Class: Rack::Deflater

Inherits:
Object show all
Defined in:
vendor/bundler/ruby/3.4.0/bundler/gems/rack-40d68f842b5f/lib/rack/deflater.rb

Overview

This middleware enables content encoding of http responses, usually for purposes of compression.

Currently supported encodings:

  • gzip
  • identity (no transformation)

This middleware automatically detects when encoding is supported and allowed. For example no encoding is made when a cache directive of 'no-transform' is present, when the response status code is one that doesn't allow an entity body, or when the body is empty.

Note that despite the name, Deflater does not support the +deflate+ encoding.

Defined Under Namespace

Classes: GzipStream

Instance Method Summary collapse

Constructor Details

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

Creates Rack::Deflater middleware. Options:

:if :: a lambda enabling / disabling deflation based on returned boolean value (e.g use Rack::Deflater, :if => lambda { |*, body| sum=0; body.each { |i| sum += i.length }; sum > 512 }). However, be aware that calling body.each inside the block will break cases where body.each is not idempotent, such as when it is an +IO+ instance. :include :: a list of content types that should be compressed. By default, all content types are compressed. :sync :: determines if the stream is going to be flushed after every chunk. Flushing after every chunk reduces latency for time-sensitive streaming applications, but hurts compression and throughput. Defaults to +true+.



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rack-40d68f842b5f/lib/rack/deflater.rb', line 39

def initialize(app, options = {})
  @app = app
  @condition = options[:if]
  @compressible_types = options[:include]
  @sync = options.fetch(:sync, true)
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rack-40d68f842b5f/lib/rack/deflater.rb', line 46

def call(env)
  status, headers, body = response = @app.call(env)

  unless should_deflate?(env, status, headers, body)
    return response
  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.any?{|v| v.downcase == 'accept-encoding'}
    headers["vary"] = vary.push("Accept-Encoding").join(",")
  end

  case encoding
  when "gzip"
    headers['content-encoding'] = "gzip"
    headers.delete(CONTENT_LENGTH)
    mtime = headers["last-modified"]
    mtime = Time.httpdate(mtime).to_i if mtime
    response[2] = GzipStream.new(body, mtime, @sync)
    response
  when "identity"
    response
  else # when nil
    # Only possible encoding values here are 'gzip', 'identity', and 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