Class: RightScale::Log

Inherits:
Object show all
Includes:
Singleton
Defined in:
lib/right_agent/log.rb

Overview

Logs both to syslog and to local file

Defined Under Namespace

Classes: Formatter

Constant Summary collapse

LEVELS_MAP =

Map of log levels symbols associated with corresponding Logger constant

{:debug => Logger::DEBUG,
:info  => Logger::INFO,
:warn  => Logger::WARN,
:error => Logger::ERROR,
:fatal => Logger::FATAL}
@@inverted_levels_map = 
nil

Instance Method Summary collapse

Methods included from Singleton

included

Constructor Details

#initialize ⇒ Log

Returns a new instance of Log.



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# File 'lib/right_agent/log.rb', line 113

def initialize
  # Was log ever used?
  @initialized = false
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(m, *args) ⇒ Object

Forward all method calls to underlying Logger object created with init Return the result of only the first registered logger to keep the interface consistent with that of a Logger

Parameters

m(Symbol)

Forwarded method name

args(Array)

Forwarded method arguments

Return

(Object)

Result from first registered logger



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# File 'lib/right_agent/log.rb', line 128

def method_missing(m, *args)
  init unless @initialized
  @logger.level = level_from_sym(level) if @level_frozen
  @logger.__send__(m, *args)
end

Instance Method Details

#add_logger(logger) ⇒ Object

Add new logger to list of multiplexed loggers

Parameters

logger(Object)

Logger that should get log messages

Return

@logger(RightScale::Multiplexer)

Multiplexer logger



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# File 'lib/right_agent/log.rb', line 255

def add_logger(logger)
  init unless @initialized
  logger.level = level_from_sym(Log.instance.level)
  @logger.add(logger)
end

#error(description, exception = nil, backtrace = :caller) ⇒ Object

Log error and optionally append exception information

Parameters

description(String)

Error description

exception(Exception|String)

Associated exception or other parenthetical error information

backtrace(Symbol)

Exception backtrace extent: :no_trace, :caller, or :trace,

defaults to :caller

Return

(Object)

Result from first registered logger



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# File 'lib/right_agent/log.rb', line 176

def error(description, exception = nil, backtrace = :caller)
  init unless @initialized
  @logger.error(format(description, exception, backtrace))
end

#facility=(facility) ⇒ Object

Sets the syslog facility that will be used when emitting syslog messages. Can only be successfully called before logging is initialized

Parameters

facility(String)

A syslog facility name, e.g. ‘user’ or ‘local0’

Return

program_name(String)

The input string

Raise

RuntimeError

If logger is already initialized



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# File 'lib/right_agent/log.rb', line 325

def facility=(facility)
  raise 'Logger already initialized' if @initialized
  @facility = facility
end

#force_debug ⇒ Object

Force log level to debug and disregard any further attempt to change it

Return

true

Always return true



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# File 'lib/right_agent/log.rb', line 388

def force_debug
  self.level = :debug
  @level_frozen = true
end

#force_logger(logger) ⇒ Object

Force use of given logger and override all defaults

Parameters

logger(Logger)

Logger compatible object

Return

true

Always return true



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# File 'lib/right_agent/log.rb', line 400

def force_logger(logger)
  @initialized = true
  @logger = logger
end

#format(description, exception = nil, backtrace = :caller) ⇒ Object

Format error information

Parameters

description(String)

Error description

exception(Exception|String)

Associated exception or other parenthetical error information

backtrace(Symbol)

Exception backtrace extent: :no_trace, :caller, or :trace,

defaults to :caller

Return

(Object)

Result from first registered logger



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# File 'lib/right_agent/log.rb', line 191

def format(description, exception = nil, backtrace = :caller)
  if exception
    if exception.respond_to?(:message)
      description += " (#{exception.class}: #{exception.message}"
    else
      description += " (#{exception}"
      backtrace = :no_trace
    end
    case backtrace
    when :no_trace then description += ")"
    when :caller   then description += " in " + exception.backtrace[0] + ")"
    when :trace    then description += " in\n  " + exception.backtrace.join("\n  ") + ")"
    end
  end
  description
end

#initialized ⇒ Object

Was logger initialized?

Return

true

if logger has been initialized

false

Otherwise



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# File 'lib/right_agent/log.rb', line 292

def initialized
  @initialized
end

#level ⇒ Object

Current log level

Return

level(Symbol)

One of :debug, :info, :warn, :error or :fatal



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# File 'lib/right_agent/log.rb', line 364

def level
  init unless @initialized
  level = level_to_sym(@level)
end

#level=(level) ⇒ Object

Sets the level for the Logger by symbol or by Logger constant

Parameters

level(Object)

One of :debug, :info, :warn, :error, :fatal or one of “debug”, “info”, “warn”, “error”, “fatal” or one of Logger::INFO … Logger::FATAL

Return

level(Symbol)

