package rabbitmq
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import (
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"errors"
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"fmt"
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amqp "github.com/rabbitmq/amqp091-go"
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"github.com/wagslane/go-rabbitmq/internal/connectionmanager"
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"github.com/wagslane/go-rabbitmq/internal/logger"
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)
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// Action is an action that occurs after processed this delivery
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type Action int
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// Handler defines the handler of each Delivery and return Action
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type Handler func(d Delivery) (action Action)
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const (
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// Ack default ack this msg after you have successfully processed this delivery.
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Ack Action = iota
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// NackDiscard the message will be dropped or delivered to a server configured dead-letter queue.
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NackDiscard
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// NackRequeue deliver this message to a different consumer.
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NackRequeue
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)
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// Consumer allows you to create and connect to queues for data consumption.
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type Consumer struct {
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connManager *connectionmanager.ConnectionManager
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reconnectErrCh <-chan error
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closeConnectionToManagerCh chan<- struct{}
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options ConsumerOptions
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}
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// ConsumerOptions are used to describe a consumer's configuration.
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// Logger specifies a custom Logger interface implementation.
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type ConsumerOptions struct {
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Logger logger.Logger
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}
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// Delivery captures the fields for a previously delivered message resident in
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// a queue to be delivered by the server to a consumer from Channel.Consume or
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// Channel.Get.
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type Delivery struct {
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amqp.Delivery
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}
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// NewConsumer returns a new Consumer connected to the given rabbitmq server
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func NewConsumer(conn *Conn, optionFuncs ...func(*ConsumerOptions)) (*Consumer, error) {
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options := &ConsumerOptions{
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Logger: &stdDebugLogger{},
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}
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for _, optionFunc := range optionFuncs {
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optionFunc(options)
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}
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if conn.connectionManager == nil {
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return nil, errors.New("connection manager can't be nil")
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}
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reconnectErrCh, closeCh := conn.connectionManager.NotifyReconnect()
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consumer := &Consumer{
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connManager: conn.connectionManager,
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reconnectErrCh: reconnectErrCh,
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closeConnectionToManagerCh: closeCh,
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options: *options,
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}
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return consumer, nil
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}
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// WithConsumerOptionsLogging uses a default logger that writes to std out
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func WithConsumerOptionsLogging(options *ConsumerOptions) {
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options.Logger = &stdDebugLogger{}
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}
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// WithConsumerOptionsLogger sets logging to a custom interface.
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// Use WithConsumerOptionsLogging to just log to stdout.
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func WithConsumerOptionsLogger(log logger.Logger) func(options *ConsumerOptions) {
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return func(options *ConsumerOptions) {
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options.Logger = log
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}
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}
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// StartConsuming starts n goroutines where n="ConsumeOptions.QosOptions.Concurrency".
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// Each goroutine spawns a handler that consumes off of the given queue which binds to the routing key(s).
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// The provided handler is called once for each message. If the provided queue doesn't exist, it
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// will be created on the cluster
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func (consumer *Consumer) StartConsuming(
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handler Handler,
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queue string,
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optionFuncs ...func(*ConsumeOptions),
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) error {
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defaultOptions := getDefaultConsumeOptions(queue)
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options := &defaultOptions
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for _, optionFunc := range optionFuncs {
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optionFunc(options)
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}
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err := consumer.startGoroutines(
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handler,
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*options,
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)
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if err != nil {
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return err
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}
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go func() {
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for err := range consumer.reconnectErrCh {
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consumer.options.Logger.Infof("successful recovery from: %v", err)
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err = consumer.startGoroutines(
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handler,
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*options,
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)
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if err != nil {
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consumer.options.Logger.Errorf("error restarting consumer goroutines after cancel or close: %v", err)
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}
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}
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}()
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return nil
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}
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// Close cleans up resources and closes the consumer.
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// It does not close the connection manager, just the subscription
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// to the connection manager
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func (consumer *Consumer) Close() {
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consumer.options.Logger.Infof("closing consumer...")
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consumer.closeConnectionToManagerCh <- struct{}{}
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}
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// startGoroutines declares the queue if it doesn't exist,
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// binds the queue to the routing key(s), and starts the goroutines
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// that will consume from the queue
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func (consumer *Consumer) startGoroutines(
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handler Handler,
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options ConsumeOptions,
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) error {
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err := declareExchange(consumer.connManager, options.ExchangeOptions)
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if err != nil {
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return fmt.Errorf("declare exchange failed: %w", err)
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}
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err = declareQueue(consumer.connManager, options.QueueOptions)
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if err != nil {
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return fmt.Errorf("declare queue failed: %w", err)
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}
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err = declareBindings(consumer.connManager, options)
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if err != nil {
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return fmt.Errorf("declare bindings failed: %w", err)
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}
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msgs, err := consumer.connManager.ConsumeSafe(
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options.QueueOptions.Name,
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options.RabbitConsumerOptions.Name,
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options.RabbitConsumerOptions.AutoAck,
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options.RabbitConsumerOptions.Exclusive,
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false, // no-local is not supported by RabbitMQ
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options.RabbitConsumerOptions.NoWait,
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tableToAMQPTable(options.RabbitConsumerOptions.Args),
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)
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if err != nil {
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return err
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}
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for i := 0; i < options.Concurrency; i++ {
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go handlerGoroutine(consumer, msgs, options, handler)
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}
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consumer.options.Logger.Infof("Processing messages on %v goroutines", options.Concurrency)
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return nil
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}
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func handlerGoroutine(consumer *Consumer, msgs <-chan amqp.Delivery, consumeOptions ConsumeOptions, handler Handler) {
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for msg := range msgs {
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if consumeOptions.RabbitConsumerOptions.AutoAck {
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handler(Delivery{msg})
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continue
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}
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switch handler(Delivery{msg}) {
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case Ack:
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err := msg.Ack(false)
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if err != nil {
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consumer.options.Logger.Errorf("can't ack message: %v", err)
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}
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case NackDiscard:
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err := msg.Nack(false, false)
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if err != nil {
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consumer.options.Logger.Errorf("can't nack message: %v", err)
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}
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case NackRequeue:
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err := msg.Nack(false, true)
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if err != nil {
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consumer.options.Logger.Errorf("can't nack message: %v", err)
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}
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}
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}
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consumer.options.Logger.Infof("rabbit consumer goroutine closed")
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}
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