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|
module ActiveSupport
module Cache
module Strategy
module LocalCache
# this allows caching of the fact that there is nothing in the remote cache
NULL = 'remote_cache_store:null'
def with_local_cache
Thread.current[thread_local_key] = MemoryStore.new
yield
ensure
Thread.current[thread_local_key] = nil
end
def middleware
@middleware ||= begin
klass = Class.new
klass.class_eval(<<-EOS, __FILE__, __LINE__)
def initialize(app)
@app = app
end
def call(env)
Thread.current[:#{thread_local_key}] = MemoryStore.new
@app.call(env)
ensure
Thread.current[:#{thread_local_key}] = nil
end
EOS
klass
end
end
def read(key, options = nil)
value = local_cache && local_cache.read(key)
if value == NULL
nil
elsif value.nil?
value = super
local_cache.write(key, value || NULL) if local_cache
value
else
# forcing the value to be immutable
value.dup
end
end
def write(key, value, options = nil)
value = value.to_s if respond_to?(:raw?) && raw?(options)
local_cache.write(key, value || NULL) if local_cache
super
end
def delete(key, options = nil)
local_cache.write(key, NULL) if local_cache
super
end
def exist(key, options = nil)
value = local_cache.read(key) if local_cache
if value == NULL
false
elsif value
true
else
super
end
end
def increment(key, amount = 1)
if value = super
local_cache.write(key, value.to_s) if local_cache
value
else
nil
end
end
def decrement(key, amount = 1)
if value = super
local_cache.write(key, value.to_s) if local_cache
value
else
nil
end
end
def clear
local_cache.clear if local_cache
super
end
private
def thread_local_key
@thread_local_key ||= "#{self.class.name.underscore}_local_cache".gsub("/", "_").to_sym
end
def local_cache
Thread.current[thread_local_key]
end
end
end
end
end
|
