end
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# Returns the date format (string passed to +strftime+) being used (it's set
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# using datetime_format=)
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# Returns the date format being used. See #datetime_format=
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def datetime_format
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@default_formatter.datetime_format
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end
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# Logging formatter. formatter#call is invoked with 4 arguments; severity,
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# time, progname and msg for each log. Bear in mind that time is a Time and
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# msg is an Object that user passed and it could not be a String. It is
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# expected to return a logdev#write-able Object. Default formatter is used
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# when no formatter is set.
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# Logging formatter, as a +Proc+ that will take four arguments and
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# return the formatted message. The arguments are:
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#
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# +severity+:: The Severity of the log message
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# +time+:: A Time instance representing when the message was logged
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# +progname+:: The #progname configured, or passed to the logger method
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# +msg+:: The _Object_ the user passed to the log message; not necessarily a String.
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#
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# The block should return an Object that can be written to the logging device via +write+. The
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# default formatter is used when no formatter is set.
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attr_accessor :formatter
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alias sev_threshold level
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| ... | ... | |
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#
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# * Logfile is not locked.
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# * Append open does not need to lock file.
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# * But on the OS which supports multi I/O, records possibly be mixed.
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# * If the OS which supports multi I/O, records possibly be mixed.
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#
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def add(severity, message = nil, progname = nil, &block)
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severity ||= UNKNOWN
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| ... | ... | |
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end
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#
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# :call-seq:
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# info(message)
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# info(progname,&block)
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#
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# Log an +INFO+ message.
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#
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# The message can come either from the +progname+ argument or the +block+. If
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# both are provided, then the +block+ is used as the message, and +progname+
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# is used as the program name.
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# +message+:: the message to log; does not need to be a String
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# +progname+:: in the block form, this is the #progname to use in the
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# the log message. The default can be set with #progname=
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# <tt>&block</tt>:: evaluates to the message to log. This is not evaluated
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# unless the logger's level is sufficient
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# to log the message. This allows you to create
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# potentially expensive logging messages that are
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# only called when the logger is configured to show them.
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#
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# === Examples
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#
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| ... | ... | |
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# logger.info { "User typed #{input}" }
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#
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# You'll probably stick to the second form above, unless you want to provide a
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# program name (which you can do with <tt>Logger#progname=</tt> as well).
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# program name (which you can do with #progname= as well).
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#
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# === Return
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#
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| ... | ... | |
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end
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#
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# Log an +UNKNOWN+ message. This will be printed no matter what the logger
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# Log an +UNKNOWN+ message. This will be printed no matter what the logger's
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# level.
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#
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# See #info for more information.
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| ... | ... | |
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end
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# Default formatter for log messages
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class Formatter
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Format = "%s, [%s#%d] %5s -- %s: %s\n"
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| ... | ... | |
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end
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# Device used for logging messages.
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class LogDevice
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attr_reader :dev
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attr_reader :filename
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