mirror of
https://github.com/minio/minio.git
synced 2025-11-07 21:02:58 -05:00
lock: Make some cleanup and moving the code around. (#2718)
This patch just avoids lot of ifs and inverts some logic.
This commit is contained in:
Harshavardhana
GitHub
@@ -70,20 +70,71 @@ func isWriteLock(lri []lockRequesterInfo) bool {
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// lockServer is type for RPC handlers
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type lockServer struct {
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rpcPath string
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mutex sync.Mutex
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lockMap map[string][]lockRequesterInfo
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timestamp time.Time // Timestamp set at the time of initialization. Resets naturally on minio server restart.
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rpcPath string
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mutex sync.Mutex
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lockMap map[string][]lockRequesterInfo
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// Timestamp set at the time of initialization. Resets naturally on minio server restart.
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timestamp time.Time
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}
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func (l *lockServer) verifyArgs(args *LockArgs) error {
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if !l.timestamp.Equal(args.Timestamp) {
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return errInvalidTimestamp
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// Initialize distributed name space lock.
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func initDistributedNSLock(mux *router.Router, serverConfig serverCmdConfig) {
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lockServers := newLockServers(serverConfig)
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registerStorageLockers(mux, lockServers)
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}
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// Create one lock server for every local storage rpc server.
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func newLockServers(serverConfig serverCmdConfig) (lockServers []*lockServer) {
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// Initialize posix storage API.
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exports := serverConfig.disks
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ignoredExports := serverConfig.ignoredDisks
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// Save ignored disks in a map
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skipDisks := make(map[string]bool)
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for _, ignoredExport := range ignoredExports {
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skipDisks[ignoredExport] = true
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}
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if !isRPCTokenValid(args.Token) {
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return errInvalidToken
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for _, export := range exports {
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if skipDisks[export] {
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continue
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}
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// Not local storage move to the next node.
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if !isLocalStorage(export) {
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continue
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}
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if idx := strings.LastIndex(export, ":"); idx != -1 {
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export = export[idx+1:]
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}
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// Create handler for lock RPCs
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locker := &lockServer{
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rpcPath: export,
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mutex: sync.Mutex{},
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lockMap: make(map[string][]lockRequesterInfo),
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timestamp: time.Now().UTC(),
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}
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// Start loop for stale lock maintenance
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go func() {
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// Start with random sleep time, so as to avoid "synchronous checks" between servers
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time.Sleep(time.Duration(rand.Float64() * float64(lockMaintenanceLoop)))
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for {
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time.Sleep(lockMaintenanceLoop)
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locker.lockMaintenance(lockCheckValidityInterval)
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}
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}()
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lockServers = append(lockServers, locker)
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}
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return lockServers
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}
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// registerStorageLockers - register locker rpc handlers for net/rpc library clients
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func registerStorageLockers(mux *router.Router, lockServers []*lockServer) {
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for _, lockServer := range lockServers {
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lockRPCServer := rpc.NewServer()
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lockRPCServer.RegisterName("Dsync", lockServer)
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lockRouter := mux.PathPrefix(reservedBucket).Subrouter()
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lockRouter.Path(path.Join("/lock", lockServer.rpcPath)).Handler(lockRPCServer)
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}
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return nil
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}
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/// Distributed lock handlers
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@@ -110,12 +161,21 @@ func (l *lockServer) LoginHandler(args *RPCLoginArgs, reply *RPCLoginReply) erro
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func (l *lockServer) Lock(args *LockArgs, reply *bool) error {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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if err := l.verifyArgs(args); err != nil {
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if err := l.validateLockArgs(args); err != nil {
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return err
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}
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_, *reply = l.lockMap[args.Name]
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if !*reply { // No locks held on the given name, so claim write lock
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l.lockMap[args.Name] = []lockRequesterInfo{{writer: true, node: args.Node, rpcPath: args.RPCPath, uid: args.UID, timestamp: time.Now(), timeLastCheck: time.Now()}}
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l.lockMap[args.Name] = []lockRequesterInfo{
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{
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writer: true,
