common/lru: fix race in lru (#26164)

This fixes a problem in the SizeConstrainedLRU. The SCLRU uses an underlying simple lru which is not thread safe.
During the Get operation, the recentness of the accessed item is updated, so it is not a pure read-operation. Therefore, the mutex we need is a full mutex, not RLock.

This PR changes the mutex to be a regular Mutex, instead of RWMutex, so a reviewer can at a glance see that all affected locations are fixed.
pull/26176/head
Martin Holst Swende 2 years ago committed by GitHub
parent ea65edaa28
commit 8334b5f51a
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GPG Key ID: 4AEE18F83AFDEB23
  1. 6
      common/lru/blob_lru.go

@ -33,7 +33,7 @@ type SizeConstrainedLRU struct {
size uint64
maxSize uint64
lru *simplelru.LRU
lock sync.RWMutex
lock sync.Mutex
}
// NewSizeConstrainedLRU creates a new SizeConstrainedLRU.
@ -78,8 +78,8 @@ func (c *SizeConstrainedLRU) Add(key common.Hash, value []byte) (evicted bool) {
// 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()
c.lock.Lock()
defer c.lock.Unlock()
if v, ok := c.lru.Get(key); ok {
return v.([]byte)

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