Go implementation by AlexanderYastrebov (#298)

* Go implementation by AlexanderYastrebov

This is a proof-of-concept to demonstrate non-java submission.
It requires Docker with BuildKit plugin to build and export binary.

Updates
* #67
* #253

* Use collision-free id lookup

* Use number of buckets greater than max number of keys

1 files changed, 86 insertions, 0 deletions

diff --git a/src/main/go/AlexanderYastrebov/calc_test.go b/src/main/go/AlexanderYastrebov/calc_test.go
new file mode 100644
index 0000000..db7e27a
--- /dev/null
+++ b/src/main/go/AlexanderYastrebov/calc_test.go
@@ -0,0 +1,86 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+func TestRoundJava(t *testing.T) {
+	for _, tc := range []struct {
+		value    float64
+		expected string
+	}{
+		{value: -1.5, expected: "-1.0"},
+		{value: -1.0, expected: "-1.0"},
+		{value: -0.7, expected: "-1.0"},
+		{value: -0.5, expected: "0.0"},
+		{value: -0.3, expected: "0.0"},
+		{value: 0.0, expected: "0.0"},
+		{value: 0.3, expected: "0.0"},
+		{value: 0.5, expected: "1.0"},
+		{value: 0.7, expected: "1.0"},
+		{value: 1.0, expected: "1.0"},
+		{value: 1.5, expected: "2.0"},
+	} {
+		if rounded := roundJava(tc.value); fmt.Sprintf("%.1f", rounded) != tc.expected {
+			t.Errorf("Wrong rounding of %v, expected: %s, got: %.1f", tc.value, tc.expected, rounded)
+		}
+	}
+}
+
+func TestParseNumber(t *testing.T) {
+	for _, tc := range []struct {
+		value    string
+		expected string
+	}{
+		{value: "-99.9", expected: "-999"},
+		{value: "-12.3", expected: "-123"},
+		{value: "-1.5", expected: "-15"},
+		{value: "-1.0", expected: "-10"},
+		{value: "0.0", expected: "0"},
+		{value: "0.3", expected: "3"},
+		{value: "12.3", expected: "123"},
+		{value: "99.9", expected: "999"},
+	} {
+		if number := parseNumber([]byte(tc.value)); fmt.Sprintf("%d", number) != tc.expected {
+			t.Errorf("Wrong parsing of %v, expected: %s, got: %d", tc.value, tc.expected, number)
+		}
+	}
+}
+
+var parseNumberSink int64
+
+func BenchmarkParseNumber(b *testing.B) {
+	data1 := []byte("1.2")
+	data2 := []byte("-12.3")
+
+	for i := 0; i < b.N; i++ {
+		parseNumberSink = parseNumber(data1) + parseNumber(data2)
+	}
+}
+
+func BenchmarkProcess(b *testing.B) {
+	// $ ./create_measurements.sh 1000000 && mv measurements.txt measurements-1e6.txt
+	// Created file with 1,000,000 measurements in 514 ms
+	const filename = "../../../../measurements-1e6.txt"
+
+	data, err := os.ReadFile(filename)
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	measurements := process(data)
+	rows := int64(0)
+	for _, m := range measurements {
+		rows += m.count
+	}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	b.ReportMetric(float64(rows), "rows/op")
+
+	for i := 0; i < b.N; i++ {
+		process(data)
+	}
+}