Batch db write in order to resolve test slowliness (#1732)

* first version of batching

* batching db writes to solve test slowliness

* remove debug msg

* variable problem

* remove exesive code

beacon-chain/db/db.go

@@ -35,7 +35,9 @@ func (db *BeaconDB) Close() error {
 func (db *BeaconDB) update(fn func(*bolt.Tx) error) error {
 	return db.db.Update(fn)
 }
-
+func (db *BeaconDB) batch(fn func(*bolt.Tx) error) error {
+	return db.db.Batch(fn)
+}
 func (db *BeaconDB) view(fn func(*bolt.Tx) error) error {
 	return db.db.View(fn)
 }

beacon-chain/db/validator.go

@@ -23,6 +23,19 @@ func (db *BeaconDB) SaveValidatorIndex(pubKey []byte, index int) error {
 	})
 }
 
+// SaveValidatorIndexBatch accepts a public key and validator index and writes them to disk.
+func (db *BeaconDB) SaveValidatorIndexBatch(pubKey []byte, index int) error {
+	h := hashutil.Hash(pubKey)
+
+	return db.batch(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket(validatorBucket)
+		buf := make([]byte, binary.MaxVarintLen64)
+		n := binary.PutUvarint(buf, uint64(index))
+		return bucket.Put(h[:], buf[:n])
+	})
+
+}
+
 // ValidatorIndex accepts a public key and returns the corresponding validator index.
 func (db *BeaconDB) ValidatorIndex(pubKey []byte) (uint64, error) {
 	if !db.HasValidator(pubKey) {

beacon-chain/rpc/validator_server_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -183,11 +184,22 @@ func TestCommitteeAssignment_OK(t *testing.T) {
 	if err := db.UpdateChainHead(genesis, state); err != nil {
 		t.Fatalf("Could not save genesis state: %v", err)
 	}
-
-	for i := 0; i < int(params.BeaconConfig().DepositsForChainStart); i++ {
+	var wg sync.WaitGroup
+	numOfValidators := int(params.BeaconConfig().DepositsForChainStart)
+	errs := make(chan error, numOfValidators)
+	for i := 0; i < numOfValidators; i++ {
 		pubKeyBuf := make([]byte, binary.MaxVarintLen64)
 		n := binary.PutUvarint(pubKeyBuf, uint64(i))
-		if err := db.SaveValidatorIndex(pubKeyBuf[:n], i); err != nil {
+		wg.Add(1)
+		go func(index int) {
+			errs <- db.SaveValidatorIndexBatch(pubKeyBuf[:n], index)
+			wg.Done()
+		}(i)
+	}
+	wg.Wait()
+	close(errs)
+	for err := range errs {
+		if err != nil {
 			t.Fatalf("Could not save validator index: %v", err)
 		}
 	}