fix initialization issues with unicorn

amend unicorn script to demonize sidekiq
create a sidekiq demon that unicorn consumes
correct bug in exec_sql with empty params

lib/demon/sidekiq.rb

@@ -0,0 +1,164 @@
+module Demon; end
+
+# intelligent fork based demonizer for sidekiq
+class Demon::Base
+
+  def self.start(count)
+    @demons ||= {}
+    count.times do |i|
+      (@demons["#{prefix}_#{i}"] ||= new(i)).start
+    end
+  end
+
+  def self.stop
+    @demons.values.each do |demon|
+      demon.stop
+    end
+  end
+
+  def initialize(index)
+    @index = index
+    @pid = nil
+    @parent_pid = Process.pid
+    @monitor = nil
+  end
+
+  def pid_file
+    "#{Rails.root}/tmp/pids/#{self.class.prefix}_#{@index}.pid"
+  end
+
+  def stop
+    if @monitor
+      @monitor.kill
+      @monitor.join
+      @monitor = nil
+    end
+
+    if @pid
+      Process.kill("SIGHUP",@pid)
+      @pid = nil
+    end
+  end
+
+  def start
+    if existing = already_running?
+      # should not happen ... so kill violently
+      Process.kill("SIGTERM",existing)
+    end
+
+    return if @pid
+
+    if @pid = fork
+      write_pid_file
+      monitor_child
+      return
+    end
+
+    monitor_parent
+    establish_app
+    after_fork
+  end
+
+  def already_running?
+    if File.exists? pid_file
+      pid = File.read(pid_file).to_i
+      if alive?(pid)
+        return pid
+      end
+    end
+
+    nil
+  end
+
+  private
+
+  def monitor_child
+    @monitor ||= Thread.new do
+      while true
+        sleep 5
+        unless alive?(@pid)
+          STDERR.puts "#{@pid} died, restarting sidekiq"
+          @pid = nil
+          start
+        end
+      end
+    end
+  end
+
+  def write_pid_file
+    FileUtils.mkdir_p(Rails.root + "tmp/pids")
+    File.open(pid_file,'w') do |f|
+      f.write(@pid)
+    end
+  end
+
+  def delete_pid_file
+    File.delete(pid_file)
+  end
+
+  def monitor_parent
+    Thread.new do
+      while true
+        exit unless alive?(@parent_pid)
+        sleep 1
+      end
+    end
+  end
+
+  def alive?(pid)
+    begin
+      Process.getpgid(pid)
+      true
+    rescue Errno::ESRCH
+      false
+    end
+  end
+
+  def establish_app
+
+
+    ActiveRecord::Base.connection_handler.clear_active_connections!
+    ActiveRecord::Base.establish_connection
+    $redis.client.reconnect
+    Rails.cache.reconnect
+    MessageBus.after_fork
+
+    Signal.trap("HUP") do
+      begin
+        delete_pid_file
+      ensure
+        exit
+      end
+    end
+
+    # keep stuff simple for now
+    $stdout.reopen("/dev/null", "w")
+    # $stderr.reopen("/dev/null", "w")
+  end
+
+  def after_fork
+  end
+end
+
+class Demon::Sidekiq < Demon::Base
+  def self.prefix
+    "sidekiq"
+  end
+
+  private
+
+  def after_fork
+    require 'sidekiq/cli'
+
+    begin
+      cli = Sidekiq::CLI.instance
+      cli.parse([])
+      cli.run
+    rescue => e
+      STDERR.puts e.message
+      STDERR.puts e.backtrace.join("\n")
+      exit 1
+    end
+
+  end
+end