// Copyright 2024 PingCAP, 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 join

import (
	"runtime"
	"testing"
	"unsafe"

	"github.com/pingcap/tidb/pkg/util"
)

func BenchmarkHashTableBuild(b *testing.B) {
	b.StopTimer()
	rowTable, tagBits, err := createRowTable(3000000)
	if err != nil {
		b.Fatal(err)
	}
	tagHelper := &tagPtrHelper{}
	tagHelper.init(tagBits)
	subTable := newSubTable(rowTable)
	segmentCount := len(rowTable.segments)
	b.StartTimer()
	subTable.build(0, segmentCount, tagHelper)
}

func BenchmarkHashTableConcurrentBuild(b *testing.B) {
	b.StopTimer()
	rowTable, tagBits, err := createRowTable(3000000)
	if err != nil {
		b.Fatal(err)
	}
	tagHelper := &tagPtrHelper{}
	tagHelper.init(tagBits)
	subTable := newSubTable(rowTable)
	segmentCount := len(rowTable.segments)
	buildThreads := 3
	wg := util.WaitGroupWrapper{}
	b.StartTimer()
	for i := 0; i < buildThreads; i++ {
		segmentStart := segmentCount / buildThreads * i
		segmentEnd := segmentCount / buildThreads * (i + 1)
		if i == buildThreads-1 {
			segmentEnd = segmentCount
		}
		wg.Run(func() {
			subTable.build(segmentStart, segmentEnd, tagHelper)
		})
	}
	wg.Wait()
}

func BenchmarkTestUnsafePointer(b *testing.B) {
	size := int(1e3)
	a := make([]byte, size*8)
	p := make([]unsafe.Pointer, size)
	b.StopTimer()
	for i := 0; i < size; i++ {
		p[i] = unsafe.Pointer(&a[i*8])
	}
	for i := 0; i < size; i++ {
		*(*int64)(p[i]) = int64(i)
	}
	runtime.KeepAlive(a)
	runtime.KeepAlive(p)
}

func BenchmarkTestUseUintptrAsUnsafePointer(b *testing.B) {
	size := int(1e3)
	a := make([]byte, size*8)
	p := make([]uintptr, size)
	b.StopTimer()
	for i := 0; i < size; i++ {
		*(*unsafe.Pointer)(unsafe.Pointer(&p[i])) = unsafe.Pointer(&a[i*8])
	}
	for i := 0; i < size; i++ {
		*(*int64)((unsafe.Pointer)(&p[i])) = int64(i)
	}
	runtime.KeepAlive(a)
	runtime.KeepAlive(p)
}