# frozen_string_literal: true
# logger.rb - simple logging utility
# Copyright (C) 2000-2003, 2005, 2008, 2011 NAKAMURA, Hiroshi <nahi@ruby-lang.org>.
#
# Documentation:: NAKAMURA, Hiroshi and Gavin Sinclair
# License::
# You can redistribute it and/or modify it under the same terms of Ruby's
# license; either the dual license version in 2003, or any later version.
# Revision:: $Id$
#
# A simple system for logging messages. See Logger for more documentation.
require 'monitor'
require_relative 'logger/version'
require_relative 'logger/formatter'
require_relative 'logger/log_device'
require_relative 'logger/severity'
require_relative 'logger/errors'
# == Description
#
# The Logger class provides a simple but sophisticated logging utility that
# you can use to output messages.
#
# 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 or higher will be printed.
#
# The levels are:
#
# +UNKNOWN+:: An unknown message that should always be logged.
# +FATAL+:: An unhandleable error that results in a program crash.
# +ERROR+:: A handleable error condition.
# +WARN+:: A warning.
# +INFO+:: Generic (useful) information about system operation.
# +DEBUG+:: Low-level information for developers.
#
# 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.
# 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 #formatter= for escaping all data.
#
# original_formatter = Logger::Formatter.new
# logger.formatter = proc { |severity, datetime, progname, msg|
# original_formatter.call(severity, datetime, progname, msg.dump)
# }
# logger.info(input)
#
# === Example
#
# This creates a Logger that outputs to the standard output stream, with a
# level of +WARN+:
#
# require 'logger'
#
# logger = Logger.new(STDOUT)
# logger.level = Logger::WARN
#
# logger.debug("Created logger")
# logger.info("Program started")
# logger.warn("Nothing to do!")
#
# path = "a_non_existent_file"
#
# begin
# File.foreach(path) do |line|
# unless line =~ /^(\w+) = (.*)$/
# logger.error("Line in wrong format: #{line.chomp}")
# end
# end
# rescue => err
# logger.fatal("Caught exception; exiting")
# logger.fatal(err)
# end
#
# Because the Logger's level is set to +WARN+, only the warning, error, and
# fatal messages are recorded. The debug and info messages are silently
# discarded.
#
# === Features
#
# There are several interesting features that Logger provides, like
# auto-rolling of log files, setting the format of log messages, and
# specifying a program name in conjunction with the message. The next section
# shows you how to achieve these things.
#
#
# == HOWTOs
#
# === How to create a logger
#
# The options below give you various choices, in more or less increasing
# complexity.
#
# 1. Create a logger which logs messages to STDERR/STDOUT.
#
# logger = Logger.new(STDERR)
# logger = Logger.new(STDOUT)
#
# 2. Create a logger for the file which has the specified name.
#
# logger = Logger.new('logfile.log')
#
# 3. Create a logger for the specified file.
#
# file = File.open('foo.log', File::WRONLY | File::APPEND)
# # To create new logfile, add File::CREAT like:
# # file = File.open('foo.log', File::WRONLY | File::APPEND | File::CREAT)
# logger = Logger.new(file)
#
# 4. Create a logger which ages the logfile once it reaches a certain size.
# Leave 10 "old" log files where each file is about 1,024,000 bytes.
#
# logger = Logger.new('foo.log', 10, 1024000)
#
# 5. Create a logger which ages the logfile daily/weekly/monthly.
#
# logger = Logger.new('foo.log', 'daily')
# logger = Logger.new('foo.log', 'weekly')
# logger = Logger.new('foo.log', 'monthly')
#
# === 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
# +debug+. +add+ is used below to log a message of an arbitrary (perhaps
# dynamic) level.
#
# 1. Message in a block.
#
# logger.fatal { "Argument 'foo' not given." }
#
# 2. Message as a string.
#
# logger.error "Argument #{@foo} mismatch."
#
# 3. With progname.
#
# logger.info('initialize') { "Initializing..." }
#
# 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
#
# logger.close
#
# === Setting severity threshold
#
# 1. Original interface.
#
# logger.sev_threshold = Logger::WARN
#
# 2. Log4r (somewhat) compatible interface.
#
# logger.level = Logger::INFO
#
# # DEBUG < INFO < WARN < ERROR < FATAL < UNKNOWN
#
# 3. Symbol or String (case insensitive)
#
# logger.level = :info
# logger.level = 'INFO'
#
# # :debug < :info < :warn < :error < :fatal < :unknown
#
# 4. Constructor
#
# Logger.new(logdev, level: Logger::INFO)
# Logger.new(logdev, level: :info)
# Logger.new(logdev, level: 'INFO')
#
# == Format
#
# Log messages are rendered in the output stream in a certain format by
# default. The default format and a sample are shown below:
#
# Log format:
# SeverityID, [DateTime #pid] SeverityLabel -- ProgName: message
#
# Log sample:
# I, [1999-03-03T02:34:24.895701 #19074] INFO -- Main: info.
#
# 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"
#
# or via the constructor.
#
# Logger.new(logdev, datetime_format: '%Y-%m-%d %H:%M:%S')
#
# Or, you may change the overall format via the #formatter= method.
#
# logger.formatter = proc do |severity, datetime, progname, msg|
# "#{datetime}: #{msg}\n"
# end
# # e.g. "2005-09-22 08:51:08 +0900: hello world"
#
# or via the constructor.
#
# Logger.new(logdev, formatter: proc {|severity, datetime, progname, msg|
# "#{datetime}: #{msg}\n"
# })
#
class Logger
_, name, rev = %w$Id$
if name
name = name.chomp(",v")
else
name = File.basename(__FILE__)
end
rev ||= "v#{VERSION}"
ProgName = "#{name}/#{rev}"
include Severity
# Logging severity threshold (e.g. <tt>Logger::INFO</tt>).
attr_reader :level
# Set logging severity threshold.
#
# +severity+:: The Severity of the log message.
def level=(severity)
if severity.is_a?(Integer)
@level = severity
else
case severity.to_s.downcase
when 'debug'
@level = DEBUG
when 'info'
@level = INFO
when 'warn'
@level = WARN
when 'error'
@level = ERROR
when 'fatal'
@level = FATAL
when 'unknown'
@level = UNKNOWN
else
raise ArgumentError, "invalid log level: #{severity}"
