From 91119ca790e4691ef07c180ada441ae969495596 Mon Sep 17 00:00:00 2001
From: Sebastian Zagrodzki <sebek@zagrodzki.net>
Date: Wed, 8 Feb 2017 23:28:52 +0100
Subject: [PATCH] Add a benchmark option.

---
 rawread/main.go | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/rawread/main.go b/rawread/main.go
index 55ab813..4e56e1e 100644
--- a/rawread/main.go
+++ b/rawread/main.go
@@ -21,6 +21,8 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"sync/atomic"
+	"time"
 
 	"github.com/kylelemons/gousb/usb"
 	"github.com/kylelemons/gousb/usbid"
@@ -36,7 +38,8 @@ var (
 	setup    = flag.Uint("setup", 0, "Endpoint to which to connect")
 	endpoint = flag.Uint("endpoint", 1, "Endpoint to which to connect")
 	debug    = flag.Int("debug", 3, "Debug level for libusb")
-	size     = flag.Uint("read_size", 1024, "Maximum number of bytes of data to read. Collected will be printed to STDOUT.")
+	size     = flag.Uint("read_size", 1024, "Number of bytes of data to read in a single transaction.")
+	bench    = flag.Bool("benchmark", false, "When true, keep reading from the endpoint and periodically report the measured throughput. If false,  only one read operation is performed and obtained data is printed to STDOUT.")
 )
 
 func main() {
@@ -117,17 +120,41 @@ func main() {
 		log.Printf("    --------------\n")
 	}
 
-	log.Printf("Connecting to endpoint...")
+	log.Print("Connecting to endpoint...")
 	ep, err := dev.OpenEndpoint(uint8(*config), uint8(*iface), uint8(*setup), uint8(*endpoint)|uint8(usb.ENDPOINT_DIR_IN))
 	if err != nil {
 		log.Fatalf("open: %s", err)
 	}
+	log.Print("Reading...")
 
-	buf := make([]byte, *size)
-	num, err := ep.Read(buf)
-	if err != nil {
-		log.Fatalf("Reading from device failed: %v", err)
+	var total uint64
+	if *bench {
+		go func() {
+			var last uint64
+			var before = time.Now()
+			for {
+				time.Sleep(4 * time.Second)
+				cur := atomic.LoadUint64(&total)
+				now := time.Now()
+				dur := now.Sub(before)
+				log.Printf("%.2f B/s\n", float64(cur-last)/(float64(dur)/float64(time.Second)))
+				before = now
+				last = cur
+			}
+		}()
+	}
+
+	for {
+		buf := make([]byte, *size)
+		num, err := ep.Read(buf)
+		if err != nil {
+			log.Fatalf("Reading from device failed: %v", err)
+		}
+		if !*bench {
+			log.Printf("Read %d bytes of data", num)
+			os.Stdout.Write(buf[:num])
+			return
+		}
+		atomic.AddUint64(&total, uint64(num))
 	}
-	log.Printf("Read %d bytes of data", num)
-	os.Stdout.Write(buf[:num])
 }