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node: args.Node,
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rpcPath: args.RPCPath,
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uid: args.UID,
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timestamp: time.Now().UTC(),
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timeLastCheck: time.Now().UTC(),
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},
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}
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}
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*reply = !*reply // Negate *reply to return true when lock is granted or false otherwise
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return nil
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@@ -125,39 +185,44 @@ func (l *lockServer) Lock(args *LockArgs, reply *bool) error {
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func (l *lockServer) Unlock(args *LockArgs, reply *bool) error {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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if err := l.verifyArgs(args); err != nil {
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if err := l.validateLockArgs(args); err != nil {
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return err
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}
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var lri []lockRequesterInfo
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lri, *reply = l.lockMap[args.Name]
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if !*reply { // No lock is held on the given name
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if lri, *reply = l.lockMap[args.Name]; !*reply { // No lock is held on the given name
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return fmt.Errorf("Unlock attempted on an unlocked entity: %s", args.Name)
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}
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if *reply = isWriteLock(lri); !*reply { // Unless it is a write lock
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return fmt.Errorf("Unlock attempted on a read locked entity: %s (%d read locks active)", args.Name, len(lri))
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}
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if l.removeEntry(args.Name, args.UID, &lri) {
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return nil
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if !l.removeEntry(args.Name, args.UID, &lri) {
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return fmt.Errorf("Unlock unable to find corresponding lock for uid: %s", args.UID)
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}
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return fmt.Errorf("Unlock unable to find corresponding lock for uid: %s", args.UID)
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return nil
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}
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// RLock - rpc handler for read lock operation.
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func (l *lockServer) RLock(args *LockArgs, reply *bool) error {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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if err := l.verifyArgs(args); err != nil {
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if err := l.validateLockArgs(args); err != nil {
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return err
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}
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var lri []lockRequesterInfo
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lri, *reply = l.lockMap[args.Name]
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if !*reply { // No locks held on the given name, so claim (first) read lock
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l.lockMap[args.Name] = []lockRequesterInfo{{writer: false, node: args.Node, rpcPath: args.RPCPath, uid: args.UID, timestamp: time.Now(), timeLastCheck: time.Now()}}
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*reply = true
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} else {
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lrInfo := lockRequesterInfo{
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writer: false,
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node: args.Node,
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rpcPath: args.RPCPath,
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uid: args.UID,
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timestamp: time.Now().UTC(),
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timeLastCheck: time.Now().UTC(),
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}
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if lri, ok := l.lockMap[args.Name]; ok {
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if *reply = !isWriteLock(lri); *reply { // Unless there is a write lock
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l.lockMap[args.Name] = append(l.lockMap[args.Name], lockRequesterInfo{writer: false, node: args.Node, rpcPath: args.RPCPath, uid: args.UID, timestamp: time.Now(), timeLastCheck: time.Now()})
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l.lockMap[args.Name] = append(l.lockMap[args.Name], lrInfo)
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}
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} else { // No locks held on the given name, so claim (first) read lock
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l.lockMap[args.Name] = []lockRequesterInfo{lrInfo}
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*reply = true
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}
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return nil
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}
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@@ -166,7 +231,7 @@ func (l *lockServer) RLock(args *LockArgs, reply *bool) error {
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func (l *lockServer) RUnlock(args *LockArgs, reply *bool) error {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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if err := l.verifyArgs(args); err != nil {
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if err := l.validateLockArgs(args); err != nil {
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return err
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}
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var lri []lockRequesterInfo
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@@ -176,49 +241,33 @@ func (l *lockServer) RUnlock(args *LockArgs, reply *bool) error {
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if *reply = !isWriteLock(lri); !*reply { // A write-lock is held, cannot release a read lock
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return fmt.Errorf("RUnlock attempted on a write locked entity: %s", args.Name)
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}
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if l.removeEntry(args.Name, args.UID, &lri) {
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return nil
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if !l.removeEntry(args.Name, args.UID, &lri) {
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return fmt.Errorf("RUnlock unable to find corresponding read lock for uid: %s", args.UID)
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}
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return fmt.Errorf("RUnlock unable to find corresponding read lock for uid: %s", args.UID)
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return nil
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}
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// Active - rpc handler for active lock status.
