util: add PreAlloc4Row and Insert for Chunk and List

util/chunk/chunk.go

@@ -15,6 +15,7 @@ package chunk
 
 import (
 	"encoding/binary"
+	"reflect"
 	"unsafe"
 
 	"github.com/cznic/mathutil"
@@ -277,6 +278,74 @@ func (c *Chunk) AppendPartialRow(colIdx int, row Row) {
 	}
 }
 
+// PreAlloc pre-allocates the memory space in a Chunk to store the Row.
+// NOTE:
+// 1. The Chunk must be empty or holds no useful data.
+// 2. The schema of the Row must be the same with the Chunk.
+// 3. This API is paired with the `Insert()` function, which inserts all the
+//    rows data into the Chunk after the pre-allocation.
+// 4. We set the null bitmap here instead of in the Insert() function because
+//    when the Insert() function is called parallelly, the data race on a byte
+//    can not be avoided although the manipulated bits are different inside a
+//    byte.
+func (c *Chunk) PreAlloc(row Row) {
+	for i, srcCol := range row.c.columns {
+		dstCol := c.columns[i]
+		dstCol.appendNullBitmap(!srcCol.isNull(row.idx))
+		elemLen := len(srcCol.elemBuf)
+		if !srcCol.isFixed() {
+			elemLen = int(srcCol.offsets[row.idx+1] - srcCol.offsets[row.idx])
+			dstCol.offsets = append(dstCol.offsets, int32(len(dstCol.data)+elemLen))
+		}
+		dstCol.length++
+		needCap := len(dstCol.data) + elemLen
+		if needCap <= cap(dstCol.data) {
+			(*reflect.SliceHeader)(unsafe.Pointer(&dstCol.data)).Len = len(dstCol.data) + elemLen
+			continue
+		}
+		// Grow the capacity according to golang.growslice.
+		newCap := cap(dstCol.data)
+		doubleCap := newCap << 1
+		if needCap > doubleCap {
+			newCap = needCap
+		} else {
+			if len(dstCol.data) < 1024 {
+				newCap = doubleCap
+			} else {
+				for 0 < newCap && newCap < needCap {
+					newCap += newCap / 4
+				}
+				if newCap <= 0 {
+					newCap = needCap
+				}
+			}
+		}
+		dstCol.data = make([]byte, len(dstCol.data)+elemLen, newCap)
+	}
+}
+
+// Insert inserts `row` on the position specified by `rowIdx`.
+// Note: Insert will cover the origin data, it should be called after
+// PreAlloc.
+func (c *Chunk) Insert(rowIdx int, row Row) {
+	for i, srcCol := range row.c.columns {
+		if row.IsNull(i) {
+			continue
+		}
+		dstCol := c.columns[i]
+		var srcStart, srcEnd, destStart, destEnd int
+		if srcCol.isFixed() {
+			srcElemLen, destElemLen := len(srcCol.elemBuf), len(dstCol.elemBuf)
+			srcStart, destStart = row.idx*srcElemLen, rowIdx*destElemLen
+			srcEnd, destEnd = srcStart+srcElemLen, destStart+destElemLen
+		} else {
+			srcStart, srcEnd = int(srcCol.offsets[row.idx]), int(srcCol.offsets[row.idx+1])
+			destStart, destEnd = int(dstCol.offsets[rowIdx]), int(dstCol.offsets[rowIdx+1])
+		}
+		copy(dstCol.data[destStart:destEnd], srcCol.data[srcStart:srcEnd])
+	}
+}
+
 // Append appends rows in [begin, end) in another Chunk to a Chunk.
 func (c *Chunk) Append(other *Chunk, begin, end int) {
 	for colID, src := range other.columns {

util/chunk/chunk_test.go

@@ -18,6 +18,8 @@ import (
 	"fmt"
 	"math"
 	"strconv"
+	"strings"
+	"sync"
 	"testing"
 	"time"
 	"unsafe"
@@ -517,6 +519,107 @@ func (s *testChunkSuite) TestSwapColumn(c *check.C) {
 	checkRef()
 }
 
