class Rack::Cache::Response
Provides access to the response generated by the downstream application. The response
, original_response
, and entry
objects exposed by the Core caching engine are instances of this class.
Response
objects respond to a variety of convenience methods, including those defined in Rack::Response::Helpers, Rack::Cache::Headers, and Rack::Cache::ResponseHeaders.
Note that Rack::Cache::Response
is not a subclass of Rack::Response and does not perform many of the same initialization and finalization tasks. For example, the body is not slurped during initialization and there are no facilities for generating response output.
Constants
- CACHEABLE_RESPONSE_CODES
Status codes of responses that MAY be stored by a cache or used in reply to a subsequent request.
- NOT_MODIFIED_OMIT_HEADERS
Headers that MUST NOT be included with 304 Not Modified responses.
Attributes
Rack
response tuple accessors.
Rack
response tuple accessors.
The time when the Response
object was instantiated.
Rack
response tuple accessors.
Public Class Methods
Create a Response
instance given the response status code, header hash, and body.
# File lib/rack/cache/response.rb 32 def initialize(status, headers, body) 33 @status = status.to_i 34 @headers = Rack::Utils::HeaderHash.new(headers) 35 @body = body 36 @now = Time.now 37 @headers['Date'] ||= @now.httpdate 38 end
Public Instance Methods
The age of the response.
# File lib/rack/cache/response.rb 148 def age 149 (headers['Age'] || [(now - date).to_i, 0].max).to_i 150 end
A Hash of name=value pairs that correspond to the Cache-Control header. Valueless parameters (e.g., must-revalidate, no-store) have a Hash value of true. This method always returns a Hash, empty if no Cache-Control header is present.
# File lib/rack/cache/response.rb 68 def cache_control 69 @cache_control ||= CacheControl.new(headers['Cache-Control']) 70 end
Set the Cache-Control header to the values specified by the Hash. See the cache_control
method for information on expected Hash structure.
# File lib/rack/cache/response.rb 74 def cache_control=(value) 75 if value.respond_to? :to_hash 76 cache_control.clear 77 cache_control.merge!(value) 78 value = cache_control.to_s 79 end 80 81 if value.nil? || value.empty? 82 headers.delete('Cache-Control') 83 else 84 headers['Cache-Control'] = value 85 end 86 end
Determine if the response is worth caching under any circumstance. Responses marked “private” with an explicit Cache-Control directive are considered uncacheable
Responses with neither a freshness lifetime (Expires, max-age) nor cache validator (Last-Modified, ETag) are considered uncacheable.
# File lib/rack/cache/response.rb 102 def cacheable? 103 return false unless CACHEABLE_RESPONSE_CODES.include?(status) 104 return false if cache_control.no_store? || cache_control.private? 105 validateable? || fresh? 106 end
Set the response's time-to-live for private/client caches. This adjusts the Cache-Control/max-age directive.
# File lib/rack/cache/response.rb 205 def client_ttl=(seconds) 206 self.max_age = age + seconds 207 end
The date, as specified by the Date header. When no Date header is present, set the Date header to Time.now and return.
# File lib/rack/cache/response.rb 138 def date 139 if date = headers['Date'] 140 Time.httpdate(date) 141 else 142 headers['Date'] = now.httpdate unless headers.frozen? 143 now 144 end 145 end
The literal value of ETag HTTP header or nil if no ETag is specified.
# File lib/rack/cache/response.rb 216 def etag 217 headers['ETag'] 218 end
Mark the response stale by setting the Age header to be equal to the maximum age of the response.
# File lib/rack/cache/response.rb 132 def expire! 133 headers['Age'] = max_age.to_s if fresh? 134 end
The value of the Expires header as a Time object.
# File lib/rack/cache/response.rb 165 def expires 166 headers['Expires'] && Time.httpdate(headers['Expires']) 167 rescue ArgumentError 168 nil 169 end
Determine if the response is “fresh”. Fresh responses may be served from cache without any interaction with the origin. A response is considered fresh when it includes a Cache-Control/max-age indicator or Expiration header and the calculated age is less than the freshness lifetime.
