Esempio n. 1
0
// TransferRangeLease transfers the lease for a range from whoever has it to
// a particular store. That store must already have a replica of the range. If
// that replica already has the (active) lease, this method is a no-op.
func (tc *TestCluster) TransferRangeLease(
	rangeDesc *roachpb.RangeDescriptor, dest ReplicationTarget,
) error {
	destReplicaDesc, ok := rangeDesc.GetReplicaDescriptor(dest.StoreID)
	if !ok {
		log.Fatalf("Couldn't find store %d in range %+v", dest.StoreID, rangeDesc)
	}

	leaseHolderDesc, err := tc.FindRangeLeaseHolder(rangeDesc,
		&ReplicationTarget{
			NodeID:  destReplicaDesc.NodeID,
			StoreID: destReplicaDesc.StoreID,
		})
	if err != nil {
		return err
	}
	if leaseHolderDesc.StoreID == dest.StoreID {
		// The intended replica already has the lease. Nothing to do.
		return nil
	}
	oldStore, err := tc.findMemberStore(leaseHolderDesc.StoreID)
	if err != nil {
		return err
	}
	oldReplica, err := oldStore.GetReplica(rangeDesc.RangeID)
	if err != nil {
		return err
	}
	// Ask the lease holder to transfer the lease.
	if err := oldReplica.AdminTransferLease(destReplicaDesc); err != nil {
		return err
	}
	return nil
}
Esempio n. 2
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// TestSendRPCRetry verifies that sendRPC failed on first address but succeed on
// second address, the second reply should be successfully returned back.
func TestSendRPCRetry(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()
	g.SetNodeID(1)
	if err := g.SetNodeDescriptor(&roachpb.NodeDescriptor{NodeID: 1}); err != nil {
		t.Fatal(err)
	}
	// Fill RangeDescriptor with 2 replicas
	var descriptor = roachpb.RangeDescriptor{
		RangeID:  1,
		StartKey: roachpb.RKey("a"),
		EndKey:   roachpb.RKey("z"),
	}
	for i := 1; i <= 2; i++ {
		addr := util.MakeUnresolvedAddr("tcp", fmt.Sprintf("node%d", i))
		nd := &roachpb.NodeDescriptor{
			NodeID:  roachpb.NodeID(i),
			Address: util.MakeUnresolvedAddr(addr.Network(), addr.String()),
		}
		if err := g.AddInfoProto(gossip.MakeNodeIDKey(roachpb.NodeID(i)), nd, time.Hour); err != nil {
			t.Fatal(err)
		}

		descriptor.Replicas = append(descriptor.Replicas, roachpb.ReplicaDescriptor{
			NodeID:  roachpb.NodeID(i),
			StoreID: roachpb.StoreID(i),
		})
	}
	// Define our rpcSend stub which returns success on the second address.
	var testFn rpcSendFn = func(_ rpc.Options, method string, addrs []net.Addr, getArgs func(addr net.Addr) proto.Message, getReply func() proto.Message, _ *rpc.Context) ([]proto.Message, error) {
		if method == "Node.Batch" {
			// reply from first address failed
			_ = getReply()
			// reply from second address succeed
			batchReply := getReply().(*roachpb.BatchResponse)
			reply := &roachpb.ScanResponse{}
			batchReply.Add(reply)
			reply.Rows = append([]roachpb.KeyValue{}, roachpb.KeyValue{Key: roachpb.Key("b"), Value: roachpb.Value{}})
			return []proto.Message{batchReply}, nil
		}
		return nil, util.Errorf("unexpected method %v", method)
	}
	ctx := &DistSenderContext{
		RPCSend: testFn,
		RangeDescriptorDB: mockRangeDescriptorDB(func(_ roachpb.RKey, _, _ bool) ([]roachpb.RangeDescriptor, *roachpb.Error) {
			return []roachpb.RangeDescriptor{descriptor}, nil
		}),
	}
	ds := NewDistSender(ctx, g)
	scan := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("d"), 1)
	sr, err := client.SendWrapped(ds, nil, scan)
	if err != nil {
		t.Fatal(err)
	}
	if l := len(sr.(*roachpb.ScanResponse).Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
}
Esempio n. 3
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// intersect returns the intersection of the current span and the
// descriptor's range.
func (rs rSpan) intersect(desc *roachpb.RangeDescriptor) rSpan {
	key := rs.key
	if !desc.ContainsKey(key) {
		key = desc.StartKey
	}
	endKey := rs.endKey
	if !desc.ContainsKeyRange(desc.StartKey, endKey) || endKey == nil {
		endKey = desc.EndKey
	}
	return rSpan{key, endKey}
}
Esempio n. 4
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// TestSendRPCRetry verifies that sendRPC failed on first address but succeed on
// second address, the second reply should be successfully returned back.
func TestSendRPCRetry(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()
	g.SetNodeID(1)
	if err := g.SetNodeDescriptor(&roachpb.NodeDescriptor{NodeID: 1}); err != nil {
		t.Fatal(err)
	}
	// Fill RangeDescriptor with 2 replicas
	var descriptor = roachpb.RangeDescriptor{
		RangeID:  1,
		StartKey: roachpb.RKey("a"),
		EndKey:   roachpb.RKey("z"),
	}
	for i := 1; i <= 2; i++ {
		addr := util.MakeUnresolvedAddr("tcp", fmt.Sprintf("node%d", i))
		nd := &roachpb.NodeDescriptor{
			NodeID:  roachpb.NodeID(i),
			Address: util.MakeUnresolvedAddr(addr.Network(), addr.String()),
		}
		if err := g.AddInfoProto(gossip.MakeNodeIDKey(roachpb.NodeID(i)), nd, time.Hour); err != nil {
			t.Fatal(err)
		}

		descriptor.Replicas = append(descriptor.Replicas, roachpb.ReplicaDescriptor{
			NodeID:  roachpb.NodeID(i),
			StoreID: roachpb.StoreID(i),
		})
	}
	var testFn rpcSendFn = func(_ SendOptions, _ ReplicaSlice,
		args roachpb.BatchRequest, _ *rpc.Context) (proto.Message, error) {
		batchReply := &roachpb.BatchResponse{}
		reply := &roachpb.ScanResponse{}
		batchReply.Add(reply)
		reply.Rows = append([]roachpb.KeyValue{}, roachpb.KeyValue{Key: roachpb.Key("b"), Value: roachpb.Value{}})
		return batchReply, nil
	}
	ctx := &DistSenderContext{
		RPCSend: testFn,
		RangeDescriptorDB: mockRangeDescriptorDB(func(_ roachpb.RKey, _, _ bool) ([]roachpb.RangeDescriptor, *roachpb.Error) {
			return []roachpb.RangeDescriptor{descriptor}, nil
		}),
	}
	ds := NewDistSender(ctx, g)
	scan := roachpb.NewScan(roachpb.Key("a"), roachpb.Key("d"), 1)
	sr, err := client.SendWrapped(ds, nil, scan)
	if err != nil {
		t.Fatal(err)
	}
	if l := len(sr.(*roachpb.ScanResponse).Rows); l != 1 {
		t.Fatalf("expected 1 row; got %d", l)
	}
}
Esempio n. 5
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// FindRangeLeaseHolder returns the current lease holder for the given range. If
// there is no lease at the time of the call, a replica is gets one as a
// side-effect of calling this; if hint is not nil, that replica will be the
// one.
//
// One of the Stores in the cluster is used as a Sender to send a dummy read
// command, which will either result in success (if a replica on that Node has
// the lease), in a NotLeaseHolderError pointing to the current lease holder (if
// there is an active lease), or in the replica on that store acquiring the
// lease (if there isn't an active lease).
// If an active lease existed for the range, it's extended as a side-effect.
func (tc *TestCluster) FindRangeLeaseHolder(
	rangeDesc *roachpb.RangeDescriptor,
	hint *ReplicationTarget,
) (ReplicationTarget, error) {
	var hintReplicaDesc roachpb.ReplicaDescriptor
	if hint != nil {
		var ok bool
		if hintReplicaDesc, ok = rangeDesc.GetReplicaDescriptor(hint.StoreID); !ok {
			return ReplicationTarget{}, errors.Errorf(
				"bad hint; store doesn't have a replica of the range")
		}
	} else {
		hint = &ReplicationTarget{
			NodeID:  rangeDesc.Replicas[0].NodeID,
			StoreID: rangeDesc.Replicas[0].StoreID}
		hintReplicaDesc = rangeDesc.Replicas[0]
	}
	// TODO(andrei): Using a dummy GetRequest for the purpose of figuring out the
	// lease holder is a hack. Instead, we should have a dedicate admin command.
	getReq := roachpb.GetRequest{
		Span: roachpb.Span{
			Key: rangeDesc.StartKey.AsRawKey(),
		},
	}

