You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: thread_handler_extension.rb
    path of file: ./repos/passenger/src/ruby_supportlib/phusion_passenger/rack
    
    the code of the file until where you have to start completion: # encoding: binary
#  Phusion Passenger - https://www.phusionpassenger.com/
#  
    
      def process_request(env, connection, socket_wrapper, full_http_response)
        rewindable_input = PhusionPassenger::Utils::TeeInput.new(connection, env)
        begin
          env[RACK_VERSION]      = RACK_VERSION_VALUE
          env[RACK_INPUT]        = rewindable_input
          env[RACK_ERRORS]       = STDERR
          env[RACK_MULTITHREAD]  = @request_handler.concurrency > 1
          env[RACK_MULTIPROCESS] = true
          env[RACK_RUN_ONCE]     = false
          if env[HTTPS] == YES || env[HTTPS] == ON || env[HTTPS] == ONE
            env[RACK_URL_SCHEME] = HTTPS_DOWNCASE
          else
            env[RACK_URL_SCHEME] = HTTP
          end