Class: ResponseBank::Middleware

Inherits:
Object
  • Object
show all
Defined in:
lib/response_bank/middleware.rb

Constant Summary collapse

CACHEABLE_HEADERS =

Limit the cached headers TODO: Make this lowercase/case-insentitive as per rfc2616 ยง4.2

["Location", "Content-Type", "ETag", "Content-Encoding", "Last-Modified", "Cache-Control", "Expires", "Link", "Surrogate-Keys", "Cache-Tags"].freeze
REQUESTED_WITH = 
"HTTP_X_REQUESTED_WITH"
ACCEPT = 
"HTTP_ACCEPT"
USER_AGENT = 
"HTTP_USER_AGENT"

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ Middleware

Returns a new instance of Middleware.



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# File 'lib/response_bank/middleware.rb', line 13

def initialize(app)
  @app = app
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/response_bank/middleware.rb', line 17

def call(env)
  env['cacheable.cache'] = false
  content_encoding = env['response_bank.server_cache_encoding'] = ResponseBank.check_encoding(env)

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

  if env['cacheable.cache']
    if [200, 404, 301, 304].include?(status)
      headers['ETag'] = %{"#{env['cacheable.key']}"}
    end

    if [200, 404, 301].include?(status) && env['cacheable.miss']
      # Flatten down the result so that it can be stored to memcached.
      if body.is_a?(String)
        body_string = body
      else
        body_string = +""
        body.each { |part| body_string << part }
      end

      body_compressed = nil
      if body_string && body_string != ""
        headers['Content-Encoding'] = content_encoding
        body_compressed = ResponseBank.compress(body_string, content_encoding)
      end

      cached_headers = headers.slice(*CACHEABLE_HEADERS)
      # Store result
      cache_data = [status, cached_headers, body_compressed, timestamp]

      ResponseBank.write_to_cache(env['cacheable.key']) do
        payload = MessagePack.dump(cache_data)
        ResponseBank.write_to_backing_cache_store(
          env,
          env['cacheable.unversioned-key'],
          payload,
          expires_in: env['cacheable.versioned-cache-expiry'],
        )
      end

      # since we had to generate the compressed version already we may
      # as well serve it if the client wants it
      if body_compressed
        if env['HTTP_ACCEPT_ENCODING'].to_s.include?(content_encoding)
          body = [body_compressed]
        else
          # Remove content-encoding header for response with compressed content
          headers.delete('Content-Encoding')
        end
      end
    end

    # Add X-Cache header
    miss = env['cacheable.miss']
    x_cache = miss ? 'miss' : 'hit'
    x_cache += ", #{env['cacheable.store']}" unless miss
    headers['X-Cache'] = x_cache
  end

  [status, headers, body]
end