	store, err := tc.findMemberStore(hint.StoreID)
	if err != nil {
		return ReplicationTarget{}, err
	}
	_, pErr := client.SendWrappedWith(
		store, nil,
		roachpb.Header{RangeID: rangeDesc.RangeID, Replica: hintReplicaDesc},
		&getReq)
	if pErr != nil {
		if nle, ok := pErr.GetDetail().(*roachpb.NotLeaseHolderError); ok {
			if nle.LeaseHolder == nil {
				return ReplicationTarget{}, errors.Errorf(
					"unexpected NotLeaseHolderError with lease holder unknown")
			}
			return ReplicationTarget{
				NodeID: nle.LeaseHolder.NodeID, StoreID: nle.LeaseHolder.StoreID}, nil
		}
		return ReplicationTarget{}, pErr.GoError()
	}
	// The replica we sent the request to either was already or just became
	// the lease holder.
	return *hint, nil
}
Esempio n. 6
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// TestSendRPCOrder verifies that sendRPC correctly takes into account the
// leader, attributes and required consistency to determine where to send
// remote requests.
func TestSendRPCOrder(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()
	rangeID := roachpb.RangeID(99)

	nodeAttrs := map[int32][]string{
		1: {}, // The local node, set in each test case.
		2: {"us", "west", "gpu"},
		3: {"eu", "dublin", "pdu2", "gpu"},
		4: {"us", "east", "gpu"},
		5: {"us", "east", "gpu", "flaky"},
	}

	// Gets filled below to identify the replica by its address.
	addrToNode := make(map[string]int32)
	makeVerifier := func(expOrder rpc.OrderingPolicy,
		expAddrs []int32) func(rpc.Options, []net.Addr) error {
		return func(o rpc.Options, addrs []net.Addr) error {
			if o.Ordering != expOrder {
				return util.Errorf("unexpected ordering, wanted %v, got %v",
					expOrder, o.Ordering)
			}
			var actualAddrs []int32
			for i, a := range addrs {
				if len(expAddrs) <= i {
					return util.Errorf("got unexpected address: %s", a)
				}
				if expAddrs[i] == 0 {
					actualAddrs = append(actualAddrs, 0)
				} else {
					actualAddrs = append(actualAddrs, addrToNode[a.String()])
				}
			}
			if !reflect.DeepEqual(expAddrs, actualAddrs) {
				return util.Errorf("expected %d, but found %d", expAddrs, actualAddrs)
			}
			return nil
		}
	}

	testCases := []struct {
		args       roachpb.Request
		attrs      []string
		order      rpc.OrderingPolicy
		expReplica []int32
		leader     int32 // 0 for not caching a leader.
		// Naming is somewhat off, as eventually consistent reads usually
		// do not have to go to the leader when a node has a read lease.
		// Would really want CONSENSUS here, but that is not implemented.
		// Likely a test setup here will never have a read lease, but good
		// to keep in mind.
		consistent bool
	}{
		// Inconsistent Scan without matching attributes.
		{
			args:       &roachpb.ScanRequest{},
			attrs:      []string{},
			order:      rpc.OrderRandom,
			expReplica: []int32{1, 2, 3, 4, 5},
		},
		// Inconsistent Scan with matching attributes.
		// Should move the two nodes matching the attributes to the front and
		// go stable.
		{
			args:  &roachpb.ScanRequest{},
			attrs: nodeAttrs[5],
			order: rpc.OrderStable,
			// Compare only the first two resulting addresses.
			expReplica: []int32{5, 4, 0, 0, 0},
		},

		// Scan without matching attributes that requires but does not find
		// a leader.
		{
			args:       &roachpb.ScanRequest{},
			attrs:      []string{},
			order:      rpc.OrderRandom,
			expReplica: []int32{1, 2, 3, 4, 5},
			consistent: true,
		},
		// Put without matching attributes that requires but does not find leader.
		// Should go random and not change anything.
		{
			args:       &roachpb.PutRequest{},
			attrs:      []string{"nomatch"},
			order:      rpc.OrderRandom,
			expReplica: []int32{1, 2, 3, 4, 5},
		},
		// Put with matching attributes but no leader.
		// Should move the two nodes matching the attributes to the front and
		// go stable.
		{
			args:  &roachpb.PutRequest{},
			attrs: append(nodeAttrs[5], "irrelevant"),
			// Compare only the first two resulting addresses.
			order:      rpc.OrderStable,
			expReplica: []int32{5, 4, 0, 0, 0},
		},
		// Put with matching attributes that finds the leader (node 3).
		// Should address the leader and the two nodes matching the attributes
		// (the last and second to last) in that order.
		{
			args:  &roachpb.PutRequest{},
			attrs: append(nodeAttrs[5], "irrelevant"),
			// Compare only the first resulting addresses as we have a leader
			// and that means we're only trying to send there.
			order:      rpc.OrderStable,
			expReplica: []int32{2, 5, 4, 0, 0},
			leader:     2,
		},
		// Inconsistent Get without matching attributes but leader (node 3). Should just
		// go random as the leader does not matter.
		{
			args:       &roachpb.GetRequest{},
			attrs:      []string{},
			order:      rpc.OrderRandom,
			expReplica: []int32{1, 2, 3, 4, 5},
			leader:     2,
		},
	}

	descriptor := roachpb.RangeDescriptor{
		StartKey: roachpb.RKeyMin,
		EndKey:   roachpb.RKeyMax,
		RangeID:  rangeID,
		Replicas: nil,
	}

	// Stub to be changed in each test case.
	var verifyCall func(rpc.Options, []net.Addr) error

	var testFn rpcSendFn = func(opts rpc.Options, method string,
		addrs []net.Addr, getArgs func(addr net.Addr) proto.Message,
		getReply func() proto.Message, _ *rpc.Context) ([]proto.Message, error) {
		if err := verifyCall(opts, addrs); err != nil {
			return nil, err
		}
		return []proto.Message{getArgs(addrs[0]).(*roachpb.BatchRequest).CreateReply()}, nil
	}

	ctx := &DistSenderContext{
		RPCSend: testFn,
		RangeDescriptorDB: mockRangeDescriptorDB(func(roachpb.RKey, bool, bool) ([]roachpb.RangeDescriptor, *roachpb.Error) {
			return []roachpb.RangeDescriptor{descriptor}, nil
		}),
	}

	ds := NewDistSender(ctx, g)

	for n, tc := range testCases {
		verifyCall = makeVerifier(tc.order, tc.expReplica)
		descriptor.Replicas = nil // could do this once above, but more convenient here
		for i := int32(1); i <= 5; i++ {
			addr := util.MakeUnresolvedAddr("tcp", fmt.Sprintf("node%d", i))
			addrToNode[addr.String()] = i
			nd := &roachpb.NodeDescriptor{
				NodeID:  roachpb.NodeID(i),
				Address: util.MakeUnresolvedAddr(addr.Network(), addr.String()),
				Attrs: roachpb.Attributes{
					Attrs: nodeAttrs[i],
				},
			}
			if err := g.AddInfoProto(gossip.MakeNodeIDKey(roachpb.NodeID(i)), nd, time.Hour); err != nil {
				t.Fatal(err)
			}
			descriptor.Replicas = append(descriptor.Replicas, roachpb.ReplicaDescriptor{
				NodeID:  roachpb.NodeID(i),
				StoreID: roachpb.StoreID(i),
			})
		}

