From 9e4f5f33974b018fe4b6eba2766af263f8b06951 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Mon, 4 Jul 2005 19:16:28 +0000
Subject: Added an EXPERIMENTAL gateway.cgi for getting high-speed performance
 through vanilla CGI using a long-running, DRb-backed server in the background
 (using script/listener and script/tracker) #1603 [Nicholas Seckar]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1676 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
---
 railties/bin/listener           |  99 +++++++++++++++++++++++++++++++++++++
 railties/bin/tracker            | 106 ++++++++++++++++++++++++++++++++++++++++
 railties/dispatches/gateway.cgi |  57 +++++++++++++++++++++
 3 files changed, 262 insertions(+)
 create mode 100644 railties/bin/listener
 create mode 100644 railties/bin/tracker
 create mode 100644 railties/dispatches/gateway.cgi

(limited to 'railties')

diff --git a/railties/bin/listener b/railties/bin/listener
new file mode 100644
index 0000000000..2310282204
--- /dev/null
+++ b/railties/bin/listener
@@ -0,0 +1,99 @@
+require "drb"
+ENV["RAILS_ENV"] = 'production'
+require "#{File.dirname(__FILE__)}/../config/environment.rb"
+require 'fcgi_handler'
+
+VERBOSE = false
+
+class Listener
+  include DRbUndumped
+  attr_accessor :tracker
+  
+  def initialize(timeout = nil)
+    @timeout = timeout
+    @mutex = Mutex.new
+    @active = false
+    
+    @handler = RailsFCGIHandler.new
+    @handler.extend DRbUndumped
+    @output = FakeOut.new
+    $stdout = @output
+  end
+  
+  def inform_up(tracker_uri)
+    return unless tracker_uri
+    tracker = DRbObject.new_with_uri(tracker_uri)
+    tracker.register_listener self
+    @tracker = tracker
+  end
+  def inform_down
+    @tracker.remove_listener(self) if @tracker
+  end
+
+  def run(on_uri, tracker_uri)
+    on_uri ||= "drbunix:"
+    DRb.start_service(on_uri, self) # Start a server for us
+    inform_up tracker_uri
+    @handler.process!(self)
+  end
+  
+  def die!
+    inform_down
+    Kernel.exit 0
+  end 
+  
+  def process(input)
+    $stderr.puts "listener: received request -- obtaining lock" if VERBOSE 
+    @mutex.synchronize do
+      @active = true
+      
+      $stderr.puts "listener: obtained -- swaping stdin" if VERBOSE
+      $stdin = input
+      cgi = CGI.new
+      
+      $stderr.puts "listener: yielding to FCGI handler..." if VERBOSE
+      @cgi_block.call cgi
+      $stderr.puts "listener: handler finished, releasing control" if VERBOSE
+      
+      return @output.read!
+    end
+  end
+  
+  def each_cgi(&block)
+    @cgi_block = block
+    loop do
+      @timeout ? sleep(@timeout) : sleep
+      die! unless @active
+      @active = false
+    end
+  end
+end
+
+class FakeOut < Struct.new(:contents)
+  def initialize
+    super("")
+  end
+  def write(str)
+    contents << str
+  end
+  def read!
+    c = contents
+    self.contents = ''
+    return c
+  end
+end
+
+if ARGV.shift == 'start-listeners'
+  tracker = ARGV.shift
+  number = (ARGV.shift || '1').to_i
+  exit(0) if number.zero?
