Module: ActionDispatch::Http::Cache::Response
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Included In:
| |
Defined in: | actionpack/lib/action_dispatch/http/cache.rb |
Constant Summary
-
DATE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 143"Date"
-
DEFAULT_CACHE_CONTROL =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 183"max-age=0, private, must-revalidate"
-
IMMUTABLE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 189"immutable"
-
LAST_MODIFIED =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 144"Last-Modified"
-
MUST_REVALIDATE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 188"must-revalidate"
-
NO_CACHE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 185"no-cache"
-
NO_STORE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 184"no-store"
-
PRIVATE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 187"private"
-
PUBLIC =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 186"public"
-
SPECIAL_KEYS =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 145Set.new(%w[extras no-store no-cache max-age public private must-revalidate])
Instance Attribute Summary
- #cache_control readonly
- #date rw
- #date=(utc_time) rw
- #date? ⇒ Boolean rw
-
#etag=(weak_validators)
rw
This method sets a weak ETag validator on the response so browsers and proxies may cache the response, keyed on the ETag.
- #etag? ⇒ Boolean rw
- #last_modified rw
- #last_modified=(utc_time) rw
- #last_modified? ⇒ Boolean rw
- #strong_etag=(strong_validators) rw
-
#strong_etag? ⇒ Boolean
rw
True if an ETag is set, and it isn’t a weak validator (not preceded with
W/
). - #weak_etag=(weak_validators) rw
-
#weak_etag? ⇒ Boolean
rw
True if an ETag is set, and it’s a weak validator (preceded with
W/
).
Instance Method Summary
- #cache_control_headers private
- #cache_control_segments private
- #generate_strong_etag(validators) private
- #generate_weak_etag(validators) private
- #handle_conditional_get! private
- #merge_and_normalize_cache_control!(cache_control) private
- #prepare_cache_control! private
Instance Attribute Details
#cache_control (readonly)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 69
attr_reader :cache_control
#date (rw)
[ GitHub ]#date=(utc_time) (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 95
def date=(utc_time) set_header DATE, utc_time.httpdate end
#date? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 91
def date? has_header? DATE end
#etag=(weak_validators) (rw)
This method sets a weak ETag validator on the response so browsers and proxies may cache the response, keyed on the ETag. On subsequent requests, the If-None-Match
header is set to the cached ETag. If it matches the current ETag, we can return a 304 Not Modified
response with no body, letting the browser or proxy know that their cache is current. Big savings in request time and network bandwidth.
Weak ETags are considered to be semantically equivalent but not byte-for-byte identical. This is perfect for browser caching of HTML pages where we don’t care about exact equality, just what the user is viewing.
Strong ETags are considered byte-for-byte identical. They allow a browser or proxy cache to support ::Range
requests, useful for paging through a PDF file or scrubbing through a video. Some CDNs only support strong ETags and will ignore weak ETags entirely.
Weak ETags are what we almost always need, so they’re the default. Check out #strong_etag= to provide a strong ETag validator.
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 117
def etag=(weak_validators) self.weak_etag = weak_validators end
#etag? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 129
def etag?; etag; end
#last_modified (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 71
def last_modified if last = get_header(LAST_MODIFIED) Time.httpdate(last) end end
#last_modified=(utc_time) (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 81
def last_modified=(utc_time) set_header LAST_MODIFIED, utc_time.httpdate end
#last_modified? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 77
def last_modified? has_header? LAST_MODIFIED end
#strong_etag=(strong_validators) (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 125
def strong_etag=(strong_validators) set_header "ETag", generate_strong_etag(strong_validators) end
#strong_etag? ⇒ Boolean
(rw)
True if an ETag is set, and it isn’t a weak validator (not preceded with W/
).
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 138
def strong_etag? etag? && !weak_etag? end
#weak_etag=(weak_validators) (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 121
def weak_etag=(weak_validators) set_header "ETag", generate_weak_etag(weak_validators) end
#weak_etag? ⇒ Boolean
(rw)
True if an ETag is set, and it’s a weak validator (preceded with W/
).
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 132
def weak_etag? etag? && etag.start_with?('W/"') end
Instance Method Details
#cache_control_headers (private)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 161
def cache_control_headers cache_control = {} cache_control_segments&.each do |segment| directive, argument = segment.split("=", 2) if SPECIAL_KEYS.include? directive directive.tr!("-", "_") cache_control[directive.to_sym] = argument || true else cache_control[:extras] ||= [] cache_control[:extras] << segment end end cache_control end
#cache_control_segments (private)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 155
def cache_control_segments if cache_control = _cache_control cache_control.delete(" ").split(",") end end
#generate_strong_etag(validators) (private)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 151
def generate_strong_etag(validators) %("#{ActiveSupport::Digest.hexdigest(ActiveSupport::Cache. (validators))}") end
#generate_weak_etag(validators) (private)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 147
def generate_weak_etag(validators) "W/#{generate_strong_etag(validators)}" end
#handle_conditional_get! (private)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 191
def handle_conditional_get! # Normally default cache control setting is handled by ETag middleware. But, if # an etag is already set, the middleware defaults to `no-cache` unless a default # `Cache-Control` value is previously set. So, set a default one here. if (etag? || last_modified?) && !self._cache_control self._cache_control = DEFAULT_CACHE_CONTROL end end
#merge_and_normalize_cache_control!(cache_control) (private)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 200
def merge_and_normalize_cache_control!(cache_control) control = cache_control_headers return if control.empty? && cache_control.empty? # Let middleware handle default behavior if cache_control.any? # Any caching directive coming from a controller overrides no-cache/no-store in # the default Cache-Control header. control.delete(:no_cache) control.delete(:no_store) if extras = control.delete(:extras) cache_control[:extras] ||= [] cache_control[:extras] += extras cache_control[:extras].uniq! end control.merge! cache_control end = [] if control[:no_store] << PRIVATE if control[:private] << NO_STORE elsif control[:no_cache] << PUBLIC if control[:public] << NO_CACHE .concat(control[:extras]) if control[:extras] else extras = control[:extras] max_age = control[:max_age] stale_while_revalidate = control[:stale_while_revalidate] stale_if_error = control[:stale_if_error] << "max-age=#{max_age.to_i}" if max_age << (control[:public] ? PUBLIC : PRIVATE) << MUST_REVALIDATE if control[:must_revalidate] << "stale-while-revalidate=#{stale_while_revalidate.to_i}" if stale_while_revalidate << "stale-if-error=#{stale_if_error.to_i}" if stale_if_error << IMMUTABLE if control[:immutable] .concat(extras) if extras end self._cache_control = .join(", ") end
#prepare_cache_control! (private)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 179
def prepare_cache_control! @cache_control = cache_control_headers end