gitee.com/liu-zhao234568/cntest@v1.0.0/core/rawdb/freezer_table_test.go (about)

     1  // Copyright 2019 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package rawdb
    18  
    19  import (
    20  	"bytes"
    21  	"encoding/binary"
    22  	"fmt"
    23  	"io/ioutil"
    24  	"math/rand"
    25  	"os"
    26  	"path/filepath"
    27  	"sync"
    28  	"testing"
    29  	"time"
    30  
    31  	"gitee.com/liu-zhao234568/cntest/metrics"
    32  )
    33  
    34  func init() {
    35  	rand.Seed(time.Now().Unix())
    36  }
    37  
    38  // Gets a chunk of data, filled with 'b'
    39  func getChunk(size int, b int) []byte {
    40  	data := make([]byte, size)
    41  	for i := range data {
    42  		data[i] = byte(b)
    43  	}
    44  	return data
    45  }
    46  
    47  // TestFreezerBasics test initializing a freezertable from scratch, writing to the table,
    48  // and reading it back.
    49  func TestFreezerBasics(t *testing.T) {
    50  	t.Parallel()
    51  	// set cutoff at 50 bytes
    52  	f, err := newCustomTable(os.TempDir(),
    53  		fmt.Sprintf("unittest-%d", rand.Uint64()),
    54  		metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge(), 50, true)
    55  	if err != nil {
    56  		t.Fatal(err)
    57  	}
    58  	defer f.Close()
    59  	// Write 15 bytes 255 times, results in 85 files
    60  	for x := 0; x < 255; x++ {
    61  		data := getChunk(15, x)
    62  		f.Append(uint64(x), data)
    63  	}
    64  
    65  	//print(t, f, 0)
    66  	//print(t, f, 1)
    67  	//print(t, f, 2)
    68  	//
    69  	//db[0] =  000000000000000000000000000000
    70  	//db[1] =  010101010101010101010101010101
    71  	//db[2] =  020202020202020202020202020202
    72  
    73  	for y := 0; y < 255; y++ {
    74  		exp := getChunk(15, y)
    75  		got, err := f.Retrieve(uint64(y))
    76  		if err != nil {
    77  			t.Fatal(err)
    78  		}
    79  		if !bytes.Equal(got, exp) {
    80  			t.Fatalf("test %d, got \n%x != \n%x", y, got, exp)
    81  		}
    82  	}
    83  	// Check that we cannot read too far
    84  	_, err = f.Retrieve(uint64(255))
    85  	if err != errOutOfBounds {
    86  		t.Fatal(err)
    87  	}
    88  }
    89  
    90  // TestFreezerBasicsClosing tests same as TestFreezerBasics, but also closes and reopens the freezer between
    91  // every operation
    92  func TestFreezerBasicsClosing(t *testing.T) {
    93  	t.Parallel()
    94  	// set cutoff at 50 bytes
    95  	var (
    96  		fname      = fmt.Sprintf("basics-close-%d", rand.Uint64())
    97  		rm, wm, sg = metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
    98  		f          *freezerTable
    99  		err        error
   100  	)
   101  	f, err = newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   102  	if err != nil {
   103  		t.Fatal(err)
   104  	}
   105  	// Write 15 bytes 255 times, results in 85 files
   106  	for x := 0; x < 255; x++ {
   107  		data := getChunk(15, x)
   108  		f.Append(uint64(x), data)
   109  		f.Close()
   110  		f, err = newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   111  		if err != nil {
   112  			t.Fatal(err)
   113  		}
   114  	}
   115  	defer f.Close()
   116  
   117  	for y := 0; y < 255; y++ {
   118  		exp := getChunk(15, y)
   119  		got, err := f.Retrieve(uint64(y))
   120  		if err != nil {
   121  			t.Fatal(err)
   122  		}
   123  		if !bytes.Equal(got, exp) {
   124  			t.Fatalf("test %d, got \n%x != \n%x", y, got, exp)
   125  		}
   126  		f.Close()
   127  		f, err = newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   128  		if err != nil {
   129  			t.Fatal(err)
   130  		}
   131  	}
   132  }
   133  
   134  // TestFreezerRepairDanglingHead tests that we can recover if index entries are removed