		{
			// The local node needs to get its attributes during sendRPC.
			nd := &roachpb.NodeDescriptor{
				NodeID: 6,
				Attrs: roachpb.Attributes{
					Attrs: tc.attrs,
				},
			}
			g.SetNodeID(nd.NodeID)
			if err := g.SetNodeDescriptor(nd); err != nil {
				t.Fatal(err)
			}
		}

		ds.leaderCache.Update(roachpb.RangeID(rangeID), roachpb.ReplicaDescriptor{})
		if tc.leader > 0 {
			ds.leaderCache.Update(roachpb.RangeID(rangeID), descriptor.Replicas[tc.leader-1])
		}

		args := tc.args
		args.Header().Key = roachpb.Key("a")
		if roachpb.IsRange(args) {
			args.Header().EndKey = roachpb.Key("b")
		}
		consistency := roachpb.CONSISTENT
		if !tc.consistent {
			consistency = roachpb.INCONSISTENT
		}
		// Kill the cached NodeDescriptor, enforcing a lookup from Gossip.
		ds.nodeDescriptor = nil
		if _, err := client.SendWrappedWith(ds, nil, roachpb.Header{
			RangeID:         rangeID, // Not used in this test, but why not.
			ReadConsistency: consistency,
		}, args); err != nil {
			t.Errorf("%d: %s", n, err)
		}
	}
}
Esempio n. 7
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// sendChunk is in charge of sending an "admissible" piece of batch, i.e. one
// which doesn't need to be subdivided further before going to a range (so no
// mixing of forward and reverse scans, etc). The parameters and return values
// correspond to client.Sender with the exception of the returned boolean,
// which is true when indicating that the caller should retry but needs to send
// EndTransaction in a separate request.
func (ds *DistSender) sendChunk(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error, bool) {
	isReverse := ba.IsReverse()

	trace := tracer.FromCtx(ctx)

	// The minimal key range encompassing all requests contained within.
	// Local addressing has already been resolved.
	// TODO(tschottdorf): consider rudimentary validation of the batch here
	// (for example, non-range requests with EndKey, or empty key ranges).
	rs := keys.Range(ba)
	var br *roachpb.BatchResponse
	// Send the request to one range per iteration.
	for {
		considerIntents := false
		var curReply *roachpb.BatchResponse
		var desc *roachpb.RangeDescriptor
		var needAnother bool
		var pErr *roachpb.Error
		for r := retry.Start(ds.rpcRetryOptions); r.Next(); {
			// Get range descriptor (or, when spanning range, descriptors). Our
			// error handling below may clear them on certain errors, so we
			// refresh (likely from the cache) on every retry.
			descDone := trace.Epoch("meta descriptor lookup")
			var evictDesc func()
			desc, needAnother, evictDesc, pErr = ds.getDescriptors(rs, considerIntents, isReverse)
			descDone()

			// getDescriptors may fail retryably if the first range isn't
			// available via Gossip.
			if pErr != nil {
				if pErr.Retryable {
					if log.V(1) {
						log.Warning(pErr)
					}
					continue
				}
				break
			}

			if needAnother && br == nil {
				// TODO(tschottdorf): we should have a mechanism for discovering
				// range merges (descriptor staleness will mostly go unnoticed),
				// or we'll be turning single-range queries into multi-range
				// queries for no good reason.

				// If there's no transaction and op spans ranges, possibly
				// re-run as part of a transaction for consistency. The
				// case where we don't need to re-run is if the read
				// consistency is not required.
				if ba.Txn == nil && ba.IsPossibleTransaction() &&
					ba.ReadConsistency != roachpb.INCONSISTENT {
					return nil, roachpb.NewError(&roachpb.OpRequiresTxnError{}), false
				}
				// If the request is more than but ends with EndTransaction, we
				// want the caller to come again with the EndTransaction in an
				// extra call.
				if l := len(ba.Requests) - 1; l > 0 && ba.Requests[l].GetInner().Method() == roachpb.EndTransaction {
					return nil, roachpb.NewError(errors.New("cannot send 1PC txn to multiple ranges")), true /* shouldSplitET */
				}
			}

			// It's possible that the returned descriptor misses parts of the
			// keys it's supposed to scan after it's truncated to match the
			// descriptor. Example revscan [a,g), first desc lookup for "g"
			// returns descriptor [c,d) -> [d,g) is never scanned.
			// We evict and retry in such a case.
			if (isReverse && !desc.ContainsKeyRange(desc.StartKey, rs.EndKey)) || (!isReverse && !desc.ContainsKeyRange(rs.Key, desc.EndKey)) {
				evictDesc()
				continue
			}

			curReply, pErr = func() (*roachpb.BatchResponse, *roachpb.Error) {
				// Truncate the request to our current key range.
				intersected, iErr := rs.Intersect(desc)
				if iErr != nil {
					return nil, roachpb.NewError(iErr)
				}
				truncBA, numActive, trErr := truncate(ba, intersected)
				if numActive == 0 && trErr == nil {
					// This shouldn't happen in the wild, but some tests
					// exercise it.
					return nil, roachpb.NewErrorf("truncation resulted in empty batch on [%s,%s): %s",
						rs.Key, rs.EndKey, ba)
				}
				if trErr != nil {
					return nil, roachpb.NewError(trErr)
				}

				return ds.sendSingleRange(trace, truncBA, desc)
			}()
			// If sending succeeded, break this loop.
			if pErr == nil {
				break
			}

			if log.V(1) {
				log.Warningf("failed to invoke %s: %s", ba, pErr)
			}
			trace.Event(fmt.Sprintf("reply error: %T", pErr.GoError()))

			// Error handling below.
			// If retryable, allow retry. For range not found or range
			// key mismatch errors, we don't backoff on the retry,
			// but reset the backoff loop so we can retry immediately.
			switch tErr := pErr.GoError().(type) {
			case *roachpb.SendError:
				// For an RPC error to occur, we must've been unable to contact
				// any replicas. In this case, likely all nodes are down (or
				// not getting back to us within a reasonable amount of time).
				// We may simply not be trying to talk to the up-to-date
				// replicas, so clearing the descriptor here should be a good
				// idea.
				// TODO(tschottdorf): If a replica group goes dead, this
				// will cause clients to put high read pressure on the first
				// range, so there should be some rate limiting here.
				evictDesc()
				if tErr.CanRetry() {
					continue
				}
			case *roachpb.RangeNotFoundError, *roachpb.RangeKeyMismatchError:
				// Range descriptor might be out of date - evict it.
				evictDesc()
				// On addressing errors, don't backoff; retry immediately.
				r.Reset()
				if log.V(1) {
					log.Warning(tErr)
				}
				// On retries, allow [uncommitted] intents on range descriptor
				// lookups to be returned 50% of the time in order to succeed
				// at finding the transaction record pointed to by the intent
				// itself. The 50% probability of returning either the current
				// intent or the previously committed value balances between
				// the two cases where the intent's txn hasn't yet been
				// committed (the previous value is correct), or the intent's
				// txn has been committed (the intent value is correct).
				considerIntents = true
				continue
			case *roachpb.NotLeaderError:
				newLeader := tErr.Leader
				// Verify that leader is a known replica according to the
				// descriptor. If not, we've got a stale replica; evict cache.
				// Next, cache the new leader.
				if newLeader != nil {
					if i, _ := desc.FindReplica(newLeader.StoreID); i == -1 {
						if log.V(1) {
							log.Infof("error indicates unknown leader %s, expunging descriptor %s", newLeader, desc)
						}
						evictDesc()
					}
				} else {
					newLeader = &roachpb.ReplicaDescriptor{}
				}
				ds.updateLeaderCache(roachpb.RangeID(desc.RangeID), *newLeader)
				if log.V(1) {
					log.Warning(tErr)
				}
				r.Reset()
				continue
			case retry.Retryable:
				if tErr.CanRetry() {
					if log.V(1) {
						log.Warning(tErr)
					}
					continue
				}
			}
			break
		}

