refactor(blockdb): use atomic.Bool for cacheDB closed state (#4521)

Author: DracoLi

x/blockdb/cache_db.go

@@ -5,7 +5,7 @@ package blockdb
 
 import (
 	"slices"
-	"sync"
+	"sync/atomic"
 
 	"go.uber.org/zap"
 
@@ -22,11 +22,9 @@ var _ database.HeightIndex = (*cacheDB)(nil)
 // the cache and database contain different values. This limitation is acceptable
 // because concurrent writes to the same height are not an intended use case.
 type cacheDB struct {
-	db    *Database
-	cache *lru.Cache[BlockHeight, BlockData]
-
-	closeMu sync.RWMutex
-	closed  bool
+	db     *Database
+	cache  *lru.Cache[BlockHeight, BlockData]
+	closed atomic.Bool
 }
 
 func newCacheDB(db *Database, size uint16) *cacheDB {
@@ -37,10 +35,7 @@ func newCacheDB(db *Database, size uint16) *cacheDB {
 }
 
 func (c *cacheDB) Get(height BlockHeight) (BlockData, error) {
-	c.closeMu.RLock()
-	defer c.closeMu.RUnlock()
-
-	if c.closed {
+	if c.closed.Load() {
 		c.db.log.Error("Failed Get: database closed", zap.Uint64("height", height))
 		return nil, database.ErrClosed
 	}
@@ -57,10 +52,7 @@ func (c *cacheDB) Get(height BlockHeight) (BlockData, error) {
 }
 
 func (c *cacheDB) Put(height BlockHeight, data BlockData) error {
-	c.closeMu.RLock()
-	defer c.closeMu.RUnlock()
-
-	if c.closed {
+	if c.closed.Load() {
 		c.db.log.Error("Failed Put: database closed", zap.Uint64("height", height))
 		return database.ErrClosed
 	}
@@ -74,10 +66,7 @@ func (c *cacheDB) Put(height BlockHeight, data BlockData) error {
 }
 
 func (c *cacheDB) Has(height BlockHeight) (bool, error) {
-	c.closeMu.RLock()
-	defer c.closeMu.RUnlock()
-
-	if c.closed {
+	if c.closed.Load() {
 		c.db.log.Error("Failed Has: database closed", zap.Uint64("height", height))
 		return false, database.ErrClosed
 	}
@@ -89,13 +78,9 @@ func (c *cacheDB) Has(height BlockHeight) (bool, error) {
 }
 
 func (c *cacheDB) Close() error {
-	c.closeMu.Lock()
-	defer c.closeMu.Unlock()
-
-	if c.closed {
+	if !c.closed.CompareAndSwap(false, true) {
 		return database.ErrClosed
 	}
-	c.closed = true
 	c.cache.Flush()
 	return c.db.Close()
 }