func addIndexMutation(ctx context.Context, attr, token string,
tokensTable *TokensTable, edge *task.DirectedEdge, del bool) {
key := x.IndexKey(attr, token)
plist, decr := GetOrCreate(key)
defer decr()
x.AssertTruef(plist != nil, "plist is nil [%s] %d %s",
token, edge.ValueId, edge.Attr)
if del {
_, err := plist.AddMutation(ctx, edge, Del)
if err != nil {
x.TraceError(ctx, x.Wrapf(err,
"Error deleting %s for attr %s entity %d: %v",
token, edge.Attr, edge.Entity))
}
indexLog.Printf("DEL [%s] [%d] OldTerm [%s]",
edge.Attr, edge.Entity, token)
} else {
_, err := plist.AddMutation(ctx, edge, Set)
if err != nil {
x.TraceError(ctx, x.Wrapf(err,
"Error adding %s for attr %s entity %d: %v",
token, edge.Attr, edge.Entity))
}
indexLog.Printf("SET [%s] [%d] NewTerm [%s]",
edge.Attr, edge.Entity, token)
tokensTable.Add(token)
}
}
// PopulateShard gets data for predicate pred from server with id serverId and
// writes it to RocksDB.
func populateShard(ctx context.Context, pl *pool, group uint32) (int, error) {
gkeys, err := generateGroup(group)
if err != nil {
return 0, x.Wrapf(err, "While generating keys group")
}
conn, err := pl.Get()
if err != nil {
return 0, err
}
defer pl.Put(conn)
c := NewWorkerClient(conn)
stream, err := c.PredicateData(context.Background(), gkeys)
if err != nil {
return 0, err
}
x.Trace(ctx, "Streaming data for group: %v", group)
kvs := make(chan *task.KV, 1000)
che := make(chan error)
go writeBatch(ctx, kvs, che)
// We can use count to check the number of posting lists returned in tests.
count := 0
for {
kv, err := stream.Recv()
if err == io.EOF {
break
}
if err != nil {
close(kvs)
return count, err
}
count++
// We check for errors, if there are no errors we send value to channel.
select {
case kvs <- kv:
// OK
case <-ctx.Done():
x.TraceError(ctx, x.Errorf("Context timed out while streaming group: %v", group))
close(kvs)
return count, ctx.Err()
case err := <-che:
x.TraceError(ctx, x.Errorf("Error while doing a batch write for group: %v", group))
close(kvs)
return count, err
}
}
close(kvs)
if err := <-che; err != nil {
x.TraceError(ctx, x.Errorf("Error while doing a batch write for group: %v", group))
return count, err
}
x.Trace(ctx, "Streaming complete for group: %v", group)
return count, nil
}
func convertToEdges(ctx context.Context, nquads []rdf.NQuad) (mutationResult, error) {
var edges []*task.DirectedEdge
var mr mutationResult
newUids := make(map[string]uint64)
for _, nq := range nquads {
if strings.HasPrefix(nq.Subject, "_new_:") {
newUids[nq.Subject] = 0
} else if !strings.HasPrefix(nq.Subject, "_uid_:") {
uid, err := rdf.GetUid(nq.Subject)
x.Check(err)
newUids[nq.Subject] = uid
}
if len(nq.ObjectId) > 0 {
if strings.HasPrefix(nq.ObjectId, "_new_:") {
newUids[nq.ObjectId] = 0
} else if !strings.HasPrefix(nq.ObjectId, "_uid_:") {
uid, err := rdf.GetUid(nq.ObjectId)
x.Check(err)
newUids[nq.ObjectId] = uid
}
}
}
if len(newUids) > 0 {
if err := worker.AssignUidsOverNetwork(ctx, newUids); err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while GetOrAssignUidsOverNetwork"))
return mr, err
}
}
for _, nq := range nquads {
// Get edges from nquad using newUids.
edge, err := nq.ToEdgeUsing(newUids)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while converting to edge: %v", nq))
return mr, err
}
edges = append(edges, edge)
}
resultUids := make(map[string]uint64)
// Strip out _new_: prefix from the keys.
for k, v := range newUids {
if strings.HasPrefix(k, "_new_:") {
resultUids[k[6:]] = v
}
}
mr = mutationResult{
edges: edges,
newUids: resultUids,
}
return mr, nil
}
// MutateOverNetwork checks which group should be running the mutations
// according to fingerprint of the predicate and sends it to that instance.
func MutateOverNetwork(ctx context.Context, m *task.Mutations) error {
mutationMap := make(map[uint32]*task.Mutations)
addToMutationMap(mutationMap, m.Set, set)
addToMutationMap(mutationMap, m.Del, del)
errors := make(chan error, len(mutationMap))
for gid, mu := range mutationMap {
proposeOrSend(ctx, gid, mu, errors)
}
// Wait for all the goroutines to reply back.
