minio/cmd/dummy-data-generator_test.go
2022-08-26 12:52:29 -07:00

184 lines
4.8 KiB
Go

// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package cmd
import (
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"testing"
)
var alphabets = []byte("abcdefghijklmnopqrstuvwxyz0123456789")
// DummyDataGen returns a reader that repeats the bytes in `alphabets`
// upto the desired length.
type DummyDataGen struct {
b []byte
idx, length int64
}
// NewDummyDataGen returns a ReadSeeker over the first `totalLength`
// bytes from the infinite stream consisting of repeated
// concatenations of `alphabets`.
//
// The skipOffset (generally = 0) can be used to skip a given number
// of bytes from the beginning of the infinite stream. This is useful
// to compare such streams of bytes that may be split up, because:
//
// Given the function:
//
// f := func(r io.Reader) string {
// b, _ := ioutil.ReadAll(r)
// return string(b)
// }
//
// for example, the following is true:
//
// f(NewDummyDataGen(100, 0)) == f(NewDummyDataGen(50, 0)) + f(NewDummyDataGen(50, 50))
func NewDummyDataGen(totalLength, skipOffset int64) io.ReadSeeker {
if totalLength < 0 {
panic("Negative length passed to DummyDataGen!")
}
if skipOffset < 0 {
panic("Negative rotations are not allowed")
}
skipOffset %= int64(len(alphabets))
as := make([]byte, 2*len(alphabets))
copy(as, alphabets)
copy(as[len(alphabets):], alphabets)
b := as[skipOffset : skipOffset+int64(len(alphabets))]
return &DummyDataGen{
length: totalLength,
b: b,
}
}
func (d *DummyDataGen) Read(b []byte) (n int, err error) {
k := len(b)
numLetters := int64(len(d.b))
for k > 0 && d.idx < d.length {
w := copy(b[len(b)-k:], d.b[d.idx%numLetters:])
k -= w
d.idx += int64(w)
n += w
}
if d.idx >= d.length {
extraBytes := d.idx - d.length
n -= int(extraBytes)
if n < 0 {
n = 0
}
err = io.EOF
}
return
}
func (d *DummyDataGen) Seek(offset int64, whence int) (int64, error) {
switch whence {
case io.SeekStart:
if offset < 0 {
return 0, errors.New("Invalid offset")
}
d.idx = offset
case io.SeekCurrent:
if d.idx+offset < 0 {
return 0, errors.New("Invalid offset")
}
d.idx += offset
case io.SeekEnd:
if d.length+offset < 0 {
return 0, errors.New("Invalid offset")
}
d.idx = d.length + offset
}
return d.idx, nil
}
func TestDummyDataGenerator(t *testing.T) {
readAll := func(r io.Reader) string {
b, _ := ioutil.ReadAll(r)
return string(b)
}
checkEq := func(a, b string) {
if a != b {
t.Fatalf("Unexpected equality failure")
}
}
checkEq(readAll(NewDummyDataGen(0, 0)), "")
checkEq(readAll(NewDummyDataGen(10, 0)), readAll(NewDummyDataGen(10, int64(len(alphabets)))))
checkEq(readAll(NewDummyDataGen(100, 0)), readAll(NewDummyDataGen(50, 0))+readAll(NewDummyDataGen(50, 50)))
r := NewDummyDataGen(100, 0)
r.Seek(int64(len(alphabets)), 0)
checkEq(readAll(r), readAll(NewDummyDataGen(100-int64(len(alphabets)), 0)))
}
// Compares all the bytes returned by the given readers. Any Read
// errors cause a `false` result. A string describing the error is
// also returned.
func cmpReaders(r1, r2 io.Reader) (bool, string) {
bufLen := 32 * 1024
b1, b2 := make([]byte, bufLen), make([]byte, bufLen)
for i := 0; true; i++ {
n1, e1 := io.ReadFull(r1, b1)
n2, e2 := io.ReadFull(r2, b2)
if n1 != n2 {
return false, fmt.Sprintf("Read %d != %d bytes from the readers", n1, n2)
}
if !bytes.Equal(b1[:n1], b2[:n2]) {
return false, fmt.Sprintf("After reading %d equal buffers (32Kib each), we got the following two strings:\n%v\n%v\n",
i, b1, b2)
}
// Check if stream has ended
if (e1 == io.ErrUnexpectedEOF && e2 == io.ErrUnexpectedEOF) || (e1 == io.EOF && e2 == io.EOF) {
break
}
if e1 != nil || e2 != nil {
return false, fmt.Sprintf("Got unexpected error values: %v == %v", e1, e2)
}
}
return true, ""
}
func TestCmpReaders(t *testing.T) {
{
r1 := bytes.NewReader([]byte("abc"))
r2 := bytes.NewReader([]byte("abc"))
ok, msg := cmpReaders(r1, r2)
if !(ok && msg == "") {
t.Fatalf("unexpected")
}
}
{
r1 := bytes.NewReader([]byte("abc"))
r2 := bytes.NewReader([]byte("abcd"))
ok, _ := cmpReaders(r1, r2)
if ok {
t.Fatalf("unexpected")
}
}
}