   135  func TestFreezerRepairDanglingHead(t *testing.T) {
   136  	t.Parallel()
   137  	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
   138  	fname := fmt.Sprintf("dangling_headtest-%d", rand.Uint64())
   139  
   140  	{ // Fill table
   141  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   142  		if err != nil {
   143  			t.Fatal(err)
   144  		}
   145  		// Write 15 bytes 255 times
   146  		for x := 0; x < 255; x++ {
   147  			data := getChunk(15, x)
   148  			f.Append(uint64(x), data)
   149  		}
   150  		// The last item should be there
   151  		if _, err = f.Retrieve(0xfe); err != nil {
   152  			t.Fatal(err)
   153  		}
   154  		f.Close()
   155  	}
   156  	// open the index
   157  	idxFile, err := os.OpenFile(filepath.Join(os.TempDir(), fmt.Sprintf("%s.ridx", fname)), os.O_RDWR, 0644)
   158  	if err != nil {
   159  		t.Fatalf("Failed to open index file: %v", err)
   160  	}
   161  	// Remove 4 bytes
   162  	stat, err := idxFile.Stat()
   163  	if err != nil {
   164  		t.Fatalf("Failed to stat index file: %v", err)
   165  	}
   166  	idxFile.Truncate(stat.Size() - 4)
   167  	idxFile.Close()
   168  	// Now open it again
   169  	{
   170  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   171  		if err != nil {
   172  			t.Fatal(err)
   173  		}
   174  		// The last item should be missing
   175  		if _, err = f.Retrieve(0xff); err == nil {
   176  			t.Errorf("Expected error for missing index entry")
   177  		}
   178  		// The one before should still be there
   179  		if _, err = f.Retrieve(0xfd); err != nil {
   180  			t.Fatalf("Expected no error, got %v", err)
   181  		}
   182  	}
   183  }
   184  
   185  // TestFreezerRepairDanglingHeadLarge tests that we can recover if very many index entries are removed
   186  func TestFreezerRepairDanglingHeadLarge(t *testing.T) {
   187  	t.Parallel()
   188  	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
   189  	fname := fmt.Sprintf("dangling_headtest-%d", rand.Uint64())
   190  
   191  	{ // Fill a table and close it
   192  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   193  		if err != nil {
   194  			t.Fatal(err)
   195  		}
   196  		// Write 15 bytes 255 times
   197  		for x := 0; x < 0xff; x++ {
   198  			data := getChunk(15, x)
   199  			f.Append(uint64(x), data)
   200  		}
   201  		// The last item should be there
   202  		if _, err = f.Retrieve(f.items - 1); err != nil {
   203  			t.Fatal(err)
   204  		}
   205  		f.Close()
   206  	}
   207  	// open the index
   208  	idxFile, err := os.OpenFile(filepath.Join(os.TempDir(), fmt.Sprintf("%s.ridx", fname)), os.O_RDWR, 0644)
   209  	if err != nil {
   210  		t.Fatalf("Failed to open index file: %v", err)
   211  	}
   212  	// Remove everything but the first item, and leave data unaligned
   213  	// 0-indexEntry, 1-indexEntry, corrupt-indexEntry
   214  	idxFile.Truncate(indexEntrySize + indexEntrySize + indexEntrySize/2)
   215  	idxFile.Close()
   216  	// Now open it again
   217  	{
   218  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   219  		if err != nil {
   220  			t.Fatal(err)
   221  		}
   222  		// The first item should be there
   223  		if _, err = f.Retrieve(0); err != nil {
   224  			t.Fatal(err)
   225  		}
   226  		// The second item should be missing
   227  		if _, err = f.Retrieve(1); err == nil {
   228  			t.Errorf("Expected error for missing index entry")
   229  		}
   230  		// We should now be able to store items again, from item = 1
   231  		for x := 1; x < 0xff; x++ {
   232  			data := getChunk(15, ^x)
   233  			f.Append(uint64(x), data)
   234  		}
   235  		f.Close()
   236  	}
   237  	// And if we open it, we should now be able to read all of them (new values)
   238  	{
