Class: Blessing::Leader

Inherits:
Object
  • Object
show all
Defined in:
lib/blessing/leader.rb

Overview

Blessing::Leader is the main class and entry point

Constant Summary collapse

DefaultOptions = 
{
  # Run as daemon
  :daemonize => false,
  # Monitoring refresh cycle legth in seconds
  :refresh => 10,
  :verbose => false,
  :log => STDOUT,
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(patterns, opts = {}) ⇒ Leader

Initialize new Blessing::Leader with file list pattern



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# File 'lib/blessing/leader.rb', line 21

def initialize patterns, opts = {}
  @options = DefaultOptions.merge(opts)
  @mutex = Monitor.new

  initialize_logger

  logger.info "Starting Blessing::Leader"
  @patterns = patterns.is_a?(Array) ? patterns : [patterns]
  logger.debug "Patterns: #{patterns.inspect}"

  @old_confdig_files = @config_files = []
  @runners = {}

  # Trap some signals
  trap("INT"){
    logger.info "Caught SIGINT"
    at_exit
  }
  trap("TERM"){
    logger.info "Caught SIGTERM"
    at_exit
  }
  trap("USR1"){
    # Rerun cycle
    run_cycle
  }
  trap("USR2"){
    # resurrect dead Unicorns!
    run_cycle(true)
  }
end

Instance Attribute Details

#config_files ⇒ Object

Returns the value of attribute config_files.



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# File 'lib/blessing/leader.rb', line 18

def config_files
  @config_files
end

#logger ⇒ Object

Returns the value of attribute logger.



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# File 'lib/blessing/leader.rb', line 18

def logger
  @logger
end

#old_config_files ⇒ Object

Returns the value of attribute old_config_files.



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# File 'lib/blessing/leader.rb', line 18

def old_config_files
  @old_config_files
end

#patterns ⇒ Object

Returns the value of attribute patterns.



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# File 'lib/blessing/leader.rb', line 18

def patterns
  @patterns
end

#runners ⇒ Object

Returns the value of attribute runners.



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# File 'lib/blessing/leader.rb', line 18

def runners
  @runners
end

Instance Method Details

#at_exit ⇒ Object

Daemons hook to shut down properly



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# File 'lib/blessing/leader.rb', line 59

def at_exit
  logger.info "Shutting down"
  stop
end

#initialize_logger ⇒ Object 



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# File 'lib/blessing/leader.rb', line 53

def initialize_logger
  @logger = Logger.new @options[:log]
  @logger.level = @options[:verbose] ? Logger::DEBUG : Logger::INFO
end

#refresh_file_list ⇒ Object

Refresh config file list and preserve old list



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# File 'lib/blessing/leader.rb', line 105

def refresh_file_list
  logger.debug "Refreshing file list"
  # Preserve old file list
  @old_config_files = @config_files

  files = []
  @patterns.each{|p| files += Dir.glob(p)}
  @config_files = files.uniq.sort
  logger.debug "Found files: #{@config_files.inspect}"
end

#reload_runners(resurrect = false) ⇒ Object

Let each runner check itself if reload is needed



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# File 'lib/blessing/leader.rb', line 145

def reload_runners(resurrect=false)
  @runners.each_value do |runner|
    runner.check_reload(resurrect)
  end
end

#run_cycle(resurrect = false) ⇒ Object

Main cycle

  • refresh file list

  • start/stop runners

  • verify/reload runners



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# File 'lib/blessing/leader.rb', line 95

def run_cycle(resurrect=false)
  @mutex.synchronize do
    logger.debug "Next cycle"
    refresh_file_list
    start_stop_runners
    reload_runners(resurrect)
  end
end

#start ⇒ Object

Start running cycles



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# File 'lib/blessing/leader.rb', line 65

def start
  logger.info "Starting cycles"
  @run_cycles = true
  while @run_cycles do
    run_cycle
    sleep @options[:refresh]
  end
rescue => e
  if logger && logger.respond_to?(:fatal)
    logger.fatal "FATAL ERROR: Unexpected error: #{e}"
    logger.fatal e.backtrace.join("\n")
  end
  # Reraise the exception in case somebody else catches it
  raise e
end

#start_runners(files) ⇒ Object

Start runners for added config files



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# File 'lib/blessing/leader.rb', line 125

def start_runners(files)
  logger.debug "Starting runners for: #{files.inspect}" unless files.empty?
  files.each { |conf|
    @runners[conf] = runner = Blessing::Runner.new(conf, :leader => self)
    runner.start
  }
end

#start_stop_runners ⇒ Object

Find differences in old and new config file lists and start/stop runners as appropriate



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# File 'lib/blessing/leader.rb', line 118

def start_stop_runners
  start_runners @config_files - @old_config_files
  stop_runners @old_config_files - @config_files
end

#stop ⇒ Object

Stop running cycles



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# File 'lib/blessing/leader.rb', line 82

def stop
  @mutex.synchronize do
    @run_cycles = false
    logger.debug "Stopping all runners..."
    stop_runners @config_files
    logger.info "All runners stopped. Exiting..."
  end
end

#stop_runners(files) ⇒ Object

Stop runners for missing config files



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# File 'lib/blessing/leader.rb', line 134

def stop_runners(files)
  logger.debug "Stopping runners for: #{files.inspect}" unless files.empty?
  files.each { |conf| 
    if @runners[conf]
      @runners[conf].stop
      @runners.delete(conf)
    end
  }
end