解决死锁问题

client/internal/mount/vfs/cache/file.go

@@ -107,7 +107,8 @@ type CacheFile struct {
 	readers      []*CacheFileHandle
 	writers      []*CacheFileHandle
 	saveMetaChan chan any
-	stopSaveChan chan any
+	saveMetaLock *sync.Mutex
+	stopSaveMeta *bool
 	isDeleted    bool
 
 	level           CacheLevel
@@ -170,7 +171,8 @@ func createNewCacheFile(cache *Cache, pathComps []string) (*CacheFile, error) {
 		info:         info,
 		rwLock:       &sync.RWMutex{},
 		saveMetaChan: make(chan any, 1),
-		stopSaveChan: make(chan any),
+		saveMetaLock: &sync.Mutex{},
+		stopSaveMeta: new(bool),
 		level:        LevelComplete,
 		metaFile:     metaFile,
 		dataFile:     dataFile,
@@ -178,7 +180,7 @@ func createNewCacheFile(cache *Cache, pathComps []string) (*CacheFile, error) {
 		state:        cacheState{},
 	}
 
-	go ch.serving(ch.saveMetaChan, ch.stopSaveChan)
+	go ch.serving(ch.saveMetaChan, ch.stopSaveMeta)
 
 	return ch, nil
 }
@@ -242,7 +244,8 @@ func loadCacheFile(cache *Cache, pathComps []string) (*CacheFile, error) {
 		info:         *info,
 		rwLock:       &sync.RWMutex{},
 		saveMetaChan: make(chan any, 1),
-		stopSaveChan: make(chan any),
+		saveMetaLock: &sync.Mutex{},
+		stopSaveMeta: new(bool),
 		level:        LevelComplete,
 		metaFile:     metaFile,
 		dataFile:     dataFile,
@@ -250,7 +253,7 @@ func loadCacheFile(cache *Cache, pathComps []string) (*CacheFile, error) {
 		state:        cacheState{},
 	}
 
-	go ch.serving(ch.saveMetaChan, ch.stopSaveChan)
+	go ch.serving(ch.saveMetaChan, ch.stopSaveMeta)
 
 	return ch, nil
 }
@@ -300,7 +303,8 @@ func newCacheFileFromObject(cache *Cache, pathComps []string, obj *clitypes.Obje
 		remoteObj:    obj,
 		rwLock:       &sync.RWMutex{},
 		saveMetaChan: make(chan any, 1),
-		stopSaveChan: make(chan any),
+		saveMetaLock: &sync.Mutex{},
+		stopSaveMeta: new(bool),
 		level:        LevelComplete,
 		metaFile:     metaFile,
 		dataFile:     dataFile,
@@ -308,7 +312,7 @@ func newCacheFileFromObject(cache *Cache, pathComps []string, obj *clitypes.Obje
 		state:        cacheState{},
 	}
 
-	go ch.serving(ch.saveMetaChan, ch.stopSaveChan)
+	go ch.serving(ch.saveMetaChan, ch.stopSaveMeta)
 
 	return ch, nil
 }
@@ -366,6 +370,12 @@ func (f *CacheFile) Release() {
 }
 
 func (f *CacheFile) LevelDown(level CacheLevel) bool {
+	if level <= LevelReadOnly {
+		// 如果降级到不需要保存元数据的级别，就要先暂停保存元数据的操作
+		f.saveMetaLock.Lock()
+		defer f.saveMetaLock.Unlock()
+	}
+
 	f.rwLock.Lock()
 	defer f.rwLock.Unlock()
 
@@ -393,10 +403,11 @@ func (f *CacheFile) LevelDown(level CacheLevel) bool {
 			// TODO 日志
 			f.saveMeta(f.info)
 		}
-		// 这里会等待直到saveMeta线程退出
-		f.stopSaveChan <- nil
 		f.saveMetaChan = nil
-		f.stopSaveChan = nil
+		// 由于已经获取了saveMetaLock，所以这里设置true之后调用metaFile.Close不会导致saveMeta线程的保存失败
+		// 因为saveMeta线程会先检查stopSaveMete的值
+		*f.stopSaveMeta = true
+		f.stopSaveMeta = nil
 		f.metaFile.Close()
 
 		f.level = LevelReadOnly
@@ -447,11 +458,11 @@ func (f *CacheFile) LevelUp(level CacheLevel) bool {
 		}
 
 		f.saveMetaChan = make(chan any, 1)
-		f.stopSaveChan = make(chan any)
+		f.stopSaveMeta = new(bool)
 		f.metaFile = metaFile
 		f.level = LevelMetaLoaded
 
-		go f.serving(f.saveMetaChan, f.stopSaveChan)
+		go f.serving(f.saveMetaChan, f.stopSaveMeta)
 
 		if level <= f.level {
 			break
@@ -654,8 +665,8 @@ func (f *CacheFile) Truncate(size int64) error {
 	return nil
 }
 
-func (f *CacheFile) serving(saveMetaChan chan any, stopSaveChan chan any) {
-	ticker := time.NewTicker(time.Second * 5)
+func (f *CacheFile) serving(saveMetaChan chan any, stopSaveMeta *bool) {
+	ticker := time.NewTicker(time.Second * 30)
 	defer ticker.Stop()
 
 	for {
@@ -665,17 +676,21 @@ func (f *CacheFile) serving(saveMetaChan chan any, stopSaveChan chan any) {
 				return
 			}
 
-		case <-stopSaveChan:
-			return
-
 		case <-ticker.C:
 		}
 
+		f.saveMetaLock.Lock()
+		if *stopSaveMeta {
+			f.saveMetaLock.Unlock()
+			break
+		}
+
 		f.rwLock.RLock()
 		info := f.info.Clone()
 		// 如果文件已被删除，则不能再保存元数据，防止覆盖掉新创建的同名文件
 		if f.isDeleted {
 			f.rwLock.RUnlock()
+			f.saveMetaLock.Unlock()
 			break
 		}
 
@@ -684,6 +699,7 @@ func (f *CacheFile) serving(saveMetaChan chan any, stopSaveChan chan any) {
 		// TODO 错误日志
 		f.saveMeta(info)
 		f.metaFile.Sync()
+		f.saveMetaLock.Unlock()
 	}
 }