diff options
Diffstat (limited to 'actionpack/lib/action_dispatch/http/cache.rb')
| -rw-r--r-- | actionpack/lib/action_dispatch/http/cache.rb | 146 |
1 files changed, 97 insertions, 49 deletions
diff --git a/actionpack/lib/action_dispatch/http/cache.rb b/actionpack/lib/action_dispatch/http/cache.rb index cc1cb3f0f0..f67b13f657 100644 --- a/actionpack/lib/action_dispatch/http/cache.rb +++ b/actionpack/lib/action_dispatch/http/cache.rb @@ -1,26 +1,24 @@ +# frozen_string_literal: true module ActionDispatch module Http module Cache module Request - - HTTP_IF_MODIFIED_SINCE = 'HTTP_IF_MODIFIED_SINCE'.freeze - HTTP_IF_NONE_MATCH = 'HTTP_IF_NONE_MATCH'.freeze + HTTP_IF_MODIFIED_SINCE = "HTTP_IF_MODIFIED_SINCE" + HTTP_IF_NONE_MATCH = "HTTP_IF_NONE_MATCH" def if_modified_since - if since = env[HTTP_IF_MODIFIED_SINCE] + if since = get_header(HTTP_IF_MODIFIED_SINCE) Time.rfc2822(since) rescue nil end end def if_none_match - env[HTTP_IF_NONE_MATCH] + get_header HTTP_IF_NONE_MATCH end def if_none_match_etags - (if_none_match ? if_none_match.split(/\s*,\s*/) : []).collect do |etag| - etag.gsub(/^\"|\"$/, "") - end + if_none_match ? if_none_match.split(/\s*,\s*/) : [] end def not_modified?(modified_at) @@ -29,8 +27,8 @@ module ActionDispatch def etag_matches?(etag) if etag - etag = etag.gsub(/^\"|\"$/, "") - if_none_match_etags.include?(etag) + validators = if_none_match_etags + validators.include?(etag) || validators.include?("*") end end @@ -51,53 +49,96 @@ module ActionDispatch end module Response - attr_reader :cache_control, :etag - alias :etag? :etag + attr_reader :cache_control def last_modified - if last = headers[LAST_MODIFIED] + if last = get_header(LAST_MODIFIED) Time.httpdate(last) end end def last_modified? - headers.include?(LAST_MODIFIED) + has_header? LAST_MODIFIED end def last_modified=(utc_time) - headers[LAST_MODIFIED] = utc_time.httpdate + set_header LAST_MODIFIED, utc_time.httpdate end def date - if date_header = headers[DATE] + if date_header = get_header(DATE) Time.httpdate(date_header) end end def date? - headers.include?(DATE) + has_header? DATE end def date=(utc_time) - headers[DATE] = utc_time.httpdate + set_header DATE, utc_time.httpdate end - def etag=(etag) - key = ActiveSupport::Cache.expand_cache_key(etag) - @etag = self[ETAG] = %("#{Digest::MD5.hexdigest(key)}") + # 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. + def etag=(weak_validators) + self.weak_etag = weak_validators + end + + def weak_etag=(weak_validators) + set_header "ETag", generate_weak_etag(weak_validators) + end + + def strong_etag=(strong_validators) + set_header "ETag", generate_strong_etag(strong_validators) + end + + def etag?; etag; end + + # True if an ETag is set and it's a weak validator (preceded with W/) + def weak_etag? + etag? && etag.starts_with?('W/"') + end + + # True if an ETag is set and it isn't a weak validator (not preceded with W/) + def strong_etag? + etag? && !weak_etag? end private - DATE = 'Date'.freeze - LAST_MODIFIED = "Last-Modified".freeze - ETAG = "ETag".freeze - CACHE_CONTROL = "Cache-Control".freeze - SPECIAL_KEYS = Set.new(%w[extras no-cache max-age public must-revalidate]) + DATE = "Date" + LAST_MODIFIED = "Last-Modified" + SPECIAL_KEYS = Set.new(%w[extras no-cache max-age public private must-revalidate]) + + def generate_weak_etag(validators) + "W/#{generate_strong_etag(validators)}" + end + + def generate_strong_etag(validators) + %("#{ActiveSupport::Digest.hexdigest(ActiveSupport::Cache.expand_cache_key(validators))}") + end def cache_control_segments - if cache_control = self[CACHE_CONTROL] - cache_control.delete(' ').split(',') + if cache_control = _cache_control + cache_control.delete(" ").split(",") else [] end @@ -107,10 +148,10 @@ module ActionDispatch cache_control = {} cache_control_segments.each do |segment| - directive, argument = segment.split('=', 2) + directive, argument = segment.split("=", 2) if SPECIAL_KEYS.include? directive - key = directive.tr('-', '_') + key = directive.tr("-", "_") cache_control[key.to_sym] = argument || true else cache_control[:extras] ||= [] @@ -123,51 +164,58 @@ module ActionDispatch def prepare_cache_control! @cache_control = cache_control_headers - @etag = self[ETAG] end + DEFAULT_CACHE_CONTROL = "max-age=0, private, must-revalidate" + NO_CACHE = "no-cache" + PUBLIC = "public" + PRIVATE = "private" + MUST_REVALIDATE = "must-revalidate" + def handle_conditional_get! - if etag? || last_modified? || !@cache_control.empty? - set_conditional_cache_control! + # 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 - DEFAULT_CACHE_CONTROL = "max-age=0, private, must-revalidate".freeze - NO_CACHE = "no-cache".freeze - PUBLIC = "public".freeze - PRIVATE = "private".freeze - MUST_REVALIDATE = "must-revalidate".freeze - - def set_conditional_cache_control! + def merge_and_normalize_cache_control!(cache_control) control = {} cc_headers = cache_control_headers if extras = cc_headers.delete(:extras) - @cache_control[:extras] ||= [] - @cache_control[:extras] += extras - @cache_control[:extras].uniq! + cache_control[:extras] ||= [] + cache_control[:extras] += extras + cache_control[:extras].uniq! end control.merge! cc_headers - control.merge! @cache_control + control.merge! cache_control if control.empty? - self[CACHE_CONTROL] = DEFAULT_CACHE_CONTROL + # Let middleware handle default behavior elsif control[:no_cache] - self[CACHE_CONTROL] = NO_CACHE + self._cache_control = NO_CACHE if control[:extras] - self[CACHE_CONTROL] += ", #{control[:extras].join(', ')}" + self._cache_control = _cache_control + ", #{control[:extras].join(', ')}" end else - extras = control[:extras] + extras = control[:extras] max_age = control[:max_age] + stale_while_revalidate = control[:stale_while_revalidate] + stale_if_error = control[:stale_if_error] options = [] options << "max-age=#{max_age.to_i}" if max_age options << (control[:public] ? PUBLIC : PRIVATE) options << MUST_REVALIDATE if control[:must_revalidate] + options << "stale-while-revalidate=#{stale_while_revalidate.to_i}" if stale_while_revalidate + options << "stale-if-error=#{stale_if_error.to_i}" if stale_if_error options.concat(extras) if extras - self[CACHE_CONTROL] = options.join(", ") + self._cache_control = options.join(", ") end end end |