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Class: ActiveSupport::BroadcastLogger

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain:
self, LoggerThreadSafeLevel, LoggerSilence
Inherits: Object
Defined in: activesupport/lib/active_support/broadcast_logger.rb

Overview

The Broadcast logger is a logger used to write messages to multiple ::IO. It is commonly used in development to display messages on STDOUT and also write them to a file (development.log). With the Broadcast logger, you can broadcast your logs to a unlimited number of sinks.

The BroadcastLogger acts as a standard logger and all methods you are used to are available. However, all the methods on this logger will propagate and be delegated to the other loggers that are part of the broadcast.

Broadcasting your logs.

stdout_logger = Logger.new(STDOUT)
file_logger   = Logger.new("development.log")
broadcast = BroadcastLogger.new(stdout_logger, file_logger)

broadcast.info("Hello world!") # Writes the log to STDOUT and the development.log file.

Add a logger to the broadcast.

stdout_logger = Logger.new(STDOUT)
broadcast = BroadcastLogger.new(stdout_logger)
file_logger   = Logger.new("development.log")
broadcast.broadcast_to(file_logger)

broadcast.info("Hello world!") # Writes the log to STDOUT and the development.log file.

Modifying the log level for all broadcasted loggers.

stdout_logger = Logger.new(STDOUT)
file_logger   = Logger.new("development.log")
broadcast = BroadcastLogger.new(stdout_logger, file_logger)

broadcast.level = Logger::FATAL # Modify the log level for the whole broadcast.

Stop broadcasting log to a sink.

stdout_logger = Logger.new(STDOUT)
file_logger   = Logger.new("development.log")
broadcast = BroadcastLogger.new(stdout_logger, file_logger)
broadcast.info("Hello world!") # Writes the log to STDOUT and the development.log file.

broadcast.stop_broadcasting_to(file_logger)
broadcast.info("Hello world!") # Writes the log *only* to STDOUT.

At least one sink has to be part of the broadcast. Otherwise, your logs will not be written anywhere. For instance:

broadcast = BroadcastLogger.new
broadcast.info("Hello world") # The log message will appear nowhere.

If you are adding a custom logger with custom methods to the broadcast, the BroadcastLogger will proxy them and return the raw value, or an array of raw values, depending on how many loggers in the broadcasts responded to the method:

class MyLogger < ::Logger
  def loggable?
    true
  end
end

logger = BroadcastLogger.new
logger.loggable? # => A NoMethodError exception is raised because no loggers in the broadcasts could respond.

logger.broadcast_to(MyLogger.new(STDOUT))
logger.loggable? # => true
logger.broadcast_to(MyLogger.new(STDOUT))
puts logger.broadcasts # => [MyLogger, MyLogger]
logger.loggable? # [true, true]

Constant Summary

LoggerSilence - Attributes & Methods

Class Method Summary

Instance Attribute Summary

  • #broadcasts readonly

    Returns all the logger that are part of this broadcast.

  • #debug? ⇒ Boolean readonly

    True if the log level allows entries with severity Logger::DEBUG to be written to at least one broadcast.

  • #error? ⇒ Boolean readonly

    True if the log level allows entries with severity Logger::ERROR to be written to at least one broadcast.

  • #fatal? ⇒ Boolean readonly

    True if the log level allows entries with severity Logger::FATAL to be written to at least one broadcast.

  • #info? ⇒ Boolean readonly

    True if the log level allows entries with severity Logger::INFO to be written to at least one broadcast.

  • #local_level rw
  • #local_level=(level) rw
  • #progname rw
  • #warn? ⇒ Boolean readonly

    True if the log level allows entries with severity Logger::WARN to be written to at least one broadcast.

LoggerThreadSafeLevel - self

#local_level, #local_level=, #local_level_key

Instance Method Summary

LoggerThreadSafeLevel - self

#initialize, #level,
#log_at

Change the thread-local level for the duration of the given block.

LoggerSilence - Included

#silence

Silences the logger for the duration of the block.

Constructor Details

.new(*loggers) ⇒ BroadcastLogger

[ GitHub ] 

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 81



def initialize(*loggers)
  @broadcasts = []
  @progname = "Broadcast"

  broadcast_to(*loggers)
end


  







Dynamic Method Handling

  

    This class handles dynamic methods through the method_missing method




  

    #method_missing(name)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 222



def method_missing(name, ...)
  loggers = @broadcasts.select { |logger| logger.respond_to?(name) }

  if loggers.none?
    super
  elsif loggers.one?
    loggers.first.send(name, ...)
  else
    loggers.map { |logger| logger.send(name, ...) }
  end
end


  







Class Attribute Details



  

    .silencer   (rw)
    Also known as: #silencer
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/logger_silence.rb', line 12



cattr_accessor :silencer, default: true


  