   239  		f, _ := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   240  		for y := 1; y < 255; y++ {
   241  			exp := getChunk(15, ^y)
   242  			got, err := f.Retrieve(uint64(y))
   243  			if err != nil {
   244  				t.Fatal(err)
   245  			}
   246  			if !bytes.Equal(got, exp) {
   247  				t.Fatalf("test %d, got \n%x != \n%x", y, got, exp)
   248  			}
   249  		}
   250  	}
   251  }
   252  
   253  // TestSnappyDetection tests that we fail to open a snappy database and vice versa
   254  func TestSnappyDetection(t *testing.T) {
   255  	t.Parallel()
   256  	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
   257  	fname := fmt.Sprintf("snappytest-%d", rand.Uint64())
   258  	// Open with snappy
   259  	{
   260  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   261  		if err != nil {
   262  			t.Fatal(err)
   263  		}
   264  		// Write 15 bytes 255 times
   265  		for x := 0; x < 0xff; x++ {
   266  			data := getChunk(15, x)
   267  			f.Append(uint64(x), data)
   268  		}
   269  		f.Close()
   270  	}
   271  	// Open without snappy
   272  	{
   273  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, false)
   274  		if err != nil {
   275  			t.Fatal(err)
   276  		}
   277  		if _, err = f.Retrieve(0); err == nil {
   278  			f.Close()
   279  			t.Fatalf("expected empty table")
   280  		}
   281  	}
   282  
   283  	// Open with snappy
   284  	{
   285  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   286  		if err != nil {
   287  			t.Fatal(err)
   288  		}
   289  		// There should be 255 items
   290  		if _, err = f.Retrieve(0xfe); err != nil {
   291  			f.Close()
   292  			t.Fatalf("expected no error, got %v", err)
   293  		}
   294  	}
   295  
   296  }
   297  func assertFileSize(f string, size int64) error {
   298  	stat, err := os.Stat(f)
   299  	if err != nil {
   300  		return err
   301  	}
   302  	if stat.Size() != size {
   303  		return fmt.Errorf("error, expected size %d, got %d", size, stat.Size())
   304  	}
   305  	return nil
   306  
   307  }
   308  
   309  // TestFreezerRepairDanglingIndex checks that if the index has more entries than there are data,
   310  // the index is repaired
   311  func TestFreezerRepairDanglingIndex(t *testing.T) {
   312  	t.Parallel()
   313  	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
   314  	fname := fmt.Sprintf("dangling_indextest-%d", rand.Uint64())
   315  
   316  	{ // Fill a table and close it
   317  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   318  		if err != nil {
   319  			t.Fatal(err)
   320  		}
   321  		// Write 15 bytes 9 times : 150 bytes
   322  		for x := 0; x < 9; x++ {
   323  			data := getChunk(15, x)
   324  			f.Append(uint64(x), data)
   325  		}
   326  		// The last item should be there
   327  		if _, err = f.Retrieve(f.items - 1); err != nil {
   328  			f.Close()
   329  			t.Fatal(err)
   330  		}
   331  		f.Close()
   332  		// File sizes should be 45, 45, 45 : items[3, 3, 3)
   333  	}
   334  	// Crop third file
   335  	fileToCrop := filepath.Join(os.TempDir(), fmt.Sprintf("%s.0002.rdat", fname))
   336  	// Truncate third file: 45 ,45, 20
   337  	{
   338  		if err := assertFileSize(fileToCrop, 45); err != nil {
   339  			t.Fatal(err)
   340  		}
   341  		file, err := os.OpenFile(fileToCrop, os.O_RDWR, 0644)
   342  		if err != nil {
   343  			t.Fatal(err)
   344  		}
   345  		file.Truncate(20)
   346  		file.Close()
   347  	}
   348  	// Open db it again
   349  	// It should restore the file(s) to
   350  	// 45, 45, 15
   351  	// with 3+3+1 items
   352  	{
   353  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   354  		if err != nil {
   355  			t.Fatal(err)
   356  		}
   357  		if f.items != 7 {
   358  			f.Close()
   359  			t.Fatalf("expected %d items, got %d", 7, f.items)