// We return if an error was returned or the parent called ctx.Done()
for i := 0; i < len(mutationMap); i++ {
select {
case err := <-errors:
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while running all mutations"))
return err
}
case <-ctx.Done():
return ctx.Err()
}
}
close(errors)
return nil
}
func convertToNQuad(ctx context.Context, mutation string) ([]rdf.NQuad, error) {
var nquads []rdf.NQuad
r := strings.NewReader(mutation)
reader := bufio.NewReader(r)
x.Trace(ctx, "Converting to NQuad")
var strBuf bytes.Buffer
var err error
for {
err = x.ReadLine(reader, &strBuf)
if err != nil {
break
}
ln := strings.Trim(strBuf.String(), " \t")
if len(ln) == 0 {
continue
}
nq, err := rdf.Parse(ln)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while parsing RDF"))
return nquads, err
}
nquads = append(nquads, nq)
}
if err != io.EOF {
return nquads, err
}
return nquads, nil
}
func (n *node) processMutation(e raftpb.Entry, m *task.Mutations) error {
if err := mutate(n.ctx, m); err != nil {
x.TraceError(n.ctx, err)
return err
}
return nil
}
// ProcessTaskOverNetwork is used to process the query and get the result from
// the instance which stores posting list corresponding to the predicate in the
// query.
func ProcessTaskOverNetwork(ctx context.Context, q *task.Query) (*task.Result, error) {
attr := q.Attr
gid := group.BelongsTo(attr)
x.Trace(ctx, "attr: %v groupId: %v", attr, gid)
if groups().ServesGroup(gid) {
// No need for a network call, as this should be run from within this instance.
return processTask(q)
}
// Send this over the network.
// TODO: Send the request to multiple servers as described in Jeff Dean's talk.
addr := groups().AnyServer(gid)
pl := pools().get(addr)
conn, err := pl.Get()
if err != nil {
return &emptyResult, x.Wrapf(err, "ProcessTaskOverNetwork: while retrieving connection.")
}
defer pl.Put(conn)
x.Trace(ctx, "Sending request to %v", addr)
c := NewWorkerClient(conn)
reply, err := c.ServeTask(ctx, q)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while calling Worker.ServeTask"))
return &emptyResult, err
}
x.Trace(ctx, "Reply from server. length: %v Addr: %v Attr: %v",
len(reply.UidMatrix), addr, attr)
return reply, nil
}
func applyMutations(ctx context.Context, m *task.Mutations) error {
err := worker.MutateOverNetwork(ctx, m)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while MutateOverNetwork"))
return err
}
return nil
}
// AssignUidsOverNetwork assigns new uids and writes them to the umap.
func AssignUidsOverNetwork(ctx context.Context, umap map[string]uint64) error {
gid := group.BelongsTo("_uid_")
num := createNumQuery(gid, umap)
var ul *task.List
var err error
if groups().ServesGroup(gid) {
ul, err = assignUids(ctx, num)
if err != nil {
return err
}
} else {
_, addr := groups().Leader(gid)
p := pools().get(addr)
conn, err := p.Get()
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while retrieving connection"))
return err
}
defer p.Put(conn)
c := NewWorkerClient(conn)
ul, err = c.AssignUids(ctx, num)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while getting uids"))
return err
}
}
x.AssertTruef(len(ul.Uids) == int(num.Val),
"Requested: %d != Retrieved Uids: %d", num.Val, len(ul.Uids))
i := 0
for k, v := range umap {
if v == 0 {
uid := ul.Uids[i]
umap[k] = uid // Write uids to map.
i++
}
}
return nil
}
// AddMutation adds mutation to mutation layers. Note that it does not write
// anything to disk. Some other background routine will be responsible for merging
// changes in mutation layers to RocksDB. Returns whether any mutation happens.
func (l *List) AddMutation(ctx context.Context, t *task.DirectedEdge, op uint32) (bool, error) {
if atomic.LoadInt32(&l.deleteMe) == 1 {
x.TraceError(ctx, x.Errorf("DELETEME set to true. Temporary error."))
return false, ErrRetry
}
x.Trace(ctx, "AddMutation called.")
defer x.Trace(ctx, "AddMutation done.")
