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-rw-r--r--activesupport/lib/active_support/cache.rb83
1 files changed, 62 insertions, 21 deletions
diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index 4d8c2046e8..44f80dd379 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -88,10 +88,11 @@ module ActiveSupport
private
def retrieve_cache_key(key)
case
- when key.respond_to?(:cache_key) then key.cache_key
- when key.is_a?(Array) then key.map { |element| retrieve_cache_key(element) }.to_param
- when key.respond_to?(:to_a) then retrieve_cache_key(key.to_a)
- else key.to_param
+ when key.respond_to?(:cache_key_with_version) then key.cache_key_with_version
+ when key.respond_to?(:cache_key) then key.cache_key
+ when key.is_a?(Array) then key.map { |element| retrieve_cache_key(element) }.to_param
+ when key.respond_to?(:to_a) then retrieve_cache_key(key.to_a)
+ else key.to_param
end.to_s
end
@@ -219,6 +220,10 @@ module ActiveSupport
# cache = ActiveSupport::Cache::MemoryStore.new(expires_in: 5.minutes)
# cache.write(key, value, expires_in: 1.minute) # Set a lower value for one entry
#
+ # Setting <tt>:version</tt> verifies the cache stored under <tt>name</tt>
+ # is of the same version. nil is returned on mismatches despite contents.
+ # This feature is used to support recyclable cache keys.
+ #
# Setting <tt>:race_condition_ttl</tt> is very useful in situations where
# a cache entry is used very frequently and is under heavy load. If a
# cache expires and due to heavy load several different processes will try
@@ -287,6 +292,7 @@ module ActiveSupport
instrument(:read, name, options) do |payload|
cached_entry = read_entry(key, options) unless options[:force]
entry = handle_expired_entry(cached_entry, key, options)
+ entry = nil if entry && entry.mismatched?(normalize_version(name, options))
payload[:super_operation] = :fetch if payload
payload[:hit] = !!entry if payload
end
@@ -303,21 +309,30 @@ module ActiveSupport
end
end
- # Fetches data from the cache, using the given key. If there is data in
+ # Reads data from the cache, using the given key. If there is data in
# the cache with the given key, then that data is returned. Otherwise,
# +nil+ is returned.
#
+ # Note, if data was written with the <tt>:expires_in<tt> or <tt>:version</tt> options,
+ # both of these conditions are applied before the data is returned.
+ #
# Options are passed to the underlying cache implementation.
def read(name, options = nil)
options = merged_options(options)
- key = normalize_key(name, options)
+ key = normalize_key(name, options)
+ version = normalize_version(name, options)
+
instrument(:read, name, options) do |payload|
entry = read_entry(key, options)
+
if entry
if entry.expired?
delete_entry(key, options)
payload[:hit] = false if payload
nil
+ elsif entry.mismatched?(version)
+ payload[:hit] = false if payload
+ nil
else
payload[:hit] = true if payload
entry.value
@@ -341,11 +356,15 @@ module ActiveSupport
results = {}
names.each do |name|
- key = normalize_key(name, options)
- entry = read_entry(key, options)
+ key = normalize_key(name, options)
+ version = normalize_version(name, options)
+ entry = read_entry(key, options)
+
if entry
if entry.expired?
delete_entry(key, options)
+ elsif entry.mismatched?(version)
+ # Skip mismatched versions
else
results[name] = entry.value
end
@@ -396,7 +415,7 @@ module ActiveSupport
options = merged_options(options)
instrument(:write, name, options) do
- entry = Entry.new(value, options)
+ entry = Entry.new(value, options.merge(version: normalize_version(name, options)))
write_entry(normalize_key(name, options), entry, options)
end
end
@@ -420,7 +439,7 @@ module ActiveSupport
instrument(:exist?, name) do
entry = read_entry(normalize_key(name, options), options)
- (entry && !entry.expired?) || false
+ (entry && !entry.expired? && !entry.mismatched?(normalize_version(name, options))) || false
end
end
@@ -517,6 +536,17 @@ module ActiveSupport
end
end
+
+ # Prefixes a key with the namespace. Namespace and key will be delimited
+ # with a colon.
+ def normalize_key(key, options)
+ key = expanded_key(key)
+ namespace = options[:namespace] if options
+ prefix = namespace.is_a?(Proc) ? namespace.call : namespace
+ key = "#{prefix}:#{key}" if prefix
+ key
+ end
+
# Expands key to be a consistent string value. Invokes +cache_key+ if
# object responds to +cache_key+. Otherwise, +to_param+ method will be
# called. If the key is a Hash, then keys will be sorted alphabetically.
@@ -537,14 +567,16 @@ module ActiveSupport
key.to_param
end
- # Prefixes a key with the namespace. Namespace and key will be delimited
- # with a colon.
- def normalize_key(key, options)
- key = expanded_key(key)
- namespace = options[:namespace] if options
- prefix = namespace.is_a?(Proc) ? namespace.call : namespace
- key = "#{prefix}:#{key}" if prefix
- key
+ def normalize_version(key, options = nil)
+ (options && options[:version].try(:to_param)) || expanded_version(key)
+ end
+
+ def expanded_version(key)
+ case
+ when key.respond_to?(:cache_version) then key.cache_version.to_param
+ when key.is_a?(Array) then key.map { |element| expanded_version(element) }.compact.to_param
+ when key.respond_to?(:to_a) then expanded_version(key.to_a)
+ end
end
def instrument(operation, key, options = nil)
@@ -555,6 +587,7 @@ module ActiveSupport
ActiveSupport::Notifications.instrument("cache_#{operation}.active_support", payload) { yield(payload) }
end
+
def log
return unless logger && logger.debug? && !silence?
logger.debug(yield)
@@ -591,13 +624,16 @@ module ActiveSupport
end
end
- # This class is used to represent cache entries. Cache entries have a value and an optional
- # expiration time. The expiration time is used to support the :race_condition_ttl option
- # on the cache.
+ # This class is used to represent cache entries. Cache entries have a value, an optional
+ # expiration time, and an optional version. The expiration time is used to support the :race_condition_ttl option
+ # on the cache. The version is used to support the :version option on the cache for rejecting
+ # mismatches.
#
# Since cache entries in most instances will be serialized, the internals of this class are highly optimized
# using short instance variable names that are lazily defined.
class Entry # :nodoc:
+ attr_reader :version
+
DEFAULT_COMPRESS_LIMIT = 16.kilobytes
# Creates a new cache entry for the specified value. Options supported are
@@ -610,6 +646,7 @@ module ActiveSupport
@value = value
end
+ @version = options[:version]
@created_at = Time.now.to_f
@expires_in = options[:expires_in]
@expires_in = @expires_in.to_f if @expires_in
@@ -619,6 +656,10 @@ module ActiveSupport
compressed? ? uncompress(@value) : @value
end
+ def mismatched?(version)
+ @version && version && @version != version
+ end
+
# Checks if the entry is expired. The +expires_in+ parameter can override
# the value set when the entry was created.
def expired?