overdue

.rclone_repo/cmd/mount/test/seek_speed.go

@@ -0,0 +1,72 @@
+// +build ignore
+
+// Read blocks out of a single file to time the seeking code
+package main
+
+import (
+	"flag"
+	"io"
+	"log"
+	"math/rand"
+	"os"
+	"time"
+)
+
+var (
+	// Flags
+	iterations   = flag.Int("n", 25, "Iterations to try")
+	maxBlockSize = flag.Int("b", 1024*1024, "Max block size to read")
+	randSeed     = flag.Int64("seed", 1, "Seed for the random number generator")
+)
+
+func randomSeekTest(size int64, in *os.File, name string) {
+	start := rand.Int63n(size)
+	blockSize := rand.Intn(*maxBlockSize)
+	if int64(blockSize) > size-start {
+		blockSize = int(size - start)
+	}
+	log.Printf("Reading %d from %d", blockSize, start)
+
+	_, err := in.Seek(start, io.SeekStart)
+	if err != nil {
+		log.Fatalf("Seek failed on %q: %v", name, err)
+	}
+
+	buf := make([]byte, blockSize)
+	_, err = io.ReadFull(in, buf)
+	if err != nil {
+		log.Fatalf("Read failed on %q: %v", name, err)
+	}
+}
+
+func main() {
+	flag.Parse()
+	args := flag.Args()
+	if len(args) != 1 {
+		log.Fatalf("Require 1 file as argument")
+	}
+	rand.Seed(*randSeed)
+
+	name := args[0]
+	in, err := os.Open(name)
+	if err != nil {
+		log.Fatalf("Couldn't open %q: %v", name, err)
+	}
+
+	fi, err := in.Stat()
+	if err != nil {
+		log.Fatalf("Couldn't stat %q: %v", name, err)
+	}
+
+	start := time.Now()
+	for i := 0; i < *iterations; i++ {
+		randomSeekTest(fi.Size(), in, name)
+	}
+	dt := time.Since(start)
+	log.Printf("That took %v for %d iterations, %v per iteration", dt, *iterations, dt/time.Duration(*iterations))
+
+	err = in.Close()
+	if err != nil {
+		log.Fatalf("Error closing %q: %v", name, err)
+	}
+}