// All edges with a value set, have the same uid. In other words,
// an (entity, attribute) can only have one value.
if !bytes.Equal(t.Value, nil) {
t.ValueId = math.MaxUint64
}
if t.ValueId == 0 {
err := x.Errorf("ValueId cannot be zero")
x.TraceError(ctx, err)
return false, err
}
mpost := newPosting(t, op)
// Mutation arrives:
// - Check if we had any(SET/DEL) before this, stored in the mutation list.
// - If yes, then replace that mutation. Jump to a)
// a) check if the entity exists in main posting list.
// - If yes, store the mutation.
// - If no, disregard this mutation.
l.Lock()
defer l.Unlock()
hasMutated := l.updateMutationLayer(mpost)
if len(l.mlayer) > 0 {
atomic.StoreInt64(&l.dirtyTs, time.Now().UnixNano())
if dirtyChan != nil {
dirtyChan <- l.ghash
}
}
return hasMutated, nil
}
func (n *node) ProposeAndWait(ctx context.Context, proposal *task.Proposal) error {
if n.raft == nil {
return x.Errorf("RAFT isn't initialized yet")
}
proposal.Id = rand.Uint32()
slice := slicePool.Get().([]byte)
if len(slice) < proposal.Size() {
slice = make([]byte, proposal.Size())
}
defer slicePool.Put(slice)
upto, err := proposal.MarshalTo(slice)
if err != nil {
return err
}
proposalData := slice[:upto]
che := make(chan error, 1)
n.props.Store(proposal.Id, che)
if err = n.raft.Propose(ctx, proposalData); err != nil {
return x.Wrapf(err, "While proposing")
}
// Wait for the proposal to be committed.
if proposal.Mutations != nil {
x.Trace(ctx, "Waiting for the proposal: mutations.")
} else {
x.Trace(ctx, "Waiting for the proposal: membership update.")
}
select {
case err = <-che:
x.TraceError(ctx, err)
return err
case <-ctx.Done():
return ctx.Err()
}
}
// runMutate is used to run the mutations on an instance.
func proposeOrSend(ctx context.Context, gid uint32, m *task.Mutations, che chan error) {
if groups().ServesGroup(gid) {
node := groups().Node(gid)
che <- node.ProposeAndWait(ctx, &task.Proposal{Mutations: m})
return
}
_, addr := groups().Leader(gid)
pl := pools().get(addr)
conn, err := pl.Get()
if err != nil {
x.TraceError(ctx, err)
che <- err
return
}
defer pl.Put(conn)
c := NewWorkerClient(conn)
_, err = c.Mutate(ctx, m)
che <- err
}
// SortOverNetwork sends sort query over the network.
func SortOverNetwork(ctx context.Context, q *task.Sort) (*task.SortResult, error) {
gid := group.BelongsTo(q.Attr)
x.Trace(ctx, "worker.Sort attr: %v groupId: %v", q.Attr, gid)
if groups().ServesGroup(gid) {
// No need for a network call, as this should be run from within this instance.
return processSort(q)
}
// Send this over the network.
// TODO: Send the request to multiple servers as described in Jeff Dean's talk.
addr := groups().AnyServer(gid)
pl := pools().get(addr)
conn, err := pl.Get()
if err != nil {
return &emptySortResult, x.Wrapf(err, "SortOverNetwork: while retrieving connection.")
