[log] add sample log of message handle time

Signed-off-by: Leo Chen <leo@harmony.one>

consensus/consensus_v2.go

@@ -13,6 +13,7 @@ import (
 	"github.com/harmony-one/harmony/core/types"
 	vrf_bls "github.com/harmony-one/harmony/crypto/vrf/bls"
 	nodeconfig "github.com/harmony-one/harmony/internal/configs/node"
+	"github.com/harmony-one/harmony/internal/utils"
 	"github.com/harmony-one/harmony/p2p"
 	"github.com/harmony-one/harmony/shard"
 	"github.com/harmony-one/vdf/src/vdf_go"
@@ -21,6 +22,9 @@ import (
 
 // handlemessageupdate will update the consensus state according to received message
 func (consensus *Consensus) handleMessageUpdate(payload []byte) {
+	entryTime := time.Now()
+	defer utils.SampledLogger().Info().Str("cost", time.Now().Sub(entryTime).String()).Msg("[cost:handle_consensus_message]")
+
 	if len(payload) == 0 {
 		return
 	}