Class: Rack::Deflater

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

Overview

This middleware enables compression of http responses.

Currently supported compression algorithms:

* gzip
* deflate
* identity (no transformation)

The middleware automatically detects when compression is supported and allowed. For example no transformation is made when a cache directive of ‘no-transform’ is present, or when the response status code is one that doesn’t allow an entity body.

Defined Under Namespace

Classes: DeflateStream, GzipStream

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ Deflater

Returns a new instance of Deflater.



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# File 'lib/rack/deflater.rb', line 20

def initialize(app)
  @app = app
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/rack/deflater.rb', line 24

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/ ||
     (headers['Content-Encoding'] && headers['Content-Encoding'] !~ /\bidentity\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
    body.close if body.respond_to?(:close)
    message = "An acceptable encoding for the requested resource #{request.fullpath} could not be found."
    [406, {"Content-Type" => "text/plain", "Content-Length" => message.length.to_s}, [message]]
  end
end