core/rawdb: support starting offset for future deletion

2 files changed, 175 insertions, 30 deletions

diff --git a/core/rawdb/freezer_table.go b/core/rawdb/freezer_table.go
index 8e117301b..93636a5ba 100644
--- a/core/rawdb/freezer_table.go
+++ b/core/rawdb/freezer_table.go
@@ -81,9 +81,14 @@ type freezerTable struct {
 	head   *os.File            // File descriptor for the data head of the table
 	files  map[uint32]*os.File // open files
 	headId uint32              // number of the currently active head file
+	tailId uint32              // number of the earliest file
 	index  *os.File            // File descriptor for the indexEntry file of the table
 
-	items      uint64        // Number of items stored in the table
+	// In the case that old items are deleted (from the tail), we use itemOffset
+	// to count how many historic items have gone missing.
+	items      uint64 // Number of items stored in the table (including items removed from tail)
+	itemOffset uint32 // Offset (number of discarded items)
+
 	headBytes  uint32        // Number of bytes written to the head file
 	readMeter  metrics.Meter // Meter for measuring the effective amount of data read
 	writeMeter metrics.Meter // Meter for measuring the effective amount of data written
@@ -164,10 +169,19 @@ func (t *freezerTable) repair() error {
 
 	// Open the head file
 	var (
+		firstIndex  indexEntry
 		lastIndex   indexEntry
 		contentSize int64
 		contentExp  int64
 	)
+	// Read index zero, determine what file is the earliest
+	// and what item offset to use
+	t.index.ReadAt(buffer, 0)
+	firstIndex.unmarshalBinary(buffer)
+
+	t.tailId = firstIndex.offset
+	t.itemOffset = firstIndex.filenum
+
 	t.index.ReadAt(buffer, offsetsSize-indexEntrySize)
 	lastIndex.unmarshalBinary(buffer)
 	t.head, err = t.openFile(lastIndex.filenum, os.O_RDWR|os.O_CREATE|os.O_APPEND)
@@ -225,7 +239,7 @@ func (t *freezerTable) repair() error {
 		return err
 	}
 	// Update the item and byte counters and return
-	t.items = uint64(offsetsSize/indexEntrySize - 1) // last indexEntry points to the end of the data file
+	t.items = uint64(t.itemOffset) + uint64(offsetsSize/indexEntrySize-1) // last indexEntry points to the end of the data file
 	t.headBytes = uint32(contentSize)
 	t.headId = lastIndex.filenum
 
