add distributed lock manager

weed/server/filer_grpc_server_dlm.go

@@ -0,0 +1,111 @@
+package weed_server
+
+import (
+	"context"
+	"fmt"
+	"github.com/seaweedfs/seaweedfs/weed/cluster/lock_manager"
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/pb"
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+	"time"
+)
+
+// Lock is a grpc handler to handle FilerServer's LockRequest
+func (fs *FilerServer) Lock(ctx context.Context, req *filer_pb.LockRequest) (resp *filer_pb.LockResponse, err error) {
+
+	resp = &filer_pb.LockResponse{}
+	snapshot := fs.filer.LockRing.GetSnapshot()
+	if snapshot == nil {
+		resp.Error = "no lock server found"
+		return
+	} else {
+		server := lock_manager.HashKeyToServer(req.Name, snapshot)
+		if server != fs.option.Host {
+			resp.Error = fmt.Sprintf("not the lock server for %s", req.Name)
+			resp.MovedTo = string(server)
+			return
+		}
+	}
+
+	renewToken, err := fs.dlm.Lock(req.Name, time.Duration(req.SecondsToLock)*time.Second, req.PreviousLockToken)
+
+	if err != nil {
+		resp.Error = fmt.Sprintf("%v", err)
+	} else {
+		resp.RenewToken = renewToken
+	}
+
+	return resp, nil
+}
+
+// Unlock is a grpc handler to handle FilerServer's UnlockRequest
+func (fs *FilerServer) Unlock(ctx context.Context, req *filer_pb.UnlockRequest) (resp *filer_pb.UnlockResponse, err error) {
+
+	resp = &filer_pb.UnlockResponse{}
+	snapshot := fs.filer.LockRing.GetSnapshot()
+	if snapshot == nil {
+		resp.Error = "no lock server found"
+		return
+	} else {
+		server := lock_manager.HashKeyToServer(req.Name, snapshot)
+		if server != fs.option.Host {
+			resp.Error = fmt.Sprintf("not the lock server for %s", req.Name)
+			resp.MovedTo = string(server)
+			return
+		}
+	}
+
+	_, err = fs.dlm.Unlock(req.Name, req.LockToken)
+	if err != nil {
+		resp.Error = fmt.Sprintf("%v", err)
+	}
+
+	return resp, nil
+
+}
+
+// TransferLocks is a grpc handler to handle FilerServer's TransferLocksRequest
+func (fs *FilerServer) TransferLocks(ctx context.Context, req *filer_pb.TransferLocksRequest) (*filer_pb.TransferLocksResponse, error) {
+
+	now := time.Now()
+	for _, lock := range req.Locks {
+		duration := time.Duration(lock.ExpirationNs - now.UnixNano())
+		if _, err := fs.dlm.Lock(lock.Name, duration, lock.RenewToken); err != nil {
+			glog.Errorf("receive transferred lock %v to %v: %v", lock.Name, fs.option.Host, err)
+			return nil, err
+		}
+	}
+
+	return &filer_pb.TransferLocksResponse{}, nil
+
+}
+
+func (fs *FilerServer) OnDlmChangeSnapshot(snapshot []pb.ServerAddress) {
+	locks := fs.dlm.TakeOutLocksByKey(func(key string) bool {
+		server := lock_manager.HashKeyToServer(key, snapshot)
+		return server != fs.option.Host
+	})
+	if len(locks) == 0 {
+		return
+	}
+
+	for _, lock := range locks {
+		server := lock_manager.HashKeyToServer(lock.Key, snapshot)
+		if err := pb.WithFilerClient(false, 0, server, fs.grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {
+			_, err := client.TransferLocks(context.Background(), &filer_pb.TransferLocksRequest{
+				Locks: []*filer_pb.Lock{
+					{
+						Name:         lock.Key,
+						RenewToken:   lock.Token,
+						ExpirationNs: lock.ExpirationNs,
+					},
+				},
+			})
+			return err
+		}); err != nil {
+			// it may not be worth retrying, since the lock may have expired
+			glog.Errorf("transfer lock %v to %v: %v", lock.Key, server, err)
+		}
+	}
+
+}