plugeth/common/lru/blob_lru.go

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// 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
}