@@ -245,7 +259,7 @@ func (t *freezerTable) preopen() (err error) {
 	// The repair might have already opened (some) files
 	t.releaseFilesAfter(0, false)
 	// Open all except head in RDONLY
-	for i := uint32(0); i < t.headId; i++ {
+	for i := uint32(t.tailId); i < t.headId; i++ {
 		if _, err = t.openFile(i, os.O_RDONLY); err != nil {
 			return err
 		}
@@ -259,7 +273,8 @@ func (t *freezerTable) preopen() (err error) {
 func (t *freezerTable) truncate(items uint64) error {
 	t.lock.Lock()
 	defer t.lock.Unlock()
-	// If out item count is corrent, don't do anything
+
+	// If our item count is correct, don't do anything
 	if atomic.LoadUint64(&t.items) <= items {
 		return nil
 	}
@@ -275,6 +290,7 @@ func (t *freezerTable) truncate(items uint64) error {
 	}
 	var expected indexEntry
 	expected.unmarshalBinary(buffer)
+
 	// We might need to truncate back to older files
 	if expected.filenum != t.headId {
 		// If already open for reading, force-reopen for writing
@@ -290,7 +306,6 @@ func (t *freezerTable) truncate(items uint64) error {
 		t.head = newHead
 		atomic.StoreUint32(&t.headId, expected.filenum)
 	}
-
 	if err := t.head.Truncate(int64(expected.offset)); err != nil {
 		return err
 	}
@@ -330,9 +345,9 @@ func (t *freezerTable) openFile(num uint32, flag int) (f *os.File, err error) {
 	if f, exist = t.files[num]; !exist {
 		var name string
 		if t.noCompression {
-			name = fmt.Sprintf("%s.%d.rdat", t.name, num)
+			name = fmt.Sprintf("%s.%04d.rdat", t.name, num)
 		} else {
-			name = fmt.Sprintf("%s.%d.cdat", t.name, num)
+			name = fmt.Sprintf("%s.%04d.cdat", t.name, num)
 		}
 		f, err = os.OpenFile(filepath.Join(t.path, name), flag, 0644)
 		if err != nil {
@@ -376,11 +391,13 @@ func (t *freezerTable) Append(item uint64, blob []byte) error {
 	t.lock.RLock()
 	// Ensure the table is still accessible
 	if t.index == nil || t.head == nil {
+		t.lock.RUnlock()
 		return errClosed
 	}
 	// Ensure only the next item can be written, nothing else
 	if atomic.LoadUint64(&t.items) != item {
-		panic(fmt.Sprintf("appending unexpected item: want %d, have %d", t.items, item))
+		t.lock.RUnlock()
+		return fmt.Errorf("appending unexpected item: want %d, have %d", t.items, item)
 	}
 	// Encode the blob and write it into the data file
 	if !t.noCompression {
@@ -461,13 +478,20 @@ func (t *freezerTable) Retrieve(item uint64) ([]byte, error) {
 	if atomic.LoadUint64(&t.items) <= item {
 		return nil, errOutOfBounds
 	}
+	// Ensure the item was not deleted from the tail either
+	offset := atomic.LoadUint32(&t.itemOffset)
+	if uint64(offset) > item {
+		return nil, errOutOfBounds
+	}
 	t.lock.RLock()
-	startOffset, endOffset, filenum, err := t.getBounds(item)
+	startOffset, endOffset, filenum, err := t.getBounds(item - uint64(offset))
 	if err != nil {
+		t.lock.RUnlock()
 		return nil, err
 	}
 	dataFile, exist := t.files[filenum]
 	if !exist {
+		t.lock.RUnlock()
 		return nil, fmt.Errorf("missing data file %d", filenum)
 	}
 	// Retrieve the data itself, decompress and return
@@ -499,3 +523,26 @@ func (t *freezerTable) Sync() error {
 	}
 	return t.head.Sync()
 }
+
+// printIndex is a debug print utility function for testing
+func (t *freezerTable) printIndex() {
+	buf := make([]byte, indexEntrySize)
+
+	fmt.Printf("|-----------------|\n")
+	fmt.Printf("| fileno | offset |\n")
+	fmt.Printf("|--------+--------|\n")
+
+	for i := uint64(0); ; i++ {
+		if _, err := t.index.ReadAt(buf, int64(i*indexEntrySize)); err != nil {
+			break
+		}
+		var entry indexEntry
+		entry.unmarshalBinary(buf)
+		fmt.Printf("|  %03d   |  %03d   | \n", entry.filenum, entry.offset)
+		if i > 100 {
+			fmt.Printf(" ... \n")
+			break
+		}
+	}
+	fmt.Printf("|-----------------|\n")
+}
diff --git a/core/rawdb/freezer_table_test.go b/core/rawdb/freezer_table_test.go
index d6ce6e93c..9a7eec505 100644
--- a/core/rawdb/freezer_table_test.go
+++ b/core/rawdb/freezer_table_test.go
@@ -19,12 +19,13 @@ package rawdb
 import (
 	"bytes"
 	"fmt"
-	"github.com/ethereum/go-ethereum/metrics"
 	"math/rand"
 	"os"
 	"path/filepath"
 	"testing"
 	"time"
+
+	"github.com/ethereum/go-ethereum/metrics"
 )
 
 func init() {
@@ -32,10 +33,10 @@ func init() {
 }
 
 // Gets a chunk of data, filled with 'b'
-func getChunk(size int, b byte) []byte {
+func getChunk(size int, b int) []byte {
 	data := make([]byte, size)
 	for i, _ := range data {
-		data[i] = b
+		data[i] = byte(b)
 	}
 	return data
 }
@@ -61,7 +62,7 @@ func TestFreezerBasics(t *testing.T) {
 	}
 	defer f.Close()
 	// Write 15 bytes 255 times, results in 85 files
-	for x := byte(0); x < 255; x++ {
+	for x := 0; x < 255; x++ {
 		data := getChunk(15, x)
 		f.Append(uint64(x), data)
 	}
@@ -74,7 +75,7 @@ func TestFreezerBasics(t *testing.T) {
 	//db[1] =  010101010101010101010101010101
 	//db[2] =  020202020202020202020202020202
 
-	for y := byte(0); y < 255; y++ {
+	for y := 0; y < 255; y++ {
 		exp := getChunk(15, y)
 		got, err := f.Retrieve(uint64(y))
 		if err != nil {
@@ -84,6 +85,11 @@ func TestFreezerBasics(t *testing.T) {
 			t.Fatalf("test %d, got \n%x != \n%x", y, got, exp)
 		}
 	}
+	// Check that we cannot read too far
+	_, err = f.Retrieve(uint64(255))
+	if err != errOutOfBounds {
+		t.Fatal(err)
+	}
 }
 
