github.com/10XDev/rclone@v1.52.3-0.20200626220027-16af9ab76b2a/cmd/mount/test/seeker.go (about)

     1  // +build ignore
     2  
     3  // Read two files with lots of seeking to stress test the seek code
     4  package main
     5  
     6  import (
     7  	"bytes"
     8  	"flag"
     9  	"io"
    10  	"io/ioutil"
    11  	"log"
    12  	"math/rand"
    13  	"os"
    14  	"time"
    15  )
    16  
    17  var (
    18  	// Flags
    19  	iterations   = flag.Int("n", 1e6, "Iterations to try")
    20  	maxBlockSize = flag.Int("b", 1024*1024, "Max block size to read")
    21  )
    22  
    23  func init() {
    24  	rand.Seed(time.Now().UnixNano())
    25  }
    26  
    27  func randomSeekTest(size int64, in1, in2 *os.File, file1, file2 string) {
    28  	start := rand.Int63n(size)
    29  	blockSize := rand.Intn(*maxBlockSize)
    30  	if int64(blockSize) > size-start {
    31  		blockSize = int(size - start)
    32  	}
    33  	log.Printf("Reading %d from %d", blockSize, start)
    34  
    35  	_, err := in1.Seek(start, io.SeekStart)
    36  	if err != nil {
    37  		log.Fatalf("Seek failed on %q: %v", file1, err)
    38  	}
    39  	_, err = in2.Seek(start, io.SeekStart)
    40  	if err != nil {
    41  		log.Fatalf("Seek failed on %q: %v", file2, err)
    42  	}
    43  
    44  	buf1 := make([]byte, blockSize)
    45  	n1, err := io.ReadFull(in1, buf1)
    46  	if err != nil {
    47  		log.Fatalf("Read failed on %q: %v", file1, err)
    48  	}
    49  
    50  	buf2 := make([]byte, blockSize)
    51  	n2, err := io.ReadFull(in2, buf2)
    52  	if err != nil {
    53  		log.Fatalf("Read failed on %q: %v", file2, err)
    54  	}
    55  
    56  	if n1 != n2 {
    57  		log.Fatalf("Read different lengths %d (%q) != %d (%q)", n1, file1, n2, file2)
    58  	}
    59  
    60  	if !bytes.Equal(buf1, buf2) {
    61  		log.Printf("Dumping different blocks")
    62  		err = ioutil.WriteFile("/tmp/z1", buf1, 0777)
    63  		if err != nil {
    64  			log.Fatalf("Failed to write /tmp/z1: %v", err)
    65  		}
    66  		err = ioutil.WriteFile("/tmp/z2", buf2, 0777)
    67  		if err != nil {
    68  			log.Fatalf("Failed to write /tmp/z2: %v", err)
    69  		}
    70  		log.Fatalf("Read different contents - saved in /tmp/z1 and /tmp/z2")
    71  	}
    72  }
    73  
    74  func main() {
    75  	flag.Parse()
    76  	args := flag.Args()
    77  	if len(args) != 2 {
    78  		log.Fatalf("Require 2 files as argument")
    79  	}
    80  	file1, file2 := args[0], args[1]
    81  	in1, err := os.Open(file1)
    82  	if err != nil {
    83  		log.Fatalf("Couldn't open %q: %v", file1, err)
    84  	}
    85  	in2, err := os.Open(file2)
    86  	if err != nil {
    87  		log.Fatalf("Couldn't open %q: %v", file2, err)
    88  	}
    89  
    90  	fi1, err := in1.Stat()
    91  	if err != nil {
    92  		log.Fatalf("Couldn't stat %q: %v", file1, err)
    93  	}
    94  	fi2, err := in2.Stat()
    95  	if err != nil {
    96  		log.Fatalf("Couldn't stat %q: %v", file2, err)
    97  	}
    98  
    99  	if fi1.Size() != fi2.Size() {
   100  		log.Fatalf("Files not the same size")
   101  	}
   102  
   103  	for i := 0; i < *iterations; i++ {
   104  		randomSeekTest(fi1.Size(), in1, in2, file1, file2)
   105  	}
   106  
   107  	err = in1.Close()
   108  	if err != nil {
   109  		log.Fatalf("Error closing %q: %v", file1, err)
   110  	}
   111  	err = in2.Close()
   112  	if err != nil {
   113  		log.Fatalf("Error closing %q: %v", file2, err)
   114  	}
   115  }