package weed_server import ( "context" "fmt" "github.com/seaweedfs/seaweedfs/weed/cluster" "github.com/seaweedfs/seaweedfs/weed/glog" "github.com/seaweedfs/seaweedfs/weed/pb" "github.com/seaweedfs/seaweedfs/weed/pb/filer_pb" "github.com/seaweedfs/seaweedfs/weed/pb/volume_server_pb" "math/rand" "sync" "time" "github.com/seaweedfs/seaweedfs/weed/pb/master_pb" ) /* How exclusive lock works? ----------- Shell ------ When shell lock, * lease an admin token (lockTime, token) * start a goroutine to renew the admin token periodically When shell unlock * stop the renewal goroutine * sends a release lock request Master ------ Master maintains: * randomNumber * lastLockTime When master receives the lease/renew request from shell If lastLockTime still fresh { if is a renew and token is valid { // for renew generate the randomNumber => token return } refuse return } else { // for fresh lease request generate the randomNumber => token return } When master receives the release lock request from shell set the lastLockTime to zero The volume server does not need to verify. This makes the lock/unlock optional, similar to what golang code usually does. */ const ( LockDuration = 10 * time.Second ) type AdminLock struct { accessSecret int64 accessLockTime time.Time lastClient string lastMessage string } type AdminLocks struct { locks map[string]*AdminLock sync.RWMutex } func NewAdminLocks() *AdminLocks { return &AdminLocks{ locks: make(map[string]*AdminLock), } } func (locks *AdminLocks) isLocked(lockName string) (clientName string, message string, isLocked bool) { locks.RLock() defer locks.RUnlock() adminLock, found := locks.locks[lockName] if !found { return "", "", false } glog.V(4).Infof("isLocked %v: %v", adminLock.lastClient, adminLock.lastMessage) return adminLock.lastClient, adminLock.lastMessage, adminLock.accessLockTime.Add(LockDuration).After(time.Now()) } func (locks *AdminLocks) isValidToken(lockName string, ts time.Time, token int64) bool { locks.RLock() defer locks.RUnlock() adminLock, found := locks.locks[lockName] if !found { return false } return adminLock.accessLockTime.Equal(ts) && adminLock.accessSecret == token } func (locks *AdminLocks) generateToken(lockName string, clientName string) (ts time.Time, token int64) { locks.Lock() defer locks.Unlock() lock := &AdminLock{ accessSecret: rand.Int63(), accessLockTime: time.Now(), lastClient: clientName, } locks.locks[lockName] = lock return lock.accessLockTime, lock.accessSecret } func (locks *AdminLocks) deleteLock(lockName string) { locks.Lock() defer locks.Unlock() delete(locks.locks, lockName) } func (ms *MasterServer) LeaseAdminToken(ctx context.Context, req *master_pb.LeaseAdminTokenRequest) (*master_pb.LeaseAdminTokenResponse, error) { resp := &master_pb.LeaseAdminTokenResponse{} if lastClient, lastMessage, isLocked := ms.adminLocks.isLocked(req.LockName); isLocked { glog.V(4).Infof("LeaseAdminToken %v", lastClient) if req.PreviousToken != 0 && ms.adminLocks.isValidToken(req.LockName, time.Unix(0, req.PreviousLockTime), req.PreviousToken) { // for renew ts, token := ms.adminLocks.generateToken(req.LockName, req.ClientName) resp.Token, resp.LockTsNs = token, ts.UnixNano() return resp, nil } // refuse since still locked return resp, fmt.Errorf("already locked by %v: %v", lastClient, lastMessage) } // for fresh lease request ts, token := ms.adminLocks.generateToken(req.LockName, req.ClientName) resp.Token, resp.LockTsNs = token, ts.UnixNano() return resp, nil } func (ms *MasterServer) ReleaseAdminToken(ctx context.Context, req *master_pb.ReleaseAdminTokenRequest) (*master_pb.ReleaseAdminTokenResponse, error) { resp := &master_pb.ReleaseAdminTokenResponse{} if ms.adminLocks.isValidToken(req.LockName, time.Unix(0, req.PreviousLockTime), req.PreviousToken) { ms.adminLocks.deleteLock(req.LockName) } return resp, nil } func (ms *MasterServer) Ping(ctx context.Context, req *master_pb.PingRequest) (resp *master_pb.PingResponse, pingErr error) { resp = &master_pb.PingResponse{ StartTimeNs: time.Now().UnixNano(), } if req.TargetType == cluster.FilerType { pingErr = pb.WithFilerClient(false, pb.ServerAddress(req.Target), ms.grpcDialOption, func(client filer_pb.SeaweedFilerClient) error { pingResp, err := client.Ping(ctx, &filer_pb.PingRequest{}) if pingResp != nil { resp.RemoteTimeNs = pingResp.StartTimeNs } return err }) } if req.TargetType == cluster.VolumeServerType { pingErr = pb.WithVolumeServerClient(false, pb.ServerAddress(req.Target), ms.grpcDialOption, func(client volume_server_pb.VolumeServerClient) error { pingResp, err := client.Ping(ctx, &volume_server_pb.PingRequest{}) if pingResp != nil { resp.RemoteTimeNs = pingResp.StartTimeNs } return err }) } if req.TargetType == cluster.MasterType { pingErr = pb.WithMasterClient(false, pb.ServerAddress(req.Target), ms.grpcDialOption, func(client master_pb.SeaweedClient) error { pingResp, err := client.Ping(ctx, &master_pb.PingRequest{}) if pingResp != nil { resp.RemoteTimeNs = pingResp.StartTimeNs } return err }) } if pingErr != nil { pingErr = fmt.Errorf("ping %s %s: %v", req.TargetType, req.Target, pingErr) } resp.StopTimeNs = time.Now().UnixNano() return }