Golang clientv3.WithLease函數代碼示例

func ExampleLease_keepAliveOnce() {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close()

	resp, err := cli.Grant(context.TODO(), 5)
	if err != nil {
		log.Fatal(err)
	}

	_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(resp.ID))
	if err != nil {
		log.Fatal(err)
	}

	// to renew the lease only once
	ka, kaerr := cli.KeepAliveOnce(context.TODO(), resp.ID)
	if kaerr != nil {
		log.Fatal(kaerr)
	}

	fmt.Println("ttl:", ka.TTL)
	// Output: ttl: 5
}

func ExampleLease_keepAliveOnce() {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close()

	resp, err := cli.Grant(context.TODO(), 5)
	if err != nil {
		log.Fatal(err)
	}

	_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(clientv3.LeaseID(resp.ID)))
	if err != nil {
		log.Fatal(err)
	}

	// to renew the lease only once
	_, err = cli.KeepAliveOnce(context.TODO(), clientv3.LeaseID(resp.ID))
	if err != nil {
		log.Fatal(err)
	}
}

func getPutOp(cmd *cobra.Command, args []string) (string, string, []clientv3.OpOption) {
	if len(args) == 0 {
		ExitWithError(ExitBadArgs, fmt.Errorf("put command needs 1 argument and input from stdin or 2 arguments."))
	}

	key := args[0]
	value, err := argOrStdin(args, os.Stdin, 1)
	if err != nil {
		ExitWithError(ExitBadArgs, fmt.Errorf("put command needs 1 argument and input from stdin or 2 arguments."))
	}

	id, err := strconv.ParseInt(leaseStr, 16, 64)
	if err != nil {
		ExitWithError(ExitBadArgs, fmt.Errorf("bad lease ID (%v), expecting ID in Hex", err))
	}

	opts := []clientv3.OpOption{}
	if id != 0 {
		opts = append(opts, clientv3.WithLease(clientv3.LeaseID(id)))
	}
	if putPrevKV {
		opts = append(opts, clientv3.WithPrevKV())
	}

	return key, value, opts
}

func ExampleLease_create() {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close()

	kvc := clientv3.NewKV(cli)
	lapi := clientv3.NewLease(cli)
	defer lapi.Close()

	// minimum lease TTL is 5-second
	resp, err := lapi.Create(context.TODO(), 5)
	if err != nil {
		log.Fatal(err)
	}

	// after 5 seconds, the key 'foo' will be removed
	_, err = kvc.Put(context.TODO(), "foo", "bar", clientv3.WithLease(lease.LeaseID(resp.ID)))
	if err != nil {
		log.Fatal(err)
	}
}

func ExampleLease_revoke() {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close()

	resp, err := cli.Create(context.TODO(), 5)
	if err != nil {
		log.Fatal(err)
	}

	_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(clientv3.LeaseID(resp.ID)))
	if err != nil {
		log.Fatal(err)
	}

	// revoking lease expires the key attached to its lease ID
	_, err = cli.Revoke(context.TODO(), clientv3.LeaseID(resp.ID))
	if err != nil {
		log.Fatal(err)
	}

	gresp, err := cli.Get(context.TODO(), "foo")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println("number of keys:", len(gresp.Kvs))
	// number of keys: 0
}

func ExampleLease_keepAlive() {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close()

	resp, err := cli.Create(context.TODO(), 5)
	if err != nil {
		log.Fatal(err)
	}

	_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(clientv3.LeaseID(resp.ID)))
	if err != nil {
		log.Fatal(err)
	}

	// the key 'foo' will be kept forever
	_, err = cli.KeepAlive(context.TODO(), clientv3.LeaseID(resp.ID))
	if err != nil {
		log.Fatal(err)
	}
}

func TestLeaseRevoke(t *testing.T) {
	defer testutil.AfterTest(t)

	clus := integration.NewClusterV3(t, &integration.ClusterConfig{Size: 3})
	defer clus.Terminate(t)

	lapi := clientv3.NewLease(clus.RandClient())
	defer lapi.Close()

	kv := clientv3.NewKV(clus.RandClient())

	resp, err := lapi.Create(context.Background(), 10)
	if err != nil {
		t.Errorf("failed to create lease %v", err)
	}

	_, err = lapi.Revoke(context.Background(), lease.LeaseID(resp.ID))
	if err != nil {
		t.Errorf("failed to revoke lease %v", err)
	}