 // TestFreezerBasicsClosing tests same as TestFreezerBasics, but also closes and reopens the freezer between
@@ -102,18 +108,15 @@ func TestFreezerBasicsClosing(t *testing.T) {
 		t.Fatal(err)
 	}
 	// Write 15 bytes 255 times, results in 85 files
-	for x := byte(0); x < 255; x++ {
+	for x := 0; x < 255; x++ {
 		data := getChunk(15, x)
 		f.Append(uint64(x), data)
 		f.Close()
 		f, err = newCustomTable(os.TempDir(), fname, m1, m2, 50, true)
-		if err != nil {
-			t.Fatal(err)
-		}
 	}
 	defer f.Close()
 
-	for y := byte(0); y < 255; y++ {
+	for y := 0; y < 255; y++ {
 		exp := getChunk(15, y)
 		got, err := f.Retrieve(uint64(y))
 		if err != nil {
@@ -142,7 +145,7 @@ func TestFreezerRepairDanglingHead(t *testing.T) {
 			t.Fatal(err)
 		}
 		// Write 15 bytes 255 times
-		for x := byte(0); x < 0xff; x++ {
+		for x := 0; x < 255; x++ {
 			data := getChunk(15, x)
 			f.Append(uint64(x), data)
 		}
@@ -190,7 +193,7 @@ func TestFreezerRepairDanglingHeadLarge(t *testing.T) {
 			t.Fatal(err)
 		}
 		// Write 15 bytes 255 times
-		for x := byte(0); x < 0xff; x++ {
+		for x := 0; x < 0xff; x++ {
 			data := getChunk(15, x)
 			f.Append(uint64(x), data)
 		}
@@ -223,7 +226,7 @@ func TestFreezerRepairDanglingHeadLarge(t *testing.T) {
 			t.Errorf("Expected error for missing index entry")
 		}
 		// We should now be able to store items again, from item = 1
-		for x := byte(1); x < 0xff; x++ {
+		for x := 1; x < 0xff; x++ {
 			data := getChunk(15, ^x)
 			f.Append(uint64(x), data)
 		}
@@ -232,7 +235,7 @@ func TestFreezerRepairDanglingHeadLarge(t *testing.T) {
 	// And if we open it, we should now be able to read all of them (new values)
 	{
 		f, _ := newCustomTable(os.TempDir(), fname, rm, wm, 50, true)
-		for y := byte(1); y < 255; y++ {
+		for y := 1; y < 255; y++ {
 			exp := getChunk(15, ^y)
 			got, err := f.Retrieve(uint64(y))
 			if err != nil {
@@ -257,7 +260,7 @@ func TestSnappyDetection(t *testing.T) {
 			t.Fatal(err)
 		}
 		// Write 15 bytes 255 times
-		for x := byte(0); x < 0xff; x++ {
+		for x := 0; x < 0xff; x++ {
 			data := getChunk(15, x)
 			f.Append(uint64(x), data)
 		}
@@ -308,7 +311,7 @@ func TestFreezerRepairDanglingIndex(t *testing.T) {
 			t.Fatal(err)
 		}
 		// Write 15 bytes 9 times : 150 bytes
-		for x := byte(0); x < 9; x++ {
+		for x := 0; x < 9; x++ {
 			data := getChunk(15, x)
 			f.Append(uint64(x), data)
 		}
@@ -321,7 +324,7 @@ func TestFreezerRepairDanglingIndex(t *testing.T) {
 		// File sizes should be 45, 45, 45 : items[3, 3, 3)
 	}
 	// Crop third file
-	fileToCrop := filepath.Join(os.TempDir(), fmt.Sprintf("%s.2.rdat", fname))
+	fileToCrop := filepath.Join(os.TempDir(), fmt.Sprintf("%s.0002.rdat", fname))
 	// Truncate third file: 45 ,45, 20
 	{
 		if err := assertFileSize(fileToCrop, 45); err != nil {
@@ -365,7 +368,7 @@ func TestFreezerTruncate(t *testing.T) {
 			t.Fatal(err)
 		}
 		// Write 15 bytes 30 times
-		for x := byte(0); x < 30; x++ {
+		for x := 0; x < 30; x++ {
 			data := getChunk(15, x)
 			f.Append(uint64(x), data)
 		}
@@ -416,7 +419,7 @@ func TestFreezerRepairFirstFile(t *testing.T) {
 		f.Close()
 	}
 	// Truncate the file in half
-	fileToCrop := filepath.Join(os.TempDir(), fmt.Sprintf("%s.1.rdat", fname))
+	fileToCrop := filepath.Join(os.TempDir(), fmt.Sprintf("%s.0001.rdat", fname))
 	{
 		if err := assertFileSize(fileToCrop, 40); err != nil {
 			t.Fatal(err)
@@ -463,7 +466,7 @@ func TestFreezerReadAndTruncate(t *testing.T) {
 			t.Fatal(err)
 		}
 		// Write 15 bytes 30 times
-		for x := byte(0); x < 30; x++ {
+		for x := 0; x < 30; x++ {
 			data := getChunk(15, x)
 			f.Append(uint64(x), data)
 		}
@@ -489,7 +492,7 @@ func TestFreezerReadAndTruncate(t *testing.T) {
 		// Now, truncate back to zero
 		f.truncate(0)
 		// Write the data again
-		for x := byte(0); x < 30; x++ {
+		for x := 0; x < 30; x++ {
 			data := getChunk(15, ^x)
 			if err := f.Append(uint64(x), data); err != nil {
 				t.Fatalf("error %v", err)
@@ -499,6 +502,101 @@ func TestFreezerReadAndTruncate(t *testing.T) {
 	}
 }
 
