2 # A class to manage a number of named caches. Each cache can have a unique
3 # timeout for keys in it and each cache has an independent Mutex protecting
6 # This cache is setup early in the process of loading the mcollective
7 # libraries, before any threads are created etc making it suitable as a
8 # cross thread cache or just a store for Mutexes you need to use across
9 # threads like in an Agent or something.
11 # # sets up a new cache, noop if it already exist
12 # Cache.setup(:ddl, 600)
15 # # writes an item to the :ddl cache, this item will
16 # # be valid on the cache for 600 seconds
17 # Cache.write(:ddl, :something, "value")
20 # # reads from the cache, read failures due to non existing
21 # # data or expired data will raise an exception
22 # Cache.read(:ddl, :something)
25 # # time left till expiry, raises if nothing is found
26 # Cache.ttl(:ddl, :something)
29 # # forcibly evict something from the cache
30 # Cache.invalidate!(:ddl, :something)
33 # # deletes an entire named cache and its mutexes
37 # # you can also just use this cache as a global mutex store
38 # Cache.setup(:mylock)
40 # Cache.synchronize(:mylock) do
47 # protects access to @cache_locks and top level @cache
48 @locks_mutex = Mutex.new
50 # stores a mutex per named cache
53 # the named caches protected by items in @cache_locks
56 def self.setup(cache_name, ttl=300)
57 @locks_mutex.synchronize do
58 break if @cache_locks.include?(cache_name)
60 @cache_locks[cache_name] = Mutex.new
62 @cache_locks[cache_name].synchronize do
63 @cache[cache_name] = {:max_age => Float(ttl)}
70 def self.check_cache!(cache_name)
71 raise_code(:PLMC13, "Could not find a cache called '%{cache_name}'", :debug, :cache_name => cache_name) unless has_cache?(cache_name)
74 def self.has_cache?(cache_name)
75 @locks_mutex.synchronize do
76 @cache.include?(cache_name)
80 def self.delete!(cache_name)
81 check_cache!(cache_name)
83 @locks_mutex.synchronize do
84 @cache_locks.delete(cache_name)
85 @cache.delete(cache_name)
91 def self.write(cache_name, key, value)
92 check_cache!(cache_name)
94 @cache_locks[cache_name].synchronize do
95 @cache[cache_name][key] ||= {}
96 @cache[cache_name][key][:cache_create_time] = Time.now
97 @cache[cache_name][key][:value] = value
103 def self.read(cache_name, key)
104 check_cache!(cache_name)
106 unless ttl(cache_name, key) > 0
107 raise_code(:PLMC11, "Cache expired on '%{cache_name}' key '%{item}'", :debug, :cache_name => cache_name, :item => key)
110 log_code(:PLMC12, "Cache hit on '%{cache_name}' key '%{item}'", :debug, :cache_name => cache_name, :item => key)
112 @cache_locks[cache_name].synchronize do
113 @cache[cache_name][key][:value]
117 def self.ttl(cache_name, key)
118 check_cache!(cache_name)
120 @cache_locks[cache_name].synchronize do
121 unless @cache[cache_name].include?(key)
122 raise_code(:PLMC15, "No item called '%{item}' for cache '%{cache_name}'", :debug, :cache_name => cache_name, :item => key)
125 @cache[cache_name][:max_age] - (Time.now - @cache[cache_name][key][:cache_create_time])
129 def self.synchronize(cache_name)
130 check_cache!(cache_name)
132 raise_code(:PLMC14, "No block supplied to synchronize on cache '%{cache_name}'", :debug, :cache_name => cache_name) unless block_given?
134 @cache_locks[cache_name].synchronize do
139 def self.invalidate!(cache_name, key)
140 check_cache!(cache_name)
142 @cache_locks[cache_name].synchronize do
143 return false unless @cache[cache_name].include?(key)
145 @cache[cache_name].delete(key)