tm-bench: Improve code shape

* return error so main controls exit states
* formatting
* order imports

tm-bench/README.md

@@ -14,7 +14,10 @@ will output:
     Txs/sec           833        427        1326     
     Blocks/sec        0.900      0.300      1
 
-These stats are derived by sending transactions at the specified rate for the specified time. After the specified time, it iterates over all of the blocks that were created in that time. The average and stddev per second are computed based off of that, by grouping the data by second.
+These stats are derived by sending transactions at the specified rate for the
+specified time. After the specified time, it iterates over all of the blocks
+that were created in that time. The average and stddev per second are computed
+based off of that, by grouping the data by second.
 
 ## Quick Start
 

tm-bench/main.go

@@ -7,14 +7,13 @@ import (
 	"math"
 	"os"
 	"strings"
+	"text/tabwriter"
 	"time"
 
 	"github.com/go-kit/kit/log/term"
 	metrics "github.com/rcrowley/go-metrics"
-
-	"text/tabwriter"
-
 	tmrpc "github.com/tendermint/tendermint/rpc/client"
+
 	"github.com/tendermint/tmlibs/log"
 )
 
@@ -77,33 +76,54 @@ Examples:
 		fmt.Printf("Running %ds test @ %s\n", duration, flag.Arg(0))
 	}
 
-	if broadcastTxMethod != "async" && broadcastTxMethod != "sync" && broadcastTxMethod != "commit" {
-		fmt.Fprintln(os.Stderr, "broadcast-tx-method should be either 'sync', 'async' or 'commit'.")
+	if broadcastTxMethod != "async" &&
+		broadcastTxMethod != "sync" &&
+		broadcastTxMethod != "commit" {
+		fmt.Fprintln(
+			os.Stderr,
+			"broadcast-tx-method should be either 'sync', 'async' or 'commit'.",
+		)
 		os.Exit(1)
 	}
 
-	endpoints := strings.Split(flag.Arg(0), ",")
-
-	client := tmrpc.NewHTTP(endpoints[0], "/websocket")
-
-	initialHeight := latestBlockHeight(client)
+	var (
+		endpoints     = strings.Split(flag.Arg(0), ",")
+		client        = tmrpc.NewHTTP(endpoints[0], "/websocket")
+		initialHeight = latestBlockHeight(client)
+	)
 	logger.Info("Latest block height", "h", initialHeight)
 
 	// record time start
 	timeStart := time.Now()
 	logger.Info("Time started", "t", timeStart)
 
-	transacters := startTransacters(endpoints, connections, txsRate, "broadcast_tx_"+broadcastTxMethod)
+	transacters := startTransacters(
+		endpoints,
+		connections,
+		txsRate,
+		"broadcast_tx_"+broadcastTxMethod,
+	)
 
 	select {
 	case <-time.After(time.Duration(duration) * time.Second):
 		for _, t := range transacters {
 			t.Stop()
 		}
+
 		timeStop := time.Now()
 		logger.Info("Time stopped", "t", timeStop)
 
-		stats := calculateStatistics(client, initialHeight, timeStart, timeStop, duration)
+		stats, err := calculateStatistics(
+			client,
+			initialHeight,
+			timeStart,
+			timeStop,
+			duration,
+		)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
 
 		printStatistics(stats, outputFormat)
 
@@ -120,9 +140,15 @@ func latestBlockHeight(client tmrpc.Client) int64 {
 	return status.SyncInfo.LatestBlockHeight
 }
 
-// Calculates the tx / second, and blocks / second based off of the number the transactions
-// and number of blocks that occured from the start block, and the end time.
-func calculateStatistics(client tmrpc.Client, minHeight int64, timeStart, timeStop time.Time, duration int) *statistics {
+// calculateStatistics calculates the tx / second, and blocks / second based
+// off of the number the transactions and number of blocks that occurred from
+// the start block, and the end time.
+func calculateStatistics(
+	client tmrpc.Client,
+	minHeight int64,
+	timeStart, timeStop time.Time,
+	duration int,
+) (*statistics, error) {
 	stats := &statistics{
 		BlocksThroughput: metrics.NewHistogram(metrics.NewUniformSample(1000)),
 		TxsThroughput:    metrics.NewHistogram(metrics.NewUniformSample(1000)),
@@ -132,28 +158,31 @@ func calculateStatistics(client tmrpc.Client, minHeight int64, timeStart, timeSt
 	// This returns max(minHeight,(last_height - 20)) to last_height
 	info, err := client.BlockchainInfo(minHeight, 0)
 	if err != nil {
-		fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
+		return nil, err
 	}
 
-	lastHeight := info.LastHeight
-	diff := lastHeight - minHeight
+	var (
+		blockMetas = info.BlockMetas
+		lastHeight = info.LastHeight
+		diff       = lastHeight - minHeight
+		offset     = len(blockMetas)
+	)
 
-	blockMetas := info.BlockMetas
-	offset := len(blockMetas)
-	for len(blockMetas) < int(diff) {
+	for offset < int(diff) {
 		// get blocks between minHeight and last height
 		info, err := client.BlockchainInfo(minHeight, lastHeight-int64(offset))
 		if err != nil {
-			fmt.Fprintln(os.Stderr, err)
-			os.Exit(1)
+			return nil, err
 		}
 		blockMetas = append(blockMetas, info.BlockMetas...)
 		offset = len(blockMetas)
 	}
 
-	numBlocksPerSec := make(map[int64]int64)
-	numTxsPerSec := make(map[int64]int64)
+	var (
+		numBlocksPerSec = make(map[int64]int64)
+		numTxsPerSec    = make(map[int64]int64)
+	)
+
 	// because during some seconds blocks won't be created...
 	for i := int64(0); i < int64(duration); i++ {
 		numBlocksPerSec[i] = 0
@@ -188,14 +217,19 @@ func calculateStatistics(client tmrpc.Client, minHeight int64, timeStart, timeSt
 		stats.TxsThroughput.Update(n)
 	}
 
-	return stats
+	return stats, nil
 }
 
 func secondsSinceTimeStart(timeStart, timePassed time.Time) int64 {
 	return int64(math.Round(timePassed.Sub(timeStart).Seconds()))
 }
 
-func startTransacters(endpoints []string, connections, txsRate int, broadcastTxMethod string) []*transacter {
+func startTransacters(
+	endpoints []string,
+	connections,
+	txsRate int,
+	broadcastTxMethod string,
+) []*transacter {
 	transacters := make([]*transacter, len(endpoints))
 
 	for i, e := range endpoints {

tm-bench/transacter.go

@@ -16,8 +16,8 @@ import (
 
 	"github.com/gorilla/websocket"
 	"github.com/pkg/errors"
-
 	rpctypes "github.com/tendermint/tendermint/rpc/lib/types"
+
 	"github.com/tendermint/tmlibs/log"
 )