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require 'active_support/core_ext/object/duplicable'
require 'active_support/core_ext/string/inflections'
module ActiveSupport
module Cache
module Strategy
# Caches that implement LocalCache will be backed by an in memory cache for the
# duration of a block. Repeated calls to the cache for the same key will hit the
# in memory cache for faster access.
module LocalCache
# Simple memory backed cache. This cache is not thread safe but is intended only
# for serving as a temporary memory cache for a single thread.
class LocalStore < Store
def initialize
super
@data = {}
end
# Since it isn't thread safe, don't allow synchronizing.
def synchronize # :nodoc:
yield
end
def clear(options = nil)
@data.clear
end
def read_entry(key, options)
@data[key]
end
def write_entry(key, value, options)
@data[key] = value
true
end
def delete_entry(key, options)
!!@data.delete(key)
end
end
# Use a local cache to front for the cache for the duration of a block.
def with_local_cache
save_val = Thread.current[thread_local_key]
begin
Thread.current[thread_local_key] = LocalStore.new
yield
ensure
Thread.current[thread_local_key] = save_val
end
end
# Middleware class can be inserted as a Rack handler to use a local cache for the
# duration of a request.
def middleware
@middleware ||= begin
klass = Class.new
klass.class_eval(<<-EOS, __FILE__, __LINE__ + 1)
class << self
def name
"ActiveSupport::Cache::Strategy::LocalCache"
end
alias :to_s :name
end
def initialize(app)
@app = app
end
def call(env)
Thread.current[:#{thread_local_key}] = LocalStore.new
@app.call(env)
ensure
Thread.current[:#{thread_local_key}] = nil
end
EOS
klass
end
end
def clear(options = nil) # :nodoc:
local_cache.clear(options) if local_cache
super
end
def cleanup(options = nil) # :nodoc:
local_cache.clear(options) if local_cache
super
end
def increment(name, amount = 1, options = nil) # :nodoc:
value = bypass_local_cache{super}
if local_cache
local_cache.mute do
if value
local_cache.write(name, value, options)
else
local_cache.delete(name, options)
end
end
end
value
end
def decrement(name, amount = 1, options = nil) # :nodoc:
value = bypass_local_cache{super}
if local_cache
local_cache.mute do
if value
local_cache.write(name, value, options)
else
local_cache.delete(name, options)
end
end
end
value
end
protected
def read_entry(key, options) # :nodoc:
if local_cache
entry = local_cache.read_entry(key, options)
unless entry
entry = super
local_cache.write_entry(key, entry, options)
end
entry
else
super
end
end
def write_entry(key, entry, options) # :nodoc:
local_cache.write_entry(key, entry, options) if local_cache
super
end
def delete_entry(key, options) # :nodoc:
local_cache.delete_entry(key, options) if local_cache
super
end
private
def thread_local_key
@thread_local_key ||= "#{self.class.name.underscore}_local_cache_#{object_id}".gsub(/[\/-]/, '_').to_sym
end
def local_cache
Thread.current[thread_local_key]
end
def bypass_local_cache
save_cache = Thread.current[thread_local_key]
begin
Thread.current[thread_local_key] = nil
yield
ensure
Thread.current[thread_local_key] = save_cache
end
end
end
end
end
end
|