		// Immediately return if querying a range failed non-retryably.
		if pErr != nil {
			return nil, pErr, false
		}

		ba.Txn.Update(curReply.Txn)

		if br == nil {
			// First response from a Range.
			br = curReply
		} else {
			// This was the second or later call in a cross-Range request.
			// Combine the new response with the existing one.
			if err := br.Combine(curReply); err != nil {
				return nil, roachpb.NewError(err), false
			}
		}

		// If this request has a bound (such as MaxResults in
		// ScanRequest) and we are going to query at least one more range,
		// check whether enough rows have been retrieved.
		// TODO(tschottdorf): need tests for executing a multi-range batch
		// with various bounded requests which saturate at different times.
		if needAnother {
			// Start with the assumption that all requests are saturated.
			// Below, we look at each and decide whether that's true.
			// Everything that is indeed saturated is "masked out" from the
			// batch request; only if that's all requests does needAnother
			// remain false.
			needAnother = false
			if br == nil {
				// Clone ba.Requests. This is because we're multi-range, and
				// some requests may be bounded, which could lead to them being
				// masked out once they're saturated. We don't want to risk
				// removing requests that way in the "master copy" since that
				// could lead to omitting requests in certain retry scenarios.
				ba.Requests = append([]roachpb.RequestUnion(nil), ba.Requests...)
			}
			for i, union := range ba.Requests {
				args := union.GetInner()
				if _, ok := args.(*roachpb.NoopRequest); ok {
					// NoopRequests are skipped.
					continue
				}
				boundedArg, ok := args.(roachpb.Bounded)
				if !ok {
					// Non-bounded request. We will have to query all ranges.
					needAnother = true
					continue
				}
				prevBound := boundedArg.GetBound()
				cReply, ok := curReply.Responses[i].GetInner().(roachpb.Countable)
				if !ok || prevBound <= 0 {
					// Request bounded, but without max results. Again, will
					// need to query everything we can. The case in which the reply
					// isn't countable occurs when the request wasn't active for
					// that range (since it didn't apply to it), so the response
					// is a NoopResponse.
					needAnother = true
					continue
				}
				nextBound := prevBound - cReply.Count()
				if nextBound <= 0 {
					// We've hit max results for this piece of the batch. Mask
					// it out (we've copied the requests slice above, so this
					// is kosher).
					ba.Requests[i].Reset() // necessary (no one-of?)
					if !ba.Requests[i].SetValue(&roachpb.NoopRequest{}) {
						panic("RequestUnion excludes NoopRequest")
					}
					continue
				}
				// The request isn't saturated yet.
				needAnother = true
				boundedArg.SetBound(nextBound)
			}
		}

		// If this was the last range accessed by this call, exit loop.
		if !needAnother {
			return br, nil, false
		}

		if isReverse {
			// In next iteration, query previous range.
			// We use the StartKey of the current descriptor as opposed to the
			// EndKey of the previous one since that doesn't have bugs when
			// stale descriptors come into play.
			rs.EndKey = prev(ba, desc.StartKey)
		} else {
			// In next iteration, query next range.
			// It's important that we use the EndKey of the current descriptor
			// as opposed to the StartKey of the next one: if the former is stale,
			// it's possible that the next range has since merged the subsequent
			// one, and unless both descriptors are stale, the next descriptor's
			// StartKey would move us to the beginning of the current range,
			// resulting in a duplicate scan.
			rs.Key = next(ba, desc.EndKey)
		}
		trace.Event("querying next range")
	}
}
Esempio n. 8
0
// sendChunk is in charge of sending an "admissible" piece of batch, i.e. one
// which doesn't need to be subdivided further before going to a range (so no
// mixing of forward and reverse scans, etc). The parameters and return values
// correspond to client.Sender with the exception of the returned boolean,
// which is true when indicating that the caller should retry but needs to send
// EndTransaction in a separate request.
func (ds *DistSender) sendChunk(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error, bool) {
	isReverse := ba.IsReverse()

	// TODO(radu): when contexts are properly plumbed, we should be able to get
	// the tracer from ctx, not from the DistSender.
	ctx, cleanup := tracing.EnsureContext(ctx, tracing.TracerFromCtx(ds.Ctx))
	defer cleanup()

	// The minimal key range encompassing all requests contained within.
	// Local addressing has already been resolved.
	// TODO(tschottdorf): consider rudimentary validation of the batch here
	// (for example, non-range requests with EndKey, or empty key ranges).
	rs, err := keys.Range(ba)
	if err != nil {
		return nil, roachpb.NewError(err), false
	}
	var br *roachpb.BatchResponse

	// Send the request to one range per iteration.
	for {
		// Increase the sequence counter only once before sending RPCs to
		// the ranges involved in this chunk of the batch (as opposed to for
		// each RPC individually). On RPC errors, there's no guarantee that
		// the request hasn't made its way to the target regardless of the
		// error; we'd like the second execution to be caught by the sequence
		// cache if that happens. There is a small chance that that we address
		// a range twice in this chunk (stale/suboptimal descriptors due to
		// splits/merges) which leads to a transaction retry.
		// TODO(tschottdorf): it's possible that if we don't evict from the
		//   cache we could be in for a busy loop.
		ba.SetNewRequest()

		var curReply *roachpb.BatchResponse
		var desc *roachpb.RangeDescriptor
		var evictToken *evictionToken
		var needAnother bool
		var pErr *roachpb.Error
		var finished bool
		var numAttempts int
		for r := retry.StartWithCtx(ctx, ds.rpcRetryOptions); r.Next(); {
			numAttempts++
			{
				const magicLogCurAttempt = 20

				var seq int32
				if ba.Txn != nil {
					seq = ba.Txn.Sequence
				}

				if numAttempts%magicLogCurAttempt == 0 || seq%magicLogCurAttempt == 0 {
					// Log a message if a request appears to get stuck for a long
					// time or, potentially, forever. See #8975.
					// The local counter captures this loop here; the Sequence number
					// should capture anything higher up (as it needs to be
					// incremented every time this method is called).
					log.Warningf(
						ctx,
						"%d retries for an RPC at sequence %d, last error was: %s, remaining key ranges %s: %s",
						numAttempts, seq, pErr, rs, ba,
					)
				}
			}
			// Get range descriptor (or, when spanning range, descriptors). Our
			// error handling below may clear them on certain errors, so we
			// refresh (likely from the cache) on every retry.
			log.Trace(ctx, "meta descriptor lookup")
			var err error
			desc, needAnother, evictToken, err = ds.getDescriptors(ctx, rs, evictToken, isReverse)

			// getDescriptors may fail retryably if, for example, the first
			// range isn't available via Gossip. Assume that all errors at
			// this level are retryable. Non-retryable errors would be for
			// things like malformed requests which we should have checked
			// for before reaching this point.
			if err != nil {
				log.Trace(ctx, "range descriptor lookup failed: "+err.Error())
				if log.V(1) {
					log.Warning(ctx, err)
				}
				pErr = roachpb.NewError(err)
				continue
			}

			if needAnother && br == nil {
				// TODO(tschottdorf): we should have a mechanism for discovering
				// range merges (descriptor staleness will mostly go unnoticed),
				// or we'll be turning single-range queries into multi-range
				// queries for no good reason.

