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require 'thread'
require 'singleton'
module Mauve
#
# This is a class to wrap our threads that have processing loops.
#
# The thread is kept in a wrapper to allow it to be frozen and thawed at
# convenient times.
#
class MauveThread
#
# The sleep interval between runs of the main loop. Defaults to 5 seconds.
#
attr_reader :poll_every
#
# Set the thread up
#
def initialize
@thread = nil
end
# @return [Log4r::Logger]
def logger
@logger ||= Log4r::Logger.new(self.class.to_s)
end
# Set the sleep interval between runs of the main loop. This can be
# anything greater than or equal to zero. If a number less than zero gets
# entered, it will be increased to zero.
#
# @param [Numeric] i The number of seconds to sleep
# @raise [ArgumentError] If +i+ is not numeric
# @return [Numeric]
#
def poll_every=(i)
raise ArgumentError.new("poll_every must be numeric") unless i.is_a?(Numeric)
#
# Set the minimum poll frequency.
#
if i.to_f < 0
logger.debug "Increasing thread polling interval to 0s from #{i}"
i = 0
end
@poll_every = i
end
# This determines if a thread should stop
#
# @return [Boolean]
def should_stop?
[:freezing, :stopping].include?(self.state)
end
# This is the current state of the thread. It can be one of
# [:stopped, :starting, :started, :freezing, :frozen, :stopping, :killing, :killed]
#
# If the thread is not alive it will be +:stopped+.
#
# @return [Symbol] One of [:stopped, :starting, :started, :freezing,
# :frozen, :stopping, :killing, :killed]
def state
if self.alive?
@thread.key?(:state) ? @thread[:state] : :unknown
else
:stopped
end
end
# This sets the state of a thread. It also records the last time the
# thread changed status.
#
# @param [Symbol] s One of [:stopped, :starting, :started, :freezing,
# :frozen, :stopping, :killing, :killed]
# @raise [ArgumentError] if +s+ is not a valid symbol or the thread is not
# ready
# @return [Symbol] the current thread state.
#
def state=(s)
raise ArgumentError, "Bad state for mauve_thread #{s.inspect}" unless [:stopped, :starting, :started, :freezing, :frozen, :stopping, :killing, :killed].include?(s)
raise ArgumentError, "Thread not ready yet." unless @thread.is_a?(Thread)
unless @thread[:state] == s
@thread[:state] = s
@thread[:last_state_change] = Time.now
logger.debug(s.to_s.capitalize)
end
@thread[:state]
end
# This returns the time of the last state change, or nil if the thread is dead.
#
# @return [Time or Nilclass]
def last_state_change
if self.alive? and @thread.key?(:last_state_change)
return @thread[:last_state_change]
else
return nil
end
end
# This asks the thread to freeze at the next opportunity.
#
def freeze
self.state = :freezing
20.times { Kernel.sleep 0.2 ; break if @thread.stop? }
logger.warn("Thread has not frozen!") unless @thread.stop?
end
# This returns true if the thread has frozen successfully.
#
# @return [Boolean]
def frozen?
self.stop? and self.state == :frozen
end
# This starts the thread. It wakes it up if it is alive, or starts it from
# fresh if it is dead.
#
def run
if self.alive?
# Wake up if we're stopped.
if self.stop?
@thread.wakeup
end
else
@logger = nil
Thread.new do
run_thread { main_loop }
end
end
end
alias start run
alias thaw run
# This checks to see if the thread is alive
#
# @return [Boolean]
def alive?
@thread.is_a?(Thread) and @thread.alive?
end
# This checks to see if the thread is stopped
#
# @return [Boolean]
def stop?
self.alive? and @thread.stop?
end
# This joins the thread
#
def join
@thread.join if @thread.is_a?(Thread)
end
# def raise(ex)
# @thread.raise(ex)
# end
# This returns the thread's backtrace
#
# @return [Array or Nilclass]
def backtrace
@thread.backtrace if @thread.is_a?(Thread)
end
# This restarts the thread
#
#
def restart
self.stop
self.start
end
# This stops the thread
#
#
def stop
self.state = :stopping
10.times do
break unless self.alive?
Kernel.sleep 1 if self.alive?
end
#
# OK I've had enough now.
#
self.kill if self.alive?
self.join
end
alias exit stop
# This kills the thread -- faster than #stop
#
def kill
self.state = :killing
@thread.kill
self.state = :killed
end
# This returns the thread itself.
#
# @return [Thread]
def thread
@thread
end
private
# This is the main run loop for the thread. In here are all the calls
# allowing use to freeze and thaw the thread neatly.
#
# This thread will run untill the thread state is changed to :stopping.
#
def run_thread(interval = 5.0)
#
# Good to go.
#
@thread = Thread.current
self.state = :starting
@poll_every ||= interval
#
# Make sure we get a number.
#
@poll_every = 5 unless @poll_every.is_a?(Numeric)
rate_limit = 0.1
while self.state != :stopping do
self.state = :started if self.state == :starting
#
# Schtop!
#
if self.state == :freezing
self.state = :frozen
Thread.stop
self.state = :started
end
yield_start = Time.now.to_f
yield
#
# Ah-ha! Sleep with a break clause. Make sure we poll every @poll_every seconds.
#
((@poll_every.to_f - Time.now.to_f + yield_start.to_f)/rate_limit).
round.to_i.times do
break if self.should_stop?
#
# This is a rate-limiting step
#
Kernel.sleep rate_limit
end
end
self.state = :stopped
end
end
end
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