home_data/gatherer/connections.go

package main

import (
	"log"
	"os"
	"time"

	amqp "github.com/rabbitmq/amqp091-go"
)

type AMQPConnection struct {
	conn       *amqp.Connection
	channel    *amqp.Channel
	error_chan chan *amqp.Error
	observers  []chan<- bool
}

func (amqpConn *AMQPConnection) Init() {
	amqpConn.error_chan = make(chan *amqp.Error)
}

func (amqpConn *AMQPConnection) Connect() error {
	amqpConn.Close()

	amqp_url := os.Getenv("AMQP_URL")
	for {
		conn, err := amqp.Dial(amqp_url)
		if err != nil {
			log.Printf("Failed to connect to RabbitMQ: %s", err)
			time.Sleep(5 * time.Second)
		} else {
			amqpConn.conn = conn
			break
		}
	}
	amqpConn.conn.NotifyClose(amqpConn.error_chan)

	ch, err := amqpConn.conn.Channel()
	if err != nil {
		return err
	}
	amqpConn.channel = ch
	amqpConn.channel.NotifyClose(amqpConn.error_chan)

	go func() {
		for err := range amqpConn.error_chan {
			log.Printf("AMQP error: %s", err)
			amqpConn.Connect()
			log.Println("Reconnected to RabbitMQ")
			for _, observer := range amqpConn.observers {
				observer <- true
				log.Println("Notified observer")
			}
		}
	}()

	return nil
}

func (amqpConn *AMQPConnection) ConnectToQueue(name string, routing_key string) (<-chan amqp.Delivery, error) {
	q, err := amqpConn.channel.QueueDeclare(
		name,  // name
		false, // durable
		false, // delete when unused
		true,  // exclusive
		false, // no-wait
		nil,   // arguments
	)
	if err != nil {
		return nil, err
	}

	err = amqpConn.channel.QueueBind(
		q.Name,      // queue name
		routing_key, // routing key
		"amq.topic", // exchange
		false,
		nil,
	)
	if err != nil {
		return nil, err
	}

	msgs, err := amqpConn.channel.Consume(
		q.Name, // queue
		"",     // consumer
		true,   // auto ack
		false,  // exclusive
		false,  // no local
		false,  // no wait
		nil,    // args
	)
	if err != nil {
		return nil, err
	}

	return msgs, nil
}

func (amqpConn *AMQPConnection) NotifyError() <-chan bool {
	notify := make(chan bool)
	amqpConn.observers = append(amqpConn.observers, notify)
	return notify
}

func (amqpConn *AMQPConnection) Close() {
	if amqpConn.channel != nil {
		amqpConn.channel.Close()
	}

	if amqpConn.conn != nil {
		amqpConn.conn.Close()
	}

	amqpConn.channel = nil
	amqpConn.conn = nil
}