Class: Mongrel::HttpServer

Inherits:
Object
  • Object
show all
Defined in:
lib/mongrel.rb

Overview

This is the main driver of Mongrel, while the Mongrel::HttpParser and Mongrel::URIClassifier make up the majority of how the server functions. It's a very simple class that just has a thread accepting connections and a simple HttpServer.process_client function to do the heavy lifting with the IO and Ruby.

You use it by doing the following:

server = HttpServer.new("0.0.0.0", 3000)
server.register("/stuff", MyNiftyHandler.new)
server.run.join

The last line can be just server.run if you don't want to join the thread used. If you don't though Ruby will mysteriously just exit on you.

Ruby's thread implementation is “interesting” to say the least. Experiments with many different types of IO processing simply cannot make a dent in it. Future releases of Mongrel will find other creative ways to make threads faster, but don't hold your breath until Ruby 1.9 is actually finally useful.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(host, port, num_processors = 950, throttle = 0, timeout = 60) ⇒ HttpServer

Creates a working server on host:port (strange things happen if port isn't a Number). Use HttpServer::run to start the server and HttpServer.acceptor.join to join the thread that's processing incoming requests on the socket.

The num_processors optional argument is the maximum number of concurrent processors to accept, anything over this is closed immediately to maintain server processing performance. This may seem mean but it is the most efficient way to deal with overload. Other schemes involve still parsing the client's request which defeats the point of an overload handling system.

The throttle parameter is a sleep timeout (in hundredths of a second) that is placed between socket.accept calls in order to give the server a cheap throttle time. It defaults to 0 and actually if it is 0 then the sleep is not done at all.


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# File 'lib/mongrel.rb', line 90

def initialize(host, port, num_processors=950, throttle=0, timeout=60)
  
  tries = 0
  @socket = TCPServer.new(host, port) 
  
  @classifier = URIClassifier.new
  @host = host
  @port = port
  @workers = ThreadGroup.new
  @throttle = throttle / 100.0
  @num_processors = num_processors
  @timeout = timeout
end

Instance Attribute Details

#acceptorObject (readonly)

Returns the value of attribute acceptor


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# File 'lib/mongrel.rb', line 68

def acceptor
  @acceptor
end

#classifierObject (readonly)

Returns the value of attribute classifier


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# File 'lib/mongrel.rb', line 70

def classifier
  @classifier
end

#hostObject (readonly)

Returns the value of attribute host


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# File 'lib/mongrel.rb', line 71

def host
  @host
end

#num_processorsObject (readonly)

Returns the value of attribute num_processors


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# File 'lib/mongrel.rb', line 75

def num_processors
  @num_processors
end

#portObject (readonly)

Returns the value of attribute port


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# File 'lib/mongrel.rb', line 72

def port
  @port
end

#throttleObject (readonly)

Returns the value of attribute throttle


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# File 'lib/mongrel.rb', line 73

def throttle
  @throttle
end

#timeoutObject (readonly)

Returns the value of attribute timeout


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# File 'lib/mongrel.rb', line 74

def timeout
  @timeout
end

#workersObject (readonly)

Returns the value of attribute workers


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# File 'lib/mongrel.rb', line 69

def workers
  @workers
end

Instance Method Details

#configure_socket_optionsObject


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# File 'lib/mongrel.rb', line 240

def configure_socket_options
  case RUBY_PLATFORM
  when /linux/
    # 9 is currently TCP_DEFER_ACCEPT
    $tcp_defer_accept_opts = [Socket::SOL_TCP, 9, 1]
    $tcp_cork_opts = [Socket::SOL_TCP, 3, 1]
  when /freebsd(([1-4]\..{1,2})|5\.[0-4])/
    # Do nothing, just closing a bug when freebsd <= 5.4
  when /freebsd/
    # Use the HTTP accept filter if available.
    # The struct made by pack() is defined in /usr/include/sys/socket.h as accept_filter_arg
    unless `/sbin/sysctl -nq net.inet.accf.http`.empty?
      $tcp_defer_accept_opts = [Socket::SOL_SOCKET, Socket::SO_ACCEPTFILTER, ['httpready', nil].pack('a16a240')]
    end
  end
end

#graceful_shutdownObject

Performs a wait on all the currently running threads and kills any that take too long. It waits by @timeout seconds, which can be set in .initialize or via mongrel_rails. The @throttle setting does extend this waiting period by that much longer.


