github.com/pingcap/ticdc@v0.0.0-20220526033649-485a10ef2652/pkg/regionspan/region.go (about)

     1  // Copyright 2020 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package regionspan
    15  
    16  import (
    17  	"sort"
    18  
    19  	"github.com/pingcap/kvproto/pkg/metapb"
    20  )
    21  
    22  // CheckRegionsLeftCover checks whether the regions cover the left part of given span
    23  func CheckRegionsLeftCover(regions []*metapb.Region, span ComparableSpan) bool {
    24  	if len(regions) == 0 {
    25  		return false
    26  	}
    27  	sort.Slice(regions, func(i, j int) bool {
    28  		return StartCompare(regions[i].StartKey, regions[j].StartKey) == -1
    29  	})
    30  
    31  	if StartCompare(regions[0].StartKey, span.Start) == 1 {
    32  		return false
    33  	}
    34  
    35  	nextStart := regions[0].StartKey
    36  	for _, region := range regions {
    37  		// incontinuous regions
    38  		if StartCompare(nextStart, region.StartKey) != 0 {
    39  			return false
    40  		}
    41  		nextStart = region.EndKey
    42  	}
    43  	return true
    44  }