MB-54131: Geoshape query decode optimization (#14)

* MB-54131: Geoshape query decode optimization

	- Added buffer pool pointer to polygon
	- Added parent polygon pointer to loop
	- Added decoder function to select, populate and return a pointer to the buffer from a pool of buffers
	- Updated loop decode function to handle chunks of data being read
	- Updated polygon decode function to pass on the buffer pool to the loops
	- Updated extractShapesFromBytes and FilterGeoShapesOnRelation to include the buffer pool in its parameters

* MB-54131: Geoshape query decode optimization

 - Changed buffer pool from pointer to slice
 - Removed randomly formatted comments

* MB-54131: Geoshape query decode

  + add .gitignore

* MB-54131: Geoshape query decode optimization

 - Added a buffer pool struct
 - Increased size of the maximum buffer to 24KB
 - Added better comments

* MB-54131: Geoshape query decode optimization

 - Minor formatting fixes
 - Reusing buffers instead of creating everytime

* MB-54131: Geoshape query decode optimization

 - Better comments
 - Removed some magic numbers

* MB-54131: Geoshape query decode optimization

 - Changed buffer pool implementation to give the smallest buffer that fits the data completely
 - Changed decoder implementation to allow buffer sizes bigger than number of bytes needed

* MB-54131: Geoshape query decode optimization

 - Renamed some constants

* MB-54131: Geoshape query decode optimization

 - Added benchmark for loop decode

.gitignore

@@ -0,0 +1 @@
+.DS_Store

geojson/geojson_shapes_util.go

@@ -31,9 +31,9 @@ var jsoniter = jsoniterator.ConfigCompatibleWithStandardLibrary
 // the `relation` filter and confirms whether the shape in the document
 //  satisfies the given relation.
 func FilterGeoShapesOnRelation(shape index.GeoJSON, targetShapeBytes []byte,
-	relation string, reader **bytes.Reader) (bool, error) {
+	relation string, reader **bytes.Reader, bufPool *s2.GeoBufferPool) (bool, error) {
 
-	shapeInDoc, err := extractShapesFromBytes(targetShapeBytes, reader)
+	shapeInDoc, err := extractShapesFromBytes(targetShapeBytes, reader, bufPool)
 	if err != nil {
 		return false, err
 	}
@@ -43,7 +43,7 @@ func FilterGeoShapesOnRelation(shape index.GeoJSON, targetShapeBytes []byte,
 
 // extractShapesFromBytes unmarshal the bytes to retrieve the
 // embedded geojson shape.
-func extractShapesFromBytes(targetShapeBytes []byte, r **bytes.Reader) (
+func extractShapesFromBytes(targetShapeBytes []byte, r **bytes.Reader, bufPool *s2.GeoBufferPool) (
 	index.GeoJSON, error) {
 	if (*r) == nil {
 		*r = bytes.NewReader(targetShapeBytes[1:])
@@ -109,7 +109,7 @@ func extractShapesFromBytes(targetShapeBytes []byte, r **bytes.Reader) (
 		return mls, nil
 
 	case PolygonTypePrefix:
-		pgn := &Polygon{s2pgn: &s2.Polygon{}}
+		pgn := &Polygon{s2pgn: &s2.Polygon{BufPool: bufPool}}
 		err := pgn.s2pgn.Decode(*r)
 		if err != nil {
 			return nil, err
@@ -156,7 +156,7 @@ func extractShapesFromBytes(targetShapeBytes []byte, r **bytes.Reader) (
 		gc := &GeometryCollection{Shapes: make([]index.GeoJSON, numShapes)}
 
 		for i := int32(0); i < numShapes; i++ {
-			shape, err := extractShapesFromBytes(inputBytes[:lengths[i]], r)
+			shape, err := extractShapesFromBytes(inputBytes[:lengths[i]], r, nil)
 			if err != nil {
 				return nil, err
 			}

