github.com/rclone/rclone@v1.66.1-0.20240517100346-7b89735ae726/cmd/mount/test/seeker.go (about)

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