	_, err = kv.Put(context.TODO(), "foo", "bar", clientv3.WithLease(lease.LeaseID(resp.ID)))
	if err != v3rpc.ErrLeaseNotFound {
		t.Fatalf("err = %v, want %v", err, v3rpc.ErrLeaseNotFound)
	}
}

func ExampleLease_keepAlive() {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close()

	resp, err := cli.Grant(context.TODO(), 5)
	if err != nil {
		log.Fatal(err)
	}

	_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(resp.ID))
	if err != nil {
		log.Fatal(err)
	}

	// the key 'foo' will be kept forever
	ch, kaerr := cli.KeepAlive(context.TODO(), resp.ID)
	if kaerr != nil {
		log.Fatal(kaerr)
	}

	ka := <-ch
	fmt.Println("ttl:", ka.TTL)
	// Output: ttl: 5
}

// Lock locks the mutex with a cancellable context. If the context is cancelled
// while trying to acquire the lock, the mutex tries to clean its stale lock entry.
func (m *Mutex) Lock(ctx context.Context) error {
	s, serr := NewSession(m.client)
	if serr != nil {
		return serr
	}

	m.myKey = fmt.Sprintf("%s/%x", m.pfx, s.Lease())
	cmp := v3.Compare(v3.CreateRevision(m.myKey), "=", 0)
	// put self in lock waiters via myKey; oldest waiter holds lock
	put := v3.OpPut(m.myKey, "", v3.WithLease(s.Lease()))
	// reuse key in case this session already holds the lock
	get := v3.OpGet(m.myKey)
	resp, err := m.client.Txn(ctx).If(cmp).Then(put).Else(get).Commit()
	if err != nil {
		return err
	}
	m.myRev = resp.Header.Revision
	if !resp.Succeeded {
		m.myRev = resp.Responses[0].GetResponseRange().Kvs[0].CreateRevision
	}

	// wait for deletion revisions prior to myKey
	err = waitDeletes(ctx, m.client, m.pfx, v3.WithPrefix(), v3.WithRev(m.myRev-1))
	// release lock key if cancelled
	select {
	case <-ctx.Done():
		m.Unlock()
	default:
	}
	return err
}

// ttlOpts returns client options based on given ttl.
// ttl: if ttl is non-zero, it will attach the key to a lease with ttl of roughly the same length
func (s *store) ttlOpts(ctx context.Context, ttl int64) ([]clientv3.OpOption, error) {
	if ttl == 0 {
		return nil, nil
	}
	// TODO: one lease per ttl key is expensive. Based on current use case, we can have a long window to
	// put keys within into same lease. We shall benchmark this and optimize the performance.
	lcr, err := s.client.Lease.Grant(ctx, ttl)
	if err != nil {
		return nil, err
	}
	return []clientv3.OpOption{clientv3.WithLease(clientv3.LeaseID(lcr.ID))}, nil
}

// putNewKV attempts to create the given key, only succeeding if the key did
// not yet exist.
func putNewKV(kv v3.KV, key, val string, leaseID v3.LeaseID) (int64, error) {
	cmp := v3.Compare(v3.Version(key), "=", 0)
	req := v3.OpPut(key, val, v3.WithLease(leaseID))
	txnresp, err := kv.Txn(context.TODO()).If(cmp).Then(req).Commit()
	if err != nil {
		return 0, err
	}
	if !txnresp.Succeeded {
		return 0, ErrKeyExists
	}
	return txnresp.Header.Revision, nil
}

// newSequentialKV allocates a new sequential key <prefix>/nnnnn with a given
// value and lease.  Note: a bookkeeping node __<prefix> is also allocated.
func newSequentialKV(kv v3.KV, prefix, val string, leaseID v3.LeaseID) (*RemoteKV, error) {
	resp, err := kv.Get(context.TODO(), prefix, v3.WithLastKey()...)
	if err != nil {
		return nil, err
	}

	// add 1 to last key, if any
	newSeqNum := 0
	if len(resp.Kvs) != 0 {
		fields := strings.Split(string(resp.Kvs[0].Key), "/")
		_, serr := fmt.Sscanf(fields[len(fields)-1], "%d", &newSeqNum)
		if serr != nil {
			return nil, serr
		}
		newSeqNum++
	}
	newKey := fmt.Sprintf("%s/%016d", prefix, newSeqNum)

	// base prefix key must be current (i.e., <=) with the server update;
	// the base key is important to avoid the following:
	// N1: LastKey() == 1, start txn.
	// N2: New Key 2, New Key 3, Delete Key 2
	// N1: txn succeeds allocating key 2 when it shouldn't
	baseKey := "__" + prefix