s2/buffer_pool.go

@@ -0,0 +1,64 @@
+//  Copyright (c) 2023 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package s2
+
+// GeoBufferPool represents a pool of buffers ranging from a given
+// max size to a min size in steps of 2. It uses a lazy approach only allocating
+// the buffers when it is needed.
+
+type GeoBufferPool struct {
+	buffers [][]byte
+	maxSize int
+	minSize int
+}
+
+func NewGeoBufferPool(maxSize int, minSize int) *GeoBufferPool {
+	// Calculating the number of buffers required. Assuming that
+	// the value of minSize is correct, the buffers will be of size
+	// minSize, 2 * minSize, 4 * minSize and so on till it is less
+	// than or equal to the maxSize. If it is not equal to maxSize,
+	// then a suitable value less than maxSize will be set as maxSize
+	length := 0
+	temp := minSize
+	for temp <= maxSize {
+		length = length + 1
+		temp = temp * 2
+	}
+	maxSize = temp / 2
+
+	return &GeoBufferPool{
+		buffers: make([][]byte, length),
+		maxSize: maxSize,
+		minSize: minSize,
+	}
+}
+
+func (b *GeoBufferPool) Get(size int) ([]byte) {
+	bufSize := b.minSize
+
+	for i := range b.buffers {
+		if size <= bufSize || i == len(b.buffers) - 1{
+			if b.buffers[i] == nil {
+				b.buffers[i] = make([]byte, bufSize)
+			}
+
+			return b.buffers[i]
+		} else {
+			bufSize = bufSize * 2
+		}
+	}
+
+	return nil
+}

s2/encode.go

@@ -222,3 +222,17 @@ func (d *decoder) readUvarint() (x uint64) {
 	x, d.err = binary.ReadUvarint(d.r)
 	return
 }
+
+func (d *decoder) readFloat64Array(size int, buf []byte) int {
+	if d.err != nil || buf == nil {
+		return 0
+	}
+
+	if size >= len(buf) {
+		_, d.err = io.ReadFull(d.r, buf)
+		return len(buf)
+	} else {
+		_, d.err = io.ReadFull(d.r, buf[0:size])
+		return size
+	}
+}

s2/loop.go

@@ -15,6 +15,7 @@
 package s2
 
 import (
+	"encoding/binary"
 	"fmt"
 	"io"
 	"math"
@@ -24,6 +25,9 @@ import (
 	"github.com/golang/geo/s1"
 )
 
+const SizeOfFloat = 8
+const SizeOfVertex = 3 * SizeOfFloat
+
 // Loop represents a simple spherical polygon. It consists of a sequence
 // of vertices where the first vertex is implicitly connected to the
 // last. All loops are defined to have a CCW orientation, i.e. the interior of
@@ -66,6 +70,9 @@ type Loop struct {
 
 	// index is the spatial index for this Loop.
 	index *ShapeIndex
+
+	// A buffer pool to be used while decoding the polygon
+	BufPool *GeoBufferPool
 }
 
 // LoopFromPoints constructs a loop from the given points.
@@ -1287,11 +1294,34 @@ func (l *Loop) decode(d *decoder) {
 		return
 	}
 	l.vertices = make([]Point, nvertices)
-	for i := range l.vertices {
-		l.vertices[i].X = d.readFloat64()
-		l.vertices[i].Y = d.readFloat64()
-		l.vertices[i].Z = d.readFloat64()
+
+	// Each vertex requires 24 bytes of storage
+	numBytesNeeded := int(nvertices) * SizeOfVertex
+
+	i := 0
+
+	for numBytesNeeded > 0 {
+		arr := l.BufPool.Get(numBytesNeeded)
+		numBytesRead := d.readFloat64Array(numBytesNeeded, arr)
+
+		if numBytesRead == 0 {
+			break
+		}
+
+		numBytesNeeded = numBytesNeeded - numBytesRead 
+
+		// Parsing one vertex at a time into the vertex array of the loop
+		// by going through the buffer in steps of SizeOfVertex and converting
+		// floatSize worth of bytes into the float values
+		for j := 0; j < int(numBytesRead/SizeOfVertex); j++ {
+			l.vertices[i+j].X = math.Float64frombits(binary.LittleEndian.Uint64(arr[SizeOfFloat*(j*3) : SizeOfFloat*(j*3+1)]))
+			l.vertices[i+j].Y = math.Float64frombits(binary.LittleEndian.Uint64(arr[SizeOfFloat*(j*3+1) : SizeOfFloat*(j*3+2)]))
+			l.vertices[i+j].Z = math.Float64frombits(binary.LittleEndian.Uint64(arr[SizeOfFloat*(j*3+2) : SizeOfFloat*(j*3+3)]))
+		}
+
+		i = i + int(numBytesRead/SizeOfVertex)
 	}
+
 	l.index = NewShapeIndex()
 	l.originInside = d.readBool()
 	l.depth = int(d.readUint32())