+func (s *testChunkSuite) TestPreAlloc4RowAndInsert(c *check.C) {
+	fieldTypes := make([]*types.FieldType, 0, 4)
+	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeFloat})
+	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeLonglong})
+	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeNewDecimal})
+	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeVarchar})
+
+	srcChk := NewChunkWithCapacity(fieldTypes, 10)
+	for i := int64(0); i < 10; i++ {
+		srcChk.AppendFloat32(0, float32(i))
+		srcChk.AppendInt64(1, i)
+		srcChk.AppendMyDecimal(2, types.NewDecFromInt(i))
+		srcChk.AppendString(3, strings.Repeat(strconv.FormatInt(i, 10), int(i)))
+	}
+
+	destChk := NewChunkWithCapacity(fieldTypes, 3)
+
+	// Test Chunk.PreAlloc.
+	for i := 0; i < srcChk.NumRows(); i++ {
+		c.Assert(destChk.NumRows(), check.Equals, i)
+		destChk.PreAlloc(srcChk.GetRow(i))
+	}
+	for i, srcCol := range srcChk.columns {
+		destCol := destChk.columns[i]
+		c.Assert(len(srcCol.elemBuf), check.Equals, len(destCol.elemBuf))
+		c.Assert(len(srcCol.data), check.Equals, len(destCol.data))
+		c.Assert(len(srcCol.offsets), check.Equals, len(destCol.offsets))
+		c.Assert(len(srcCol.nullBitmap), check.Equals, len(destCol.nullBitmap))
+		c.Assert(srcCol.length, check.Equals, destCol.length)
+		c.Assert(srcCol.nullCount, check.Equals, destCol.nullCount)
+
+		for _, val := range destCol.data {
+			c.Assert(val == 0, check.IsTrue)
+		}
+		for j, val := range srcCol.offsets {
+			c.Assert(val, check.Equals, destCol.offsets[j])
+		}
+		for j, val := range srcCol.nullBitmap {
+			c.Assert(val, check.Equals, destCol.nullBitmap[j])
+		}
+		for _, val := range destCol.elemBuf {
+			c.Assert(val == 0, check.IsTrue)
+		}
+	}
+
+	// Test Chunk.Insert.
+	for i := srcChk.NumRows() - 1; i >= 0; i-- {
+		destChk.Insert(i, srcChk.GetRow(i))
+	}
+	for i, srcCol := range srcChk.columns {
+		destCol := destChk.columns[i]
+
+		for j, val := range srcCol.data {
+			c.Assert(val, check.Equals, destCol.data[j])
+		}
+		for j, val := range srcCol.offsets {
+			c.Assert(val, check.Equals, destCol.offsets[j])
+		}
+		for j, val := range srcCol.nullBitmap {
+			c.Assert(val, check.Equals, destCol.nullBitmap[j])
+		}
+		for _, val := range destCol.elemBuf {
+			c.Assert(val == 0, check.IsTrue)
+		}
+	}
+
+	// Test parallel Chunk.Insert.
+	destChk.Reset()
+	startWg, endWg := &sync.WaitGroup{}, &sync.WaitGroup{}
+	startWg.Add(1)
+	for i := 0; i < srcChk.NumRows(); i++ {
+		destChk.PreAlloc(srcChk.GetRow(i))
+		endWg.Add(1)
+		go func(rowIdx int) {
+			defer func() {
+				endWg.Done()
+			}()
+			startWg.Wait()
+			destChk.Insert(rowIdx, srcChk.GetRow(rowIdx))
+		}(i)
+	}
+	startWg.Done()
+	endWg.Wait()
+	for i, srcCol := range srcChk.columns {
+		destCol := destChk.columns[i]
+
+		for j, val := range srcCol.data {
+			c.Assert(val, check.Equals, destCol.data[j])
+		}
+		for j, val := range srcCol.offsets {
+			c.Assert(val, check.Equals, destCol.offsets[j])
+		}
+		for j, val := range srcCol.nullBitmap {
+			c.Assert(val, check.Equals, destCol.nullBitmap[j])
+		}
+		for _, val := range destCol.elemBuf {
+			c.Assert(val == 0, check.IsTrue)
+		}
+	}
+}
+
 func BenchmarkAppendInt(b *testing.B) {
 	b.ReportAllocs()
 	chk := newChunk(8)