				// If there's no transaction and op spans ranges, possibly
				// re-run as part of a transaction for consistency. The
				// case where we don't need to re-run is if the read
				// consistency is not required.
				if ba.Txn == nil && ba.IsPossibleTransaction() &&
					ba.ReadConsistency != roachpb.INCONSISTENT {
					return nil, roachpb.NewError(&roachpb.OpRequiresTxnError{}), false
				}
				// If the request is more than but ends with EndTransaction, we
				// want the caller to come again with the EndTransaction in an
				// extra call.
				if l := len(ba.Requests) - 1; l > 0 && ba.Requests[l].GetInner().Method() == roachpb.EndTransaction {
					return nil, roachpb.NewError(errors.New("cannot send 1PC txn to multiple ranges")), true /* shouldSplitET */
				}
			}

			// It's possible that the returned descriptor misses parts of the
			// keys it's supposed to scan after it's truncated to match the
			// descriptor. Example revscan [a,g), first desc lookup for "g"
			// returns descriptor [c,d) -> [d,g) is never scanned.
			// We evict and retry in such a case.
			includesFrontOfCurSpan := func(rd *roachpb.RangeDescriptor) bool {
				if isReverse {
					return desc.ContainsExclusiveEndKey(rs.EndKey)
				}
				return desc.ContainsKey(rs.Key)
			}
			if !includesFrontOfCurSpan(desc) {
				if err := evictToken.Evict(ctx); err != nil {
					return nil, roachpb.NewError(err), false
				}
				// On addressing errors, don't backoff; retry immediately.
				r.Reset()
				continue
			}

			curReply, pErr = func() (*roachpb.BatchResponse, *roachpb.Error) {
				// Truncate the request to our current key range.
				intersected, iErr := rs.Intersect(desc)
				if iErr != nil {
					return nil, roachpb.NewError(iErr)
				}
				truncBA, numActive, trErr := truncate(ba, intersected)
				if numActive == 0 && trErr == nil {
					// This shouldn't happen in the wild, but some tests
					// exercise it.
					return nil, roachpb.NewErrorf("truncation resulted in empty batch on [%s,%s): %s",
						rs.Key, rs.EndKey, ba)
				}
				if trErr != nil {
					return nil, roachpb.NewError(trErr)
				}
				return ds.sendSingleRange(ctx, truncBA, desc)
			}()
			// If sending succeeded, break this loop.
			if pErr == nil {
				finished = true
				break
			}

			log.VTracef(1, ctx, "reply error %s: %s", ba, pErr)

			// Error handling: If the error indicates that our range
			// descriptor is out of date, evict it from the cache and try
			// again. Errors that apply only to a single replica were
			// handled in send().
			//
			// TODO(bdarnell): Don't retry endlessly. If we fail twice in a
			// row and the range descriptor hasn't changed, return the error
			// to our caller.
			switch tErr := pErr.GetDetail().(type) {
			case *roachpb.SendError:
				// We've tried all the replicas without success. Either
				// they're all down, or we're using an out-of-date range
				// descriptor. Invalidate the cache and try again with the new
				// metadata.
				if err := evictToken.Evict(ctx); err != nil {
					return nil, roachpb.NewError(err), false
				}
				continue
			case *roachpb.RangeKeyMismatchError:
				// Range descriptor might be out of date - evict it. This is
				// likely the result of a range split. If we have new range
				// descriptors, insert them instead as long as they are different
				// from the last descriptor to avoid endless loops.
				var replacements []roachpb.RangeDescriptor
				different := func(rd *roachpb.RangeDescriptor) bool {
					return !desc.RSpan().Equal(rd.RSpan())
				}
				if tErr.MismatchedRange != nil && different(tErr.MismatchedRange) {
					replacements = append(replacements, *tErr.MismatchedRange)
				}
				if tErr.SuggestedRange != nil && different(tErr.SuggestedRange) {
					if includesFrontOfCurSpan(tErr.SuggestedRange) {
						replacements = append(replacements, *tErr.SuggestedRange)

					}
				}
				// Same as Evict() if replacements is empty.
				if err := evictToken.EvictAndReplace(ctx, replacements...); err != nil {
					return nil, roachpb.NewError(err), false
				}
				// On addressing errors, don't backoff; retry immediately.
				r.Reset()
				if log.V(1) {
					log.Warning(ctx, tErr)
				}
				continue
			}
			break
		}

		// Immediately return if querying a range failed non-retryably.
		if pErr != nil {
			return nil, pErr, false
		} else if !finished {
			select {
			case <-ds.rpcRetryOptions.Closer:
				return nil, roachpb.NewError(&roachpb.NodeUnavailableError{}), false
			case <-ctx.Done():
				return nil, roachpb.NewError(ctx.Err()), false
			default:
				log.Fatal(ctx, "exited retry loop with nil error but finished=false")
			}
		}

		ba.UpdateTxn(curReply.Txn)

		if br == nil {
			// First response from a Range.
			br = curReply
		} else {
			// This was the second or later call in a cross-Range request.
			// Combine the new response with the existing one.
			if err := br.Combine(curReply); err != nil {
				return nil, roachpb.NewError(err), false
			}
		}

		if isReverse {
			// In next iteration, query previous range.
			// We use the StartKey of the current descriptor as opposed to the
			// EndKey of the previous one since that doesn't have bugs when
			// stale descriptors come into play.
			rs.EndKey, err = prev(ba, desc.StartKey)
		} else {
			// In next iteration, query next range.
			// It's important that we use the EndKey of the current descriptor
			// as opposed to the StartKey of the next one: if the former is stale,
			// it's possible that the next range has since merged the subsequent
			// one, and unless both descriptors are stale, the next descriptor's
			// StartKey would move us to the beginning of the current range,
			// resulting in a duplicate scan.
			rs.Key, err = next(ba, desc.EndKey)
		}
		if err != nil {
			return nil, roachpb.NewError(err), false
		}

		if ba.MaxSpanRequestKeys > 0 {
			// Count how many results we received.
			var numResults int64
			for _, resp := range curReply.Responses {
				numResults += resp.GetInner().Header().NumKeys
			}
			if numResults > ba.MaxSpanRequestKeys {
				panic(fmt.Sprintf("received %d results, limit was %d", numResults, ba.MaxSpanRequestKeys))
			}
			ba.MaxSpanRequestKeys -= numResults
			if ba.MaxSpanRequestKeys == 0 {
				// prepare the batch response after meeting the max key limit.
				fillSkippedResponses(ba, br, rs)
				// done, exit loop.
				return br, nil, false
			}
		}

		// If this was the last range accessed by this call, exit loop.
		if !needAnother {
			return br, nil, false
		}

		// key cannot be less that the end key.
		if !rs.Key.Less(rs.EndKey) {
			panic(fmt.Sprintf("start key %s is less than %s", rs.Key, rs.EndKey))
		}

		log.Trace(ctx, "querying next range")
	}
}
Esempio n. 9
0
func testRangeCacheHandleDoubleSplit(t *testing.T, useReverseScan bool) {
	db := initTestDescriptorDB(t)
	db.disablePrefetch = true

	// A request initially looks up the range descriptor ["a"-"b").
	doLookup(t, db.cache, "aa")
	db.assertLookupCountEq(t, 2, "aa")

	// A split breaks up the range into ["a"-"an"), ["an"-"at"), ["at"-"b").
	db.splitRange(t, roachpb.RKey("an"))
	db.splitRange(t, roachpb.RKey("at"))