+  
+  if number > 1
+    fork do
+      exec 'ruby', __FILE__, 'start-listeners', tracker, (number - 1).to_s
+    end
+  end
+  
+  l = Listener.new(90)
+  l.run(nil, tracker)
+end
\ No newline at end of file
diff --git a/railties/bin/tracker b/railties/bin/tracker
new file mode 100644
index 0000000000..3a0c3aafc9
--- /dev/null
+++ b/railties/bin/tracker
@@ -0,0 +1,106 @@
+require "drb"
+
+VERBOSE = false
+
+class Tracker
+  include DRbUndumped
+  
+  def initialize(timeout = 90, uri = nil)
+    @timeout = timeout
+    @waiting = []
+    @working = []
+    
+    @waiting_mutex = Mutex.new
+    
+    DRb.start_service(uri, self)
+    @uri = DRb.uri
+  end
+  def run
+    start_listener 3
+    sleep 3
+    
+    background
+  end
+  
+  def register_listener(listener)
+    @waiting.push listener
+    nil
+  end
+  def remove_listener(listener)
+    @waiting.delete listener
+    @working.delete listener
+    nil
+  end
+  
+  def with_listener
+    listener = @waiting.shift
+    unless listener
+      start_listener(2) unless @waiting.length + @working.length > 6
+      @waiting_mutex.synchronize do
+	10.times do
+          sleep 0.5
+          listener = @waiting.shift
+          break if listener
+        end
+        unless listener
+          ($stderr.puts "Dropping request due to lack of listeners!!!" unless listener) if VERBOSE
+          return
+        end
+      end
+    end
+    
+    @working << listener
+    yield listener
+  ensure
+    if listener
+      @working.delete listener
+      @waiting << listener
+    end
+  end
+  
+  def background
+    loop do
+      @timeout ? sleep(@timeout) : sleep
+      unless @processed
+        $stderr.puts "Idle for #{@timeout} -- shutting down tracker." if VERBOSE
+        Kernel.exit 0 
+      end
+      @processed = false
+    end
+  end
+    
+  def process(input)
+    output = nil
+    $stderr.puts "tracker: received request.. obtaining listener" if VERBOSE
+    with_listener do |listener|
+      $stderr.puts "tracker: obtained -- forwarding request to listener.." if VERBOSE
+      @processed = true
+      output = listener.process(input)
+      $stderr.puts "tracker: listener released control." if VERBOSE
+    end
+    return output
+  end
+  
+  def start_listener(n = 1)
+    tracker_uri = @uri
+    listener_path = File.join(File.dirname(__FILE__), 'listener')
+    fork do
+      exec 'ruby', listener_path, 'start-listeners', tracker_uri, n.to_s 
+    end
+  end
+  
+  def ping
+    true
+  end
+end
+
+if ARGV.first == "start"
+  tracker = Tracker.new(90, ARGV[1])
+  socket = (/druby:([^?]*)\?/ =~ ARGV[1]) ? $1 : nil
+  require 'fileutils' if socket
+
+  begin tracker.run
+  ensure 
+    FileUtils.rm_f(socket) if socket
+  end
+end
diff --git a/railties/dispatches/gateway.cgi b/railties/dispatches/gateway.cgi
new file mode 100644
index 0000000000..b8d44acef2
--- /dev/null
+++ b/railties/dispatches/gateway.cgi
@@ -0,0 +1,57 @@
+#!/usr/bin/ruby
+
+# This is an experimental feature for getting high-speed CGI by using a long-running, DRb-backed server in the background
+
+require File.join(File.dirname(__FILE__), 'drb')
+require 'cgi'
+
+VERBOSE = false
+
+AppName = File.split(File.expand_path(File.join(__FILE__, '..'))).last
+SocketPath = File.expand_path(File.join(File.dirname(__FILE__), '../log/drb_gateway.sock'))
+ConnectionUri = "drbunix:#{SocketPath}"
+attempted_start = false
+
+def start_tracker
+  tracker_path = File.join(File.dirname(__FILE__), '../script/tracker')
+  fork do
+    Process.setsid
+    STDIN.reopen "/dev/null"
+    STDOUT.reopen "/dev/null", "a"
+    
+    exec 'ruby', tracker_path, 'start', ConnectionUri
+  end
+  
+  $stderr.puts "dispatch: waiting for tracker to start..." if VERBOSE
+  10.times do
+    sleep 0.5
+    return if File.exists? SocketPath
+  end
+  
+  $stderr.puts "Can't start tracker!!! Dropping request!"
+  Kernel.exit 1
+end
+
+unless File.exists?(SocketPath)
+  $stderr.puts "tracker not running: starting it..." if VERBOSE
+  start_tracker
+end
+
+$stderr.puts "dispatch: attempting to contact tracker..." if VERBOSE
+tracker = DRbObject.new_with_uri(ConnectionUri)
+tracker.ping # Test connection
+
+$stdout.extend DRbUndumped
+$stdin.extend DRbUndumped
+  
+DRb.start_service "drbunix:", $stdin
+$stderr.puts "dispatch: publishing stdin..." if VERBOSE
+
+$stderr.puts "dispatch: sending request to tracker" if VERBOSE
+puts tracker.process($stdin)
+
+$stdout.flush
+[$stdin, $stdout].each {|io| io.close}
+$stderr.puts "dispatch: finished..." if VERBOSE
+
+
-- 
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