feat: KLL float sketch

Author: proost

common/item_sketch_float.go

@@ -0,0 +1,76 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 common
+
+import (
+	"encoding/binary"
+	"math"
+)
+
+var ItemSketchFloatComparator = func(reverseOrder bool) CompareFn[float32] {
+	return func(a float32, b float32) bool {
+		if reverseOrder {
+			return a > b
+		}
+		return a < b
+	}
+}
+
+// ItemSketchFloatSerDe handles serialization and deserialization of floating-point sketch items.
+type ItemSketchFloatSerDe struct{}
+
+func (s ItemSketchFloatSerDe) SizeOf(item float32) int {
+	return 4
+}
+
+func (s ItemSketchFloatSerDe) SizeOfMany(mem []byte, offsetBytes int, numItems int) (int, error) {
+	return numItems * 4, nil
+}
+
+func (s ItemSketchFloatSerDe) SerializeOneToSlice(item float32) []byte {
+	bytes := make([]byte, 4)
+	binary.LittleEndian.PutUint32(bytes, math.Float32bits(item))
+	return bytes
+}
+
+func (s ItemSketchFloatSerDe) SerializeManyToSlice(items []float32) []byte {
+	if len(items) == 0 {
+		return []byte{}
+	}
+
+	bytes := make([]byte, 4*len(items))
+	offset := 0
+	for _, item := range items {
+		binary.LittleEndian.PutUint32(bytes[offset:], math.Float32bits(item))
+		offset += 4
+	}
+	return bytes
+}
+
+func (s ItemSketchFloatSerDe) DeserializeManyFromSlice(mem []byte, offsetBytes int, numItems int) ([]float32, error) {
+	if numItems == 0 {
+		return []float32{}, nil
+	}
+
+	array := make([]float32, 0, numItems)
+	for i := 0; i < numItems; i++ {
+		array = append(array, math.Float32frombits(binary.LittleEndian.Uint32(mem[offsetBytes:])))
+		offsetBytes += 4
+	}
+	return array, nil
+}