Class: Bosh::ThreadPool

Inherits:
Object
  • Object
show all
Defined in:
lib/common/thread_pool.rb

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ ThreadPool

Returns a new instance of ThreadPool.



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# File 'lib/common/thread_pool.rb', line 5

def initialize(options = {})
  @actions = []
  @lock = Mutex.new
  @cv = ConditionVariable.new
  @max_threads = options[:max_threads] || 1
  @available_threads = @max_threads
  @logger = options[:logger]
  @boom = nil
  @original_thread = Thread.current
  @threads = []
  @state = :open
end

Instance Method Details

#create_thread ⇒ Object 



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# File 'lib/common/thread_pool.rb', line 60

def create_thread
  thread = Thread.new do
    begin
      loop do
        action = nil
        @lock.synchronize do
          action = @actions.shift unless @boom
          unless action
            @logger.debug('Thread is no longer needed, cleaning up')
            @available_threads += 1
            @threads.delete(thread) if @state == :open
          end
        end

        break unless action

        begin
          action.call
        rescue Exception => e
          raise_worker_exception(e)
        end
      end
    end
    @lock.synchronize { @cv.signal unless working? }
  end
  @threads << thread
end

#pause ⇒ Object 



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# File 'lib/common/thread_pool.rb', line 27

def pause
  @lock.synchronize do
    @state = :paused
  end
end

#process(&block) ⇒ Object 



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# File 'lib/common/thread_pool.rb', line 43

def process(&block)
  @lock.synchronize do
    @actions << block
    if @state == :open
      if @available_threads > 0
        @logger.debug('Creating new thread')
        @available_threads -= 1
        create_thread
      else
        @logger.debug('All threads are currently busy, queuing action')
      end
    elsif @state == :paused
      @logger.debug('Pool is paused, queueing action')
    end
  end
end

#raise_worker_exception(exception) ⇒ Object 



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# File 'lib/common/thread_pool.rb', line 88

def raise_worker_exception(exception)
  if exception.respond_to?(:backtrace)
    @logger.error("Worker thread raised exception: #{exception} - #{exception.backtrace.join("\n")}")
  else
    @logger.error("Worker thread raised exception: #{exception}")
  end
  @lock.synchronize do
    @boom = exception if @boom.nil?
  end
end

#resume ⇒ Object 



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# File 'lib/common/thread_pool.rb', line 33

def resume
  @lock.synchronize do
    @state = :open
    [@available_threads, @actions.size].min.times do
      @available_threads -= 1
      create_thread
    end
  end
end

#shutdown ⇒ Object 



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# File 'lib/common/thread_pool.rb', line 111

def shutdown
  return if @state == :closed
  @logger.debug('Shutting down pool')
  @lock.synchronize do
    return if @state == :closed
    @state = :closed
    @actions.clear
  end
  @threads.each { |t| t.join }
end

#wait ⇒ Object 



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# File 'lib/common/thread_pool.rb', line 103

def wait
  @logger.debug('Waiting for tasks to complete')
  @lock.synchronize do
    @cv.wait(@lock) while working?
    raise @boom if @boom
  end
end

#working? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/common/thread_pool.rb', line 99

def working?
  @boom.nil? && (@available_threads != @max_threads || !@actions.empty?)
end

#wrap ⇒ Object 



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# File 'lib/common/thread_pool.rb', line 18

def wrap
  begin
    yield self
    wait
  ensure
    shutdown
  end
end