// Copyright 2020 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 applycache

import (
	"strconv"
	"strings"
	"sync"
	"testing"

	"github.com/pingcap/tidb/pkg/parser/mysql"
	"github.com/pingcap/tidb/pkg/types"
	"github.com/pingcap/tidb/pkg/util/chunk"
	"github.com/pingcap/tidb/pkg/util/mock"
	"github.com/stretchr/testify/require"
)

func TestApplyCache(t *testing.T) {
	ctx := mock.NewContext()
	ctx.GetSessionVars().MemQuotaApplyCache = 100
	applyCache, err := NewApplyCache(ctx)
	require.NoError(t, err)

	fields := []*types.FieldType{types.NewFieldType(mysql.TypeLonglong)}
	value := make([]*chunk.List, 3)
	key := make([][]byte, 3)
	for i := 0; i < 3; i++ {
		value[i] = chunk.NewList(fields, 1, 1)
		srcChunk := chunk.NewChunkWithCapacity(fields, 1)
		srcChunk.AppendInt64(0, int64(i))
		srcRow := srcChunk.GetRow(0)
		value[i].AppendRow(srcRow)
		key[i] = []byte(strings.Repeat(strconv.Itoa(i), 100))

		// TODO: *chunk.List.GetMemTracker().BytesConsumed() is not accurate, fix it later.
		require.Equal(t, int64(100), applyCacheKVMem(key[i], value[i]))
	}

	ok, err := applyCache.Set(key[0], value[0])
	require.NoError(t, err)
	require.True(t, ok)
	result, err := applyCache.Get(key[0])
	require.NoError(t, err)
	require.NotNil(t, result)

	ok, err = applyCache.Set(key[1], value[1])
	require.NoError(t, err)
	require.True(t, ok)
	result, err = applyCache.Get(key[1])
	require.NoError(t, err)
	require.NotNil(t, result)

	ok, err = applyCache.Set(key[2], value[2])
	require.NoError(t, err)
	require.True(t, ok)
	result, err = applyCache.Get(key[2])
	require.NoError(t, err)
	require.NotNil(t, result)

	// Both key[0] and key[1] are not in the cache
	result, err = applyCache.Get(key[0])
	require.NoError(t, err)
	require.Nil(t, result)

	result, err = applyCache.Get(key[1])
	require.NoError(t, err)
	require.Nil(t, result)
}

func TestApplyCacheConcurrent(t *testing.T) {
	ctx := mock.NewContext()
	ctx.GetSessionVars().MemQuotaApplyCache = 100
	applyCache, err := NewApplyCache(ctx)
	require.NoError(t, err)

	fields := []*types.FieldType{types.NewFieldType(mysql.TypeLonglong)}
	value := make([]*chunk.List, 2)
	key := make([][]byte, 2)
	for i := 0; i < 2; i++ {
		value[i] = chunk.NewList(fields, 1, 1)
		srcChunk := chunk.NewChunkWithCapacity(fields, 1)
		srcChunk.AppendInt64(0, int64(i))
		srcRow := srcChunk.GetRow(0)
		value[i].AppendRow(srcRow)
		key[i] = []byte(strings.Repeat(strconv.Itoa(i), 100))

		// TODO: *chunk.List.GetMemTracker().BytesConsumed() is not accurate, fix it later.
		require.Equal(t, int64(100), applyCacheKVMem(key[i], value[i]))
	}

	applyCache.Set(key[0], value[0])
	var wg sync.WaitGroup
	wg.Add(2)
	var func1 = func() {
		for i := 0; i < 100; i++ {
			for {
				result, err := applyCache.Get(key[0])
				require.NoError(t, err)
				if result != nil {
					applyCache.Set(key[1], value[1])
					break
				}
			}
		}
		wg.Done()
	}
	var func2 = func() {
		for i := 0; i < 100; i++ {
			for {
				result, err := applyCache.Get(key[1])
				require.NoError(t, err)
				if result != nil {
					applyCache.Set(key[0], value[0])
					break
				}
			}
		}
		wg.Done()
	}
	go func1()
	go func2()
	wg.Wait()
	result, err := applyCache.Get(key[0])
	require.NoError(t, err)
	require.NotNil(t, result)
}