util: support spill offset into disk when spilling

util/chunk/disk.go

@@ -18,7 +18,6 @@ import (
 	"io"
 	"os"
 	"strconv"
-	"sync"
 
 	errors2 "github.com/pingcap/errors"
 	"github.com/pingcap/tidb/config"
@@ -32,27 +31,74 @@ import (
 
 // ListInDisk represents a slice of chunks storing in temporary disk.
 type ListInDisk struct {
-	fieldTypes []*types.FieldType
-	// offsets stores the offsets in disk of all RowPtr,
-	// the offset of one RowPtr is offsets[RowPtr.ChkIdx][RowPtr.RowIdx].
-	offsets [][]int64
+	fieldTypes         []*types.FieldType
+	numRowForEachChunk []int
+	numRowPrefixSum    []int // indicates the offsets of each chunk's offsets in OffsetFile.
+	numRowsInDisk      int
+	diskTracker        *disk.Tracker // track disk usage.
+
+	dataFile   diskFileReaderWriter
+	offsetFile diskFileReaderWriter
+}
+
+// diskFileReaderWriter represents a Reader and a Writer for the temporary disk file,
+// without considering the detail of checksum and encryption.
+type diskFileReaderWriter struct {
+	disk *os.File
+	w    io.WriteCloser
 	// offWrite is the current offset for writing.
 	offWrite int64
 
-	disk          *os.File
-	w             io.WriteCloser
-	bufFlushMutex sync.RWMutex
-	diskTracker   *disk.Tracker // track disk usage.
-	numRowsInDisk int
-
 	checksumWriter *checksum.Writer
 	cipherWriter   *encrypt.Writer
 
 	// ctrCipher stores the key and nonce using by aes encrypt io layer
 	ctrCipher *encrypt.CtrCipher
 }
 
+func (l *diskFileReaderWriter) initWithFileName(fileName string) (err error) {
+	l.disk, err = os.CreateTemp(config.GetGlobalConfig().TempStoragePath, fileName)
+	if err != nil {
+		return errors2.Trace(err)
+	}
+	var underlying io.WriteCloser = l.disk
+	if config.GetGlobalConfig().Security.SpilledFileEncryptionMethod != config.SpilledFileEncryptionMethodPlaintext {
+		// The possible values of SpilledFileEncryptionMethod are "plaintext", "aes128-ctr"
+		l.ctrCipher, err = encrypt.NewCtrCipher()
+		if err != nil {
+			return
+		}
+		l.cipherWriter = encrypt.NewWriter(l.disk, l.ctrCipher)
+		underlying = l.cipherWriter
+	}
+	l.checksumWriter = checksum.NewWriter(underlying)
+	l.w = l.checksumWriter
+	return
+}
+
+func (l *diskFileReaderWriter) getReader() io.ReaderAt {
+	var underlying io.ReaderAt = l.disk
+	if l.ctrCipher != nil {
+		underlying = NewReaderWithCache(encrypt.NewReader(l.disk, l.ctrCipher), l.cipherWriter.GetCache(), l.cipherWriter.GetCacheDataOffset())
+	}
+	if l.checksumWriter != nil {
+		underlying = NewReaderWithCache(checksum.NewReader(underlying), l.checksumWriter.GetCache(), l.checksumWriter.GetCacheDataOffset())
+	}
+	return underlying
+}
+
+func (l *diskFileReaderWriter) getSectionReader(off int64) *io.SectionReader {
+	checksumReader := l.getReader()
+	r := io.NewSectionReader(checksumReader, off, l.offWrite-off)
+	return r
+}
+
+func (l *diskFileReaderWriter) getWriter() io.Writer {
+	return l.w
+}
+
 var defaultChunkListInDiskPath = "chunk.ListInDisk"
+var defaultChunkListInDiskOffsetPath = "chunk.ListInDiskOffset"
 
