Class: Webtube::Vital_Statistics

Inherits:
Object
  • Object
show all
Defined in:
lib/webtube/vital-statistics.rb

Overview

A tracker for live [[Webtube]] instances and their threads. This allows a shutdowning WEBrick to gently close the pending WebSockets.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(logger) ⇒ Vital_Statistics

Returns a new instance of Vital_Statistics.



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# File 'lib/webtube/vital-statistics.rb', line 26

def initialize logger
  super()
  @logger = logger
  @webtubes = Set.new
  @mutex = Mutex.new
  @thread_group = ThreadGroup.new
  return
end

Instance Attribute Details

#thread_group ⇒ Object (readonly)

A [[ThreadGroup]] into which the Webtube threads can add themselves. Note that [[Vital_Statistics]] does not forcefully move them (nor could it – a Webtube does not get a thread before [[Webtube#run]] is called, which is normally after [[Vital_Statistics#birth]] gets called).

When Webtube is being integrated with WEBrick by [[webtube/webrick.rb]], assigning Webtube-specific threads into this group will cause WEBrick’s standard shutdown procedure to not try to [[Thread#join]] them as it does to ordinary WEBrick threads. Instead, the integration code will call [[Vital_Statistics#close_all]], to request that each Webtube close itself, and then join the threads from [[Vital_Statistics#thread_group]].



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# File 'lib/webtube/vital-statistics.rb', line 24

def thread_group
  @thread_group
end

Instance Method Details

#birth(webtube) ⇒ Object 



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# File 'lib/webtube/vital-statistics.rb', line 35

def birth webtube
  @mutex.synchronize do
    @webtubes.add webtube
  end
  return
end

#close_all(status_code = 1001, explanation = "") ⇒ Object

The default status code in a shutdown situation is 1001 ‘going away’.



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# File 'lib/webtube/vital-statistics.rb', line 60

def close_all status_code = 1001, explanation = ""
  # Note that we're only mutexing off extracting the content
  # of [[@webtubes]] (see [[to_a]]).  We can't mutex the
  # whole block, for as the webtubes will be closing,
  # they'll want to notify us about it, and that is also
  # mutexed.
  #
  # This is not as bad as it may sound, for the webserver
  # shouldn't be accepting new connections anymore anyway by
  # the time it'll start closing the old ones.
  self.to_a.each do |webtube|
    begin
      webtube.close status_code, explanation
    rescue Exception => e
      # log and continue
      logger.error e
    end
  end
  return
end

#death(webtube) ⇒ Object 



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# File 'lib/webtube/vital-statistics.rb', line 42

def death webtube
  @mutex.synchronize do
    @webtubes.delete webtube
  end
  return
end

#to_a ⇒ Object

Construct a list of all the currently living [[Webtube]] instances. Note that while the operation is atomic, the Webtube infrastructure is inherently multithreaded, so the list can get slightly stale immediately and should, in most contexts, be considered informative.



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# File 'lib/webtube/vital-statistics.rb', line 54

def to_a
  return @mutex.synchronize{@webtubes.to_a}
end