1 files changed, 355 insertions, 0 deletions
diff --git a/lib/puppet/event-loop/event-loop.rb b/lib/puppet/event-loop/event-loop.rb
new file mode 100644
index 000000000..5d78844ef
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+++ b/lib/puppet/event-loop/event-loop.rb
@@ -0,0 +1,355 @@
+## event-loop.rb --- high-level IO multiplexer
+# Copyright (C) 2005  Daniel Brockman
+
+# This program is free software; you can redistribute it
+# and/or modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation;
+# either version 2 of the License, or (at your option) any
+# later version.
+
+# This file is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty
+# of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public
+# License along with this program; if not, write to the Free
+# Software Foundation, 51 Franklin Street, Fifth Floor,
+# Boston, MA 02110-1301, USA.
+
+require "puppet/event-loop/better-definers"
+require "puppet/event-loop/signal-system"
+
+require "fcntl"
+
+class EventLoop
+  include SignalEmitter
+
+  IO_STATES = [:readable, :writable, :exceptional]
+
+  class << self
+    def default ; @default ||= new end
+    def default= x ; @default = x end
+
+    def current
+      Thread.current["event-loop::current"] || default end
+    def current= x
+      Thread.current["event-loop::current"] = x end
+
+    def with_current (new)
+      if current == new
+        yield
+      else
+        begin
+          old = self.current
+          self.current = new
+          yield
+        ensure
+          self.current = old
+        end
+      end
+    end
+
+    def method_missing (name, *args, &block)
+      if current.respond_to? name
+        current.__send__(name, *args, &block)
+      else
+        super
+      end
+    end
+  end
+
+  define_signals :before_sleep, :after_sleep
+
+  def initialize
+    @running = false
+    @awake = false
+    @wakeup_time = nil
+    @timers = []
+
+    @io_arrays = [[], [], []]
+    @ios = Hash.new do |h, k| raise ArgumentError,
+      "invalid IO event: #{k}", caller(2) end
+    IO_STATES.each_with_index { |x, i| @ios[x] = @io_arrays[i] }
+
+    @notify_src, @notify_snk = IO.pipe
+
+    @notify_src.will_block = false
+    @notify_snk.will_block = false
+
+    # Each time a byte is sent through the notification pipe
+    # we need to read it, or IO.select will keep returning.
+    monitor_io(@notify_src, :readable)
+    @notify_src.extend(Watchable)
+    @notify_src.on_readable do
+      begin
+        @notify_src.sysread(256)
+      rescue Errno::EAGAIN
+        # The pipe wasn't readable after all.
+      end
+    end
+  end
+
+  define_opposite_accessors \
+    :stopped?  => :running?,
+    :sleeping? => :awake?
+
+  def run
+    if block_given?
+      thread = Thread.new { run }
+      yield ; quit ; thread.join
+    else
+      running!
+      iterate while running?
+    end
+  ensure
+    quit
+  end
+
+  def iterate (user_timeout=nil)
+    t1, t2 = user_timeout, max_timeout
+    timeout = t1 && t2 ? [t1, t2].min : t1 || t2
+    select(timeout).zip(IO_STATES) do |ios, state|
+      ios.each { |x| x.signal(state) } if ios
+    end
+  end
+
+ private
+
+  def select (timeout)
+    @wakeup_time = timeout ? Time.now + timeout : nil
+    # puts "waiting: #{timeout} seconds"
+    signal :before_sleep ; sleeping!
+    IO.select(*@io_arrays + [timeout]) || []
+  ensure
+    awake! ; signal :after_sleep
+    @timers.each { |x| x.sound_alarm if x.ready? }
+  end
+
+ public
+
+  def quit ; stopped! ; wake_up ; self end
+
+  def monitoring_io? (io, event)
+    @ios[event].include? io end
+  def monitoring_timer? (timer)
+    @timers.include? timer end
+
+  def monitor_io (io, *events)
+    for event in events do
+      unless monitoring_io?(io, event)
+        @ios[event] << io ; wake_up
+      end
+    end
+  end
+
+  def monitor_timer (timer)
+    unless monitoring_timer? timer
+      @timers << timer
+    end
+  end
+
+  def check_timer (timer)
+    wake_up if timer.end_time < @wakeup_time
+  end
+
+  def ignore_io (io, *events)
+    events = IO_STATES if events.empty?
+    for event in events do
+      wake_up if @ios[event].delete(io)
+    end
+  end
+
+  def ignore_timer (timer)
+    # Don't need to wake up for this.
+    @timers.delete(timer)
+  end
+
+  def max_timeout
+    return nil if @timers.empty?