	// A request is sent to the stale descriptor on the right half
	// such that a RangeKeyMismatchError is returned.
	_, evictToken := doLookup(t, db.cache, "az")
	// mismatchErrRange mocks out a RangeKeyMismatchError.Range response.
	ranges, _, pErr := db.getDescriptors(roachpb.RKey("aa"), false, false)
	if pErr != nil {
		t.Fatal(pErr)
	}
	mismatchErrRange := ranges[0]
	// The stale descriptor is evicted, the new descriptor from the error is
	// replaced, and a new lookup is initialized.
	if err := evictToken.EvictAndReplace(context.Background(), mismatchErrRange); err != nil {
		t.Fatal(err)
	}

	// Requests to all parts of the split are sent:

	// [reverse case]
	// - "aa" and "an" will hit the cache
	// - all others will join a coalesced request to "az"
	//   + will lookup the meta2 desc
	//   + will lookup the ["at"-"b") desc
	// - "az" will get the right range back
	// - "at" will make a second lookup
	//   + will lookup the ["an"-"at") desc
	//
	// [non-reverse case]
	// - "aa" will hit the cache
	// - all others will join a coalesced request to "an"
	//   + will lookup the meta2 desc
	//   + will lookup the ["an"-"at") desc
	// - "an" and "ao" will get the right range back
	// - "at" and "az" will make a second lookup
	//   + will lookup the ["at"-"b") desc
	var wg, waitJoin sync.WaitGroup
	db.pauseRangeLookups()
	numRetries := int64(0)
	for _, k := range []string{"aa", "an", "ao", "at", "az"} {
		wg.Add(1)
		waitJoin.Add(1)
		go func(key roachpb.RKey) {
			reqEvictToken := evictToken
			waitJoinCopied := &waitJoin
			var desc *roachpb.RangeDescriptor
			for {
				// Each request goes to a different key.
				var err error
				if desc, reqEvictToken, err = db.cache.lookupRangeDescriptorInternal(
					context.Background(), key, reqEvictToken, false, /* considerIntents */
					useReverseScan, waitJoinCopied); err != nil {
					waitJoinCopied = nil
					atomic.AddInt64(&numRetries, 1)
					continue
				}
				break
			}
			if useReverseScan {
				if !desc.ContainsExclusiveEndKey(key) {
					t.Errorf("desc %s does not contain exclusive end key %s", desc, key)
				}
			} else {
				if !desc.ContainsKey(key) {
					t.Errorf("desc %s does not contain key %s", desc, key)
				}
			}

			wg.Done()
		}(roachpb.RKey(k))
	}
	// Wait until all lookup requests hit the cache or join into a coalesced request.
	waitJoin.Wait()
	db.resumeRangeLookups()

	wg.Wait()
	db.assertLookupCountEq(t, 3, "an and az")
	if numRetries == 0 {
		t.Error("expected retry on desc lookup")
	}

	// All three descriptors are now correctly cached.
	doLookup(t, db.cache, "aa")
	db.assertLookupCountEq(t, 0, "aa")
	doLookup(t, db.cache, "ao")
	db.assertLookupCountEq(t, 0, "ao")
	doLookup(t, db.cache, "az")
	db.assertLookupCountEq(t, 0, "az")
}
Esempio n. 10
0
// truncate restricts all contained requests to the given key range.
// Even on error, the returned closure must be executed; it undoes any
// truncations performed.
// First, the boundaries of the truncation are obtained: This is the
// intersection between [from,to) and the descriptor's range.
// Secondly, all requests contained in the batch are "truncated" to
// the resulting range, inserting NoopRequest appropriately to
// replace requests which are left without a key range to operate on.
// The number of non-noop requests after truncation is returned along
// with a closure which must be executed to undo the truncation, even
// in case of an error.
// TODO(tschottdorf): Consider returning a new BatchRequest, which has more
// overhead in the common case of a batch which never needs truncation but is
// less magical.
func truncate(br *roachpb.BatchRequest, desc *roachpb.RangeDescriptor, from, to roachpb.RKey) (func(), int, error) {
	if !desc.ContainsKey(from) {
		from = desc.StartKey
	}
	if !desc.ContainsKeyRange(desc.StartKey, to) || to == nil {
		to = desc.EndKey
	}
	truncateOne := func(args roachpb.Request) (bool, []func(), error) {
		if _, ok := args.(*roachpb.NoopRequest); ok {
			return true, nil, nil
		}
		header := args.Header()
		if !roachpb.IsRange(args) {
			// This is a point request.
			if len(header.EndKey) > 0 {
				return false, nil, util.Errorf("%T is not a range command, but EndKey is set", args)
			}
			if !desc.ContainsKey(keys.Addr(header.Key)) {
				return true, nil, nil
			}
			return false, nil, nil
		}
		// We're dealing with a range-spanning request.
		var undo []func()
		keyAddr, endKeyAddr := keys.Addr(header.Key), keys.Addr(header.EndKey)
		if l, r := !keyAddr.Equal(header.Key), !endKeyAddr.Equal(header.EndKey); l || r {
			if !desc.ContainsKeyRange(keyAddr, endKeyAddr) {
				return false, nil, util.Errorf("local key range must not span ranges")
			}
			if !l || !r {
				return false, nil, util.Errorf("local key mixed with global key in range")
			}
		}
		// Below, {end,}keyAddr equals header.{End,}Key, so nothing is local.
		if keyAddr.Less(from) {
			{
				origKey := header.Key
				undo = append(undo, func() { header.Key = origKey })
			}
			header.Key = from.AsRawKey() // "from" can't be local
			keyAddr = from
		}
		if !endKeyAddr.Less(to) {
			{
				origEndKey := header.EndKey
				undo = append(undo, func() { header.EndKey = origEndKey })
			}
			header.EndKey = to.AsRawKey() // "to" can't be local
			endKeyAddr = to
		}
		// Check whether the truncation has left any keys in the range. If not,
		// we need to cut it out of the request.
		return !keyAddr.Less(endKeyAddr), undo, nil
	}

	var fns []func()
	gUndo := func() {
		for _, f := range fns {
			f()
		}
	}

	var numNoop int
	for pos, arg := range br.Requests {
		omit, undo, err := truncateOne(arg.GetInner())
		if omit {
			numNoop++
			nReq := &roachpb.RequestUnion{}
			if !nReq.SetValue(&roachpb.NoopRequest{}) {
				panic("RequestUnion excludes NoopRequest")
			}
			oReq := br.Requests[pos]
			br.Requests[pos] = *nReq
			posCpy := pos // for closure
			undo = append(undo, func() {
				br.Requests[posCpy] = oReq
			})
		}
		fns = append(fns, undo...)
		if err != nil {
			return gUndo, 0, err
		}
	}
	return gUndo, len(br.Requests) - numNoop, nil
}
Esempio n. 11
0
// sendChunk is in charge of sending an "admissible" piece of batch, i.e. one
// which doesn't need to be subdivided further before going to a range (so no
// mixing of forward and reverse scans, etc). The parameters and return values
// correspond to client.Sender with the exception of the returned boolean,
// which is true when indicating that the caller should retry but needs to send
// EndTransaction in a separate request.
func (ds *DistSender) sendChunk(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error, bool) {
	isReverse := ba.IsReverse()

	ctx, cleanup := tracing.EnsureContext(ctx, ds.Tracer)
	defer cleanup()

	// The minimal key range encompassing all requests contained within.
	// Local addressing has already been resolved.
	// TODO(tschottdorf): consider rudimentary validation of the batch here
	// (for example, non-range requests with EndKey, or empty key ranges).
	rs, err := keys.Range(ba)
	if err != nil {
		return nil, roachpb.NewError(err), false
	}
	var br *roachpb.BatchResponse

