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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
# Class for storing and registering the local caches.
class LocalCacheRegistry # :nodoc:
extend ActiveSupport::PerThreadRegistry
def initialize
@registry = {}
end
def cache_for(local_cache_key)
@registry[local_cache_key]
end
def set_cache_for(local_cache_key, value)
@registry[local_cache_key] = value
end
def self.set_cache_for(l, v); instance.set_cache_for l, v; end
def self.cache_for(l); instance.cache_for l; end
end
# Simple memory backed cache. This cache is not thread safe and is intended only
# for serving as a temporary memory cache for a single thread.
class LocalStore < Store
def initialize
super
@data = {}
end
# Don't allow synchronizing since it isn't thread safe,
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 for the duration of block.
def with_local_cache
use_temporary_local_cache(LocalStore.new) { yield }
end
#--
# This class wraps up local storage for middlewares. Only the middleware method should
# construct them.
class Middleware # :nodoc:
attr_reader :name, :local_cache_key
def initialize(name, local_cache_key)
@name = name
@local_cache_key = local_cache_key
@app = nil
end
def new(app)
@app = app
self
end
def call(env)
LocalCacheRegistry.set_cache_for(local_cache_key, LocalStore.new)
@app.call(env)
ensure
LocalCacheRegistry.set_cache_for(local_cache_key, nil)
end
end
# Middleware class can be inserted as a Rack handler to be local cache for the
# duration of request.
def middleware
@middleware ||= Middleware.new(
"ActiveSupport::Cache::Strategy::LocalCache",
local_cache_key)
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}
increment_or_decrement(value, name, amount, options)
value
end
def decrement(name, amount = 1, options = nil) # :nodoc:
value = bypass_local_cache{super}
increment_or_decrement(value, name, amount, options)
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 increment_or_decrement(value, name, amount, options)
if local_cache
local_cache.mute do
if value
local_cache.write(name, value, options)
else
local_cache.delete(name, options)
end
end
end
end
def local_cache_key
@local_cache_key ||= "#{self.class.name.underscore}_local_cache_#{object_id}".gsub(/[\/-]/, '_').to_sym
end
def local_cache
LocalCacheRegistry.cache_for(local_cache_key)
end
def bypass_local_cache
use_temporary_local_cache(nil) { yield }
end
def use_temporary_local_cache(temporary_cache)
save_cache = LocalCacheRegistry.cache_for(local_cache_key)
begin
LocalCacheRegistry.set_cache_for(local_cache_key, temporary_cache)
yield
ensure
LocalCacheRegistry.set_cache_for(local_cache_key, save_cache)
end
end
end
end
end
end
|
