A class to manage a number of named caches. Each cache can have a unique timeout for keys in it and each cache has an independent Mutex protecting access to it.
This cache is setup early in the process of loading the mcollective libraries, before any threads are created etc making it suitable as a cross thread cache or just a store for Mutexes you need to use across threads like in an Agent or something.
# sets up a new cache, noop if it already exist Cache.setup(:ddl, 600) => true # writes an item to the :ddl cache, this item will # be valid on the cache for 600 seconds Cache.write(:ddl, :something, "value") => "value" # reads from the cache, read failures due to non existing # data or expired data will raise an exception Cache.read(:ddl, :something) => "value" # time left till expiry, raises if nothing is found Cache.ttl(:ddl, :something) => 500 # forcibly evict something from the cache Cache.invalidate!(:ddl, :something) => "value" # deletes an entire named cache and its mutexes Cache.delete!(:ddl) => true # you can also just use this cache as a global mutex store Cache.setup(:mylock) Cache.synchronize(:mylock) do do_something() end
# File lib/mcollective/cache.rb, line 70 def self.check_cache!(cache_name) raise_code(:PLMC13, "Could not find a cache called '%{cache_name}'", :debug, :cache_name => cache_name) unless has_cache?(cache_name) end
# File lib/mcollective/cache.rb, line 80 def self.delete!(cache_name) check_cache!(cache_name) @locks_mutex.synchronize do @cache_locks.delete(cache_name) @cache.delete(cache_name) end true end
# File lib/mcollective/cache.rb, line 74 def self.has_cache?(cache_name) @locks_mutex.synchronize do @cache.include?(cache_name) end end
# File lib/mcollective/cache.rb, line 139 def self.invalidate!(cache_name, key) check_cache!(cache_name) @cache_locks[cache_name].synchronize do return false unless @cache[cache_name].include?(key) @cache[cache_name].delete(key) end end
# File lib/mcollective/cache.rb, line 103 def self.read(cache_name, key) check_cache!(cache_name) unless ttl(cache_name, key) > 0 raise_code(:PLMC11, "Cache expired on '%{cache_name}' key '%{item}'", :debug, :cache_name => cache_name, :item => key) end log_code(:PLMC12, "Cache hit on '%{cache_name}' key '%{item}'", :debug, :cache_name => cache_name, :item => key) @cache_locks[cache_name].synchronize do @cache[cache_name][key][:value] end end
# File lib/mcollective/cache.rb, line 56 def self.setup(cache_name, ttl=300) @locks_mutex.synchronize do break if @cache_locks.include?(cache_name) @cache_locks[cache_name] = Mutex.new @cache_locks[cache_name].synchronize do @cache[cache_name] = {:max_age => Float(ttl)} end end true end
# File lib/mcollective/cache.rb, line 129 def self.synchronize(cache_name) check_cache!(cache_name) raise_code(:PLMC14, "No block supplied to synchronize on cache '%{cache_name}'", :debug, :cache_name => cache_name) unless block_given? @cache_locks[cache_name].synchronize do yield end end
# File lib/mcollective/cache.rb, line 117 def self.ttl(cache_name, key) check_cache!(cache_name) @cache_locks[cache_name].synchronize do unless @cache[cache_name].include?(key) raise_code(:PLMC15, "No item called '%{item}' for cache '%{cache_name}'", :debug, :cache_name => cache_name, :item => key) end @cache[cache_name][:max_age] - (Time.now - @cache[cache_name][key][:cache_create_time]) end end
# File lib/mcollective/cache.rb, line 91 def self.write(cache_name, key, value) check_cache!(cache_name) @cache_locks[cache_name].synchronize do @cache[cache_name][key] ||= {} @cache[cache_name][key][:cache_create_time] = Time.now @cache[cache_name][key][:value] = value end value end
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