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# 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: logger.rb 41954 2013-07-13 15:16:09Z nagachika $
#
# 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
# 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 (and to remove old) 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
#
# == 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, 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"
#
class Logger
VERSION = "1.2.7"
_, name, rev = %w$Id: logger.rb 41954 2013-07-13 15:16:09Z nagachika $
if name
name = name.chomp(",v")
else
name = File.basename(__FILE__)
end
rev ||= "v#{VERSION}"
ProgName = "#{name}/#{rev}"
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
# 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
# Returns +true+ iff the current severity level allows for the printing of
# +INFO+ messages.
def info?; @level <= INFO; end
# Returns +true+ iff the current severity level allows for the printing of
# +WARN+ messages.
def warn?; @level <= WARN; end
# Returns +true+ iff the current severity level allows for the printing of
# +ERROR+ messages.
def error?; @level <= ERROR; end
# Returns +true+ iff the current severity level allows for the printing of
# +FATAL+ messages.
def fatal?; @level <= FATAL; end
#
# :call-seq:
# Logger.new(name, shift_age = 7, shift_size = 1048576)
# Logger.new(name, shift_age = 'weekly')
#
# === 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+).
# +shift_size+::
# Maximum logfile size (only applies when +shift_age+ is a number).
#
# === Description
#
# Create an instance.
#
def initialize(logdev, shift_age = 0, shift_size = 1048576)
@progname = nil
@level = DEBUG
@default_formatter = Formatter.new
@formatter = nil
@logdev = nil
if logdev
@logdev = LogDevice.new(logdev, :shift_age => shift_age,
:shift_size => shift_size)
end
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
#
# +true+ if successful, +false+ otherwise.
#
# 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, &block)
severity ||= UNKNOWN
if @logdev.nil? or severity < @level
return true
end
progname ||= @progname
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)
unless @logdev.nil?
@logdev.write(msg)
end
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 if @logdev
end
private
# Severity label for logging (max 5 chars).
SEV_LABEL = %w(DEBUG INFO WARN ERROR FATAL ANY)
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
# Default formatter for log messages.
class Formatter
Format = "%s, [%s#%d] %5s -- %s: %s\n"
attr_accessor :datetime_format
def initialize
@datetime_format = nil
end
def call(severity, time, progname, msg)
Format % [severity[0..0], format_datetime(time), $$, severity, progname,
msg2str(msg)]
end
private
def format_datetime(time)
if @datetime_format.nil?
time.strftime("%Y-%m-%dT%H:%M:%S.") << "%06d " % time.usec
else
time.strftime(@datetime_format)
end
end
def msg2str(msg)
case msg
when ::String
msg
when ::Exception
"#{ msg.message } (#{ msg.class })\n" <<
(msg.backtrace || []).join("\n")
else
msg.inspect
end
end
end
# Device used for logging messages.
class LogDevice
attr_reader :dev
attr_reader :filename
class LogDeviceMutex
include MonitorMixin
end
def initialize(log = nil, opt = {})
@dev = @filename = @shift_age = @shift_size = nil
@mutex = LogDeviceMutex.new
if log.respond_to?(:write) and log.respond_to?(:close)
@dev = log
else
@dev = open_logfile(log)
@dev.sync = true
@filename = log
@shift_age = opt[:shift_age] || 7
@shift_size = opt[:shift_size] || 1048576
end
end
def write(message)
begin
@mutex.synchronize do
if @shift_age and @dev.respond_to?(:stat)
begin
check_shift_log
rescue
warn("log shifting failed. #{$!}")
end
end
begin
@dev.write(message)
rescue
warn("log writing failed. #{$!}")
end
end
rescue Exception => ignored
warn("log writing failed. #{ignored}")
end
end
def close
begin
@mutex.synchronize do
@dev.close rescue nil
end
rescue Exception
@dev.close rescue nil
end
end
private
def open_logfile(filename)
if (FileTest.exist?(filename))
open(filename, (File::WRONLY | File::APPEND))
else
create_logfile(filename)
end
end
def create_logfile(filename)
logdev = open(filename, (File::WRONLY | File::APPEND | File::CREAT))
logdev.sync = true
add_log_header(logdev)
logdev
end
def add_log_header(file)
file.write(
"# Logfile created on %s by %s\n" % [Time.now.to_s, Logger::ProgName]
)
end
SiD = 24 * 60 * 60
def check_shift_log
if @shift_age.is_a?(Integer)
