README.md

Forked from a gist by gregclermont

Original README

This file combines 7bda8d4 & d860397 from rack 1.5.2 to fix a race condition in Rack::Deflater. It can be used to patch rack 1.4.5 for apps that can't upgrade to rack 1.5.2 (e.g. as an initializer in a rails 3.2 app)

edit: added 6c186f2, too

Added by me

edit: added 0f8cd05

rack_patch.rb

module Rack
  class Deflater
    def call(env)
      status, headers, body = @app.call(env)
      headers = Utils::HeaderHash.new(headers)

      # Skip compressing empty entity body responses and responses with
      # no-transform set.
      if Utils::STATUS_WITH_NO_ENTITY_BODY.include?(status) ||
          headers['Cache-Control'].to_s =~ /\bno-transform\b/
        return [status, headers, body]
      end

      request = Request.new(env)

      encoding = Utils.select_best_encoding(%w(gzip deflate identity),
                                            request.accept_encoding)

      # Set the Vary HTTP header.
      vary = headers["Vary"].to_s.split(",").map { |v| v.strip }
      unless vary.include?("*") || vary.include?("Accept-Encoding")
        headers["Vary"] = vary.push("Accept-Encoding").join(",")
      end

      case encoding
        when "gzip"
          headers['Content-Encoding'] = "gzip"
          headers.delete('Content-Length')
          mtime = headers.key?("Last-Modified") ?
              Time.httpdate(headers["Last-Modified"]) : Time.now
          [status, headers, GzipStream.new(body, mtime)]
        when "deflate"
          headers['Content-Encoding'] = "deflate"
          headers.delete('Content-Length')
          [status, headers, DeflateStream.new(body)]
        when "identity"
          [status, headers, body]
        when nil
          message = "An acceptable encoding for the requested resource #{request.fullpath} could not be found."
          bp = Rack::BodyProxy.new([message]) { body.close if body.respond_to?(:close) }
          [406, {"Content-Type" => "text/plain", "Content-Length" => message.length.to_s}, bp]
      end
    end

    class GzipStream
      def initialize(body, mtime)
        @body = body
        @mtime = mtime
        @closed = false
      end

      def each(&block)
        @writer = block
        gzip  =::Zlib::GzipWriter.new(self)
        gzip.mtime = @mtime
        @body.each { |part|
          gzip.write(part)
          gzip.flush
        }
      ensure
        gzip.close
        @writer = nil
      end

      def close
        return if @closed
        @closed = true
        @body.close if @body.respond_to?(:close)
      end
    end

    class DeflateStream
      def initialize(body)
        @body = body
        @closed = false
      end

      def each
        deflator = ::Zlib::Deflate.new(*DEFLATE_ARGS)
        @body.each { |part| yield deflator.deflate(part, Zlib::SYNC_FLUSH) }
        yield deflator.finish
        nil
      ensure
        deflator.close
      end

      def close
        return if @closed
        @closed = true
        @body.close if @body.respond_to?(:close)
      end
    end
  end
end

@robotfelix I'm getting these errors after applying the patch:

/app/config/initializers/rack_patch.rb in call at line 4
NoMethodError: undefined method `id' for nil:NilClass

/app/config/initializers/rack_patch.rb in call at line 4
RuntimeError: invalid state

Any idead on waht might be?
The 1st one happens ina GET request, the 2nd on a POST