}
defer pl.Put(conn)
x.Trace(ctx, "Sending request to %v", addr)
c := NewWorkerClient(conn)
var reply *task.SortResult
cerr := make(chan error, 1)
go func() {
var err error
reply, err = c.Sort(ctx, q)
cerr <- err
}()
select {
case <-ctx.Done():
return &emptySortResult, ctx.Err()
case err := <-cerr:
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while calling Worker.Sort"))
}
return reply, err
}
}
// newGraph returns the SubGraph and its task query.
func newGraph(ctx context.Context, gq *gql.GraphQuery) (*SubGraph, error) {
euid, exid := gq.UID, gq.XID
// This would set the Result field in SubGraph,
// and populate the children for attributes.
if len(exid) > 0 {
x.AssertTruef(!strings.HasPrefix(exid, "_new_:"), "Query shouldn't contain _new_")
euid = farm.Fingerprint64([]byte(exid))
x.Trace(ctx, "Xid: %v Uid: %v", exid, euid)
}
if euid == 0 && gq.Func == nil {
err := x.Errorf("Invalid query, query internal id is zero and generator is nil")
x.TraceError(ctx, err)
return nil, err
}
// For the root, the name to be used in result is stored in Alias, not Attr.
// The attr at root (if present) would stand for the source functions attr.
args := params{
AttrType: schema.TypeOf(gq.Alias),
isDebug: gq.Alias == "debug",
Alias: gq.Alias,
}
sg := &SubGraph{
Params: args,
}
if gq.Func != nil {
sg.Attr = gq.Func.Attr
sg.SrcFunc = append(sg.SrcFunc, gq.Func.Name)
sg.SrcFunc = append(sg.SrcFunc, gq.Func.Args...)
}
if euid > 0 {
// euid is the root UID.
sg.SrcUIDs = &task.List{Uids: []uint64{euid}}
sg.uidMatrix = []*task.List{&task.List{Uids: []uint64{euid}}}
}
sg.values = createNilValuesList(1)
return sg, nil
}
// ProcessGraph processes the SubGraph instance accumulating result for the query
// from different instances. Note: taskQuery is nil for root node.
func ProcessGraph(ctx context.Context, sg, parent *SubGraph, rch chan error) {
var err error
if len(sg.Attr) == 0 {
// If we have a filter SubGraph which only contains an operator,
// it won't have any attribute to work on.
// This is to allow providing SrcUIDs to the filter children.
sg.DestUIDs = sg.SrcUIDs
} else if parent == nil && len(sg.SrcFunc) == 0 {
// I am root. I don't have any function to execute, and my
// result has been prepared for me already.
sg.DestUIDs = algo.MergeSorted(sg.uidMatrix) // Could also be = sg.SrcUIDs
} else {
taskQuery := createTaskQuery(sg)
result, err := worker.ProcessTaskOverNetwork(ctx, taskQuery)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while processing task"))
rch <- err
return
}
sg.uidMatrix = result.UidMatrix
sg.values = result.Values
if len(sg.values) > 0 {
v := sg.values[0]
x.Trace(ctx, "Sample value for attr: %v Val: %v", sg.Attr, string(v.Val))
}
sg.counts = result.Counts
if sg.Params.DoCount && len(sg.Filters) == 0 {
// If there is a filter, we need to do more work to get the actual count.
x.Trace(ctx, "Zero uids. Only count requested")
rch <- nil
return
}
if result.IntersectDest {
sg.DestUIDs = algo.IntersectSorted(result.UidMatrix)
} else {
sg.DestUIDs = algo.MergeSorted(result.UidMatrix)
}
}
if len(sg.DestUIDs.Uids) == 0 {
// Looks like we're done here. Be careful with nil srcUIDs!
x.Trace(ctx, "Zero uids for %q. Num attr children: %v", sg.Attr, len(sg.Children))
rch <- nil
return
}
// Apply filters if any.
if len(sg.Filters) > 0 {
// Run all filters in parallel.
filterChan := make(chan error, len(sg.Filters))
for _, filter := range sg.Filters {
filter.SrcUIDs = sg.DestUIDs
go ProcessGraph(ctx, filter, sg, filterChan)
}
for _ = range sg.Filters {
select {
case err = <-filterChan:
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while processing filter task"))
rch <- err
return
}
case <-ctx.Done():
x.TraceError(ctx, x.Wrapf(ctx.Err(), "Context done before full execution"))
rch <- ctx.Err()
return
}
}
// Now apply the results from filter.