   360  		}
   361  		if err := assertFileSize(fileToCrop, 15); err != nil {
   362  			t.Fatal(err)
   363  		}
   364  	}
   365  }
   366  
   367  func TestFreezerTruncate(t *testing.T) {
   368  
   369  	t.Parallel()
   370  	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
   371  	fname := fmt.Sprintf("truncation-%d", rand.Uint64())
   372  
   373  	{ // Fill table
   374  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   375  		if err != nil {
   376  			t.Fatal(err)
   377  		}
   378  		// Write 15 bytes 30 times
   379  		for x := 0; x < 30; x++ {
   380  			data := getChunk(15, x)
   381  			f.Append(uint64(x), data)
   382  		}
   383  		// The last item should be there
   384  		if _, err = f.Retrieve(f.items - 1); err != nil {
   385  			t.Fatal(err)
   386  		}
   387  		f.Close()
   388  	}
   389  	// Reopen, truncate
   390  	{
   391  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   392  		if err != nil {
   393  			t.Fatal(err)
   394  		}
   395  		defer f.Close()
   396  		f.truncate(10) // 150 bytes
   397  		if f.items != 10 {
   398  			t.Fatalf("expected %d items, got %d", 10, f.items)
   399  		}
   400  		// 45, 45, 45, 15 -- bytes should be 15
   401  		if f.headBytes != 15 {
   402  			t.Fatalf("expected %d bytes, got %d", 15, f.headBytes)
   403  		}
   404  
   405  	}
   406  
   407  }
   408  
   409  // TestFreezerRepairFirstFile tests a head file with the very first item only half-written.
   410  // That will rewind the index, and _should_ truncate the head file
   411  func TestFreezerRepairFirstFile(t *testing.T) {
   412  	t.Parallel()
   413  	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
   414  	fname := fmt.Sprintf("truncationfirst-%d", rand.Uint64())
   415  	{ // Fill table
   416  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   417  		if err != nil {
   418  			t.Fatal(err)
   419  		}
   420  		// Write 80 bytes, splitting out into two files
   421  		f.Append(0, getChunk(40, 0xFF))
   422  		f.Append(1, getChunk(40, 0xEE))
   423  		// The last item should be there
   424  		if _, err = f.Retrieve(f.items - 1); err != nil {
   425  			t.Fatal(err)
   426  		}
   427  		f.Close()
   428  	}
   429  	// Truncate the file in half
   430  	fileToCrop := filepath.Join(os.TempDir(), fmt.Sprintf("%s.0001.rdat", fname))
   431  	{
   432  		if err := assertFileSize(fileToCrop, 40); err != nil {
   433  			t.Fatal(err)
   434  		}
   435  		file, err := os.OpenFile(fileToCrop, os.O_RDWR, 0644)
   436  		if err != nil {
   437  			t.Fatal(err)
   438  		}
   439  		file.Truncate(20)
   440  		file.Close()
   441  	}
   442  	// Reopen
   443  	{
   444  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   445  		if err != nil {
   446  			t.Fatal(err)
   447  		}
   448  		if f.items != 1 {
   449  			f.Close()
   450  			t.Fatalf("expected %d items, got %d", 0, f.items)
   451  		}
   452  		// Write 40 bytes
   453  		f.Append(1, getChunk(40, 0xDD))
   454  		f.Close()
   455  		// Should have been truncated down to zero and then 40 written
   456  		if err := assertFileSize(fileToCrop, 40); err != nil {
   457  			t.Fatal(err)
   458  		}
   459  	}
   460  }
   461  
   462  // TestFreezerReadAndTruncate tests:
   463  // - we have a table open
   464  // - do some reads, so files are open in readonly
   465  // - truncate so those files are 'removed'
   466  // - check that we did not keep the rdonly file descriptors
   467  func TestFreezerReadAndTruncate(t *testing.T) {
   468  	t.Parallel()
   469  	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
   470  	fname := fmt.Sprintf("read_truncate-%d", rand.Uint64())
   471  	{ // Fill table
   472  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   473  		if err != nil {
