memobus_relay_server/peer/manager.go

package peer

import (
	"context"
	"log"
	"memobus_relay_server/config"
	"sync"

	"github.com/redis/go-redis/v9"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
)

// Manager 负责管理到其他对等服务器的 gRPC 客户端连接
type Manager struct {
	redisClient *redis.Client
	clients     map[string]*grpc.ClientConn
	mu          sync.RWMutex
}

var GlobalManager *Manager

func InitManager(redisCli *redis.Client) {
	if !config.Cfg.Redis.Enabled {
		return // 单机模式下不需要 Peer 管理器
	}
	GlobalManager = &Manager{
		redisClient: redisCli,
		clients:     make(map[string]*grpc.ClientConn),
	}
	log.Println("Peer manager initialized for cluster communication.")
}

// GetClient 查找或创建一个到目标实例的 gRPC 客户端连接
func (m *Manager) GetClient(targetInstanceID string) (*grpc.ClientConn, error) {
	m.mu.RLock()
	client, ok := m.clients[targetInstanceID]
	m.mu.RUnlock()

	if ok {
		return client, nil
	}

	// 连接未找到, 使用写锁创建一个新的
	m.mu.Lock()
	defer m.mu.Unlock()

	// 双重检查, 以防在我们等待锁的时候, 其他 goroutine 已经创建了它
	if client, ok = m.clients[targetInstanceID]; ok {
		return client, nil
	}

	// 从 Redis 发现目标实例的地址
	addr, err := m.redisClient.HGet(context.Background(), config.Cfg.Redis.InstanceRegistryKey, targetInstanceID).Result()
	if err != nil {
		return nil, err
	}

	log.Printf("Creating new gRPC client connection to peer %s at %s", targetInstanceID, addr)
	// 生产环境应使用 TLS 凭证替换 insecure
	conn, err := grpc.Dial(addr, grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		return nil, err
	}

	m.clients[targetInstanceID] = conn
	return conn, nil
}