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client.go
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client.go
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/*
* Copyright 2016 Dgraph Labs, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package client
import (
"context"
"fmt"
"sync"
"sync/atomic"
"time"
"google.golang.org/grpc"
"github.com/dgraph-io/dgraph/query/graph"
)
type Op int
const (
SET Op = iota
DEL
)
// Req wraps the graph.Request so that we can define helper methods for the
// client around it.
type Req struct {
gr graph.Request
}
// Request returns the graph request object which is sent to the server to perform
// a query/mutation.
func (req *Req) Request() *graph.Request {
return &req.gr
}
func checkNQuad(nq graph.NQuad) error {
if len(nq.Subject) == 0 {
return fmt.Errorf("Subject can't be empty")
}
if len(nq.Predicate) == 0 {
return fmt.Errorf("Predicate can't be empty")
}
hasVal := nq.ObjectValue != nil
if len(nq.ObjectId) == 0 && !hasVal {
return fmt.Errorf("Both objectId and objectValue can't be nil")
}
if len(nq.ObjectId) > 0 && hasVal {
return fmt.Errorf("Only one out of objectId and objectValue can be set")
}
return nil
}
// SetQuery sets a query as part of the request.
// Example usage
// req := client.Req{}
// req.SetQuery("{ me(_xid_: alice) { name falls.in } }")
// resp, err := c.Query(context.Background(), req.Request())
// Check response and handle errors
func (req *Req) SetQuery(q string) {
req.gr.Query = q
}
func (req *Req) addMutation(nq graph.NQuad, op Op) {
if req.gr.Mutation == nil {
req.gr.Mutation = new(graph.Mutation)
}
if op == SET {
req.gr.Mutation.Set = append(req.gr.Mutation.Set, &nq)
} else if op == DEL {
req.gr.Mutation.Del = append(req.gr.Mutation.Del, &nq)
}
}
// AddMutation adds a SET/DELETE mutation operation.
//
// Example usage
// req := client.Req{}
// To set a string value
// if err := req.AddMutation(graph.NQuad{
// Sub: "alice",
// Pred: "name",
// Value: client.Str("Alice"),
// }, client.SET); err != nil {
// ....
// handle error
// ....
// }
// To set an integer value
// if err := req.AddMutation(graph.NQuad{
// Sub: "alice",
// Pred: "age",
// Value: client.Int(13),
// }, client.SET); err != nil {
// ....
// handle error
// ....
// }
// To add a mutation with a DELETE operation
// if err := req.AddMutation(graph.NQuad{
// Sub: "alice",
// Pred: "name",
// Value: client.Str("Alice"),
// }, client.DEL); err != nil {
// ....
// handle error
// ....
// }
func (req *Req) AddMutation(nq graph.NQuad, op Op) error {
if err := checkNQuad(nq); err != nil {
return err
}
req.addMutation(nq, op)
return nil
}
func (req *Req) size() int {
if req.gr.Mutation == nil {
return 0
}
return len(req.gr.Mutation.Set) + len(req.gr.Mutation.Del)
}
func (req *Req) reset() {
req.gr.Query = ""
req.gr.Mutation.Set = req.gr.Mutation.Set[:0]
req.gr.Mutation.Del = req.gr.Mutation.Del[:0]
}
type nquadOp struct {
nq graph.NQuad
op Op
}
type BatchMutation struct {
size int
pending int
nquads chan nquadOp
dc graph.DgraphClient
wg sync.WaitGroup
// Miscellaneous information to print counters.
// Num of RDF's sent
rdfs uint64
// Num of mutations sent
mutations uint64
// To get time elapsed.
start time.Time
}
func (batch *BatchMutation) request(req *Req) {
counter := atomic.AddUint64(&batch.mutations, 1)
RETRY:
_, err := batch.dc.Run(context.Background(), &req.gr)
if err != nil {
fmt.Printf("Retrying req: %d. Error: %v\n", counter, err)
time.Sleep(5 * time.Millisecond)
goto RETRY
}
req.reset()
}
func (batch *BatchMutation) makeRequests() {
req := new(Req)
for n := range batch.nquads {
req.addMutation(n.nq, n.op)
if req.size() == batch.size {
batch.request(req)
}
}
if req.size() > 0 {
batch.request(req)
}
batch.wg.Done()
}
func NewBatchMutation(ctx context.Context, conn *grpc.ClientConn,
size int, pending int) *BatchMutation {
bm := BatchMutation{
size: size,
pending: pending,
nquads: make(chan nquadOp, 2*size),
start: time.Now(),
dc: graph.NewDgraphClient(conn),
}
for i := 0; i < pending; i++ {
bm.wg.Add(1)
go bm.makeRequests()
}
return &bm
}
func (batch *BatchMutation) AddMutation(nq graph.NQuad, op Op) error {
if err := checkNQuad(nq); err != nil {
return err
}
batch.nquads <- nquadOp{nq: nq, op: op}
atomic.AddUint64(&batch.rdfs, 1)
return nil
}
type Counter struct {
Rdfs uint64
Mutations uint64
Elapsed time.Duration
}
func (batch *BatchMutation) Counter() Counter {
return Counter{
Rdfs: atomic.LoadUint64(&batch.rdfs),
Mutations: atomic.LoadUint64(&batch.mutations),
Elapsed: time.Since(batch.start),
}
}
func (batch *BatchMutation) Flush() {
close(batch.nquads)
batch.wg.Wait()
}