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
* 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: GzipStream

Instance Method Summary collapse

Constructor Details

#initialize(app, options = {}) ⇒ Deflater

Creates Rack::Deflater middleware.

app

rack app instance

options

hash of deflater options, i.e. 'if' - a lambda enabling / disabling deflation based on returned boolean value

e.g use Rack::Deflater, :if => lambda { |env, status, headers, body| body.map(&:bytesize).reduce(0, :+) > 512 }

'include' - a list of content types that should be compressed


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# File 'lib/rack/deflater.rb', line 26

def initialize(app, options = {})
  @app = app

  @condition = options[:if]
  @compressible_types = options[:include]
end

Instance Method Details

#call(env) ⇒ Object


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# File 'lib/rack/deflater.rb', line 33

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

  unless should_deflate?(env, status, headers, body)
    return [status, headers, body]
  end

  request = Request.new(env)

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

  # Set the Vary HTTP header.
  vary = headers["Vary"].to_s.split(",").map(&: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 "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