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main.go
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main.go
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package rabbitmq
import (
"fmt"
"log/slog"
"os"
"time"
"context"
amqp "github.com/rabbitmq/amqp091-go"
)
var logger = slog.New(slog.NewJSONHandler(os.Stdout, nil))
type MessageCenter struct {
ServerUrl string
Connection *amqp.Connection
Channel *amqp.Channel
}
func (m *MessageCenter) Connect(channel string, attempts int, intervalSeconds int) error {
interval := time.Duration(intervalSeconds) * time.Second
var conn *amqp.Connection
var err error
for i := 0; i < attempts; i++ {
conn, err = amqp.Dial(m.ServerUrl)
logger.Info(fmt.Sprintf("Waiting for RabbitMQ Connection. Attempt %d\n", i+1))
if conn == nil {
time.Sleep(interval)
}
}
if conn != nil {
logger.Info("Connection is successful!")
m.Connection = conn
m.Channel, err = m.Connection.Channel()
if err != nil {
panic(err)
}
return nil
} else {
logger.Info("Connection timed out")
return err
}
}
func (m *MessageCenter) CreateQueue(name string, durable bool, deleteUnused bool,
exclusive bool, noWait bool, arguments map[string]interface{}) error {
logger.Info(fmt.Sprintf("Creating queue: %s", name))
_, err := m.Channel.QueueDeclare(name, durable, deleteUnused, exclusive, noWait, arguments)
if err != nil {
return err
}
return nil
}
func (m *MessageCenter) ReceiveMessage(replyChannel chan string, queue string) {
// Listen for messages
messages, err := m.ConsumeMessage(queue, "", true, false, false, false, nil)
if err != nil {
logger.Error(err.Error())
}
for message := range messages {
// Continue to receive messages
logger.Info(fmt.Sprintf("Received message on %s", queue))
logger.Debug(fmt.Sprintf("Received message on %s: %s", queue, message.Body))
replyChannel <- string(message.Body)
}
}
func (m *MessageCenter) PublishMessage(queue string, message []byte, exchange string, mandatory bool, immediate bool, contentType string, correlationId string, replyTo string) error {
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
logger.Info(fmt.Sprintf("Publishing message on queue: %s", queue))
logger.Debug(fmt.Sprintf("Publishing message %v on queue: %s", message, queue))
err := m.Channel.PublishWithContext(ctx,
exchange, // exchange ""
queue, // routing key
mandatory, // mandatory
immediate, // immediate
amqp.Publishing{
CorrelationId: correlationId,
ReplyTo: replyTo,
ContentType: contentType, //"text/plain"
Body: message,
})
if err != nil {
return err
} else {
return nil
}
}
func (m *MessageCenter) ConsumeMessage(queue string, consumer string, autoAck bool, exclusive bool,
noLocal bool, noWait bool, arguments map[string]interface{}) (<-chan amqp.Delivery, error) {
logger.Info(fmt.Sprintf("Consuming on queue: %s", queue))
messages, err := m.Channel.Consume(
queue, // queue name
consumer, // consumer ""
autoAck, // auto-ack true
exclusive, // exclusive false
noLocal, // no local false
noWait, // no wait false
arguments, // arguments nil
)
if err != nil {
return nil, err
}
return messages, nil
}
func (s *Saga) StartSaga(m *MessageCenter) {
/*
err := messageCenter.Connect(e.ChannelName, 5, 5)
if err != nil {
panic(err)
}
defer messageCenter.Connection.Close()
defer messageCenter.Channel.Close()
*/
// Loop through steps
for _, step := range s.SagaSteps {
logger.Info(fmt.Sprintf("Step: %s", step.StepName))
if step.ActionType == "publish_and_confirm" {
// Create reply queue
err := m.CreateQueue(step.ReplyQueueName, false, false, false, false, nil)
if err != nil {
panic(err)
}
// Publish message
err = m.PublishMessage(step.QueueName, step.DataObject, "", false, false, "text/plain", s.CorrelationId, step.ReplyQueueName)
if err != nil {
panic(err)
}
// Wait for reply
// Startup service channels
replyChannel := make(chan string)
go m.ReceiveMessage(replyChannel, step.ReplyQueueName)
<-replyChannel
}
}
}