Files
cloudpods/pkg/monitor/registry/registry.go
2020-03-02 20:00:08 +08:00

119 lines
3.1 KiB
Go

// Copyright 2019 Yunion
//
// 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 registry
import (
"context"
"reflect"
"sort"
)
type Descriptor struct {
Name string
Instance Service
InitPriority Priority
}
var services []*Descriptor
func RegisterService(instance Service) {
services = append(services, &Descriptor{
Name: reflect.TypeOf(instance).Elem().Name(),
Instance: instance,
InitPriority: Low,
})
}
func Register(descriptor *Descriptor) {
services = append(services, descriptor)
}
func GetServices() []*Descriptor {
slice := getServicesWithOverrides()
sort.Slice(slice, func(i, j int) bool {
return slice[i].InitPriority > slice[j].InitPriority
})
return slice
}
type OverrideServiceFunc func(descriptor Descriptor) (*Descriptor, bool)
var overrides []OverrideServiceFunc
func getServicesWithOverrides() []*Descriptor {
slice := []*Descriptor{}
for _, s := range services {
var descriptor *Descriptor
for _, fn := range overrides {
if newDescriptor, override := fn(*s); override {
descriptor = newDescriptor
break
}
}
if descriptor != nil {
slice = append(slice, descriptor)
} else {
slice = append(slice, s)
}
}
return slice
}
// Service interface is the lowest common shape that services
// are expected to forfill to be started within monitor.
type Service interface {
// Init is called by monitor main process which gives the service
// the possibility do some initial work before its started. Things
// like adding routes, bus handlers should be done in the Init function
Init() error
}
// CanBeDisabled allows the services to decide if it should
// be started or not by itself. This is useful for services
// that might not always be started, ex alerting.
// This will be called after `Init()`.
type CanBeDisabled interface {
// IsDisabled should return a bool saying if it can be started or not.
IsDisabled() bool
}
// BackgroundService should be implemented for services that have
// long running tasks in the background.
type BackgroundService interface {
// Run starts the background process of the service after `Init` have been called
// on all services. The `context.Context` passed into the function should be used
// to subscribe to ctx.Done() so the service can be notified when monitor shuts down.
Run(ctx context.Context) error
}
// IsDisabled takes an service and return true if its disabled
func IsDisabled(srv Service) bool {
canBeDisabled, ok := srv.(CanBeDisabled)
return ok && canBeDisabled.IsDisabled()
}
type Priority int
const (
High Priority = 100
Low Priority = 0
)