map-benchmark.go

func prepareNonuniform(size int) []int {
	samples := make([]int, size, size)
	for i := 0; i < size; i++ {
		for {
			grg := gaussian()
			index := int(((2.0 + grg) / 4.0) * float64(size-1))
			if (index >= 0) && (index < size) {
				samples[i] = index
				break
			}
		}
	}
	return samples
}

// Run the same test with the Go map API for comparison
func BenchmarkMapStore(b *testing.B) {
	b.ReportAllocs()
	//b.N = 100 * 1000
	keys := make([]string, b.N, b.N)
	for i := 0; i < b.N; i++ {
		keys[i] = fmt.Sprintf("%d", b.N-i)
	}
	m := make(map[string]uintptr, b.N)
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		key := keys[i]
		m[key] = uintptr(i)
	}
}

func BenchmarkMapStoreNonuniform(b *testing.B) {
	b.ReportAllocs()
	//b.N = 100 * 1000
	keys := make([]string, b.N, b.N)
	for i := 0; i < b.N; i++ {
		keys[i] = fmt.Sprintf("%d", b.N-i)
	}
	samples := prepareNonuniform(b.N)
	m := make(map[string]uintptr, b.N)
	b.ResetTimer()
	skipped := 0
	for i := 0; i < b.N; i++ {
		sample := samples[i]
		if sample < 0 || sample >= b.N {
			//b.Logf("Skipped %d", sample)
			skipped++
			continue
		}
		key := keys[sample]
		m[key] = uintptr(i)
	}
	b.Logf("Skipped total %d", skipped)
}

func BenchmarkMapLoadNonuniform(b *testing.B) {
	b.ReportAllocs()
	//b.N = 100 * 1000
	keys := make([]string, b.N, b.N)
	for i := 0; i < b.N; i++ {
		keys[i] = fmt.Sprintf("%d", b.N-i)
	}
	samples := prepareNonuniform(b.N)
	m := make(map[string]uintptr, b.N)
	for i := 0; i < b.N; i++ {
		sample := samples[i]
		if sample < 0 || sample >= b.N {
			continue
		}
		key := keys[sample]
		m[key] = uintptr(i)
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		sample := samples[i]
		if sample < 0 || sample >= b.N {
			continue
		}
		key := keys[sample]
		v := m[key]
		if v != uintptr(i) {
			b.Fatalf("Wrong value %d, expected %d", v, i)
		}
	}
}