	// current revision might contain modification so +1
	cmp := v3.Compare(v3.ModRevision(baseKey), "<", resp.Header.Revision+1)
	reqPrefix := v3.OpPut(baseKey, "", v3.WithLease(leaseID))
	reqNewKey := v3.OpPut(newKey, val, v3.WithLease(leaseID))

	txn := kv.Txn(context.TODO())
	txnresp, err := txn.If(cmp).Then(reqPrefix, reqNewKey).Commit()
	if err != nil {
		return nil, err
	}
	if !txnresp.Succeeded {
		return newSequentialKV(kv, prefix, val, leaseID)
	}
	return &RemoteKV{kv, newKey, txnresp.Header.Revision, val}, nil
}

func TestLeaseTimeToLive(t *testing.T) {
	defer testutil.AfterTest(t)

	clus := integration.NewClusterV3(t, &integration.ClusterConfig{Size: 3})
	defer clus.Terminate(t)

	lapi := clientv3.NewLease(clus.RandClient())
	defer lapi.Close()

	resp, err := lapi.Grant(context.Background(), 10)
	if err != nil {
		t.Errorf("failed to create lease %v", err)
	}

	kv := clientv3.NewKV(clus.RandClient())
	keys := []string{"foo1", "foo2"}
	for i := range keys {
		if _, err = kv.Put(context.TODO(), keys[i], "bar", clientv3.WithLease(resp.ID)); err != nil {
			t.Fatal(err)
		}
	}

	lresp, lerr := lapi.TimeToLive(context.Background(), resp.ID, clientv3.WithAttachedKeys())
	if lerr != nil {
		t.Fatal(lerr)
	}
	if lresp.ID != resp.ID {
		t.Fatalf("leaseID expected %d, got %d", resp.ID, lresp.ID)
	}
	if lresp.GrantedTTL != int64(10) {
		t.Fatalf("GrantedTTL expected %d, got %d", 10, lresp.GrantedTTL)
	}
	if lresp.TTL == 0 || lresp.TTL > lresp.GrantedTTL {
		t.Fatalf("unexpected TTL %d (granted %d)", lresp.TTL, lresp.GrantedTTL)
	}
	ks := make([]string, len(lresp.Keys))
	for i := range lresp.Keys {
		ks[i] = string(lresp.Keys[i])
	}
	sort.Strings(ks)
	if !reflect.DeepEqual(ks, keys) {
		t.Fatalf("keys expected %v, got %v", keys, ks)
	}

	lresp, lerr = lapi.TimeToLive(context.Background(), resp.ID)
	if lerr != nil {
		t.Fatal(lerr)
	}
	if len(lresp.Keys) != 0 {
		t.Fatalf("unexpected keys %+v", lresp.Keys)
	}
}

func (n *ng) setVal(key string, val []byte, ttl time.Duration) error {
	ops := []etcd.OpOption{}
	if ttl > 0 {
		lgr, err := n.client.Grant(n.context, int64(ttl.Seconds()))
		if err != nil {
			return err
		}
		ops = append(ops, etcd.WithLease(lgr.ID))
	}

	_, err := n.client.Put(n.context, key, string(val), ops...)
	return convertErr(err)
}

// Lock locks resources on sync
// This call blocks until you can get lock
func (s *Sync) Lock(path string, block bool) error {
	for {
		if s.HasLock(path) {
			return nil
		}
		var err error
		lease, err := s.etcdClient.Grant(s.withTimeout(), masterTTL)
		var resp *etcd.TxnResponse
		if err == nil {
			cmp := etcd.Compare(etcd.CreateRevision(path), "=", 0)
			put := etcd.OpPut(path, s.processID, etcd.WithLease(lease.ID))
			resp, err = s.etcdClient.Txn(s.withTimeout()).If(cmp).Then(put).Commit()
		}
		if err != nil || !resp.Succeeded {
			msg := fmt.Sprintf("failed to lock path %s", path)
			if err != nil {
				msg = fmt.Sprintf("failed to lock path %s: %s", path, err)
			}
			log.Notice(msg)

			s.locks.Remove(path)
			if !block {
				return errors.New(msg)
			}
			time.Sleep(masterTTL * time.Second)
			continue
		}
		log.Info("Locked %s", path)
		s.locks.Set(path, lease.ID)
		//Refresh master token
		go func() {
			defer func() {
				log.Notice("releasing keepalive lock for %s", path)
				s.locks.Remove(path)
			}()
			for s.HasLock(path) {
				ch, err := s.etcdClient.KeepAlive(s.withTimeout(), lease.ID)
				if err != nil {
					log.Notice("failed to keepalive lock for %s %s", path, err)
					return
				}
				for range ch {
				}
			}
		}()

		return nil
	}
}