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, line 40 def initialize(status, headers, body) @status = status.to_i @headers = Headers[headers] @body = body @now = Time.now @headers['date'] ||= @now.httpdate end
Public Instance Methods
The age of the response.
# File lib/rack/cache/response.rb, line 160 def age (headers['age'] || [(now - date).to_i, 0].max).to_i 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, line 77 def cache_control @cache_control ||= CacheControl.new(headers['cache-control']) 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, line 83 def cache_control=(value) if value.respond_to? :to_hash cache_control.clear cache_control.merge!(value) value = cache_control.to_s end if value.nil? || value.empty? headers.delete('cache-control') else headers['cache-control'] = value end 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, line 111 def cacheable? return false unless CACHEABLE_RESPONSE_CODES.include?(status) return false if cache_control.no_store? || cache_control.private? validateable? || fresh? 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, line 217 def client_ttl=(seconds) self.max_age = age + seconds end
The date, as specified by the Date header. When no Date header is present or is unparseable, set the Date header to Time.now and return.
# File lib/rack/cache/response.rb, line 147 def date if date = headers['date'] Time.httpdate(date) else headers['date'] = now.httpdate unless headers.frozen? now end rescue ArgumentError headers['date'] = now.httpdate unless headers.frozen? now end
The literal value of etag HTTP header or nil if no etag is specified.
# File lib/rack/cache/response.rb, line 228 def etag headers['etag'] 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, line 141 def expire! headers['age'] = max_age.to_s if fresh? end
The value of the expires header as a Time object.
# File lib/rack/cache/response.rb, line 177 def expires headers['expires'] && Time.httpdate(headers['expires']) rescue ArgumentError nil 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, line 101 def fresh? ttl && ttl > 0 end
# File lib/rack/cache/response.rb, line 48 def initialize_copy(other) super @headers = other.headers.dup @cache_control = nil 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, line 223 def last_modified headers['last-modified'] 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, line 169 def max_age cache_control.reverse_max_age || cache_control.shared_max_age || cache_control.max_age || (expires && (expires - date)) 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, line 185 def max_age=(value) self.cache_control = cache_control.merge('max-age' => value.to_s) 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, line 135 def must_revalidate? cache_control.must_revalidate || cache_control.proxy_revalidate 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, line 250 def not_modified! body.close if body.respond_to?(:close) self.status = 304 self.body = [] NOT_MODIFIED_OMIT_HEADERS.each { |name| headers.delete(name) } nil end
Mark the response “private”, making it ineligible for serving other clients.
# File lib/rack/cache/response.rb, line 125 def private=(value) value = value ? true : nil self.cache_control = cache_control. merge('public' => !value, 'private' => value) end
Like shared_max_age= but sets the r-maxage directive, which applies only to reverse caches.
# File lib/rack/cache/response.rb, line 197 def reverse_max_age=(value) self.cache_control = cache_control.merge('r-maxage' => value.to_s) end
Return the status, headers, and body in a three-tuple.
# File lib/rack/cache/response.rb, line 55 def to_a [status, headers.to_hash, body] 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, line 205 def ttl max_age - age if max_age 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, line 211 def ttl=(seconds) self.shared_max_age = age + seconds 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, line 119 def validateable? headers.key?('last-modified') || headers.key?('etag') end
The literal value of the vary header, or nil when no header is present.
# File lib/rack/cache/response.rb, line 259 def vary headers['vary'] end
Does the response include a vary header?
# File lib/rack/cache/response.rb, line 264 def vary? ! vary.nil? 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, line 270 def vary_header_names return [] unless vary = headers['vary'] vary.split(/[\s,]+/) end