s2/loop_test.go

@@ -17,6 +17,7 @@ package s2
 import (
 	"fmt"
 	"math"
+	"os"
 	"testing"
 
 	"github.com/golang/geo/r1"
@@ -1817,3 +1818,61 @@ func BenchmarkLoopContainsPoint(b *testing.B) {
 		vertices *= 2
 	}
 }
+
+func BenchmarkLoopDecode(b *testing.B) {
+
+	points := make([][]float64, 0)
+
+	points = append(points, []float64{10, 10})
+	for i := 1; i < 2000; i++ {
+		points = append(points, []float64{10 - 0.01*float64(i), 10})
+	}
+	points = append(points, []float64{-10, 10})
+	for i := 1; i < 2000; i++ {
+		points = append(points, []float64{-10, 10 - 0.01*float64(i)})
+	}
+	points = append(points, []float64{-10, -10})
+	for i := 1; i < 2000; i++ {
+		points = append(points, []float64{-10 + 0.01*float64(i), -10})
+	}
+	points = append(points, []float64{10, -10})
+	for i := 1; i < 2000; i++ {
+		points = append(points, []float64{10, -10 + 0.01*float64(i)})
+	}
+	points = append(points, []float64{10, 10})
+
+	pointString := ""
+
+	for i := 0; i < len(points); i++ {
+
+		if i == 0 {
+			pointString = pointString + fmt.Sprintf("%f:%f", points[i][0], points[i][1])
+		} else {
+			pointString = pointString + fmt.Sprintf(", %f:%f", points[i][0], points[i][1])
+		}
+	}
+
+	loop := LoopFromPoints(parsePoints(pointString))
+
+	f, err := os.OpenFile("testLoop.txt", os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0600)
+    if err != nil {
+        b.Fatalf("%v", err)
+    }
+	loop.Encode(f)
+	f.Close()
+
+	bufPool := NewGeoBufferPool(24 * 1024, 24)
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		f, err := os.Open("testLoop.txt")
+		if err != nil {
+			b.Fatalf("%v", err)
+		}
+		l := &Loop{
+			BufPool: bufPool,
+		}
+		l.decode(&decoder{r: asByteReader(f)})
+		f.Close()
+	}
+	os.Remove("testLoop.txt")
+}

s2/polygon.go

@@ -77,6 +77,9 @@ type Polygon struct {
 	// preceding loops in the polygon. This field is used for polygons that
 	// have a large number of loops, and may be empty for polygons with few loops.
 	cumulativeEdges []int
+
+	// A buffer pool to be used while decoding the polygon
+	BufPool *GeoBufferPool
 }
 
 // PolygonFromLoops constructs a polygon from the given set of loops. The polygon
@@ -1133,7 +1136,7 @@ func (p *Polygon) Decode(r io.Reader) error {
 const maxEncodedLoops = 10000000
 
 func (p *Polygon) decode(d *decoder) {
-	*p = Polygon{}
+	*p = Polygon{BufPool: p.BufPool}
 	d.readUint8() // Ignore irrelevant serialized owns_loops_ value.
 
 	p.hasHoles = d.readBool()
@@ -1151,6 +1154,7 @@ func (p *Polygon) decode(d *decoder) {
 	p.loops = make([]*Loop, nloops)
 	for i := range p.loops {
 		p.loops[i] = new(Loop)
+		p.loops[i].BufPool = p.BufPool
 		p.loops[i].decode(d)
 		p.numVertices += len(p.loops[i].vertices)
 	}