# File lib/rack/cache/response.rb 92 def fresh? 93 ttl && ttl > 0 94 end
# File lib/rack/cache/response.rb 40 def initialize_copy(other) 41 super 42 @headers = other.headers.dup 43 end
The String value of the Last-Modified header exactly as it appears in the response (i.e., no date parsing / conversion is performed).
# File lib/rack/cache/response.rb 211 def last_modified 212 headers['Last-Modified'] 213 end
The number of seconds after the time specified in the response's Date header when the the response should no longer be considered fresh. First check for a r-maxage directive, then a s-maxage directive, then a max-age directive, and then fall back on an expires header; return nil when no maximum age can be established.
# File lib/rack/cache/response.rb 157 def max_age 158 cache_control.reverse_max_age || 159 cache_control.shared_max_age || 160 cache_control.max_age || 161 (expires && (expires - date)) 162 end
The number of seconds after which the response should no longer be considered fresh. Sets the Cache-Control max-age directive.
# File lib/rack/cache/response.rb 173 def max_age=(value) 174 self.cache_control = cache_control.merge('max-age' => value.to_s) 175 end
Indicates that the cache must not serve a stale response in any circumstance without first revalidating with the origin. When present, the TTL of the response should not be overriden to be greater than the value provided by the origin.
# File lib/rack/cache/response.rb 126 def must_revalidate? 127 cache_control.must_revalidate || cache_control.proxy_revalidate 128 end
Modify the response so that it conforms to the rules defined for '304 Not Modified'. This sets the status, removes the body, and discards any headers that MUST NOT be included in 304 responses.
tools.ietf.org/html/rfc2616#section-10.3.5
# File lib/rack/cache/response.rb 238 def not_modified! 239 body.close if body.respond_to?(:close) 240 self.status = 304 241 self.body = [] 242 NOT_MODIFIED_OMIT_HEADERS.each { |name| headers.delete(name) } 243 nil 244 end
Mark the response “private”, making it ineligible for serving other clients.
# File lib/rack/cache/response.rb 116 def private=(value) 117 value = value ? true : nil 118 self.cache_control = cache_control. 119 merge('public' => !value, 'private' => value) 120 end
Like shared_max_age=
but sets the r-maxage directive, which applies only to reverse caches.
# File lib/rack/cache/response.rb 185 def reverse_max_age=(value) 186 self.cache_control = cache_control.merge('r-maxage' => value.to_s) 187 end
Return the status, headers, and body in a three-tuple.
# File lib/rack/cache/response.rb 46 def to_a 47 [status, headers.to_hash, body] 48 end
The response's time-to-live in seconds, or nil when no freshness information is present in the response. When the responses ttl
is <= 0, the response may not be served from cache without first revalidating with the origin.
# File lib/rack/cache/response.rb 193 def ttl 194 max_age - age if max_age 195 end
Set the response's time-to-live for shared caches to the specified number of seconds. This adjusts the Cache-Control/s-maxage directive.
# File lib/rack/cache/response.rb 199 def ttl=(seconds) 200 self.shared_max_age = age + seconds 201 end
Determine if the response includes headers that can be used to validate the response with the origin using a conditional GET request.
# File lib/rack/cache/response.rb 110 def validateable? 111 headers.key?('Last-Modified') || headers.key?('ETag') 112 end
The literal value of the Vary header, or nil when no header is present.
# File lib/rack/cache/response.rb 247 def vary 248 headers['Vary'] 249 end
Does the response include a Vary header?
# File lib/rack/cache/response.rb 252 def vary? 253 ! vary.nil? 254 end
An array of header names given in the Vary header or an empty array when no Vary header is present.
# File lib/rack/cache/response.rb 258 def vary_header_names 259 return [] unless vary = headers['Vary'] 260 vary.split(/[\s,]+/) 261 end