etcdserver: add --max-txn-ops flag

--max-txn-ops allows users to define the maximum transaction operations
for each txn request. it defaults at 128.

Fixes #7826

clientv3/integration/txn_test.go

@@ -41,7 +41,7 @@ func TestTxnError(t *testing.T) {
 		t.Fatalf("expected %v, got %v", rpctypes.ErrDuplicateKey, err)
 	}
 
-	ops := make([]clientv3.Op, v3rpc.MaxOpsPerTxn+10)
+	ops := make([]clientv3.Op, v3rpc.MaxTxnOps+10)
 	for i := range ops {
 		ops[i] = clientv3.OpPut(fmt.Sprintf("foo%d", i), "")
 	}

embed/config.go

@@ -40,6 +40,7 @@ const (
 	DefaultName         = "default"
 	DefaultMaxSnapshots = 5
 	DefaultMaxWALs      = 5
+	DefaultMaxTxnOps    = uint(128)
 
 	DefaultListenPeerURLs   = "http://localhost:2380"
 	DefaultListenClientURLs = "http://localhost:2379"
@@ -85,6 +86,7 @@ type Config struct {
 	TickMs            uint  `json:"heartbeat-interval"`
 	ElectionMs        uint  `json:"election-timeout"`
 	QuotaBackendBytes int64 `json:"quota-backend-bytes"`
+	MaxTxnOps         uint  `json:"max-txn-ops"`
 
 	// clustering
 
@@ -172,6 +174,7 @@ func NewConfig() *Config {
 		MaxWalFiles:         DefaultMaxWALs,
 		Name:                DefaultName,
 		SnapCount:           etcdserver.DefaultSnapCount,
+		MaxTxnOps:           DefaultMaxTxnOps,
 		TickMs:              100,
 		ElectionMs:          1000,
 		LPUrls:              []url.URL{*lpurl},

embed/etcd.go

@@ -139,6 +139,7 @@ func StartEtcd(inCfg *Config) (e *Etcd, err error) {
 		ElectionTicks:           cfg.ElectionTicks(),
 		AutoCompactionRetention: cfg.AutoCompactionRetention,
 		QuotaBackendBytes:       cfg.QuotaBackendBytes,
+		MaxTxnOps:               cfg.MaxTxnOps,
 		StrictReconfigCheck:     cfg.StrictReconfigCheck,
 		ClientCertAuthEnabled:   cfg.ClientTLSInfo.ClientCertAuth,
 		AuthToken:               cfg.AuthToken,

etcdmain/config.go

@@ -138,6 +138,7 @@ func newConfig() *config {
 	fs.UintVar(&cfg.TickMs, "heartbeat-interval", cfg.TickMs, "Time (in milliseconds) of a heartbeat interval.")
 	fs.UintVar(&cfg.ElectionMs, "election-timeout", cfg.ElectionMs, "Time (in milliseconds) for an election to timeout.")
 	fs.Int64Var(&cfg.QuotaBackendBytes, "quota-backend-bytes", cfg.QuotaBackendBytes, "Raise alarms when backend size exceeds the given quota. 0 means use the default quota.")
+	fs.UintVar(&cfg.MaxTxnOps, "max-txn-ops", cfg.MaxTxnOps, "Maximum operations per txn that etcd server allows; defaults to 128.")
 
 	// clustering
 	fs.Var(flags.NewURLsValue(embed.DefaultInitialAdvertisePeerURLs), "initial-advertise-peer-urls", "List of this member's peer URLs to advertise to the rest of the cluster.")

etcdmain/help.go

@@ -66,6 +66,8 @@ member flags:
 		comma-separated whitelist of origins for CORS (cross-origin resource sharing).
 	--quota-backend-bytes '0'
 		raise alarms when backend size exceeds the given quota (0 defaults to low space quota).
+	--max-txn-ops '128' 
+		maximum operations per txn that etcd server allows; defaults to 128.
 
 clustering flags:
 

etcdserver/api/v3rpc/key.go

@@ -27,19 +27,20 @@ import (
 
 var (
 	plog = capnslog.NewPackageLogger("github.com/coreos/etcd", "etcdserver/api/v3rpc")
-
-	// Max operations per txn list. For example, Txn.Success can have at most 128 operations,
-	// and Txn.Failure can have at most 128 operations.
-	MaxOpsPerTxn = 128
 )
 
 type kvServer struct {
 	hdr header
 	kv  etcdserver.RaftKV
+	// maxTxnOps is the max operations per txn.
+	// e.g suppose maxTxnOps = 128.
+	// Txn.Success can have at most 128 operations,
+	// and Txn.Failure can have at most 128 operations.
+	maxTxnOps uint
 }
 
 func NewKVServer(s *etcdserver.EtcdServer) pb.KVServer {
-	return &kvServer{hdr: newHeader(s), kv: s}
+	return &kvServer{hdr: newHeader(s), kv: s, maxTxnOps: s.Cfg.MaxTxnOps}
 }
 
 func (s *kvServer) Range(ctx context.Context, r *pb.RangeRequest) (*pb.RangeResponse, error) {
@@ -94,7 +95,7 @@ func (s *kvServer) DeleteRange(ctx context.Context, r *pb.DeleteRangeRequest) (*
 }
 
 func (s *kvServer) Txn(ctx context.Context, r *pb.TxnRequest) (*pb.TxnResponse, error) {
-	if err := checkTxnRequest(r); err != nil {
+	if err := checkTxnRequest(r, int(s.maxTxnOps)); err != nil {
 		return nil, err
 	}
 
@@ -150,8 +151,9 @@ func checkDeleteRequest(r *pb.DeleteRangeRequest) error {
 	return nil
 }
 
-func checkTxnRequest(r *pb.TxnRequest) error {
+func checkTxnRequest(r *pb.TxnRequest, maxTxnOps int) error {
-	if len(r.Compare) > MaxOpsPerTxn || len(r.Success) > MaxOpsPerTxn || len(r.Failure) > MaxOpsPerTxn {
+	plog.Infof("maxTxnOps %v", maxTxnOps)
+	if len(r.Compare) > maxTxnOps || len(r.Success) > maxTxnOps || len(r.Failure) > maxTxnOps {
 		return rpctypes.ErrGRPCTooManyOps
 	}
 

etcdserver/config.go

@@ -54,6 +54,7 @@ type ServerConfig struct {
 
 	AutoCompactionRetention int
 	QuotaBackendBytes       int64
+	MaxTxnOps               uint
 
 	StrictReconfigCheck bool
 

integration/v3_grpc_test.go

@@ -201,7 +201,7 @@ func TestV3TxnTooManyOps(t *testing.T) {
 
 	for i, tt := range tests {
 		txn := &pb.TxnRequest{}
-		for j := 0; j < v3rpc.MaxOpsPerTxn+1; j++ {
+		for j := 0; j < v3rpc.MaxTxnOps+1; j++ {
 			tt(txn)
 		}