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func (l *lockServer) Active(args *LockArgs, reply *bool) error {
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// Expired - rpc handler for expired lock status.
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func (l *lockServer) Expired(args *LockArgs, reply *bool) error {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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if err := l.verifyArgs(args); err != nil {
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if err := l.validateLockArgs(args); err != nil {
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return err
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}
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var lri []lockRequesterInfo
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if lri, *reply = l.lockMap[args.Name]; !*reply {
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return nil // No lock is held on the given name so return false
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}
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// Check whether uid is still active
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for _, entry := range lri {
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if *reply = entry.uid == args.UID; *reply {
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return nil // When uid found return true
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}
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}
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return nil // None found so return false
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}
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// removeEntry either, based on the uid of the lock message, removes a single entry from the
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// lockRequesterInfo array or the whole array from the map (in case of a write lock or last read lock)
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func (l *lockServer) removeEntry(name, uid string, lri *[]lockRequesterInfo) bool {
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// Find correct entry to remove based on uid
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for index, entry := range *lri {
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if entry.uid == uid {
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if len(*lri) == 1 {
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delete(l.lockMap, name) // Remove the (last) lock
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} else {
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// Remove the appropriate read lock
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*lri = append((*lri)[:index], (*lri)[index+1:]...)
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l.lockMap[name] = *lri
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// Lock found, proceed to verify if belongs to given uid.
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if lri, ok := l.lockMap[args.Name]; ok {
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// Check whether uid is still active
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for _, entry := range lri {
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if entry.uid == args.UID {
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*reply = false // When uid found, lock is still active so return not expired.
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return nil // When uid found *reply is set to true.
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}
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return true
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}
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}
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return false
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// When we get here lock is no longer active due to either args.Name
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// being absent from map or uid not found for given args.Name
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*reply = true
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return nil
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}
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// nameLockRequesterInfoPair is a helper type for lock maintenance
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@@ -227,132 +276,41 @@ type nameLockRequesterInfoPair struct {
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lri lockRequesterInfo
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}
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// getLongLivedLocks returns locks that are older than a certain time and
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// have not been 'checked' for validity too soon enough
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func getLongLivedLocks(m map[string][]lockRequesterInfo, interval time.Duration) []nameLockRequesterInfoPair {
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rslt := []nameLockRequesterInfoPair{}
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for name, lriArray := range m {
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for idx := range lriArray {
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// Check whether enough time has gone by since last check
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if time.Since(lriArray[idx].timeLastCheck) >= interval {
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rslt = append(rslt, nameLockRequesterInfoPair{name: name, lri: lriArray[idx]})
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lriArray[idx].timeLastCheck = time.Now()
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}
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}
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}
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return rslt
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}
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// lockMaintenance loops over locks that have been active for some time and checks back
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// with the original server whether it is still alive or not
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//
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// Following logic inside ignores the errors generated for Dsync.Active operation.
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// - server at client down
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// - some network error (and server is up normally)
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//
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// We will ignore the error, and we will retry later to get a resolve on this lock
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func (l *lockServer) lockMaintenance(interval time.Duration) {
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l.mutex.Lock()
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// get list of locks to check
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// Get list of long lived locks to check for staleness.
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nlripLongLived := getLongLivedLocks(l.lockMap, interval)
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l.mutex.Unlock()
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// Validate if long lived locks are indeed clean.
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for _, nlrip := range nlripLongLived {
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// Initialize client based on the long live locks.