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# File 'lib/mongrel.rb', line 233

def graceful_shutdown
  while reap_dead_workers("shutdown") > 0
    STDERR.puts "Waiting for #{@workers.list.length} requests to finish, could take #{@timeout + @throttle} seconds."
    sleep @timeout / 10
  end
end

#process_client(client) ⇒ Object

Does the majority of the IO processing. It has been written in Ruby using about 7 different IO processing strategies and no matter how it's done the performance just does not improve. It is currently carefully constructed to make sure that it gets the best possible performance, but anyone who thinks they can make it faster is more than welcome to take a crack at it.


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# File 'lib/mongrel.rb', line 109

def process_client(client)
  begin
    parser = HttpParser.new
    params = HttpParams.new
    request = nil
    data = client.readpartial(Const::CHUNK_SIZE)
    nparsed = 0

    # Assumption: nparsed will always be less since data will get filled with more
    # after each parsing.  If it doesn't get more then there was a problem
    # with the read operation on the client socket.  Effect is to stop processing when the
    # socket can't fill the buffer for further parsing.
    while nparsed < data.length
      nparsed = parser.execute(params, data, nparsed)

      if parser.finished?
        if not params[Const::REQUEST_PATH]
          # it might be a dumbass full host request header
          uri = URI.parse(params[Const::REQUEST_URI])
          params[Const::REQUEST_PATH] = uri.path
        end

        raise "No REQUEST PATH" if not params[Const::REQUEST_PATH]

        script_name, path_info, handlers = @classifier.resolve(params[Const::REQUEST_PATH])

        if handlers
          params[Const::PATH_INFO] = path_info
          params[Const::SCRIPT_NAME] = script_name

          # From http://www.ietf.org/rfc/rfc3875 :
          # "Script authors should be aware that the REMOTE_ADDR and REMOTE_HOST
          #  meta-variables (see sections 4.1.8 and 4.1.9) may not identify the
          #  ultimate source of the request.  They identify the client for the
          #  immediate request to the server; that client may be a proxy, gateway,
          #  or other intermediary acting on behalf of the actual source client."
          params[Const::REMOTE_ADDR] = client.peeraddr.last

          # select handlers that want more detailed request notification
          notifiers = handlers.select { |h| h.request_notify }
          request = HttpRequest.new(params, client, notifiers)

          # in the case of large file uploads the user could close the socket, so skip those requests
          break if request.body == nil  # nil signals from HttpRequest::initialize that the request was aborted

          # request is good so far, continue processing the response
          response = HttpResponse.new(client)

          # Process each handler in registered order until we run out or one finalizes the response.
          handlers.each do |handler|
            handler.process(request, response)
            break if response.done or client.closed?
          end

          # And finally, if nobody closed the response off, we finalize it.
          unless response.done or client.closed? 
            response.finished
          end
        else
          # Didn't find it, return a stock 404 response.
          client.write(Const::ERROR_404_RESPONSE)
        end

        break #done
      else
        # Parser is not done, queue up more data to read and continue parsing
        chunk = client.readpartial(Const::CHUNK_SIZE)
        break if !chunk or chunk.length == 0  # read failed, stop processing

        data << chunk
        if data.length >= Const::MAX_HEADER
          raise HttpParserError.new("HEADER is longer than allowed, aborting client early.")
        end
      end
    end
  rescue EOFError,Errno::ECONNRESET,Errno::EPIPE,Errno::EINVAL,Errno::EBADF
    client.close rescue nil
  rescue HttpParserError => e
    STDERR.puts "#{Time.now}: HTTP parse error, malformed request (#{params[Const::HTTP_X_FORWARDED_FOR] || client.peeraddr.last}): #{e.inspect}"
    STDERR.puts "#{Time.now}: REQUEST DATA: #{data.inspect}\n---\nPARAMS: #{params.inspect}\n---\n"
  rescue Errno::EMFILE
    reap_dead_workers('too many files')
  rescue Object => e
    STDERR.puts "#{Time.now}: Read error: #{e.inspect}"
    STDERR.puts e.backtrace.join("\n")
  ensure
    begin
      client.close
    rescue IOError
      # Already closed
    rescue Object => e
      STDERR.puts "#{Time.now}: Client error: #{e.inspect}"
      STDERR.puts e.backtrace.join("\n")
    end
    request.body.delete if request and request.body.class == Tempfile
  end
end

#reap_dead_workers(reason = 'unknown') ⇒ Object

Used internally to kill off any worker threads that have taken too long to complete processing. Only called if there are too many processors currently servicing. It returns the count of workers still active after the reap is done. It only runs if there are workers to reap.