New log level, or current level if frozen



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# File 'lib/right_agent/log.rb', line 339

def level=(level)
  init unless @initialized
  unless @level_frozen
    new_level = case level
    when Symbol then
      level_from_sym(level)
    when String then
      level_from_sym(level.to_sym)
    else
      level
    end
    if new_level != @level
      @logger.info("[setup] Setting log level to #{level_to_sym(new_level).to_s.upcase}")
      @logger.level = @level = new_level
    end
    # Notify even if unchanged since don't know when callback was set
    @notify.each { |n| n.call(@level) } if @notify
  end
  level = level_to_sym(@level)
end

#level_from_sym(sym) ⇒ Object

Map symbol log level to Logger constant

Parameters

sym(Symbol)

Log level symbol, one of :debug, :info, :warn, :error or :fatal

Return

lvl(Constant)

One of Logger::DEBUG … Logger::FATAL

Raise

(RightScale::Exceptions::Argument)

if level symbol is invalid

Raises:



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# File 'lib/right_agent/log.rb', line 218

def level_from_sym(sym)
  raise Exceptions::Argument, "Invalid log level symbol :#{sym}" unless LEVELS_MAP.include?(sym)
  lvl = LEVELS_MAP[sym]
end

#level_to_sym(lvl) ⇒ Object

Map Logger log level constant to symbol

Parameters

lvl(Constant)

Log level constant, one of Logger::DEBUG … Logger::FATAL

Return

sym(Symbol)

One of :debug, :info, :warn, :error or :fatal

Raise

(RightScale::Exceptions::Argument)

if level is invalid

Raises:



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# File 'lib/right_agent/log.rb', line 233

def level_to_sym(lvl)
  @@inverted_levels_map ||= LEVELS_MAP.invert
  raise Exceptions::Argument, "Invalid log level: #{lvl}" unless @@inverted_levels_map.include?(lvl)
  sym = @@inverted_levels_map[lvl]
end

#log_to_file_only(val) ⇒ Object

Set whether syslog should be used or to log to an agent-specific file This should be called before anything else

Parameters

val(Boolean)

Whether syslog should be used (false) or a agent-specific log file (true)

Raise

RuntimeError

If logger is already initialized



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# File 'lib/right_agent/log.rb', line 282

def log_to_file_only(val)
  raise 'Logger already initialized' if @initialized
  @log_to_file_only = !!val
end

#logger ⇒ Object

Read access to internal multiplexer

Return

logger(RightScale::Multiplexer)

Multiplexer logger



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# File 'lib/right_agent/log.rb', line 243

def logger
  init unless @initialized
  logger = @logger
end

#notify(callback) ⇒ Object

Register callback to be activated when there is a logging configuration change Currently the only logging change reported is log level

Parameters

callback(Proc)

Block to be activated with following parameter when log level changes:

log_level(Symbol)

Current log level

Return

true

Always return true



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# File 'lib/right_agent/log.rb', line 378

def notify(callback)
  @notify = (@notify ||= []) << callback
  true
end

#program_name=(prog_name) ⇒ Object

Sets the syslog program name that will be reported Can only be successfully called before logging is initialized

Parameters

prog_name(String)

An arbitrary string, or “nil” to use

the default name that is based on the agent's identity

Return

program_name(String)

The input string

Raise

RuntimeError

If logger is already initialized



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# File 'lib/right_agent/log.rb', line 309

def program_name=(prog_name)
  raise 'Logger already initialized' if @initialized
  @program_name = prog_name
end

#remove_logger(logger) ⇒ Object

Remove logger from list of multiplexed loggers

Parameters

logger(Object)

Logger to be removed

Return

@logger(RightScale::Multiplexer)

Multiplexer logger



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# File 'lib/right_agent/log.rb', line 268

def remove_logger(logger)
  init unless @initialized
  @logger.remove(logger)
end

#respond_to?(m) ⇒ Boolean

Determine whether this object, or its method_missing proxy, responds to the given method name. This follows the best practice of always overriding #respond_to? whenever one implements dynamic dispatch via #method_missing.

Parameters

m(Symbol)

Forwarded method name

Return

(true|false)

True if this object or its proxy responds to the names method, false otherwise

Returns:

  • (Boolean) 


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# File 'lib/right_agent/log.rb', line 144

def respond_to?(m)
  init unless @initialized
  super(m) || @logger.respond_to?(m)
end

#warning(description, exception = nil, backtrace = :caller) ⇒ Object Also known as: warn

Log warning and optionally append exception information

Parameters

description(String)

Error description

exception(Exception|String)

Associated exception or other parenthetical error information

backtrace(Symbol)

Exception backtrace extent: :no_trace, :caller, or :trace,

defaults to :caller

Return

(Object)

Result from first registered logger



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# File 'lib/right_agent/log.rb', line 159

def warning(description, exception = nil, backtrace = :caller)
  init unless @initialized
  @logger.warn(format(description, exception, backtrace))
end