etcdserver: add --max-ops-per-txn flag

Fixes etcd-io#7826

Author: fanminshi

embed/config.go

@@ -85,6 +85,7 @@ type Config struct {
 	TickMs            uint  `json:"heartbeat-interval"`
 	ElectionMs        uint  `json:"election-timeout"`
 	QuotaBackendBytes int64 `json:"quota-backend-bytes"`
+	MaxOpsPerTxn      uint  `json:"max-ops-per-txn"`
 
 	// clustering
 

embed/etcd.go

@@ -139,6 +139,7 @@ func StartEtcd(inCfg *Config) (e *Etcd, err error) {
 		ElectionTicks:           cfg.ElectionTicks(),
 		AutoCompactionRetention: cfg.AutoCompactionRetention,
 		QuotaBackendBytes:       cfg.QuotaBackendBytes,
+		MaxOpsPerTxn:            cfg.MaxOpsPerTxn,
 		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.MaxOpsPerTxn, "max-ops-per-txn", cfg.MaxOpsPerTxn, "maximum operations per txn that etcd server allows (0 is unlimited); defaults to unlimited.")
 
 	// 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-ops-per-txn '0' 
+		maximum operations per txn that etcd server allows (0 is unlimited); defaults to unlimited.
 
 clustering flags:
 

etcdserver/api/v3rpc/key.go

@@ -28,9 +28,11 @@ 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,
+	// MaxOpsPerTxn is the max operations per txn.
+	// e.g suppose maxOpsPerTxn = 128.
+	// Txn.Success can have at most 128 operations,
 	// and Txn.Failure can have at most 128 operations.
-	MaxOpsPerTxn = 128
+	MaxOpsPerTxn = 0
 )
 
 type kvServer struct {
@@ -39,6 +41,7 @@ type kvServer struct {
 }
 
 func NewKVServer(s *etcdserver.EtcdServer) pb.KVServer {
+	MaxOpsPerTxn = int(s.Cfg.MaxOpsPerTxn)
 	return &kvServer{hdr: newHeader(s), kv: s}
 }
 
@@ -151,7 +154,7 @@ func checkDeleteRequest(r *pb.DeleteRangeRequest) error {
 }
 
 func checkTxnRequest(r *pb.TxnRequest) error {
-	if len(r.Compare) > MaxOpsPerTxn || len(r.Success) > MaxOpsPerTxn || len(r.Failure) > MaxOpsPerTxn {
+	if (len(r.Compare) > MaxOpsPerTxn || len(r.Success) > MaxOpsPerTxn || len(r.Failure) > MaxOpsPerTxn) && MaxOpsPerTxn != 0 {
 		return rpctypes.ErrGRPCTooManyOps
 	}
 

etcdserver/config.go

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