// Copyright 2023 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 aggregate

import (
	"sync/atomic"

	"github.com/pingcap/tidb/pkg/util/logutil"
	"github.com/pingcap/tidb/pkg/util/memory"
	"go.uber.org/zap"
)

// maxSpillTimes indicates how many times the data can spill at most.
const maxSpillTimes = 10

// AggSpillDiskAction implements memory.ActionOnExceed for unparalleled HashAgg.
// If the memory quota of a query is exceeded, AggSpillDiskAction.Action is
// triggered.
type AggSpillDiskAction struct {
	memory.BaseOOMAction
	e          *HashAggExec
	spillTimes uint32
}

// Action set HashAggExec spill mode.
func (a *AggSpillDiskAction) Action(t *memory.Tracker) {
	// Guarantee that processed data is at least 20% of the threshold, to avoid spilling too frequently.
	if atomic.LoadUint32(&a.e.inSpillMode) == 0 && a.spillTimes < maxSpillTimes && a.e.memTracker.BytesConsumed() >= t.GetBytesLimit()/5 {
		a.spillTimes++
		logutil.BgLogger().Info("memory exceeds quota, set aggregate mode to spill-mode",
			zap.Uint32("spillTimes", a.spillTimes),
			zap.Int64("consumed", t.BytesConsumed()),
			zap.Int64("quota", t.GetBytesLimit()))
		atomic.StoreUint32(&a.e.inSpillMode, 1)
		memory.QueryForceDisk.Add(1)
		return
	}
	if fallback := a.GetFallback(); fallback != nil {
		fallback.Action(t)
	}
}

// GetPriority get the priority of the Action
func (*AggSpillDiskAction) GetPriority() int64 {
	return memory.DefSpillPriority
}