Instance Attribute Details



  

    #broadcasts   (readonly)
  



  

    

Returns all the logger that are part of this broadcast.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 78



attr_reader :broadcasts


  








  

    #debug?  ⇒ Boolean  (readonly)
  



  

    

True if the log level allows entries with severity Logger::DEBUG to be written to at least one broadcast. False otherwise.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 141



def debug?
  @broadcasts.any? { |logger| logger.debug? }
end


  








  

    #error?  ⇒ Boolean  (readonly)
  



  

    

True if the log level allows entries with severity Logger::ERROR to be written to at least one broadcast. False otherwise.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 174



def error?
  @broadcasts.any? { |logger| logger.error? }
end


  








  

    #fatal?  ⇒ Boolean  (readonly)
  



  

    

True if the log level allows entries with severity Logger::FATAL to be written to at least one broadcast. False otherwise.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 185



def fatal?
  @broadcasts.any? { |logger| logger.fatal? }
end


  








  

    #info?  ⇒ Boolean  (readonly)
  



  

    

True if the log level allows entries with severity Logger::INFO to be written to at least one broadcast. False otherwise.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 152



def info?
  @broadcasts.any? { |logger| logger.info? }
end


  








  

    #local_level   (rw)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 113



def local_level
  loggers = @broadcasts.select { |logger| logger.respond_to?(:local_level) }

  loggers.map do |logger|
    logger.local_level
  end.first
end


  








  

    #local_level=(level)   (rw)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 107



def local_level=(level)
  @broadcasts.each do |logger|
    logger.local_level = level if logger.respond_to?(:local_level=)
  end
end


  








  

    #progname   (rw)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 79



attr_accessor :progname


  








  

    #silencer   (rw)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/logger_silence.rb', line 12



cattr_accessor :silencer, default: true


  








  

    #warn?  ⇒ Boolean  (readonly)
  



  

    

True if the log level allows entries with severity Logger::WARN to be written to at least one broadcast. False otherwise.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 163



def warn?
  @broadcasts.any? { |logger| logger.warn? }
end


  







Instance Method Details



  

    #broadcast_to(*loggers)  
  



  

    

Add logger(s) to the broadcast.



broadcast_logger = ActiveSupport::BroadcastLogger.new
broadcast_logger.broadcast_to(Logger.new(STDOUT), Logger.new(STDERR))


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 92



def broadcast_to(*loggers)
  @broadcasts.concat(loggers)
end


  








  

    #debug!  
  



  

    

Sets the log level to Logger::DEBUG for the whole broadcast.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 146



def debug!
  dispatch(:debug!)
end


  








  

    #dispatch(method, *args, **kwargs, &block)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 202



def dispatch(method, *args, **kwargs, &block)
  if block_given?
    # Maintain semantics that the first logger yields the block
    # as normal, but subsequent loggers won't re-execute the block.
    # Instead, the initial result is immediately returned.
    called, result = false, nil
    block = proc { |*args, **kwargs|
      if called then result
      else
        called = true
        result = yield(*args, **kwargs)
      end
    }
  end

  @broadcasts.map { |logger|
    logger.send(method, *args, **kwargs, &block)
  }.first
end


  








  

    #error!  
  



  

    

Sets the log level to Logger::ERROR for the whole broadcast.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 179



def error!
  dispatch(:error!)
end


  








  

    #fatal!  
  



  

    

Sets the log level to Logger::FATAL for the whole broadcast.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 190



def fatal!
  dispatch(:fatal!)
end


  








  

    #info!  
  



  

    

Sets the log level to Logger::INFO for the whole broadcast.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 157



def info!
  dispatch(:info!)
end


  








  

    #initialize_copy(other)  
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 194



def initialize_copy(other)
  @broadcasts = []
  @progname = other.progname.dup

  broadcast_to(*other.broadcasts.map(&:dup))
end


  








  

    #level  
  



  

    

Returns the lowest level of all the loggers in the broadcast.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 135



def level
  @broadcasts.map(&:level).min
end


  








  

    #respond_to_missing?(method, include_all)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 234



def respond_to_missing?(method, include_all)
  @broadcasts.any? { |logger| logger.respond_to?(method, include_all) }
end


  








  

    #stop_broadcasting_to(logger)  
  



  

    

Remove a logger from the broadcast. When a logger is removed, messages sent to the broadcast will no longer be written to its sink.



sink = Logger.new(STDOUT)
broadcast_logger = ActiveSupport::BroadcastLogger.new

broadcast_logger.stop_broadcasting_to(sink)


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 103



def stop_broadcasting_to(logger)
  @broadcasts.delete(logger)
end


  








  

    #warn!  
  



  

    

Sets the log level to Logger::WARN for the whole broadcast.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/broadcast_logger.rb', line 168



def warn!
  dispatch(:warn!)
end