end
end
end
# Program name to include in log messages.
attr_accessor :progname
# 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 being used. See #datetime_format=
def datetime_format
@default_formatter.datetime_format
end
# 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
alias sev_threshold= level=
# Returns +true+ iff the current severity level allows for the printing of
# +DEBUG+ messages.
def debug?; @level <= DEBUG; end
# Sets the severity to DEBUG.
def debug!; self.level = DEBUG; end
# Returns +true+ iff the current severity level allows for the printing of
# +INFO+ messages.
def info?; @level <= INFO; end
# Sets the severity to INFO.
def info!; self.level = INFO; end
# Returns +true+ iff the current severity level allows for the printing of
# +WARN+ messages.
def warn?; @level <= WARN; end
# Sets the severity to WARN.
def warn!; self.level = WARN; end
# Returns +true+ iff the current severity level allows for the printing of
# +ERROR+ messages.
def error?; @level <= ERROR; end
# Sets the severity to ERROR.
def error!; self.level = ERROR; end
# Returns +true+ iff the current severity level allows for the printing of
# +FATAL+ messages.
def fatal?; @level <= FATAL; end
# Sets the severity to FATAL.
def fatal!; self.level = FATAL; end
#
# :call-seq:
# Logger.new(logdev, shift_age = 0, shift_size = 1048576)
# Logger.new(logdev, shift_age = 'weekly')
# Logger.new(logdev, level: :info)
# Logger.new(logdev, progname: 'progname')
# Logger.new(logdev, formatter: formatter)
# Logger.new(logdev, datetime_format: '%Y-%m-%d %H:%M:%S')
#
# === Args
#
# +logdev+::
# The log device. This is a filename (String) or IO object (typically
# +STDOUT+, +STDERR+, or an open file).
# +shift_age+::
# Number of old log files to keep, *or* frequency of rotation (+daily+,
# +weekly+ or +monthly+). Default value is 0.
# +shift_size+::
# Maximum logfile size in bytes (only applies when +shift_age+ is a number).
# Defaults to +1048576+ (1MB).
# +level+::
# Logging severity threshold. Default values is Logger::DEBUG.
# +progname+::
# Program name to include in log messages. Default value is nil.
# +formatter+::
# Logging formatter. Default values is an instance of Logger::Formatter.
# +datetime_format+::
# Date and time format. Default value is '%Y-%m-%d %H:%M:%S'.
# +binmode+::
# Use binary mode on the log device. Default value is false.
# +shift_period_suffix+::
# The log file suffix format for +daily+, +weekly+ or +monthly+ rotation.
# Default is '%Y%m%d'.
#
# === Description
#
# Create an instance.
#
def initialize(logdev, shift_age = 0, shift_size = 1048576, level: DEBUG,
progname: nil, formatter: nil, datetime_format: nil,
binmode: false, shift_period_suffix: '%Y%m%d')
self.level = level
self.progname = progname
@default_formatter = Formatter.new
self.datetime_format = datetime_format
self.formatter = formatter
@logdev = nil
if logdev
@logdev = LogDevice.new(logdev, shift_age: shift_age,
shift_size: shift_size,
shift_period_suffix: shift_period_suffix,
binmode: binmode)
end
end
#
# :call-seq:
# Logger#reopen
# Logger#reopen(logdev)
#
# === Args
#
# +logdev+::
# The log device. This is a filename (String) or IO object (typically
# +STDOUT+, +STDERR+, or an open file). reopen the same filename if
# it is +nil+, do nothing for IO. Default is +nil+.
#
# === Description
#
# Reopen a log device.
#
def reopen(logdev = nil)
@logdev.reopen(logdev)
self
end
