[BREAKING] feat(zero): Make zero lease out namespace IDs

[ahsanbarkati]

This PR makes zero lease out the namespaceIDs. It changes the existing AssignUids() API to AssignIds(), which can be used to get both UIDs as well as NamespaceIDs. The lease type which is required is passed with the pb.Num to AssignIds()

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This change is 

[manishrjain]

Bunch of comments.

Reviewed 6 of 6 files at r1.
Reviewable status: all files reviewed, 8 unresolved discussions (waiting on @ahsanbarkati and @vvbalaji-dgraph)

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dgraph/cmd/zero/assign.go, line 36 at r1 (raw file):

const (
	leaseBandwidth           = uint64(10000)
	leaseTxnTs     leaseType = iota

If you make this public, then the worker package can use the int values of these in pb.Num.

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dgraph/cmd/zero/assign.go, line 174 at r1 (raw file):

	} else {
		glog.Errorf("Unknown lease type: %v\n", typ)

return this error.

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dgraph/cmd/zero/assign.go, line 179 at r1 (raw file):

}

func (s *Server) AssignUids(ctx context.Context, num *pb.Num) (*pb.AssignedIds, error) {

remove this.

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dgraph/cmd/zero/assign.go, line 183 at r1 (raw file):

}

func (s *Server) AssignNsIDs(ctx context.Context, num *pb.Num) (*pb.AssignedIds, error) {

Don't create this func.

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dgraph/cmd/zero/assign.go, line 189 at r1 (raw file):

// AssignIds is used to assign new ids (UIDs, NsIDs) by communicating with the leader of the
// RAFT group responsible for handing out ids.
func (s *Server) AssignIds(ctx context.Context, num *pb.Num, typ leaseType) (*pb.AssignedIds, error) {

Make AssignUids public func -> AssignIds. And pass the context via pb.Num. pb.Num isn't persisted, so can use the iota's int value.

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protos/pb.proto, line 166 at r1 (raw file):

	License license = 10;
	ZeroSnapshot snapshot = 11; // Used to make Zeros take a snapshot.
	uint64 maxLeaseNsID = 12;

move it next to the other uint64s.

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protos/pb.proto, line 182 at r1 (raw file):

	string cid = 8; // Used to uniquely identify the Dgraph cluster.
	License license = 9;
	uint64 maxLeaseNsID = 12;

and here. Use 10.

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protos/pb.proto, line 542 at r1 (raw file):

	rpc ShouldServe (Tablet)           returns (Tablet) {}
	rpc AssignUids (Num)               returns (AssignedIds) {}
	rpc AssignNsIDs (Num)              returns (AssignedIds) {}

remove.

[jarifibrahim]

I haven't looked at the entire PR. I'll review it again in some time.

Reviewable status: 0 of 20 files reviewed, 18 unresolved discussions (waiting on @ahsanbarkati, @manishrjain, @pawanrawal, and @vvbalaji-dgraph)

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dgraph/cmd/alpha/run_test.go, line 1697 at r2 (raw file):

	}
	zc := pb.NewZeroClient(conn)
	if _, err := zc.AssignIds(context.Background(), &pb.Num{Val: 1e6, Type: pb.Num_UID}); err != nil {

100 chars

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dgraph/cmd/zero/assign.go, line 40 at r2 (raw file):

	s.Lock()
	s.nextLease[pb.Num_UID] = s.state.MaxUID + 1
	s.nextLease[pb.Num_TXN_TS] = s.state.MaxTxnTs + 1

Does it have to be NUM_TXN_TS? TXN_TS should also suffice.

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dgraph/cmd/zero/assign.go, line 44 at r2 (raw file):

	startTs = s.nextLease[pb.Num_TXN_TS]
	glog.Infof("Updated Lease id: %d. Txn Ts: %d. NsID: %d.",

Updated UID

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dgraph/cmd/zero/assign.go, line 71 at r2 (raw file):

// so we can tackle any collisions that might happen with the leasemanager
// In essence, we just want one server to be handing out new uids.
func (s *Server) lease(ctx context.Context, num *pb.Num, typ pb.NumLeaseType) (*pb.AssignedIds,

pb.Num already has the type. You don't need to pass the typ parameter.

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dgraph/cmd/zero/raft.go, line 416 at r2 (raw file):

	case p.MaxTxnTs > state.MaxTxnTs:
		state.MaxTxnTs = p.MaxTxnTs
	case p.MaxUID != 0 || p.MaxTxnTs != 0:

Don't we need to check the NS ID as well?

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graphql/e2e/common/admin.go, line 419 at r2 (raw file):

				}
				maxUID
				maxTxnTs

Add max namespace ID here too.

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protos/pb.proto, line 166 at r2 (raw file):

	string cid = 9; // Used as unique identifier for the cluster.
	License license = 10;
	ZeroSnapshot snapshot = 11; // Used to make Zeros take a snapshot.

Add a comment after this line that 12 is already used.

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protos/pb.proto, line 182 at r2 (raw file):

	repeated Member removed = 7;
	string cid = 8; // Used to uniquely identify the Dgraph cluster.
	License license = 9;

Add a comment after this line that 10 is already used.

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worker/mutation.go, line 509 at r2 (raw file):

	con := pl.Get()
	c := pb.NewZeroClient(con)
	return c.AssignIds(ctx, num)

You should set the num.Type here (I know the caller has set it but it's useful to set it near the function call)

[ahsanbarkati]

Addressed comments.

Reviewable status: 0 of 20 files reviewed, 18 unresolved discussions (waiting on @ahsanbarkati, @jarifibrahim, @manishrjain, @pawanrawal, and @vvbalaji-dgraph)

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dgraph/cmd/zero/assign.go, line 40 at r2 (raw file):

Previously, jarifibrahim (Ibrahim Jarif) wrote…

Does it have to be NUM_TXN_TS? TXN_TS should also suffice.

NUM_TXN_TS is auto generated by protobuf. It is because TXN_TS is an enum inside the Num message type.

[jarifibrahim]

Reviewable status: 0 of 20 files reviewed, 18 unresolved discussions (waiting on @ahsanbarkati, @jarifibrahim, @manishrjain, @pawanrawal, and @vvbalaji-dgraph)

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