var lists []*task.List
for _, filter := range sg.Filters {
lists = append(lists, filter.DestUIDs)
}
if sg.FilterOp == "|" {
sg.DestUIDs = algo.MergeSorted(lists)
} else {
sg.DestUIDs = algo.IntersectSorted(lists)
}
}
if len(sg.Params.Order) == 0 {
// There is no ordering. Just apply pagination and return.
if err = sg.applyPagination(ctx); err != nil {
rch <- err
return
}
} else {
// We need to sort first before pagination.
if err = sg.applyOrderAndPagination(ctx); err != nil {
rch <- err
return
}
}
// Here we consider handling _count_ with filtering. We do this after
// pagination because otherwise, we need to do the count with pagination
// taken into account. For example, a PL might have only 50 entries but the
// user wants to skip 100 entries and return 10 entries. In this case, you
// should return a count of 0, not 10.
if sg.Params.DoCount {
x.AssertTrue(len(sg.Filters) > 0)
sg.counts = make([]uint32, len(sg.uidMatrix))
for i, ul := range sg.uidMatrix {
// A possible optimization is to return the size of the intersection
// without forming the intersection.
algo.IntersectWith(ul, sg.DestUIDs)
sg.counts[i] = uint32(len(ul.Uids))
}
rch <- nil
return
}
childChan := make(chan error, len(sg.Children))
for i := 0; i < len(sg.Children); i++ {
child := sg.Children[i]
child.SrcUIDs = sg.DestUIDs // Make the connection.
go ProcessGraph(ctx, child, sg, childChan)
}
// Now get all the results back.
for _ = range sg.Children {
select {
case err = <-childChan:
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while processing child task"))
rch <- err
return
}
case <-ctx.Done():
x.TraceError(ctx, x.Wrapf(ctx.Err(), "Context done before full execution"))
rch <- ctx.Err()
return
}
}
rch <- nil
}
func handleBackupForGroup(ctx context.Context, reqId uint64, gid uint32) *BackupPayload {
n := groups().Node(gid)
if n.AmLeader() {
x.Trace(ctx, "Leader of group: %d. Running backup.", gid)
if err := backup(gid, *backupPath); err != nil {
x.TraceError(ctx, err)
return &BackupPayload{
ReqId: reqId,
Status: BackupPayload_FAILED,
}
}
x.Trace(ctx, "Backup done for group: %d.", gid)
return &BackupPayload{
ReqId: reqId,
Status: BackupPayload_SUCCESS,
GroupId: gid,
}
}
// I'm not the leader. Relay to someone who I think is.
var addrs []string
{
// Try in order: leader of given group, any server from given group, leader of group zero.
_, addr := groups().Leader(gid)
addrs = append(addrs, addr)
addrs = append(addrs, groups().AnyServer(gid))
_, addr = groups().Leader(0)
addrs = append(addrs, addr)
}
var conn *grpc.ClientConn
for _, addr := range addrs {
pl := pools().get(addr)
var err error
conn, err = pl.Get()
if err == nil {
x.Trace(ctx, "Relaying backup request for group %d to %q", gid, pl.Addr)
defer pl.Put(conn)
break
}
x.TraceError(ctx, err)
}
// Unable to find any connection to any of these servers. This should be exceedingly rare.
// But probably not worthy of crashing the server. We can just skip the backup.
if conn == nil {
x.Trace(ctx, fmt.Sprintf("Unable to find a server to backup group: %d", gid))
return &BackupPayload{
ReqId: reqId,
Status: BackupPayload_FAILED,
GroupId: gid,
}
}
c := NewWorkerClient(conn)
nr := &BackupPayload{
ReqId: reqId,
GroupId: gid,
}
nrep, err := c.Backup(ctx, nr)
if err != nil {
x.TraceError(ctx, err)
return &BackupPayload{
ReqId: reqId,
Status: BackupPayload_FAILED,
GroupId: gid,
}
}
return nrep
}
func queryHandler(w http.ResponseWriter, r *http.Request) {
// Add a limit on how many pending queries can be run in the system.