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# File 'lib/mongrel.rb', line 211

def reap_dead_workers(reason='unknown')
  if @workers.list.length > 0
    STDERR.puts "#{Time.now}: Reaping #{@workers.list.length} threads for slow workers because of '#{reason}'"
    error_msg = "Mongrel timed out this thread: #{reason}"
    mark = Time.now
    @workers.list.each do |worker|
      worker[:started_on] = Time.now if not worker[:started_on]

      if mark - worker[:started_on] > @timeout + @throttle
        STDERR.puts "Thread #{worker.inspect} is too old, killing."
        worker.raise(TimeoutError.new(error_msg))
      end
    end
  end

  return @workers.list.length
end

#register(uri, handler, in_front = false) ⇒ Object

Simply registers a handler with the internal URIClassifier. When the URI is found in the prefix of a request then your handler's HttpHandler::process method is called. See Mongrel::URIClassifier#register for more information.

If you set in_front=true then the passed in handler will be put in the front of the list for that particular URI. Otherwise it's placed at the end of the list.


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# File 'lib/mongrel.rb', line 320

def register(uri, handler, in_front=false)
  begin
    @classifier.register(uri, [handler])
  rescue URIClassifier::RegistrationError
    handlers = @classifier.resolve(uri)[2]
    method_name = in_front ? 'unshift' : 'push'
    handlers.send(method_name, handler)
  end
  handler.listener = self
end

#runObject

Runs the thing. It returns the thread used so you can “join” it. You can also access the HttpServer::acceptor attribute to get the thread later.


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# File 'lib/mongrel.rb', line 259

def run
  BasicSocket.do_not_reverse_lookup=true

  configure_socket_options

  if defined?($tcp_defer_accept_opts) and $tcp_defer_accept_opts
    @socket.setsockopt(*$tcp_defer_accept_opts) rescue nil
  end

  @acceptor = Thread.new do
    begin
      while true
        begin
          client = @socket.accept
  
          if defined?($tcp_cork_opts) and $tcp_cork_opts
            client.setsockopt(*$tcp_cork_opts) rescue nil
          end
  
          worker_list = @workers.list
  
          if worker_list.length >= @num_processors
            STDERR.puts "Server overloaded with #{worker_list.length} processors (#@num_processors max). Dropping connection."
            client.close rescue nil
            reap_dead_workers("max processors")
          else
            thread = Thread.new(client) {|c| process_client(c) }
            thread[:started_on] = Time.now
            @workers.add(thread)
  
            sleep @throttle if @throttle > 0
          end
        rescue StopServer
          break
        rescue Errno::EMFILE
          reap_dead_workers("too many open files")
          sleep 0.5
        rescue Errno::ECONNABORTED
          # client closed the socket even before accept
          client.close rescue nil
        rescue Object => e
          STDERR.puts "#{Time.now}: Unhandled listen loop exception #{e.inspect}."
          STDERR.puts e.backtrace.join("\n")
        end
      end
      graceful_shutdown
    ensure
      @socket.close
      # STDERR.puts "#{Time.now}: Closed socket."
    end
  end

  return @acceptor
end

#stop(synchronous = false) ⇒ Object

Stops the acceptor thread and then causes the worker threads to finish off the request queue before finally exiting.


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# File 'lib/mongrel.rb', line 340

def stop(synchronous=false)
  @acceptor.raise(StopServer.new)

  if synchronous
    sleep(0.5) while @acceptor.alive?
  end
end

#unregister(uri) ⇒ Object

Removes any handlers registered at the given URI. See Mongrel::URIClassifier#unregister for more information. Remember this removes them all so the entire processing chain goes away.


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# File 'lib/mongrel.rb', line 334

def unregister(uri)
  @classifier.unregister(uri)
end