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classifier.go
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classifier.go
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// Copyright 2017 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 namespace
import (
"fmt"
"github.com/pingcap/pd/server/core"
"github.com/pkg/errors"
)
// DefaultNamespace is the namespace all the store and region belong to by
// default.
const DefaultNamespace = "global"
// DefaultClassifier is a classifier that classifies all regions and stores to
// DefaultNamespace.
var DefaultClassifier = defaultClassifier{}
// Classifier is used to determine the namespace which the store or region
// belongs.
type Classifier interface {
GetAllNamespaces() []string
GetStoreNamespace(*core.StoreInfo) string
GetRegionNamespace(*core.RegionInfo) string
IsNamespaceExist(name string) bool
AllowMerge(*core.RegionInfo, *core.RegionInfo) bool
// Reload underlying namespaces
ReloadNamespaces() error
}
type defaultClassifier struct{}
func (c defaultClassifier) GetAllNamespaces() []string {
return []string{DefaultNamespace}
}
func (c defaultClassifier) GetStoreNamespace(*core.StoreInfo) string {
return DefaultNamespace
}
func (c defaultClassifier) GetRegionNamespace(*core.RegionInfo) string {
return DefaultNamespace
}
func (c defaultClassifier) IsNamespaceExist(name string) bool {
return name == DefaultNamespace
}
func (c defaultClassifier) AllowMerge(one *core.RegionInfo, other *core.RegionInfo) bool {
return true
}
func (c defaultClassifier) ReloadNamespaces() error {
return nil
}
// CreateClassifierFunc is for creating namespace classifier.
type CreateClassifierFunc func(*core.KV, core.IDAllocator) (Classifier, error)
var classifierMap = make(map[string]CreateClassifierFunc)
// RegisterClassifier binds a classifier creator. It should be called in init()
// func of a package.
func RegisterClassifier(name string, createFn CreateClassifierFunc) {
if _, ok := classifierMap[name]; ok {
panic(fmt.Sprintf("duplicated classifier name: %v", name))
}
classifierMap[name] = createFn
}
// CreateClassifier creates a namespace classifier with registered creator func.
func CreateClassifier(name string, kv *core.KV, idAlloc core.IDAllocator) (Classifier, error) {
fn, ok := classifierMap[name]
if !ok {
return nil, errors.Errorf("create func of %v is not registered", name)
}
return fn(kv, idAlloc)
}
func init() {
RegisterClassifier("default", func(*core.KV, core.IDAllocator) (Classifier, error) {
return DefaultClassifier, nil
})
}