+func TestOffset(t *testing.T) {
+	t.Parallel()
+	wm, rm := metrics.NewMeter(), metrics.NewMeter()
+	fname := fmt.Sprintf("offset-%d", rand.Uint64())
+	{ // Fill table
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, 40, true)
+		if err != nil {
+			t.Fatal(err)
+		}
+		// Write 6 x 20 bytes, splitting out into three files
+		f.Append(0, getChunk(20, 0xFF))
+		f.Append(1, getChunk(20, 0xEE))
+
+		f.Append(2, getChunk(20, 0xdd))
+		f.Append(3, getChunk(20, 0xcc))
+
+		f.Append(4, getChunk(20, 0xbb))
+		f.Append(5, getChunk(20, 0xaa))
+		f.printIndex()
+		f.Close()
+	}
+	// Now crop it.
+	{
+		// delete files 0 and 1
+		for i := 0; i < 2; i++ {
+			p := filepath.Join(os.TempDir(), fmt.Sprintf("%v.%04d.rdat", fname, i))
+			if err := os.Remove(p); err != nil {
+				t.Fatal(err)
+			}
+		}
+		// Read the index file
+		p := filepath.Join(os.TempDir(), fmt.Sprintf("%v.ridx", fname))
+		indexFile, err := os.OpenFile(p, os.O_RDWR, 0644)
+		if err != nil {
+			t.Fatal(err)
+		}
+		indexBuf := make([]byte, 7*indexEntrySize)
+		indexFile.Read(indexBuf)
+
+		// Update the index file, so that we store
+		// [ file = 2, offset = 4 ] at index zero
+
+		tailId := uint32(2)     // First file is 2
+		itemOffset := uint32(4) // We have removed four items
+		zeroIndex := indexEntry{
+			offset:  tailId,
+			filenum: itemOffset,
+		}
+		buf := zeroIndex.marshallBinary()
+		// Overwrite index zero
+		copy(indexBuf, buf)
+		// Remove the four next indices by overwriting
+		copy(indexBuf[indexEntrySize:], indexBuf[indexEntrySize*5:])
+		indexFile.WriteAt(indexBuf, 0)
+		// Need to truncate the moved index items
+		indexFile.Truncate(indexEntrySize * (1 + 2))
+		indexFile.Close()
+
+	}
+	// Now open again
+	{
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, 40, true)
+		if err != nil {
+			t.Fatal(err)
+		}
+		f.printIndex()
+		// It should allow writing item 6
+		f.Append(6, getChunk(20, 0x99))
+
+		// It should be fine to fetch 4,5,6
+		if got, err := f.Retrieve(4); err != nil {
+			t.Fatal(err)
+		} else if exp := getChunk(20, 0xbb); !bytes.Equal(got, exp) {
+			t.Fatalf("expected %x got %x", exp, got)
+		}
+		if got, err := f.Retrieve(5); err != nil {
+			t.Fatal(err)
+		} else if exp := getChunk(20, 0xaa); !bytes.Equal(got, exp) {
+			t.Fatalf("expected %x got %x", exp, got)
+		}
+		if got, err := f.Retrieve(6); err != nil {
+			t.Fatal(err)
+		} else if exp := getChunk(20, 0x99); !bytes.Equal(got, exp) {
+			t.Fatalf("expected %x got %x", exp, got)
+		}
+
+		// It should error at 0, 1,2,3
+		for i := 0; i < 4; i++ {
+			if _, err := f.Retrieve(uint64(i)); err == nil {
+				t.Fatal("expected err")
+			}
+		}
+	}
+}
+
 // TODO (?)
 // - test that if we remove several head-files, aswell as data last data-file,
 //   the index is truncated accordingly