# Note: always returns false if '0'.
if @filename && (@shift_age > 0) && (@dev.stat.size > @shift_size)
shift_log_age
end
else
now = Time.now
period_end = previous_period_end(now)
if @dev.stat.mtime <= period_end
shift_log_period(period_end)
end
end
end
def shift_log_age
(@shift_age-3).downto(0) do |i|
if FileTest.exist?("#{@filename}.#{i}")
File.rename("#{@filename}.#{i}", "#{@filename}.#{i+1}")
end
end
@dev.close rescue nil
File.rename("#{@filename}", "#{@filename}.0")
@dev = create_logfile(@filename)
return true
end
def shift_log_period(period_end)
postfix = period_end.strftime("%Y%m%d") # YYYYMMDD
age_file = "#{@filename}.#{postfix}"
if FileTest.exist?(age_file)
# try to avoid filename crash caused by Timestamp change.
idx = 0
# .99 can be overridden; avoid too much file search with 'loop do'
while idx < 100
idx += 1
age_file = "#{@filename}.#{postfix}.#{idx}"
break unless FileTest.exist?(age_file)
end
end
@dev.close rescue nil
File.rename("#{@filename}", age_file)
@dev = create_logfile(@filename)
return true
end
def previous_period_end(now)
case @shift_age
when /^daily$/
eod(now - 1 * SiD)
when /^weekly$/
eod(now - ((now.wday + 1) * SiD))
when /^monthly$/
eod(now - now.mday * SiD)
else
now
end
end
def eod(t)
Time.mktime(t.year, t.month, t.mday, 23, 59, 59)
end
end
#
# == Description
#
# Application --- Add logging support to your application.
#
# == Usage
#
# 1. Define your application class as a sub-class of this class.
# 2. Override the +run+ method in your class to do many things.
# 3. Instantiate it and invoke #start.
#
# == Example
#
# class FooApp < Application
# def initialize(foo_app, application_specific, arguments)
# super('FooApp') # Name of the application.
# end
#
# def run
# ...
# log(WARN, 'warning', 'my_method1')
# ...
# @log.error('my_method2') { 'Error!' }
# ...
# end
# end
#
# status = FooApp.new(....).start
#
class Application
include Logger::Severity
# Name of the application given at initialize.
attr_reader :appname
#
# :call-seq:
# Application.new(appname = '')
#
# == Args
#
# +appname+:: Name of the application.
#
# == Description
#
# Create an instance. Log device is +STDERR+ by default. This can be
# changed with #set_log.
#
def initialize(appname = nil)
@appname = appname
@log = Logger.new(STDERR)
@log.progname = @appname
@level = @log.level
end
#
# Start the application. Return the status code.
#
def start
status = -1
begin
log(INFO, "Start of #{ @appname }.")
status = run
rescue
log(FATAL, "Detected an exception. Stopping ... #{$!} (#{$!.class})\n" << $@.join("\n"))
ensure
log(INFO, "End of #{ @appname }. (status: #{ status.to_s })")
end
status
end
# Logger for this application. See the class Logger for an explanation.
def logger
@log
end
#
# Sets the logger for this application. See the class Logger for an
# explanation.
#
def logger=(logger)
@log = logger
@log.progname = @appname
@log.level = @level
end
#
# Sets the log device for this application. See <tt>Logger.new</tt> for
# an explanation of the arguments.
#
def set_log(logdev, shift_age = 0, shift_size = 1024000)
@log = Logger.new(logdev, shift_age, shift_size)
@log.progname = @appname
@log.level = @level
end
def log=(logdev)
set_log(logdev)
end
#
# Set the logging threshold, just like <tt>Logger#level=</tt>.
#
def level=(level)
@level = level
@log.level = @level
end
#
# See Logger#add. This application's +appname+ is used.
#
def log(severity, message = nil, &block)
@log.add(severity, message, @appname, &block) if @log
end
private
def run
# TODO: should be an NotImplementedError
raise RuntimeError.new('Method run must be defined in the derived class.')
end
end
end