pendingQueries <- struct{}{}
defer func() { <-pendingQueries }()
addCorsHeaders(w)
if r.Method == "OPTIONS" {
return
}
if r.Method != "POST" {
x.SetStatus(w, x.ErrorInvalidMethod, "Invalid method")
return
}
ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
defer cancel()
if rand.Float64() < *tracing {
tr := trace.New("Dgraph", "Query")
defer tr.Finish()
ctx = trace.NewContext(ctx, tr)
}
var l query.Latency
l.Start = time.Now()
defer r.Body.Close()
req, err := ioutil.ReadAll(r.Body)
q := string(req)
if err != nil || len(q) == 0 {
x.TraceError(ctx, x.Wrapf(err, "Error while reading query"))
x.SetStatus(w, x.ErrorInvalidRequest, "Invalid request encountered.")
return
}
x.Trace(ctx, "Query received: %v", q)
gq, mu, err := gql.Parse(q)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while parsing query"))
x.SetStatus(w, x.ErrorInvalidRequest, err.Error())
return
}
var allocIds map[string]uint64
var allocIdsStr map[string]string
// If we have mutations, run them first.
if mu != nil && (len(mu.Set) > 0 || len(mu.Del) > 0) {
if allocIds, err = mutationHandler(ctx, mu); err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while handling mutations"))
x.SetStatus(w, x.Error, err.Error())
return
}
// convert the new UIDs to hex string.
allocIdsStr = make(map[string]string)
for k, v := range allocIds {
allocIdsStr[k] = fmt.Sprintf("%#x", v)
}
}
if gq == nil || (gq.UID == 0 && gq.Func == nil && len(gq.XID) == 0) {
mp := map[string]interface{}{
"code": x.ErrorOk,
"message": "Done",
"uids": allocIdsStr,
}
if js, err := json.Marshal(mp); err == nil {
w.Write(js)
} else {
x.SetStatus(w, "Error", "Unable to marshal map")
}
return
}
sg, err := query.ToSubGraph(ctx, gq)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while conversion o internal format"))
x.SetStatus(w, x.ErrorInvalidRequest, err.Error())
return
}
l.Parsing = time.Since(l.Start)
x.Trace(ctx, "Query parsed")
rch := make(chan error)
go query.ProcessGraph(ctx, sg, nil, rch)
err = <-rch
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while executing query"))
x.SetStatus(w, x.Error, err.Error())
return
}
l.Processing = time.Since(l.Start) - l.Parsing
x.Trace(ctx, "Graph processed")
if len(*dumpSubgraph) > 0 {
x.Checkf(os.MkdirAll(*dumpSubgraph, 0700), *dumpSubgraph)
s := time.Now().Format("20060102.150405.000000.gob")
filename := path.Join(*dumpSubgraph, s)
f, err := os.Create(filename)
x.Checkf(err, filename)
enc := gob.NewEncoder(f)
x.Check(enc.Encode(sg))
x.Checkf(f.Close(), filename)
}
js, err := sg.ToJSON(&l)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while converting to Json"))
x.SetStatus(w, x.Error, err.Error())
return
}
x.Trace(ctx, "Latencies: Total: %v Parsing: %v Process: %v Json: %v",
time.Since(l.Start), l.Parsing, l.Processing, l.Json)
w.Header().Set("Content-Type", "application/json")
w.Write(js)
}
// This method is used to execute the query and return the response to the
// client as a protocol buffer message.
func (s *grpcServer) Query(ctx context.Context,
req *graph.Request) (*graph.Response, error) {
var allocIds map[string]uint64
if rand.Float64() < *tracing {
tr := trace.New("Dgraph", "GrpcQuery")
defer tr.Finish()
ctx = trace.NewContext(ctx, tr)
}
resp := new(graph.Response)
if len(req.Query) == 0 && req.Mutation == nil {
x.TraceError(ctx, x.Errorf("Empty query and mutation."))
return resp, fmt.Errorf("Empty query and mutation.")
