From 45a7ae2e62b19ca752c066a4285827f5668be584 Mon Sep 17 00:00:00 2001
From: Greg Szabo <greg@philosobear.com>
Date: Wed, 23 Aug 2017 10:57:14 -0400
Subject: [PATCH] Fixes to tm-bench transaction content - Initialize random
 with current time as seed so transaction messages are different at every run
 - Added hash of hostname to make transactions coming from different hosts
 different in every case - Added current time to transaction to make sure that
 messages are different even if random numbers are the same in subsequent runs
 - Shortened the transaction size to 64 bytes from the original 250

---
 tm-bench/main.go       | 14 +++++++++++++-
 tm-bench/transacter.go | 31 ++++++++++++++++++++++++-------
 2 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/tm-bench/main.go b/tm-bench/main.go
index 686a6e13f..f0cbaead8 100644
--- a/tm-bench/main.go
+++ b/tm-bench/main.go
@@ -14,6 +14,8 @@ import (
 	tmtypes "github.com/tendermint/tendermint/types"
 	"github.com/tendermint/tmlibs/log"
 	"github.com/tendermint/tools/tm-monitor/monitor"
+	"math/rand"
+	"crypto/md5"
 )
 
 var version = "0.1.0"
@@ -74,6 +76,8 @@ Examples:
 	blockCh := make(chan tmtypes.Header, 100)
 	blockLatencyCh := make(chan float64, 100)
 
+	rand.Seed(time.Now().Unix())
+
 	nodes := startNodes(endpoints, blockCh, blockLatencyCh)
 
 	transacters := startTransacters(endpoints, connections, txsRate)
@@ -138,10 +142,18 @@ func startNodes(endpoints []string, blockCh chan<- tmtypes.Header, blockLatencyC
 }
 
 func startTransacters(endpoints []string, connections int, txsRate int) []*transacter {
+
+	var hostHash [16]byte
+	if hostName , err := os.Hostname(); err != nil {
+		hostHash =	md5.Sum([]byte("127.0.0.1"))
+	} else {
+		hostHash = md5.Sum([]byte(hostName))
+	}
+
 	transacters := make([]*transacter, len(endpoints))
 
 	for i, e := range endpoints {
-		t := newTransacter(e, connections, txsRate)
+		t := newTransacter(e, connections, txsRate, hostHash)
 		t.SetLogger(logger)
 		if err := t.Start(); err != nil {
 			fmt.Println(err)
diff --git a/tm-bench/transacter.go b/tm-bench/transacter.go
index 894d133f0..25e7442a1 100644
--- a/tm-bench/transacter.go
+++ b/tm-bench/transacter.go
@@ -30,6 +30,7 @@ type transacter struct {
 	Target      string
 	Rate        int
 	Connections int
+	HostHash	[16]byte
 
 	conns   []*websocket.Conn
 	wg      sync.WaitGroup
@@ -38,11 +39,12 @@ type transacter struct {
 	logger log.Logger
 }
 
-func newTransacter(target string, connections int, rate int) *transacter {
+func newTransacter(target string, connections int, rate int, hosthash [16]byte) *transacter {
 	return &transacter{
 		Target:      target,
 		Rate:        rate,
 		Connections: connections,
+		HostHash:    hosthash,
 		conns:       make([]*websocket.Conn, connections),
 		logger:      log.NewNopLogger(),
 	}
@@ -136,7 +138,7 @@ func (t *transacter) sendLoop(connIndex int) {
 
 			for i := 0; i < t.Rate; i++ {
 				// each transaction embeds connection index and tx number
-				tx := generateTx(connIndex, txNumber)
+				tx := generateTx(connIndex, txNumber, t.HostHash)
 				paramsJson, err := json.Marshal(map[string]interface{}{"tx": hex.EncodeToString(tx)})
 				if err != nil {
 					fmt.Printf("failed to encode params: %v\n", err)
@@ -189,11 +191,26 @@ func connect(host string) (*websocket.Conn, *http.Response, error) {
 	return websocket.DefaultDialer.Dial(u.String(), nil)
 }
 
-func generateTx(a int, b int) []byte {
-	tx := make([]byte, 250)
-	binary.PutUvarint(tx[:32], uint64(a))
-	binary.PutUvarint(tx[32:64], uint64(b))
-	if _, err := rand.Read(tx[234:]); err != nil {
+func generateTx(a int, b int, hosthash [16]byte) []byte {
+	// 64 byte transaction
+	tx := make([]byte, 64)
+
+	// 0-8 connection number
+	binary.PutUvarint(tx[:8], uint64(a))
+
+	// 8-16 transaction number
+	binary.PutUvarint(tx[8:16], uint64(b))
+
+	// 16-32 hostname hash
+	for i:=0; i < 16 ; i++ {
+		tx[16+i] = hosthash[i]
+	}
+
+	// 32-40 current time
+	PutUvarint(tx[32:40], uint64(time.Now().Unix()))
+
+	// 40-64 random data
+	if _, err := rand.Read(tx[40:]); err != nil {
 		panic(errors.Wrap(err, "failed to generate transaction"))
 	}
 	return tx