2 files changed, 99 insertions, 1 deletions
diff --git a/weed/shell/commands.go b/weed/shell/commands.go
index 96343971a..2faba4280 100644
--- a/weed/shell/commands.go
+++ b/weed/shell/commands.go
@@ -28,6 +28,7 @@ type CommandEnv struct {
 	env          map[string]string
 	MasterClient *wdclient.MasterClient
 	option       ShellOptions
+	locker       *ExclusiveLocker
 }
 
 type command interface {
@@ -41,11 +42,13 @@ var (
 )
 
 func NewCommandEnv(options ShellOptions) *CommandEnv {
-	return &CommandEnv{
+	ce := &CommandEnv{
 		env:          make(map[string]string),
 		MasterClient: wdclient.NewMasterClient(options.GrpcDialOption, pb.AdminShellClient, "", 0, strings.Split(*options.Masters, ",")),
 		option:       options,
 	}
+	ce.locker = NewExclusiveLocker(ce.MasterClient)
+	return ce
 }
 
 func (ce *CommandEnv) parseUrl(input string) (path string, err error) {
diff --git a/weed/shell/exclusive_locker.go b/weed/shell/exclusive_locker.go
new file mode 100644
index 000000000..9485b255c
--- /dev/null
+++ b/weed/shell/exclusive_locker.go
@@ -0,0 +1,95 @@
+package shell
+
+import (
+	"context"
+	"sync/atomic"
+	"time"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
+	"github.com/chrislusf/seaweedfs/weed/wdclient"
+)
+
+const (
+	RenewInteval     = 4 * time.Second
+	SafeRenewInteval = 3 * time.Second
+)
+
+type ExclusiveLocker struct {
+	masterClient *wdclient.MasterClient
+	token        int64
+	lockTsNs     int64
+	isLocking    bool
+}
+
+func NewExclusiveLocker(masterClient *wdclient.MasterClient) *ExclusiveLocker {
+	return &ExclusiveLocker{
+		masterClient: masterClient,
+	}
+}
+
+func (l *ExclusiveLocker) GetToken() (token int64, lockTsNs int64) {
+	for time.Unix(0, atomic.LoadInt64(&l.lockTsNs)).Add(SafeRenewInteval).Before(time.Now()) {
+		// wait until now is within the safe lock period, no immediate renewal to change the token
+		time.Sleep(100 * time.Millisecond)
+	}
+	return atomic.LoadInt64(&l.token), atomic.LoadInt64(&l.lockTsNs)
+}
+
+func (l *ExclusiveLocker) Lock() {
+	// retry to get the lease
+	for {
+		if err := l.masterClient.WithClient(func(client master_pb.SeaweedClient) error {
+			resp, err := client.LeaseAdminToken(context.Background(), &master_pb.LeaseAdminTokenRequest{
+				PreviousToken:    atomic.LoadInt64(&l.token),
+				PreviousLockTime: atomic.LoadInt64(&l.lockTsNs),
+			})
+			if err == nil {
+				atomic.StoreInt64(&l.token, resp.Token)
+				atomic.StoreInt64(&l.lockTsNs, resp.LockTsNs)
+			}
+			return err
+		}); err != nil {
+			time.Sleep(RenewInteval)
+		} else {
+			break
+		}
+	}
+
+	l.isLocking = true
+
+	// start a goroutine to renew the lease
+	go func() {
+		for l.isLocking {
+			if err := l.masterClient.WithClient(func(client master_pb.SeaweedClient) error {
+				resp, err := client.LeaseAdminToken(context.Background(), &master_pb.LeaseAdminTokenRequest{
+					PreviousToken:    atomic.LoadInt64(&l.token),
+					PreviousLockTime: atomic.LoadInt64(&l.lockTsNs),
+				})
+				if err == nil {
+					atomic.StoreInt64(&l.token, resp.Token)
+					atomic.StoreInt64(&l.lockTsNs, resp.LockTsNs)
+				}
+				return err
+			}); err != nil {
+				glog.Error("failed to renew lock: %v", err)
+				return
+			} else {
+				time.Sleep(RenewInteval)
+			}
+
+		}
+	}()
+
+}
+
+func (l *ExclusiveLocker) Unlock() {
+	l.isLocking = false
+	l.masterClient.WithClient(func(client master_pb.SeaweedClient) error {
+		client.ReleaseAdminToken(context.Background(), &master_pb.ReleaseAdminTokenRequest{
+			PreviousToken:    atomic.LoadInt64(&l.token),
+			PreviousLockTime: atomic.LoadInt64(&l.lockTsNs),
+		})
+		return nil
+	})
+}