	// Send the request to one range per iteration.
	for {
		// Increase the sequence counter only once before sending RPCs to
		// the ranges involved in this chunk of the batch (as opposed to for
		// each RPC individually). On RPC errors, there's no guarantee that
		// the request hasn't made its way to the target regardless of the
		// error; we'd like the second execution to be caught by the sequence
		// cache if that happens. There is a small chance that that we address
		// a range twice in this chunk (stale/suboptimal descriptors due to
		// splits/merges) which leads to a transaction retry.
		// TODO(tschottdorf): it's possible that if we don't evict from the
		//   cache we could be in for a busy loop.
		ba.SetNewRequest()

		var curReply *roachpb.BatchResponse
		var desc *roachpb.RangeDescriptor
		var evictToken evictionToken
		var needAnother bool
		var pErr *roachpb.Error
		var finished bool
		for r := retry.Start(ds.rpcRetryOptions); r.Next(); {
			// Get range descriptor (or, when spanning range, descriptors). Our
			// error handling below may clear them on certain errors, so we
			// refresh (likely from the cache) on every retry.
			log.Trace(ctx, "meta descriptor lookup")
			desc, needAnother, evictToken, pErr = ds.getDescriptors(rs, evictToken, isReverse)

			// getDescriptors may fail retryably if the first range isn't
			// available via Gossip.
			if pErr != nil {
				log.Trace(ctx, "range descriptor lookup failed: "+pErr.String())
				if pErr.Retryable {
					if log.V(1) {
						log.Warning(pErr)
					}
					continue
				}
				break
			} else {
				log.Trace(ctx, "looked up range descriptor")
			}

			if needAnother && br == nil {
				// TODO(tschottdorf): we should have a mechanism for discovering
				// range merges (descriptor staleness will mostly go unnoticed),
				// or we'll be turning single-range queries into multi-range
				// queries for no good reason.

				// If there's no transaction and op spans ranges, possibly
				// re-run as part of a transaction for consistency. The
				// case where we don't need to re-run is if the read
				// consistency is not required.
				if ba.Txn == nil && ba.IsPossibleTransaction() &&
					ba.ReadConsistency != roachpb.INCONSISTENT {
					return nil, roachpb.NewError(&roachpb.OpRequiresTxnError{}), false
				}
				// If the request is more than but ends with EndTransaction, we
				// want the caller to come again with the EndTransaction in an
				// extra call.
				if l := len(ba.Requests) - 1; l > 0 && ba.Requests[l].GetInner().Method() == roachpb.EndTransaction {
					return nil, roachpb.NewError(errors.New("cannot send 1PC txn to multiple ranges")), true /* shouldSplitET */
				}
			}

			// It's possible that the returned descriptor misses parts of the
			// keys it's supposed to scan after it's truncated to match the
			// descriptor. Example revscan [a,g), first desc lookup for "g"
			// returns descriptor [c,d) -> [d,g) is never scanned.
			// We evict and retry in such a case.
			includesFrontOfCurSpan := func(rd *roachpb.RangeDescriptor) bool {
				if isReverse {
					// This approach is needed because rs.EndKey is exclusive.
					return desc.ContainsKeyRange(desc.StartKey, rs.EndKey)
				}
				return desc.ContainsKey(rs.Key)
			}
			if !includesFrontOfCurSpan(desc) {
				if err := evictToken.Evict(); err != nil {
					return nil, roachpb.NewError(err), false
				}
				// On addressing errors, don't backoff; retry immediately.
				r.Reset()
				continue
			}

			curReply, pErr = func() (*roachpb.BatchResponse, *roachpb.Error) {
				// Truncate the request to our current key range.
				intersected, iErr := rs.Intersect(desc)
				if iErr != nil {
					return nil, roachpb.NewError(iErr)
				}
				truncBA, numActive, trErr := truncate(ba, intersected)
				if numActive == 0 && trErr == nil {
					// This shouldn't happen in the wild, but some tests
					// exercise it.
					return nil, roachpb.NewErrorf("truncation resulted in empty batch on [%s,%s): %s",
						rs.Key, rs.EndKey, ba)
				}
				if trErr != nil {
					return nil, roachpb.NewError(trErr)
				}
				return ds.sendSingleRange(ctx, truncBA, desc)
			}()
			// If sending succeeded, break this loop.
			if pErr == nil {
				finished = true
				break
			}

			if log.V(1) {
				log.Warningf("failed to invoke %s: %s", ba, pErr)
			}
			log.Trace(ctx, fmt.Sprintf("reply error: %T", pErr.GetDetail()))

			// Error handling below.
			// If retryable, allow retry. For range not found or range
			// key mismatch errors, we don't backoff on the retry,
			// but reset the backoff loop so we can retry immediately.
			switch tErr := pErr.GetDetail().(type) {
			case *roachpb.SendError:
				// For an RPC error to occur, we must've been unable to contact
				// any replicas. In this case, likely all nodes are down (or
				// not getting back to us within a reasonable amount of time).
				// We may simply not be trying to talk to the up-to-date
				// replicas, so clearing the descriptor here should be a good
				// idea.
				if err := evictToken.Evict(); err != nil {
					return nil, roachpb.NewError(err), false
				}
				if tErr.CanRetry() {
					continue
				}
			case *roachpb.RangeNotFoundError:
				// Range descriptor might be out of date - evict it. This is
				// likely the result of a rebalance.
				if err := evictToken.Evict(); err != nil {
					return nil, roachpb.NewError(err), false
				}
				// On addressing errors, don't backoff; retry immediately.
				r.Reset()
				if log.V(1) {
					log.Warning(tErr)
				}
				continue
			case *roachpb.RangeKeyMismatchError:
				// Range descriptor might be out of date - evict it. This is
				// likely the result of a range split. If we have new range
				// descriptors, insert them instead as long as they are different
				// from the last descriptor to avoid endless loops.
				var replacements []roachpb.RangeDescriptor
				different := func(rd *roachpb.RangeDescriptor) bool {
					return !desc.RSpan().Equal(rd.RSpan())
				}
				if tErr.MismatchedRange != nil && different(tErr.MismatchedRange) {
					replacements = append(replacements, *tErr.MismatchedRange)
				}
				if tErr.SuggestedRange != nil && different(tErr.SuggestedRange) {
					if includesFrontOfCurSpan(tErr.SuggestedRange) {
						replacements = append(replacements, *tErr.SuggestedRange)

					}
				}
				// Same as Evict() if replacements is empty.
				if err := evictToken.EvictAndReplace(replacements...); err != nil {
					return nil, roachpb.NewError(err), false
				}
				// On addressing errors, don't backoff; retry immediately.
				r.Reset()
				if log.V(1) {
					log.Warning(tErr)
				}
				continue
			case *roachpb.NotLeaderError:
				newLeader := tErr.Leader
				if newLeader != nil {
					// Verify that leader is a known replica according to the
					// descriptor. If not, we've got a stale range descriptor;
					// evict cache.
					if i, _ := desc.FindReplica(newLeader.StoreID); i == -1 {
						if log.V(1) {
							log.Infof("error indicates unknown leader %s, expunging descriptor %s", newLeader, desc)
						}
						if err := evictToken.Evict(); err != nil {
							return nil, roachpb.NewError(err), false
						}
					}
				} else {
					// If the new leader is unknown, we were talking to a
					// replica that is partitioned away from the majority. Our
					// range descriptor may be stale, so clear the cache.
					//
					// TODO(bdarnell): An unknown-leader error doesn't
					// necessarily mean our descriptor is stale. Ideally we
					// would treat these errors more like SendError: retry on
					// another node (at a lower level), and then if it reaches
					// this level then we know we've exhausted our options and
					// must clear the cache.
					if err := evictToken.Evict(); err != nil {
						return nil, roachpb.NewError(err), false
					}
					newLeader = &roachpb.ReplicaDescriptor{}
				}
				// Next, cache the new leader.
				ds.updateLeaderCache(roachpb.RangeID(desc.RangeID), *newLeader)
				if log.V(1) {
					log.Warning(tErr)
				}
				r.Reset()
				continue
			case retry.Retryable:
				if tErr.CanRetry() {
					if log.V(1) {
						log.Warning(tErr)
					}
					continue
				}
			}
			break
		}

