Class: ActiveSupport::BroadcastLogger

Inherits:
Object
  • Object
show all
Includes:
LoggerSilence
Defined in:
activesupport/lib/active_support/broadcast_logger.rb

Overview

Active Support Broadcast Logger

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 collapse

LOGGER_METHODS = 
%w[
  << log add debug info warn error fatal unknown
  level= sev_threshold= close
  formatter formatter=
]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from LoggerSilence

#silence

Methods included from Concern

#append_features, #class_methods, extended, #included, #prepend_features, #prepended

Constructor Details

#initialize(*loggers) ⇒ BroadcastLogger

Returns a new instance of BroadcastLogger.



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# 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) ⇒ Object (private) 



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# 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

Instance Attribute Details

#broadcasts ⇒ Object (readonly)

Returns all the logger that are part of this broadcast.



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

def broadcasts
  @broadcasts
end

#progname ⇒ Object

Returns the value of attribute progname.



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

def progname
  @progname
end

Instance Method Details

#broadcast_to(*loggers) ⇒ Object

Add logger(s) to the broadcast.

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



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

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

#debug! ⇒ Object

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



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

def debug!
  dispatch(:debug!)
end

#debug? ⇒ Boolean

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

Returns:

  • (Boolean) 


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

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

#error! ⇒ Object

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



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

def error!
  dispatch(:error!)
end

#error? ⇒ Boolean

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

Returns:

  • (Boolean) 


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

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

#fatal! ⇒ Object

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



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

def fatal!
  dispatch(:fatal!)
end

#fatal? ⇒ Boolean

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

Returns:

  • (Boolean) 


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

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

#info! ⇒ Object

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



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

def info!
  dispatch(:info!)
end

#info? ⇒ Boolean

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

Returns:

  • (Boolean) 


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

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

#initialize_copy(other) ⇒ Object 



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# 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 ⇒ Object

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



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

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

#local_level ⇒ Object 



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# 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) ⇒ Object 



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# 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

#stop_broadcasting_to(logger) ⇒ Object

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)



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

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

#warn! ⇒ Object

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



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

def warn!
  dispatch(:warn!)
end

#warn? ⇒ Boolean

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

Returns:

  • (Boolean) 


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

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