The copies of the data are determined to be fresh or stale based on the communication of invalidation messages.

系统将根据无效消息的通信确定数据副本是新鲜的还是陈旧的。

Invalidation methods rarely get called.

失效方法很少被调用。

This example shows invalidation based on the expire_page method.

这个事例所显示的到期失效基于expire_page方法。

These cache invalidation scenarios generally fall into two categories

这些缓存失效场景通常分为两类

Secondly, the Cache supports expiration dependencies that can force invalidation.

第二，缓存支持可以强制失效的过期依赖项。