client_statewatcher.go

/*
 * Copyright 2022 RPCPlatform 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 rpcplatform

import (
	"context"
	"strings"
	"sync"

	etcd "go.etcd.io/etcd/client/v3"
)

func (c *Client) stateWatcher(serverInfo map[string]string, revision int64) error {
	watchChan := c.etcd.Watch(context.Background(), c.target,
		etcd.WithPrefix(), etcd.WithRev(revision+1),
	)

	var (
		cancel = func() {}
		ctx    context.Context
		wg     sync.WaitGroup
	)

	go func() {
		for data := range watchChan {
			cancel()
			wg.Wait()

			for _, event := range data.Events {
				trimKey := strings.TrimPrefix(string(event.Kv.Key), c.target)

				switch event.Type {
				case etcd.EventTypeDelete:
					delete(serverInfo, trimKey)
				case etcd.EventTypePut:
					serverInfo[trimKey] = string(event.Kv.Value)
				}
			}

			if c.resolver.CC != nil {
				c.updateState(false, serverInfo)
				continue
			}

			wg.Add(1)
			ctx, cancel = context.WithCancel(context.Background())

			go func() {
				defer wg.Done()

				for {
					connState := c.client.GetState()

					if c.resolver.CC != nil {
						cancel()
						c.updateState(false, serverInfo)
						break
					}

					if !c.client.WaitForStateChange(ctx, connState) {
						break
					}
				}
			}()
		}
	}()

	return nil
}