89 lines
2.8 KiB
Go
89 lines
2.8 KiB
Go
|
// Copyright 2022 The go-ethereum Authors
|
||
|
|
// This file is part of the go-ethereum library.
|
||
|
|
//
|
||
|
|
// The go-ethereum library is free software: you can redistribute it and/or modify
|
||
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
||
|
|
// the Free Software Foundation, either version 3 of the License, or
|
||
|
|
// (at your option) any later version.
|
||
|
|
//
|
||
|
|
// The go-ethereum library is distributed in the hope that it will be useful,
|
||
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
// GNU Lesser General Public License for more details.
|
||
|
|
//
|
||
|
|
// You should have received a copy of the GNU Lesser General Public License
|
||
|
|
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
|
||
|
|
|
||
|
|
package lru
|
||
|
|
|
||
|
|
import (
|
||
|
|
"math"
|
||
|
|
"sync"
|
||
|
|
|
||
|
|
"github.com/ethereum/go-ethereum/common"
|
||
|
|
"github.com/hashicorp/golang-lru/simplelru"
|
||
|
|
)
|
||
|
|
|
||
|
|
// SizeConstrainedLRU is a wrapper around simplelru.LRU. The simplelru.LRU is capable
|
||
|
|
// of item-count constraints, but is not capable of enforcing a byte-size constraint,
|
||
|
|
// hence this wrapper.
|
||
|
|
// OBS: This cache assumes that items are content-addressed: keys are unique per content.
|
||
|
|
// In other words: two Add(..) with the same key K, will always have the same value V.
|
||
|
|
type SizeConstrainedLRU struct {
|
||
|
|
size uint64
|
||
|
|
maxSize uint64
|
||
|
|
lru *simplelru.LRU
|
||
|
|
lock sync.RWMutex
|
||
|
|
}
|
||
|
|
|
||
|
|
// NewSizeConstrainedLRU creates a new SizeConstrainedLRU.
|
||
|
|
func NewSizeConstrainedLRU(max uint64) *SizeConstrainedLRU {
|
||
|
|
lru, err := simplelru.NewLRU(math.MaxInt, nil)
|
||
|
|
if err != nil {
|
||
|
|
panic(err)
|
||
|
|
}
|
||
|
|
return &SizeConstrainedLRU{
|
||
|
|
size: 0,
|
||
|
|
maxSize: max,
|
||
|
|
lru: lru,
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Add adds a value to the cache. Returns true if an eviction occurred.
|
||
|
|
// OBS: This cache assumes that items are content-addressed: keys are unique per content.
|
||
|
|
// In other words: two Add(..) with the same key K, will always have the same value V.
|
||
|
|
// OBS: The value is _not_ copied on Add, so the caller must not modify it afterwards.
|
||
|
|
func (c *SizeConstrainedLRU) Add(key common.Hash, value []byte) (evicted bool) {
|
||
|
|
c.lock.Lock()
|
||
|
|
defer c.lock.Unlock()
|
||
|
|
|
||
|
|
// Unless it is already present, might need to evict something.
|
||
|
|
// OBS: If it is present, we still call Add internally to bump the recentness.
|
||
|
|
if !c.lru.Contains(key) {
|
||
|
|
targetSize := c.size + uint64(len(value))
|
||
|
|
for targetSize > c.maxSize {
|
||
|
|
evicted = true
|
||
|
|
_, v, ok := c.lru.RemoveOldest()
|
||
|
|
if !ok {
|
||
|
|
// list is now empty. Break
|
||
|
|
break
|
||
|
|
}
|
||
|
|
targetSize -= uint64(len(v.([]byte)))
|
||
|
|
}
|
||
|
|
c.size = targetSize
|
||
|
|
}
|
||
|
|
c.lru.Add(key, value)
|
||
|
|
return evicted
|
||
|
|
}
|
||
|
|
|
||
|
|
// Get looks up a key's value from the cache.
|
||
|
|
func (c *SizeConstrainedLRU) Get(key common.Hash) []byte {
|
||
|
|
c.lock.RLock()
|
||
|
|
defer c.lock.RUnlock()
|
||
|
|
|
||
|
|
if v, ok := c.lru.Get(key); ok {
|
||
|
|
return v.([]byte)
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|