Fix for `app error: deadlock; recursive locking (ThreadError)` with Rack::Deflater in rack 1.4.5 (rails 3.2)

README.md

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

rack_patch.rb

module Rack
  class Deflater
    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