Checkout of Instiki Trunk 1/21/2007.

vendor/rails/railties/lib/commands/ncgi/tracker

@@ -0,0 +1,69 @@
+#!/usr/local/bin/ruby
+
+require 'drb'
+require 'thread'
+
+def message(s)
+  $stderr.puts "tracker: #{s}" if ENV && ENV["DEBUG_GATEWAY"]
+end
+
+class Tracker
+  include DRbUndumped
+
+  def initialize(instances, socket_path)
+    @instances = instances
+    @socket = File.expand_path(socket_path)
+    @active = false
+
+    @listeners = []
+    @instances.times { @listeners << Mutex.new }
+
+    message "using #{@listeners.length} listeners"
+    message "opening socket at #{@socket}"
+
+    @service = DRb.start_service("drbunix://#{@socket}", self)
+  end
+
+  def with_listener
+    message "listener requested"
+
+    mutex = has_lock = index = nil
+    3.times do 
+      @listeners.each_with_index do |mutex, index|
+        has_lock = mutex.try_lock
+        break if has_lock
+      end
+      break if has_lock
+      sleep 0.05
+    end
+
+    if has_lock
+      message "obtained listener #{index}"
+      @active = true
+      begin yield index
+      ensure
+        mutex.unlock
+        message "released listener #{index}"
+      end
+    else
+      message "dropping request because no listeners are available!"
+    end
+  end
+
+  def background(check_interval = nil)
+    if check_interval
+      loop do
+        sleep check_interval
+        message "Idle for #{check_interval}, shutting down" unless @active
+        @active = false
+        Kernel.exit 0
+      end
+    else DRb.thread.join
+    end
+  end
+end
+
+socket_path = ARGV.shift
+instances = ARGV.shift.to_i
+t = Tracker.new(instances, socket_path)
+t.background(ARGV.first ? ARGV.shift.to_i : 90)