   474  			t.Fatal(err)
   475  		}
   476  		// Write 15 bytes 30 times
   477  		for x := 0; x < 30; x++ {
   478  			data := getChunk(15, x)
   479  			f.Append(uint64(x), data)
   480  		}
   481  		// The last item should be there
   482  		if _, err = f.Retrieve(f.items - 1); err != nil {
   483  			t.Fatal(err)
   484  		}
   485  		f.Close()
   486  	}
   487  	// Reopen and read all files
   488  	{
   489  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
   490  		if err != nil {
   491  			t.Fatal(err)
   492  		}
   493  		if f.items != 30 {
   494  			f.Close()
   495  			t.Fatalf("expected %d items, got %d", 0, f.items)
   496  		}
   497  		for y := byte(0); y < 30; y++ {
   498  			f.Retrieve(uint64(y))
   499  		}
   500  		// Now, truncate back to zero
   501  		f.truncate(0)
   502  		// Write the data again
   503  		for x := 0; x < 30; x++ {
   504  			data := getChunk(15, ^x)
   505  			if err := f.Append(uint64(x), data); err != nil {
   506  				t.Fatalf("error %v", err)
   507  			}
   508  		}
   509  		f.Close()
   510  	}
   511  }
   512  
   513  func TestOffset(t *testing.T) {
   514  	t.Parallel()
   515  	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
   516  	fname := fmt.Sprintf("offset-%d", rand.Uint64())
   517  	{ // Fill table
   518  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 40, true)
   519  		if err != nil {
   520  			t.Fatal(err)
   521  		}
   522  		// Write 6 x 20 bytes, splitting out into three files
   523  		f.Append(0, getChunk(20, 0xFF))
   524  		f.Append(1, getChunk(20, 0xEE))
   525  
   526  		f.Append(2, getChunk(20, 0xdd))
   527  		f.Append(3, getChunk(20, 0xcc))
   528  
   529  		f.Append(4, getChunk(20, 0xbb))
   530  		f.Append(5, getChunk(20, 0xaa))
   531  		f.DumpIndex(0, 100)
   532  		f.Close()
   533  	}
   534  	// Now crop it.
   535  	{
   536  		// delete files 0 and 1
   537  		for i := 0; i < 2; i++ {
   538  			p := filepath.Join(os.TempDir(), fmt.Sprintf("%v.%04d.rdat", fname, i))
   539  			if err := os.Remove(p); err != nil {
   540  				t.Fatal(err)
   541  			}
   542  		}
   543  		// Read the index file
   544  		p := filepath.Join(os.TempDir(), fmt.Sprintf("%v.ridx", fname))
   545  		indexFile, err := os.OpenFile(p, os.O_RDWR, 0644)
   546  		if err != nil {
   547  			t.Fatal(err)
   548  		}
   549  		indexBuf := make([]byte, 7*indexEntrySize)
   550  		indexFile.Read(indexBuf)
   551  
   552  		// Update the index file, so that we store
   553  		// [ file = 2, offset = 4 ] at index zero
   554  
   555  		tailId := uint32(2)     // First file is 2
   556  		itemOffset := uint32(4) // We have removed four items
   557  		zeroIndex := indexEntry{
   558  			filenum: tailId,
   559  			offset:  itemOffset,
   560  		}
   561  		buf := zeroIndex.marshallBinary()
   562  		// Overwrite index zero
   563  		copy(indexBuf, buf)
   564  		// Remove the four next indices by overwriting
   565  		copy(indexBuf[indexEntrySize:], indexBuf[indexEntrySize*5:])
   566  		indexFile.WriteAt(indexBuf, 0)
   567  		// Need to truncate the moved index items
   568  		indexFile.Truncate(indexEntrySize * (1 + 2))
   569  		indexFile.Close()
   570  
   571  	}
   572  	// Now open again
   573  	checkPresent := func(numDeleted uint64) {
   574  		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 40, true)
   575  		if err != nil {
   576  			t.Fatal(err)
   577  		}
   578  		f.DumpIndex(0, 100)
   579  		// It should allow writing item 6
   580  		f.Append(numDeleted+2, getChunk(20, 0x99))
   581  
   582  		// It should be fine to fetch 4,5,6
   583  		if got, err := f.Retrieve(numDeleted); err != nil {
   584  			t.Fatal(err)
   585  		} else if exp := getChunk(20, 0xbb); !bytes.Equal(got, exp) {
