- 愿意消耗一些内存空间来提升速度
- 预料到某些键会被多次查询
- 缓存中存放的数据总量不会超出内存容量
Caffeine提供三类驱逐策略：
- 基于大小（size-based）
- 基于时间（time-based）
- 基于引用（reference-based）
who is the author of ConcurrentLinkedHashMap on which Guava cache is based.
guava out
- guava sync operation
- non-blocking without aware
Caffeine uses both a Least Recently Used (LRU) eviction policy and a frequency-based admission policy relying on CountMin sketch. It has a better hit rate than LRU for many workloads.
使用ring buffers的方式，The ring buffer approach avoids allocation, is bounded (lossy), and cheaper to operate against.
Caffeine uses ring buffers to record & replay events, whereas Guava uses ConcurrentLinkedQueue.