 // NewListInDisk creates a new ListInDisk with field types.
 func NewListInDisk(fieldTypes []*types.FieldType) *ListInDisk {
@@ -69,23 +115,11 @@ func (l *ListInDisk) initDiskFile() (err error) {
 	if err != nil {
 		return
 	}
-	l.disk, err = os.CreateTemp(config.GetGlobalConfig().TempStoragePath, defaultChunkListInDiskPath+strconv.Itoa(l.diskTracker.Label()))
+	err = l.dataFile.initWithFileName(defaultChunkListInDiskPath + strconv.Itoa(l.diskTracker.Label()))
 	if err != nil {
-		return errors2.Trace(err)
-	}
-	var underlying io.WriteCloser = l.disk
-	if config.GetGlobalConfig().Security.SpilledFileEncryptionMethod != config.SpilledFileEncryptionMethodPlaintext {
-		// The possible values of SpilledFileEncryptionMethod are "plaintext", "aes128-ctr"
-		l.ctrCipher, err = encrypt.NewCtrCipher()
-		if err != nil {
-			return
-		}
-		l.cipherWriter = encrypt.NewWriter(l.disk, l.ctrCipher)
-		underlying = l.cipherWriter
+		return
 	}
-	l.checksumWriter = checksum.NewWriter(underlying)
-	l.w = l.checksumWriter
-	l.bufFlushMutex = sync.RWMutex{}
+	err = l.offsetFile.initWithFileName(defaultChunkListInDiskOffsetPath + strconv.Itoa(l.diskTracker.Label()))
 	return
 }
 
@@ -101,34 +135,45 @@ func (l *ListInDisk) GetDiskTracker() *disk.Tracker {
 
 // Add adds a chunk to the ListInDisk. Caller must make sure the input chk
 // is not empty and not used any more and has the same field types.
-// Warning: do not mix Add and GetRow (always use GetRow after you have added all the chunks), and do not use Add concurrently.
+// Warning: Do not use Add concurrently.
 func (l *ListInDisk) Add(chk *Chunk) (err error) {
 	if chk.NumRows() == 0 {
 		return errors2.New("chunk appended to List should have at least 1 row")
 	}
-	if l.disk == nil {
+	if l.dataFile.disk == nil {
 		err = l.initDiskFile()
 		if err != nil {
 			return
 		}
 	}
-	chk2 := chunkInDisk{Chunk: chk, offWrite: l.offWrite}
-	n, err := chk2.WriteTo(l.w)
-	l.offWrite += n
+	// Append data
+	chkInDisk := chunkInDisk{Chunk: chk, offWrite: l.dataFile.offWrite}
+	n, err := chkInDisk.WriteTo(l.dataFile.getWriter())
+	l.dataFile.offWrite += n
 	if err != nil {
 		return
 	}
-	l.offsets = append(l.offsets, chk2.getOffsetsOfRows())
-	l.diskTracker.Consume(n)
+
+	// Append offsets
+	offsetsOfRows := chkInDisk.getOffsetsOfRows()
+	l.numRowForEachChunk = append(l.numRowForEachChunk, len(offsetsOfRows))
+	l.numRowPrefixSum = append(l.numRowPrefixSum, l.numRowsInDisk)
+	n2, err := offsetsOfRows.WriteTo(l.offsetFile.getWriter())
+	l.offsetFile.offWrite += n2
+	if err != nil {
+		return
+	}
+
+	l.diskTracker.Consume(n + n2)
 	l.numRowsInDisk += chk.NumRows()
 	return
 }
 
 // GetChunk gets a Chunk from the ListInDisk by chkIdx.
 func (l *ListInDisk) GetChunk(chkIdx int) (*Chunk, error) {
 	chk := NewChunkWithCapacity(l.fieldTypes, l.NumRowsOfChunk(chkIdx))
-	offsets := l.offsets[chkIdx]
-	for rowIdx := range offsets {
+	chkSize := l.numRowForEachChunk[chkIdx]
+	for rowIdx := 0; rowIdx < chkSize; rowIdx++ {
 		row, err := l.GetRow(RowPtr{ChkIdx: uint32(chkIdx), RowIdx: uint32(rowIdx)})
 		if err != nil {
 			return chk, err
@@ -140,16 +185,11 @@ func (l *ListInDisk) GetChunk(chkIdx int) (*Chunk, error) {
 
