Re-worked memory management of blocks loaded from redis client to avoid

unnecessary copying them around.

cmd/mttilemapper/main.go

@@ -105,14 +105,21 @@ func main() {
 
 	renderer := common.NewRenderer(width, height, transparent)
 	renderer.SetPos(q1x, q1z)
-	yOrder := common.NewYOrder(renderer, 512)
+
+	renderFn := func(block *common.Block) error {
+		return renderer.RenderBlock(block, colors)
+	}
+
+	yOrder := common.NewYOrder(renderFn, 512)
 
 	numBlocks := 0
-	drawBlock := func(block *common.Block) {
-		if err := yOrder.RenderBlock(block, colors); err != nil {
+	drawBlock := func(block *common.Block) *common.Block {
+		block, err := yOrder.RenderBlock(block)
+		if err != nil {
 			log.Printf("WARN: rendering block failed: %s\n", err)
 		}
 		numBlocks++
+		return block
 	}
 
 	c1 := common.Coord{X: q1x, Z: q1z}
@@ -126,7 +133,7 @@ func main() {
 		if _, err = client.QueryCuboid(cuboid, drawBlock); err != nil {
 			log.Fatalf("query failed: %s", err)
 		}
-		if err = yOrder.Drain(colors); err != nil {
+		if err = yOrder.Drain(); err != nil {
 			log.Printf("WARN: rendering block failed: %s\n", err)
 		}
 		if renderer.IsFilled() {

common/basetilecreator.go

@@ -97,10 +97,12 @@ func (btc *BaseTileCreator) renderBlock(block *Block) error {
 }
 
 // blockLoaded is a callback for RedisClient.QueryCuboid.
-func (btc *BaseTileCreator) blockLoaded(block *Block) {
-	if err := btc.yOrder.RenderBlock(block); err != nil {
+func (btc *BaseTileCreator) blockLoaded(block *Block) *Block {
+	block, err := btc.yOrder.RenderBlock(block)
+	if err != nil {
 		log.Printf("WARN: rendering block failed: %s\n", err)
 	}
+	return block
 }
 
 func (btc *BaseTileCreator) CreateTile(x, z int16, i, j int) (bool, error) {

common/redisclient.go

@@ -11,13 +11,13 @@ import (
 	"fmt"
 	"net"
 	"strconv"
-	"sync"
 	"unicode"
 )
 
 type RedisClient struct {
 	conn    net.Conn
 	reader  *bufio.Reader
+	arena   []byte
 	scratch [80]byte
 }
 
@@ -89,6 +89,16 @@ func parseSize(line []byte) (int, error) {
 	return int(v), err
 }
 
+func (client *RedisClient) alloc(size int) []byte {
+	a := client.arena
+	if len(a) < size {
+		a = make([]byte, Max(size, 16*1024))
+	}
+	x := a[:size:size]
+	client.arena = a[size:]
+	return x
+}
+
 func (client *RedisClient) readBulkString(data *[]byte) (size int, err error) {
 	var line []byte
 	if line, err = client.reader.ReadBytes('\n'); err != nil {
@@ -101,7 +111,9 @@ func (client *RedisClient) readBulkString(data *[]byte) (size int, err error) {
 		return
 	}
 	if cap(*data) < size {
-		*data = make([]byte, size)
+		*data = client.alloc(size)
+	} else {
+		*data = (*data)[:size]
 	}
 	for rest := size; rest > 0; {
 		var n int
@@ -114,26 +126,18 @@ func (client *RedisClient) readBulkString(data *[]byte) (size int, err error) {
 	return
 }
 
-var dataPool = sync.Pool{
-	New: func() interface{} {
-		return make([]byte, 8*1024)
-	},
-}
-
-func (client *RedisClient) QueryCuboid(cuboid Cuboid, fn func(*Block)) (count int, err error) {
+func (client *RedisClient) QueryCuboid(cuboid Cuboid, fn func(*Block) *Block) (count int, err error) {
 	p1 := CoordToPlain(cuboid.P1)
 	p2 := CoordToPlain(cuboid.P2)
 	if err = client.writeHSpatial(p1, p2); err != nil {
 		return
 	}
 
-	data := dataPool.Get().([]byte)
-	defer dataPool.Put(data[:0])
-
 	var (
-		block = Block{}
+		block *Block
 		size  int
 		key   int64
+		data  []byte
 	)
 
 	for s := client.scratch[:]; ; count++ {
@@ -144,15 +148,22 @@ func (client *RedisClient) QueryCuboid(cuboid Cuboid, fn func(*Block)) (count in
 		if size <= 0 {
 			break
 		}
-		if key, err = DecodeStringFromBytes((*p)[:size]); err != nil {
+		if key, err = DecodeStringFromBytes(*p); err != nil {
 			return
 		}
-		block.Coord = PlainToCoord(key)
 		if size, err = client.readBulkString(&data); err != nil || size < 0 {
 			return
 		}
-		block.Data = data[:size]
-		fn(&block)
+		if block == nil {
+			block = &Block{Coord: PlainToCoord(key), Data: data}
+		} else {
+			*block = Block{Coord: PlainToCoord(key), Data: data}
+		}
+		if block = fn(block); block != nil {
+			data = block.Data[:0]
+		} else {
+			data = nil
+		}
 	}
 
 	return

common/yorder.go

@@ -43,40 +43,23 @@ func (yo *YOrder) Reset() {
 	yo.blocks = blocks[:0]
 }
 
-func copyData(data []byte) []byte {
-	l := len(data)
-	ndata := make([]byte, l, Max(l, 8*1024))
-	copy(ndata, data)
-	return ndata
-}
-
-func (yo *YOrder) RenderBlock(block *Block) (err error) {
-	var nblock *Block
+func (yo *YOrder) RenderBlock(block *Block) (*Block, error) {
 	if len(yo.blocks) == yo.capacity {
 		oblock := yo.blocks[0]
 		if oblock.Coord.Y < block.Coord.Y {
 			// New one is above highest old. Directly render new.
-			err = yo.RenderFn(block)
-			return
+			err := yo.RenderFn(block)
+			return block, err
 		}
 		// Render old one. Store copy of new in heap.
 		heap.Pop(yo)
-		err = yo.RenderFn(oblock)
-		l := len(block.Data)
-		if cap(oblock.Data) < l {
-			oblock.Data = make([]byte, l, Max(l, 8*1024))
-		} else {
-			oblock.Data = oblock.Data[:l]
-		}
-		copy(oblock.Data, block.Data)
-		oblock.Coord = block.Coord
-		nblock = oblock
-	} else {
-		nblock = &Block{Coord: block.Coord, Data: copyData(block.Data)}
+		heap.Push(yo, block)
+		err := yo.RenderFn(oblock)
+		return oblock, err
 	}
 
-	heap.Push(yo, nblock)
-	return
+	heap.Push(yo, block)
+	return nil, nil
 }
 
 func (yo *YOrder) Drain() error {