watcher.go

// 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
//
//     https://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.
//
// Original source: github.com/micro/go-micro/v3/registry/watcher.go

package registry

import "time"

// Watcher is an interface that returns updates
// about services within the registry.
type Watcher interface {
	// Next is a blocking call
	Next() (*Result, error)
	Stop()
}

// Result is returned by a call to Next on
// the watcher. Actions can be create, update, delete
type Result struct {
	Action  string
	Service *Service
}

// EventType defines registry event type
type EventType int

const (
	// Create is emitted when a new service is registered
	Create EventType = iota
	// Delete is emitted when an existing service is deregistered
	Delete
	// Update is emitted when an existing service is updated
	Update
)

// String returns human readable event type
func (t EventType) String() string {
	switch t {
	case Create:
		return "create"
	case Delete:
		return "delete"
	case Update:
		return "update"
	default:
		return "unknown"
	}
}

// Event is registry event
type Event struct {
	// Id is registry id
	Id string
	// Type defines type of event
	Type EventType
	// Timestamp is event timestamp
	Timestamp time.Time
	// Service is registry service
	Service *Service
}