MCollective::Cache

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

Public Class Methods

check_cache!(cache_name) click to toggle source

(Not documented)

    # File lib/mcollective/cache.rb, line 70
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)
72:     end

delete!(cache_name) click to toggle source

(Not documented)

    # File lib/mcollective/cache.rb, line 80
80:     def self.delete!(cache_name)
81:       check_cache!(cache_name)
82: 
83:       @locks_mutex.synchronize do
84:         @cache_locks.delete(cache_name)
85:         @cache.delete(cache_name)
86:       end
87: 
88:       true
89:     end

has_cache?(cache_name) click to toggle source

(Not documented)

    # File lib/mcollective/cache.rb, line 74
74:     def self.has_cache?(cache_name)
75:       @locks_mutex.synchronize do
76:         @cache.include?(cache_name)
77:       end
78:     end

invalidate!(cache_name, key) click to toggle source

(Not documented)

     # File lib/mcollective/cache.rb, line 139
139:     def self.invalidate!(cache_name, key)
140:       check_cache!(cache_name)
141: 
142:       @cache_locks[cache_name].synchronize do
143:         return false unless @cache[cache_name].include?(key)
144: 
145:         @cache[cache_name].delete(key)
146:       end
147:     end

read(cache_name, key) click to toggle source

(Not documented)

     # File lib/mcollective/cache.rb, line 103
103:     def self.read(cache_name, key)
104:       check_cache!(cache_name)
105: 
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)
108:       end
109: 
110:       log_code(:PLMC12, "Cache hit on '%{cache_name}' key '%{item}'", :debug, :cache_name => cache_name, :item => key)
111: 
112:       @cache_locks[cache_name].synchronize do
113:         @cache[cache_name][key][:value]
114:       end
115:     end

setup(cache_name, ttl=300) click to toggle source

(Not documented)

    # File lib/mcollective/cache.rb, line 56
56:     def self.setup(cache_name, ttl=300)
57:       @locks_mutex.synchronize do
58:         break if @cache_locks.include?(cache_name)
59: 
60:         @cache_locks[cache_name] = Mutex.new
61: 
62:         @cache_locks[cache_name].synchronize do
63:           @cache[cache_name] = {:max_age => Float(ttl)}
64:         end
65:       end
66: 
67:       true
68:     end

synchronize(cache_name) click to toggle source

(Not documented)

     # File lib/mcollective/cache.rb, line 129
129:     def self.synchronize(cache_name)
130:       check_cache!(cache_name)
131: 
132:       raise_code(:PLMC14, "No block supplied to synchronize on cache '%{cache_name}'", :debug, :cache_name => cache_name) unless block_given?
133: 
134:       @cache_locks[cache_name].synchronize do
135:         yield
136:       end
137:     end

ttl(cache_name, key) click to toggle source

(Not documented)

     # File lib/mcollective/cache.rb, line 117
117:     def self.ttl(cache_name, key)
118:       check_cache!(cache_name)
119: 
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)
123:         end
124: 
125:         @cache[cache_name][:max_age] - (Time.now - @cache[cache_name][key][:cache_create_time])
126:       end
127:     end

write(cache_name, key, value) click to toggle source

(Not documented)

     # File lib/mcollective/cache.rb, line 91
 91:     def self.write(cache_name, key, value)
 92:       check_cache!(cache_name)
 93: 
 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
 98:       end
 99: 
100:       value
101:     end

In Files

Methods

Files

Class Index

MCollective::Cache

Public Class Methods