util/chunk/list.go

@@ -140,6 +140,37 @@ func (l *List) Reset() {
 	l.consumedIdx = -1
 }
 
+// PreAlloc4Row pre-allocates the storage memory for a Row.
+// NOTE:
+// 1. The List must be empty or holds no useful data.
+// 2. The schema of the Row must be the same with the List.
+// 3. This API is paired with the `Insert()` function, which inserts all the
+//    rows data into the List after the pre-allocation.
+func (l *List) PreAlloc4Row(row Row) (ptr RowPtr) {
+	chkIdx := len(l.chunks) - 1
+	if chkIdx == -1 || l.chunks[chkIdx].NumRows() >= l.chunks[chkIdx].Capacity() {
+		newChk := l.allocChunk()
+		l.chunks = append(l.chunks, newChk)
+		if chkIdx != l.consumedIdx {
+			l.memTracker.Consume(l.chunks[chkIdx].MemoryUsage())
+			l.consumedIdx = chkIdx
+		}
+		chkIdx++
+	}
+	chk := l.chunks[chkIdx]
+	rowIdx := chk.NumRows()
+	chk.PreAlloc(row)
+	l.length++
+	return RowPtr{ChkIdx: uint32(chkIdx), RowIdx: uint32(rowIdx)}
+}
+
+// Insert inserts `row` on the position specified by `ptr`.
+// Note: Insert will cover the origin data, it should be called after
+// PreAlloc.
+func (l *List) Insert(ptr RowPtr, row Row) {
+	l.chunks[ptr.ChkIdx].Insert(int(ptr.RowIdx), row)
+}
+
 // ListWalkFunc is used to walk the list.
 // If error is returned, it will stop walking.
 type ListWalkFunc = func(row Row) error

util/chunk/list_test.go

@@ -15,6 +15,8 @@ package chunk
 
 import (
 	"math"
+	"strconv"
+	"strings"
 	"testing"
 	"time"
 
@@ -114,6 +116,47 @@ func (s *testChunkSuite) TestListMemoryUsage(c *check.C) {
 	c.Assert(list.GetMemTracker().BytesConsumed(), check.Equals, memUsage+srcChk.MemoryUsage())
 }
 
+func (s *testChunkSuite) TestListPrePreAlloc4RowAndInsert(c *check.C) {
+	fieldTypes := make([]*types.FieldType, 0, 4)
+	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeFloat})
+	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeLonglong})
+	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeNewDecimal})
+	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeVarchar})
+
+	srcChk := NewChunkWithCapacity(fieldTypes, 10)
+	for i := int64(0); i < 10; i++ {
+		srcChk.AppendFloat32(0, float32(i))
+		srcChk.AppendInt64(1, i)
+		srcChk.AppendMyDecimal(2, types.NewDecFromInt(i))
+		srcChk.AppendString(3, strings.Repeat(strconv.FormatInt(i, 10), int(i)))
+	}
+
+	srcList := NewList(fieldTypes, 3, 3)
+	destList := NewList(fieldTypes, 5, 5)
+	destRowPtr := make([]RowPtr, srcChk.NumRows())
+	for i := 0; i < srcChk.NumRows(); i++ {
+		srcList.AppendRow(srcChk.GetRow(i))
+		destRowPtr[i] = destList.PreAlloc4Row(srcChk.GetRow(i))
+	}
+
+	c.Assert(srcList.NumChunks(), check.Equals, 4)
+	c.Assert(destList.NumChunks(), check.Equals, 2)
+
+	iter4Src := NewIterator4List(srcList)
+	for row, i := iter4Src.Begin(), 0; row != iter4Src.End(); row, i = iter4Src.Next(), i+1 {
+		destList.Insert(destRowPtr[i], row)
+	}
+
+	iter4Dest := NewIterator4List(destList)
+	srcRow, destRow := iter4Src.Begin(), iter4Dest.Begin()
+	for ; srcRow != iter4Src.End(); srcRow, destRow = iter4Src.Next(), iter4Dest.Next() {
+		c.Assert(srcRow.GetFloat32(0), check.Equals, destRow.GetFloat32(0))
+		c.Assert(srcRow.GetInt64(1), check.Equals, destRow.GetInt64(1))
+		c.Assert(srcRow.GetMyDecimal(2).Compare(destRow.GetMyDecimal(2)) == 0, check.IsTrue)
+		c.Assert(srcRow.GetString(3), check.Equals, destRow.GetString(3))
+	}
+}
+
 func BenchmarkListMemoryUsage(b *testing.B) {
 	fieldTypes := make([]*types.FieldType, 0, 4)
 	fieldTypes = append(fieldTypes, &types.FieldType{Tp: mysql.TypeFloat})