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c := newClient(nlrip.lri.node, nlrip.lri.rpcPath)
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var active bool
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var expired bool
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// Call back to original server verify whether the lock is still active (based on name & uid)
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if err := c.Call("Dsync.Active", &LockArgs{Name: nlrip.name, UID: nlrip.lri.uid}, &active); err != nil {
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// We failed to connect back to the server that originated the lock, this can either be due to
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// - server at client down
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// - some network error (and server is up normally)
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//
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// We will ignore the error, and we will retry later to get resolve on this lock
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c.Close()
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} else {
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c.Close()
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c.Call("Dsync.Expired", &LockArgs{
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Name: nlrip.name,
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UID: nlrip.lri.uid,
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}, &expired)
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c.Close() // Close the connection regardless of the call response.
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if !active { // The lock is no longer active at server that originated the lock
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// so remove the lock from the map
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l.mutex.Lock()
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// Check if entry is still in map (could have been removed altogether by 'concurrent' (R)Unlock of last entry)
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if lri, ok := l.lockMap[nlrip.name]; ok {
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if !l.removeEntry(nlrip.name, nlrip.lri.uid, &lri) {
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// Remove failed, in case it is a:
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if nlrip.lri.writer {
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// Writer: this should never happen as the whole (mapped) entry should have been deleted
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log.Errorln("Lock maintenance failed to remove entry for write lock (should never happen)", nlrip.name, nlrip.lri, lri)
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} else {
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// Reader: this can happen if multiple read locks were active and the one we are looking for
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// has been released concurrently (so it is fine)
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}
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} else {
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// remove went okay, all is fine
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}
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}
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l.mutex.Unlock()
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}
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// For successful response, verify if lock is indeed active or stale.
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if expired {
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// The lock is no longer active at server that originated the lock
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// So remove the lock from the map.
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l.mutex.Lock()
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l.removeEntryIfExists(nlrip) // Purge the stale entry if it exists.
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l.mutex.Unlock()
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}
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}
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}
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// Initialize distributed lock.
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func initDistributedNSLock(mux *router.Router, serverConfig serverCmdConfig) {
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lockServers := newLockServers(serverConfig)
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registerStorageLockers(mux, lockServers)
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}
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// Create one lock server for every local storage rpc server.
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func newLockServers(serverConfig serverCmdConfig) (lockServers []*lockServer) {
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// Initialize posix storage API.
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exports := serverConfig.disks
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ignoredExports := serverConfig.ignoredDisks
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// Save ignored disks in a map
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skipDisks := make(map[string]bool)
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for _, ignoredExport := range ignoredExports {
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skipDisks[ignoredExport] = true
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}
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for _, export := range exports {
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if skipDisks[export] {
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continue
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}
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if isLocalStorage(export) {
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if idx := strings.LastIndex(export, ":"); idx != -1 {
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export = export[idx+1:]
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}
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// Create handler for lock RPCs
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locker := &lockServer{
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rpcPath: export,
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mutex: sync.Mutex{},
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lockMap: make(map[string][]lockRequesterInfo),
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timestamp: time.Now().UTC(),
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}
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// Start loop for stale lock maintenance
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go func() {
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// Start with random sleep time, so as to avoid "synchronous checks" between servers
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time.Sleep(time.Duration(rand.Float64() * float64(lockMaintenanceLoop)))
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for {
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time.Sleep(lockMaintenanceLoop)
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locker.lockMaintenance(lockCheckValidityInterval)
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}
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}()
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lockServers = append(lockServers, locker)
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}
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}
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return lockServers
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}
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// registerStorageLockers - register locker rpc handlers for net/rpc library clients
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func registerStorageLockers(mux *router.Router, lockServers []*lockServer) {
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for _, lockServer := range lockServers {
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lockRPCServer := rpc.NewServer()
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lockRPCServer.RegisterName("Dsync", lockServer)
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lockRouter := mux.PathPrefix(reservedBucket).Subrouter()
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lockRouter.Path(path.Join("/lock", lockServer.rpcPath)).Handler(lockRPCServer)
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}
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}
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Block a user