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// Copyright 2018 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package tikv
import (
"bytes"
"context"
"github.com/pingcap/kvproto/pkg/kvrpcpb"
"github.com/pingcap/tidb/store/tikv/tikvrpc"
"github.com/pkg/errors"
)
// DeleteRangeTask is used to delete all keys in a range. After
// performing DeleteRange, it keeps how many ranges it affects and
// if the task was canceled or not.
type DeleteRangeTask struct {
completedRegions int
canceled bool
store Storage
ctx context.Context
startKey []byte
endKey []byte
}
// NewDeleteRangeTask creates a DeleteRangeTask. Deleting will not be performed right away.
// WARNING: Currently, this API may leave some waste key-value pairs uncleaned in TiKV. Be careful while using it.
func NewDeleteRangeTask(ctx context.Context, store Storage, startKey []byte, endKey []byte) *DeleteRangeTask {
return &DeleteRangeTask{
completedRegions: 0,
canceled: false,
store: store,
ctx: ctx,
startKey: startKey,
endKey: endKey,
}
}
// Execute performs the delete range operation.
func (t *DeleteRangeTask) Execute() error {
startKey, rangeEndKey := t.startKey, t.endKey
for {
select {
case <-t.ctx.Done():
t.canceled = true
return nil
default:
}
bo := NewBackoffer(t.ctx, deleteRangeOneRegionMaxBackoff)
loc, err := t.store.GetRegionCache().LocateKey(bo, startKey)
if err != nil {
return errors.Trace(err)
}
// Delete to the end of the region, except if it's the last region overlapping the range
endKey := loc.EndKey
// If it is the last region
if loc.Contains(rangeEndKey) {
endKey = rangeEndKey
}
req := &tikvrpc.Request{
Type: tikvrpc.CmdDeleteRange,
DeleteRange: &kvrpcpb.DeleteRangeRequest{
StartKey: startKey,
EndKey: endKey,
},
}
resp, err := t.store.SendReq(bo, req, loc.Region, ReadTimeoutMedium)
if err != nil {
return errors.Trace(err)
}
regionErr, err := resp.GetRegionError()
if err != nil {
return errors.Trace(err)
}
if regionErr != nil {
err = bo.Backoff(BoRegionMiss, errors.New(regionErr.String()))
if err != nil {
return errors.Trace(err)
}
continue
}
deleteRangeResp := resp.DeleteRange
if deleteRangeResp == nil {
return errors.Trace(ErrBodyMissing)
}
if err := deleteRangeResp.GetError(); err != "" {
return errors.Errorf("unexpected delete range err: %v", err)
}
t.completedRegions++
if bytes.Equal(endKey, rangeEndKey) {
break
}
startKey = endKey
}
return nil
}
// CompletedRegions returns the number of regions that are affected by this delete range task
func (t *DeleteRangeTask) CompletedRegions() int {
return t.completedRegions
}
// IsCanceled returns true if the delete range operation was canceled on the half way
func (t *DeleteRangeTask) IsCanceled() bool {
return t.canceled
}
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