		// Immediately return if querying a range failed non-retryably.
		if pErr != nil {
			return nil, pErr, false
		} else if !finished {
			select {
			case <-ds.rpcRetryOptions.Closer:
				return nil, roachpb.NewError(&roachpb.NodeUnavailableError{}), false
			default:
				log.Fatal("exited retry loop with nil error but finished=false")
			}
		}

		ba.Txn.Update(curReply.Txn)

		if br == nil {
			// First response from a Range.
			br = curReply
		} else {
			// This was the second or later call in a cross-Range request.
			// Combine the new response with the existing one.
			if err := br.Combine(curReply); err != nil {
				return nil, roachpb.NewError(err), false
			}
		}

		if ba.MaxScanResults > 0 {
			// Count how many results we received.
			var numResults int64
			for _, resp := range curReply.Responses {
				if cResp, ok := resp.GetInner().(roachpb.Countable); ok {
					numResults += cResp.Count()
				}
			}
			if numResults > ba.MaxScanResults {
				panic(fmt.Sprintf("received %d results, limit was %d", numResults, ba.MaxScanResults))
			}
			ba.MaxScanResults -= numResults
			if ba.MaxScanResults == 0 {
				// We are done with this batch. Some requests might have NoopResponses; we must
				// replace them with empty responses of the proper type.
				for i, req := range ba.Requests {
					if _, ok := br.Responses[i].GetInner().(*roachpb.NoopResponse); !ok {
						continue
					}
					union := roachpb.ResponseUnion{}
					var reply roachpb.Response
					if _, ok := req.GetInner().(*roachpb.ScanRequest); ok {
						reply = &roachpb.ScanResponse{}
					} else {
						_ = req.GetInner().(*roachpb.ReverseScanRequest)
						reply = &roachpb.ReverseScanResponse{}
					}
					union.MustSetInner(reply)
					br.Responses[i] = union
				}
				return br, nil, false
			}
		}

		// If this request has a bound (such as MaxResults in
		// ScanRequest) and we are going to query at least one more range,
		// check whether enough rows have been retrieved.
		// TODO(tschottdorf): need tests for executing a multi-range batch
		// with various bounded requests which saturate at different times.
		if needAnother {
			// Start with the assumption that all requests are saturated.
			// Below, we look at each and decide whether that's true.
			// Everything that is indeed saturated is "masked out" from the
			// batch request; only if that's all requests does needAnother
			// remain false.
			needAnother = false
			if br == nil {
				// Clone ba.Requests. This is because we're multi-range, and
				// some requests may be bounded, which could lead to them being
				// masked out once they're saturated. We don't want to risk
				// removing requests that way in the "master copy" since that
				// could lead to omitting requests in certain retry scenarios.
				ba.Requests = append([]roachpb.RequestUnion(nil), ba.Requests...)
			}
			for i, union := range ba.Requests {
				args := union.GetInner()
				if _, ok := args.(*roachpb.NoopRequest); ok {
					// NoopRequests are skipped.
					continue
				}
				boundedArg, ok := args.(roachpb.Bounded)
				if !ok {
					// Non-bounded request. We will have to query all ranges.
					needAnother = true
					continue
				}
				prevBound := boundedArg.GetBound()
				cReply, ok := curReply.Responses[i].GetInner().(roachpb.Countable)
				if !ok || prevBound <= 0 {
					// Request bounded, but without max results. Again, will
					// need to query everything we can. The case in which the reply
					// isn't countable occurs when the request wasn't active for
					// that range (since it didn't apply to it), so the response
					// is a NoopResponse.
					needAnother = true
					continue
				}
				nextBound := prevBound - cReply.Count()
				if nextBound <= 0 {
					// We've hit max results for this piece of the batch. Mask
					// it out (we've copied the requests slice above, so this
					// is kosher).
					union := &ba.Requests[i] // avoid working on copy
					union.MustSetInner(&noopRequest)
					continue
				}
				// The request isn't saturated yet.
				needAnother = true
				boundedArg.SetBound(nextBound)
			}
		}

		// If this was the last range accessed by this call, exit loop.
		if !needAnother {
			return br, nil, false
		}

		if isReverse {
			// In next iteration, query previous range.
			// We use the StartKey of the current descriptor as opposed to the
			// EndKey of the previous one since that doesn't have bugs when
			// stale descriptors come into play.
			rs.EndKey, err = prev(ba, desc.StartKey)
		} else {
			// In next iteration, query next range.
			// It's important that we use the EndKey of the current descriptor
			// as opposed to the StartKey of the next one: if the former is stale,
			// it's possible that the next range has since merged the subsequent
			// one, and unless both descriptors are stale, the next descriptor's
			// StartKey would move us to the beginning of the current range,
			// resulting in a duplicate scan.
			rs.Key, err = next(ba, desc.EndKey)
		}
		if err != nil {
			return nil, roachpb.NewError(err), false
		}
		log.Trace(ctx, "querying next range")
	}
}
Esempio n. 12
0
// truncate restricts all contained requests to the given key range.
// Even on error, the returned closure must be executed; it undoes any
// truncations performed.
// First, the boundaries of the truncation are obtained: This is the
// intersection between [from,to) and the descriptor's range.
// Secondly, all requests contained in the batch are "truncated" to
// the resulting range, inserting NoopRequest appropriately to
// replace requests which are left without a key range to operate on.
// The number of non-noop requests after truncation is returned along
// with a closure which must be executed to undo the truncation, even
// in case of an error.
// TODO(tschottdorf): Consider returning a new BatchRequest, which has more
// overhead in the common case of a batch which never needs truncation but is
// less magical.
func truncate(br *roachpb.BatchRequest, desc *roachpb.RangeDescriptor, from, to roachpb.Key) (func(), int, error) {
	if !desc.ContainsKey(from) {
		from = desc.StartKey
	}
	if !desc.ContainsKeyRange(desc.StartKey, to) || to == nil {
		to = desc.EndKey
	}
	truncateOne := func(args roachpb.Request) (bool, []func(), error) {
		if _, ok := args.(*roachpb.NoopRequest); ok {
			return true, nil, nil
		}
		header := args.Header()
		if !roachpb.IsRange(args) {
			if len(header.EndKey) > 0 {
				return false, nil, util.Errorf("%T is not a range command, but EndKey is set", args)
			}
			if !desc.ContainsKey(keys.KeyAddress(header.Key)) {
				return true, nil, nil
			}
			return false, nil, nil
		}
		var undo []func()
		key, endKey := header.Key, header.EndKey
		keyAddr, endKeyAddr := keys.KeyAddress(key), keys.KeyAddress(endKey)
		if keyAddr.Less(from) {
			undo = append(undo, func() { header.Key = key })
			header.Key = from
			keyAddr = from
		}
		if !endKeyAddr.Less(to) {
			undo = append(undo, func() { header.EndKey = endKey })
			header.EndKey = to
			endKeyAddr = to
		}
		// Check whether the truncation has left any keys in the range. If not,
		// we need to cut it out of the request.
		return !keyAddr.Less(endKeyAddr), undo, nil
	}

	var fns []func()
	gUndo := func() {
		for _, f := range fns {
			f()
		}
	}

	var numNoop int
	for pos, arg := range br.Requests {
		omit, undo, err := truncateOne(arg.GetInner())
		if omit {
			numNoop++
			nReq := &roachpb.RequestUnion{}
			if !nReq.SetValue(&roachpb.NoopRequest{}) {
				panic("RequestUnion excludes NoopRequest")
			}
			oReq := br.Requests[pos]
			br.Requests[pos] = *nReq
			posCpy := pos // for closure
			undo = append(undo, func() {
				br.Requests[posCpy] = oReq
			})
		}
		fns = append(fns, undo...)
		if err != nil {
			return gUndo, 0, err
		}
	}
	return gUndo, len(br.Requests) - numNoop, nil
}