}
var l query.Latency
l.Start = time.Now()
x.Trace(ctx, "Query received: %v", req.Query)
gq, mu, err := gql.Parse(req.Query)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while parsing query"))
return resp, err
}
// If mutations are part of the query, we run them through the mutation handler
// same as the http client.
if mu != nil && (len(mu.Set) > 0 || len(mu.Del) > 0) {
if allocIds, err = mutationHandler(ctx, mu); err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while handling mutations"))
return resp, err
}
}
// If mutations are sent as part of the mutation object in the request we run
// them here.
if req.Mutation != nil && (len(req.Mutation.Set) > 0 || len(req.Mutation.Del) > 0) {
if allocIds, err = runMutations(ctx, req.Mutation); err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while handling mutations"))
return resp, err
}
}
resp.AssignedUids = allocIds
if gq == nil || (gq.UID == 0 && len(gq.XID) == 0) {
return resp, err
}
sg, err := query.ToSubGraph(ctx, gq)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while conversion to internal format"))
return resp, err
}
l.Parsing = time.Since(l.Start)
x.Trace(ctx, "Query parsed")
rch := make(chan error)
go query.ProcessGraph(ctx, sg, nil, rch)
err = <-rch
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while executing query"))
return resp, err
}
l.Processing = time.Since(l.Start) - l.Parsing
x.Trace(ctx, "Graph processed")
node, err := sg.ToProtocolBuffer(&l)
if err != nil {
x.TraceError(ctx, x.Wrapf(err, "Error while converting to ProtocolBuffer"))
return resp, err
}
resp.N = node
gl := new(graph.Latency)
gl.Parsing, gl.Processing, gl.Pb = l.Parsing.String(), l.Processing.String(),
l.ProtocolBuffer.String()
resp.L = gl
return resp, err
}
// syncMemberships needs to be called in an periodic loop.
// How syncMemberships works:
// - Each server iterates over all the nodes it's serving, present in local.
// - If serving group zero, propose membership status updates directly via RAFT.
// - Otherwise, generates a membership update, which includes status of all serving nodes.
// - Check if it has address of a server from group zero. If so, use that.
// - Otherwise, use the peer information passed down via flags.
// - Send update via UpdateMembership call to the peer.
// - If the peer doesn't serve group zero, it would return back a redirect with the right address.
// - Otherwise, it would iterate over the memberships, check for duplicates, and apply updates.
// - Once iteration is over without errors, it would return back all new updates.
// - These updates are then applied to groups().all state via applyMembershipUpdate.
func (g *groupi) syncMemberships() {
if g.ServesGroup(0) {
// This server serves group zero.
g.RLock()
defer g.RUnlock()
for _, n := range g.local {
rc := n.raftContext
if g.duplicate(rc.Group, rc.Id, rc.Addr, n.AmLeader()) {
continue
}
go func(rc *task.RaftContext, amleader bool) {
mm := &task.Membership{
Leader: amleader,
Id: rc.Id,
GroupId: rc.Group,
Addr: rc.Addr,
}
zero := g.Node(0)
x.AssertTruef(zero != nil, "Expected node 0")
if err := zero.ProposeAndWait(zero.ctx, &task.Proposal{Membership: mm}); err != nil {
x.TraceError(g.ctx, err)
}
}(rc, n.AmLeader())
}
return
}
// This server doesn't serve group zero.
// Generate membership update of all local nodes.
var mu task.MembershipUpdate
{
g.RLock()
for _, n := range g.local {
rc := n.raftContext
mu.Members = append(mu.Members,
&task.Membership{
Leader: n.AmLeader(),
Id: rc.Id,
GroupId: rc.Group,
Addr: rc.Addr,
})
}
mu.LastUpdate = g.lastUpdate
g.RUnlock()
}
// Send an update to peer.
var pl *pool
addr := g.AnyServer(0)
UPDATEMEMBERSHIP:
if len(addr) > 0 {
pl = pools().get(addr)
} else {
pl = pools().any()
}
conn, err := pl.Get()
if err == errNoConnection {
fmt.Println("Unable to sync memberships. No valid connection")
return
}
x.Check(err)
defer pl.Put(conn)
c := NewWorkerClient(conn)
update, err := c.UpdateMembership(g.ctx, &mu)
if err != nil {
x.TraceError(g.ctx, err)
return
}
// Check if we got a redirect.
if update.Redirect {
addr = update.RedirectAddr
if len(addr) == 0 {
return
}
fmt.Printf("Got redirect for: %q\n", addr)
pools().connect(addr)
goto UPDATEMEMBERSHIP
}
var lu uint64
for _, mm := range update.Members {
g.applyMembershipUpdate(update.LastUpdate, mm)
if lu < update.LastUpdate {
lu = update.LastUpdate
}
}
g.TouchLastUpdate(lu)
}