[英]memcached as an Object store in Rails
I am using Memcached as an Object Store with my Rails application where I store search results which are User objects in memcached 我在我的Rails应用程序中使用Memcached作为Object Store,我在其中存储了memcached中User对象的搜索结果
Now when I fetch the data out I get the Memcached Undefined Class/Module Error. 现在,当我获取数据时,我得到了Memcached Undefined Class / Module Error。 I found a solution for this problem in this blog 我在这个博客中找到了解决这个问题的方法
http://www.philsergi.com/2007/06/rails-memcached-undefinded-classmodule.html http://www.philsergi.com/2007/06/rails-memcached-undefinded-classmodule.html
before_filter :preload_models
def preload_models
Model1
Model2
end
which recommends pre-loading the models before hand. 建议事先预装模型。 I would like to know if there is a more elegant solution to this problem and are there any drawbacks in using the preloading technique. 我想知道是否有一个更优雅的解决方案来解决这个问题,并且使用预加载技术有任何缺点。
Thanks in advance 提前致谢
I had this problem as well and I think i came up with a nice solution. 我也有这个问题,我想我想出了一个很好的解决方案。
You can overwrite the fetch method and rescue the error and load the right constants. 您可以覆盖fetch方法并挽救错误并加载正确的常量。
module ActiveSupport
module Cache
class MemCacheStore
# Fetching the entry from memcached
# For some reason sometimes the classes are undefined
# First rescue: trying to constantize the class and try again.
# Second rescue, reload all the models
# Else raise the exception
def fetch(key, options = {})
retries = 2
begin
super
rescue ArgumentError, NameError => exc
if retries == 2
if exc.message.match /undefined class\/module (.+)$/
$1.constantize
end
retries -= 1
retry
elsif retries == 1
retries -= 1
preload_models
retry
else
raise exc
end
end
end
private
# There are errors sometimes like: undefined class module ClassName.
# With this method we re-load every model
def preload_models
#we need to reference the classes here so if coming from cache Marshal.load will find them
ActiveRecord::Base.connection.tables.each do |model|
begin
"#{model.classify}".constantize
rescue Exception
end
end
end
end
end
end
Ran across this today, managed to come up with a more terse solution that should work for all classes. 今天就这样,设法提出了一个应该适用于所有课程的更简洁的解决方案。
Rails.cache.instance_eval do
def fetch(key, options = {}, rescue_and_require=true)
super(key, options)
rescue ArgumentError => ex
if rescue_and_require && /^undefined class\/module (.+?)$/ =~ ex.message
self.class.const_missing($1)
fetch(key, options, false)
else
raise ex
end
end
end
Not sure why [MemCacheStore]
is not having is [MemCacheStore.const_missing]
method called and everything getting called in the normal “Rails-y” way. 不确定为什么[MemCacheStore]
没有调用[MemCacheStore.const_missing]
方法,所有内容都以正常的“Rails-y”方式调用。 But, this should emulate that! 但是,这应该效仿!
Cheers, 干杯,
Chris 克里斯
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