shard_sorter.go

/*
Copyright 2020 The Vitess Authors.

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 vreplication

import "strings"

// ShardSorter implements a sort.Sort() function for sorting shard ranges
type ShardSorter []string

// Len implements the required interface for a sorting function
func (s ShardSorter) Len() int {
	return len(s)
}

// Swap implements the required interface for a sorting function
func (s ShardSorter) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}

// Key returns the prefix of a shard range
func (s ShardSorter) Key(ind int) string {
	return strings.Split(s[ind], "-")[0]
}

// Less implements the required interface for a sorting function
func (s ShardSorter) Less(i, j int) bool {
	return s.Key(i) < s.Key(j)
}