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