#
# :call-seq:
# Logger#add(severity, message = nil, progname = nil) { ... }
#
# === Args
#
# +severity+::
# Severity. Constants are defined in Logger namespace: +DEBUG+, +INFO+,
# +WARN+, +ERROR+, +FATAL+, or +UNKNOWN+.
# +message+::
# The log message. A String or Exception.
# +progname+::
# Program name string. Can be omitted. Treated as a message if no
# +message+ and +block+ are given.
# +block+::
# Can be omitted. Called to get a message string if +message+ is nil.
#
# === Return
#
# When the given severity is not high enough (for this particular logger),
# log no message, and return +true+.
#
# === Description
#
# Log a message if the given severity is high enough. This is the generic
# logging method. Users will be more inclined to use #debug, #info, #warn,
# #error, and #fatal.
#
# <b>Message format</b>: +message+ can be any object, but it has to be
# converted to a String in order to log it. Generally, +inspect+ is used
# if the given object is not a String.
# A special case is an +Exception+ object, which will be printed in detail,
# including message, class, and backtrace. See #msg2str for the
# implementation if required.
#
# === Bugs
#
# * Logfile is not locked.
# * Append open does not need to lock file.
# * If the OS supports multi I/O, records possibly may be mixed.
#
def add(severity, message = nil, progname = nil)
severity ||= UNKNOWN
if @logdev.nil? or severity < @level
return true
end
if progname.nil?
progname = @progname
end
if message.nil?
if block_given?
message = yield
else
message = progname
progname = @progname
end
end
@logdev.write(
format_message(format_severity(severity), Time.now, progname, message))
true
end
alias log add
#
# Dump given message to the log device without any formatting. If no log
# device exists, return +nil+.
#
def <<(msg)
@logdev&.write(msg)
end
#
# Log a +DEBUG+ message.
#
# See #info for more information.
#
def debug(progname = nil, &block)
add(DEBUG, nil, progname, &block)
end
#
# :call-seq:
# info(message)
# info(progname, &block)
#
# Log an +INFO+ message.
#
# +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
# log message. The default can be set with #progname=.
# +block+:: 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("MainApp") { "Received connection from #{ip}" }
# # ...
# logger.info "Waiting for input from user"
# # ...
# 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 #progname= as well).
#
# === Return
#
# See #add.
#
def info(progname = nil, &block)
add(INFO, nil, progname, &block)
end
#
# Log a +WARN+ message.
#
# See #info for more information.
#
def warn(progname = nil, &block)
add(WARN, nil, progname, &block)
end
#
# Log an +ERROR+ message.
#
# See #info for more information.
#
def error(progname = nil, &block)
add(ERROR, nil, progname, &block)
end
#
# Log a +FATAL+ message.
#
# See #info for more information.
#
def fatal(progname = nil, &block)
add(FATAL, nil, progname, &block)
end
#
# Log an +UNKNOWN+ message. This will be printed no matter what the logger's
# level is.
#
# See #info for more information.
#
def unknown(progname = nil, &block)
add(UNKNOWN, nil, progname, &block)
end
#
# Close the logging device.
#
def close
@logdev&.close
end
private
# Severity label for logging (max 5 chars).
SEV_LABEL = %w(DEBUG INFO WARN ERROR FATAL ANY).freeze
def format_severity(severity)
SEV_LABEL[severity] || 'ANY'
end
def format_message(severity, datetime, progname, msg)
(@formatter || @default_formatter).call(severity, datetime, progname, msg)
end
end