   586  			t.Fatalf("expected %x got %x", exp, got)
   587  		}
   588  		if got, err := f.Retrieve(numDeleted + 1); err != nil {
   589  			t.Fatal(err)
   590  		} else if exp := getChunk(20, 0xaa); !bytes.Equal(got, exp) {
   591  			t.Fatalf("expected %x got %x", exp, got)
   592  		}
   593  		if got, err := f.Retrieve(numDeleted + 2); err != nil {
   594  			t.Fatal(err)
   595  		} else if exp := getChunk(20, 0x99); !bytes.Equal(got, exp) {
   596  			t.Fatalf("expected %x got %x", exp, got)
   597  		}
   598  
   599  		// It should error at 0, 1,2,3
   600  		for i := numDeleted - 1; i > numDeleted-10; i-- {
   601  			if _, err := f.Retrieve(i); err == nil {
   602  				t.Fatal("expected err")
   603  			}
   604  		}
   605  	}
   606  	checkPresent(4)
   607  	// Now, let's pretend we have deleted 1M items
   608  	{
   609  		// Read the index file
   610  		p := filepath.Join(os.TempDir(), fmt.Sprintf("%v.ridx", fname))
   611  		indexFile, err := os.OpenFile(p, os.O_RDWR, 0644)
   612  		if err != nil {
   613  			t.Fatal(err)
   614  		}
   615  		indexBuf := make([]byte, 3*indexEntrySize)
   616  		indexFile.Read(indexBuf)
   617  
   618  		// Update the index file, so that we store
   619  		// [ file = 2, offset = 1M ] at index zero
   620  
   621  		tailId := uint32(2)           // First file is 2
   622  		itemOffset := uint32(1000000) // We have removed 1M items
   623  		zeroIndex := indexEntry{
   624  			offset:  itemOffset,
   625  			filenum: tailId,
   626  		}
   627  		buf := zeroIndex.marshallBinary()
   628  		// Overwrite index zero
   629  		copy(indexBuf, buf)
   630  		indexFile.WriteAt(indexBuf, 0)
   631  		indexFile.Close()
   632  	}
   633  	checkPresent(1000000)
   634  }
   635  
   636  // TODO (?)
   637  // - test that if we remove several head-files, aswell as data last data-file,
   638  //   the index is truncated accordingly
   639  // Right now, the freezer would fail on these conditions:
   640  // 1. have data files d0, d1, d2, d3
   641  // 2. remove d2,d3
   642  //
   643  // However, all 'normal' failure modes arising due to failing to sync() or save a file
   644  // should be handled already, and the case described above can only (?) happen if an
   645  // external process/user deletes files from the filesystem.
   646  
   647  // TestAppendTruncateParallel is a test to check if the Append/truncate operations are
   648  // racy.
   649  //
   650  // The reason why it's not a regular fuzzer, within tests/fuzzers, is that it is dependent
   651  // on timing rather than 'clever' input -- there's no determinism.
   652  func TestAppendTruncateParallel(t *testing.T) {
   653  	dir, err := ioutil.TempDir("", "freezer")
   654  	if err != nil {
   655  		t.Fatal(err)
   656  	}
   657  	defer os.RemoveAll(dir)
   658  
   659  	f, err := newCustomTable(dir, "tmp", metrics.NilMeter{}, metrics.NilMeter{}, metrics.NilGauge{}, 8, true)
   660  	if err != nil {
   661  		t.Fatal(err)
   662  	}
   663  
   664  	fill := func(mark uint64) []byte {
   665  		data := make([]byte, 8)
   666  		binary.LittleEndian.PutUint64(data, mark)
   667  		return data
   668  	}
   669  
   670  	for i := 0; i < 5000; i++ {
   671  		f.truncate(0)
   672  		data0 := fill(0)
   673  		f.Append(0, data0)
   674  		data1 := fill(1)
   675  
   676  		var wg sync.WaitGroup
   677  		wg.Add(2)
   678  		go func() {
   679  			f.truncate(0)
   680  			wg.Done()
   681  		}()
   682  		go func() {
   683  			f.Append(1, data1)
   684  			wg.Done()
   685  		}()
   686  		wg.Wait()
   687  
   688  		if have, err := f.Retrieve(0); err == nil {
   689  			if !bytes.Equal(have, data0) {
   690  				t.Fatalf("have %x want %x", have, data0)
   691  			}
   692  		}
   693  	}
   694  }