tidb region_tree 源码
tidb region_tree 代码
文件路径：/store/pdtypes/region_tree.go
// Copyright 2022 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 pdtypes
import (
"bytes"
"github.com/pingcap/kvproto/pkg/metapb"
"golang.org/x/exp/slices"
)
// Region is a mock of PD's core.RegionInfo. For testing purpose.
type Region struct {
Meta *metapb.Region
Leader *metapb.Peer
}
// NewRegionInfo returns a new RegionInfo.
func NewRegionInfo(meta *metapb.Region, leader *metapb.Peer) *Region {
return &Region{Meta: meta, Leader: leader}
}
// RegionTree is a mock of PD's region tree. For testing purpose.
type RegionTree struct {
Regions []*Region
}
// SetRegion puts a region to region tree.
func (t *RegionTree) SetRegion(region *Region) {
rs := t.Regions[:0]
for _, r := range t.Regions {
if !overlap(r, region) {
rs = append(rs, r)
}
}
rs = append(rs, region)
t.Regions = rs
}
// ScanRange scans regions intersecting [start key, end key), returns at most
// `limit` regions. limit <= 0 means no limit.
func (t *RegionTree) ScanRange(startKey, endKey []byte, limit int) []*Region {
slices.SortFunc(t.Regions, func(i, j *Region) bool {
return bytes.Compare(i.Meta.StartKey, j.Meta.StartKey) < 0
})
pivot := NewRegionInfo(&metapb.Region{StartKey: startKey, EndKey: endKey}, nil)
var res []*Region
for _, r := range t.Regions {
if overlap(r, pivot) && (limit == 0 || len(res) < limit) {
res = append(res, r)
}
}
return res
}
func overlap(a, b *Region) bool {
// |----a----|
// |----b----|
if len(b.Meta.EndKey) > 0 && bytes.Compare(b.Meta.EndKey, a.Meta.StartKey) <= 0 {
return false
}
// |----a----|
// |----b----|
if len(a.Meta.EndKey) > 0 && bytes.Compare(a.Meta.EndKey, b.Meta.StartKey) <= 0 {
return false
}
return true
}
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