From b63633702ceac03704d92478c13021bd1ac24a9a Mon Sep 17 00:00:00 2001
From: wshwsh12 <793703860@qq.com>
Date: Thu, 5 May 2022 16:14:00 +0800
Subject: [PATCH] address comments

---
 util/chunk/disk.go | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/util/chunk/disk.go b/util/chunk/disk.go
index cb3e8350fc705..ccbc1e0c2365e 100644
--- a/util/chunk/disk.go
+++ b/util/chunk/disk.go
@@ -31,18 +31,17 @@ import (
 
 // ListInDisk represents a slice of chunks storing in temporary disk.
 type ListInDisk struct {
-	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.
+	fieldTypes                []*types.FieldType
+	numRowsOfEachChunk        []int
+	rowNumOfEachChunkFirstRow []int
+	totalNumRows              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.
+// diskFileReaderWriter represents a Reader and a Writer for the temporary disk file.
 type diskFileReaderWriter struct {
 	disk *os.File
 	w    io.WriteCloser
@@ -50,7 +49,7 @@ type diskFileReaderWriter struct {
 	offWrite int64
 
 	checksumWriter *checksum.Writer
-	cipherWriter   *encrypt.Writer
+	cipherWriter   *encrypt.Writer // cipherWriter is only enable when config SpilledFileEncryptionMethod is "aes128-ctr"
 
 	// ctrCipher stores the key and nonce using by aes encrypt io layer
 	ctrCipher *encrypt.CtrCipher
@@ -125,7 +124,7 @@ func (l *ListInDisk) initDiskFile() (err error) {
 
 // Len returns the number of rows in ListInDisk
 func (l *ListInDisk) Len() int {
-	return l.numRowsInDisk
+	return l.totalNumRows
 }
 
 // GetDiskTracker returns the memory tracker of this List.
@@ -156,8 +155,8 @@ func (l *ListInDisk) Add(chk *Chunk) (err error) {
 
 	// Append offsets
 	offsetsOfRows := chkInDisk.getOffsetsOfRows()
-	l.numRowForEachChunk = append(l.numRowForEachChunk, len(offsetsOfRows))
-	l.numRowPrefixSum = append(l.numRowPrefixSum, l.numRowsInDisk)
+	l.numRowsOfEachChunk = append(l.numRowsOfEachChunk, len(offsetsOfRows))
+	l.rowNumOfEachChunkFirstRow = append(l.rowNumOfEachChunkFirstRow, l.totalNumRows)
 	n2, err := offsetsOfRows.WriteTo(l.offsetFile.getWriter())
 	l.offsetFile.offWrite += n2
 	if err != nil {
@@ -165,14 +164,14 @@ func (l *ListInDisk) Add(chk *Chunk) (err error) {
 	}
 
 	l.diskTracker.Consume(n + n2)
-	l.numRowsInDisk += chk.NumRows()
+	l.totalNumRows += 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))
-	chkSize := l.numRowForEachChunk[chkIdx]
+	chkSize := l.numRowsOfEachChunk[chkIdx]
 	for rowIdx := 0; rowIdx < chkSize; rowIdx++ {
 		row, err := l.GetRow(RowPtr{ChkIdx: uint32(chkIdx), RowIdx: uint32(rowIdx)})
 		if err != nil {
@@ -200,7 +199,7 @@ func (l *ListInDisk) GetRow(ptr RowPtr) (row Row, err error) {
 }
 
 func (l *ListInDisk) getOffset(chkIdx uint32, rowIdx uint32) (int64, error) {
-	offsetInOffsetFile := l.numRowPrefixSum[chkIdx] + int(rowIdx)
+	offsetInOffsetFile := l.rowNumOfEachChunkFirstRow[chkIdx] + int(rowIdx)
 	b := make([]byte, 8)
 	reader := l.offsetFile.getSectionReader(int64(offsetInOffsetFile) * 8)
 	n, err := io.ReadFull(reader, b)
@@ -215,12 +214,12 @@ func (l *ListInDisk) getOffset(chkIdx uint32, rowIdx uint32) (int64, error) {
 
 // NumRowsOfChunk returns the number of rows of a chunk in the ListInDisk.
 func (l *ListInDisk) NumRowsOfChunk(chkID int) int {
-	return l.numRowForEachChunk[chkID]
+	return l.numRowsOfEachChunk[chkID]
 }
 
 // NumChunks returns the number of chunks in the ListInDisk.
 func (l *ListInDisk) NumChunks() int {
-	return len(l.numRowForEachChunk)
+	return len(l.numRowsOfEachChunk)
 }
 
 // Close releases the disk resource.