+    [@timers.collect { |x| x.time_left }.min, 0].max
+  end
+
+  def wake_up
+    @notify_snk.write('.') if sleeping?
+  end
+end
+
+class Symbol
+  def io_state?
+    EventLoop::IO_STATES.include? self
+  end
+end
+
+module EventLoop::Watchable
+  include SignalEmitter
+
+  define_signals :readable, :writable, :exceptional
+
+  def monitor_events (*events)
+    EventLoop.monitor_io(self, *events) end
+  def ignore_events (*events)
+    EventLoop.ignore_io(self, *events) end
+
+  define_soft_aliases \
+    :monitor_event => :monitor_events,
+    :ignore_event  => :ignore_events
+
+  def close ; super
+    ignore_events end
+  def close_read ; super
+    ignore_event :readable end
+  def close_write ; super
+    ignore_event :writable end
+
+  module Automatic
+    include EventLoop::Watchable
+
+    def add_signal_handler (name, &handler) super
+      monitor_event(name) if name.io_state?
+    end
+
+    def remove_signal_handler (name, handler) super
+      if @signal_handlers[name].empty?
+        ignore_event(name) if name.io_state?
+      end
+    end
+  end
+end
+
+class IO
+  def on_readable &block
+    extend EventLoop::Watchable::Automatic
+    on_readable(&block)
+  end
+
+  def on_writable &block
+    extend EventLoop::Watchable::Automatic
+    on_writable(&block)
+  end
+
+  def on_exceptional &block
+    extend EventLoop::Watchable::Automatic
+    on_exceptional(&block)
+  end
+
+  def will_block?
+    require "fcntl"
+    fcntl(Fcntl::F_GETFL, 0) & Fcntl::O_NONBLOCK == 0
+  end
+
+  def will_block= (wants_blocking)
+    require "fcntl"
+    flags = fcntl(Fcntl::F_GETFL, 0)
+    if wants_blocking
+      flags &= ~Fcntl::O_NONBLOCK
+    else
+      flags |= Fcntl::O_NONBLOCK
+    end
+    fcntl(Fcntl::F_SETFL, flags)
+  end
+end
+
+class EventLoop::Timer
+  include SignalEmitter
+
+  DEFAULT_INTERVAL = 0.0
+  DEFAULT_TOLERANCE = 0.001
+
+  def initialize (options={}, &handler)
+    @running = false
+    @start_time = nil
+
+    if options.kind_of? Numeric
+      options = { :interval => options }
+    end
+
+    if options[:interval]
+      @interval = options[:interval].to_f
+    else
+      @interval = DEFAULT_INTERVAL
+    end
+
+    if options[:tolerance]
+      @tolerance = options[:tolerance].to_f
+    elsif DEFAULT_TOLERANCE < @interval
+      @tolerance = DEFAULT_TOLERANCE
+    else
+      @tolerance = 0.0
+    end
+
+    @event_loop = options[:event_loop] || EventLoop.current
+
+    if block_given?
+      add_signal_handler(:alarm, &handler)
+      start unless options[:start?] == false
+    else
+      start if options[:start?]
+    end
+  end
+
+  define_readers :interval, :tolerance
+  define_signal :alarm
+
+  def stopped? ; @start_time == nil end
+  def running? ; @start_time != nil end
+
+  def interval= (new_interval)
+    old_interval = @interval
+    @interval = new_interval
+    if new_interval < old_interval
+      @event_loop.check_timer(self)
+    end
+  end
+
+  def end_time
+    @start_time + @interval end
+  def time_left
+    end_time - Time.now end
+  def ready?
+    time_left <= @tolerance end
+
+  def restart
+    @start_time = Time.now
+  end
+
+  def sound_alarm
+    signal :alarm
+    restart if running?
+  end
+
+  def start
+    @start_time = Time.now
+    @event_loop.monitor_timer(self)
+  end
+
+  def stop
+    @start_time = nil
+    @event_loop.ignore_timer(self)
+  end
+end
+
+if __FILE__ == $0
+  require "test/unit"
+
+  class TimerTest < Test::Unit::TestCase
+    def setup
+      @timer = EventLoop::Timer.new(:interval => 0.001)
+    end
+
+    def test_timer
+      @timer.on_alarm do
+        puts "[#{@timer.time_left} seconds left after alarm]"
+        EventLoop.quit
+      end
+      8.times do
+        t0 = Time.now
+        @timer.start ; EventLoop.run
+        t1 = Time.now
+        assert(t1 - t0 > @timer.interval - @timer.tolerance)
+      end
+    end
+  end
+end
+
+## event-loop.rb ends here.