proxy/grpcproxy/cache/store.go
func (c *cache) Compact(revision int64) {
	c.mu.Lock()
	defer c.mu.Unlock()

	if revision > c.compactedRev {
		c.compactedRev = revision
	}
}
func (c *cache) Compact(revision int64) {
	c.mu.Lock()
	defer c.mu.Unlock()

	if revision > c.compactedRev {
		c.compactedRev = revision
	}
}
// Compact invalidate all caching response before the given rev.
// Replace with the invalidation is lazy. The actual removal happens when the entries is accessed.