| Class | Rack::Cache::Response |
| In: |
lib/rack/cache/response.rb
|
| Parent: | Object |
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.
| CACHEABLE_RESPONSE_CODES | = | [ 200, # OK 203, # Non-Authoritative Information 300, # Multiple Choices 301, # Moved Permanently 302, # Found 404, # Not Found 410 | Status codes of responses that MAY be stored by a cache or used in reply to a subsequent request. | |
| NOT_MODIFIED_OMIT_HEADERS | = | %w[ Allow Content-Encoding Content-Language Content-Length Content-MD5 Content-Type Last-Modified ].to_set | Headers that MUST NOT be included with 304 Not Modified responses. |
Create a Response instance given the response status code, header hash, and body.
# File lib/rack/cache/response.rb, line 32
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
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 68
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, line 74
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, line 102
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
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, line 138
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, line 207
207: def etag
208: headers['ETag']
209: end
The value of the Expires header as a Time object.
# File lib/rack/cache/response.rb, line 164
164: def expires
165: headers['Expires'] && Time.httpdate(headers['Expires'])
166: 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 92
92: def fresh?
93: ttl && ttl > 0
94: end
# File lib/rack/cache/response.rb, line 40
40: def initialize_copy(other)
41: super
42: @headers = other.headers.dup
43: 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 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 157
157: def max_age
158: cache_control.shared_max_age ||
159: cache_control.max_age ||
160: (expires && (expires - date))
161: 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 126
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, line 229
229: def not_modified!
230: body.close if body.respond_to?(:close)
231: self.status = 304
232: self.body = []
233: NOT_MODIFIED_OMIT_HEADERS.each { |name| headers.delete(name) }
234: nil
235: end
Mark the response "private", making it ineligible for serving other clients.
# File lib/rack/cache/response.rb, line 116
116: def private=(value)
117: value = value ? true : nil
118: self.cache_control = cache_control.
119: merge('public' => !value, 'private' => value)
120: end
Return the status, headers, and body in a three-tuple.
# File lib/rack/cache/response.rb, line 46
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, line 184
184: def ttl
185: max_age - age if max_age
186: 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 110
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, line 238
238: def vary
239: headers['Vary']
240: end
Does the response include a Vary header?
# File lib/rack/cache/response.rb, line 243
243: def vary?
244: ! vary.nil?
245: end