 // GetRow gets a Row from the ListInDisk by RowPtr.
 func (l *ListInDisk) GetRow(ptr RowPtr) (row Row, err error) {
+	off, err := l.getOffset(ptr.ChkIdx, ptr.RowIdx)
 	if err != nil {
 		return
 	}
-	off := l.offsets[ptr.ChkIdx][ptr.RowIdx]
-	var underlying io.ReaderAt = l.disk
-	if l.ctrCipher != nil {
-		underlying = NewReaderWithCache(encrypt.NewReader(l.disk, l.ctrCipher), l.cipherWriter.GetCache(), l.cipherWriter.GetCacheDataOffset())
-	}
-	checksumReader := NewReaderWithCache(checksum.NewReader(underlying), l.checksumWriter.GetCache(), l.checksumWriter.GetCacheDataOffset())
-	r := io.NewSectionReader(checksumReader, off, l.offWrite-off)
+	r := l.dataFile.getSectionReader(off)
 	format := rowInDisk{numCol: len(l.fieldTypes)}
 	_, err = format.ReadFrom(r)
 	if err != nil {
@@ -159,22 +199,40 @@ func (l *ListInDisk) GetRow(ptr RowPtr) (row Row, err error) {
 	return row, err
 }
 
+func (l *ListInDisk) getOffset(chkIdx uint32, rowIdx uint32) (int64, error) {
+	offsetInOffsetFile := l.numRowPrefixSum[chkIdx] + int(rowIdx)
+	b := make([]byte, 8)
+	reader := l.offsetFile.getSectionReader(int64(offsetInOffsetFile) * 8)
+	n, err := io.ReadFull(reader, b)
+	if err != nil {
+		return 0, err
+	}
+	if n != 8 {
+		return 0, errors2.New("The file spilled is broken, can not get data offset from the disk")
+	}
+	return bytesToI64Slice(b)[0], nil
+}
+
 // NumRowsOfChunk returns the number of rows of a chunk in the ListInDisk.
 func (l *ListInDisk) NumRowsOfChunk(chkID int) int {
-	return len(l.offsets[chkID])
+	return l.numRowForEachChunk[chkID]
 }
 
 // NumChunks returns the number of chunks in the ListInDisk.
 func (l *ListInDisk) NumChunks() int {
-	return len(l.offsets)
+	return len(l.numRowForEachChunk)
 }
 
 // Close releases the disk resource.
 func (l *ListInDisk) Close() error {
-	if l.disk != nil {
+	if l.dataFile.disk != nil {
 		l.diskTracker.Consume(-l.diskTracker.BytesConsumed())
-		terror.Call(l.disk.Close)
-		terror.Log(os.Remove(l.disk.Name()))
+		terror.Call(l.dataFile.disk.Close)
+		terror.Log(os.Remove(l.dataFile.disk.Name()))
+	}
+	if l.offsetFile.disk != nil {
+		terror.Call(l.offsetFile.disk.Close)
+		terror.Log(os.Remove(l.offsetFile.disk.Name()))
 	}
 	return nil
 }
@@ -198,7 +256,15 @@ type chunkInDisk struct {
 	// offWrite is the current offset for writing.
 	offWrite int64
 	// offsetsOfRows stores the offset of each row.
-	offsetsOfRows []int64
+	offsetsOfRows offsetsOfRows
+}
+
+type offsetsOfRows []int64
+
+// WriteTo serializes the offsetsOfRow, and writes to w.
+func (off offsetsOfRows) WriteTo(w io.Writer) (written int64, err error) {
+	n, err := w.Write(i64SliceToBytes(off))
+	return int64(n), err
 }
 
 // WriteTo serializes the chunk into the format of chunkInDisk, and
@@ -222,7 +288,7 @@ func (chk *chunkInDisk) WriteTo(w io.Writer) (written int64, err error) {
 }
 
 // getOffsetsOfRows gets the offset of each row.
-func (chk *chunkInDisk) getOffsetsOfRows() []int64 { return chk.offsetsOfRows }
+func (chk *chunkInDisk) getOffsetsOfRows() offsetsOfRows { return chk.offsetsOfRows }
 
 // rowInDisk represents a Row in format of diskFormatRow.
 type rowInDisk struct {