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consumer.go
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consumer.go
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package amqp
import (
"fmt"
"log"
"github.com/streadway/amqp"
)
type Consumer struct {
conn *amqp.Connection
channel *amqp.Channel
tag string
//done chan error
}
const (
ExchangeTopic string = amqp.ExchangeTopic
)
func NewConsumer(amqpURI, exchange, exchangeType, queueName, ctag string, keys []string) (*Consumer, error) {
c := &Consumer{
conn: nil,
channel: nil,
tag: ctag,
// done: make(chan error),
}
var err error
log.Printf("dialing %q", amqpURI)
c.conn, err = amqp.Dial(amqpURI)
if err != nil {
return nil, fmt.Errorf("Dial: %s", err)
}
go func() {
fmt.Printf("closing: %s", <-c.conn.NotifyClose(make(chan *amqp.Error)))
}()
log.Printf("got Connection, getting Channel")
c.channel, err = c.conn.Channel()
if err != nil {
return nil, fmt.Errorf("Channel: %s", err)
}
log.Printf("got Channel, declaring Exchange (%q)", exchange)
if err = c.channel.ExchangeDeclare(
exchange, // name of the exchange
exchangeType, // type
true, // durable
false, // delete when complete
false, // internal
false, // noWait
nil, // arguments
); err != nil {
return nil, fmt.Errorf("Exchange Declare: %s", err)
}
log.Printf("declared Exchange, declaring Queue %q", queueName)
queue, err := c.channel.QueueDeclare(
queueName, // name of the queue
true, // durable
false, // delete when unused
false, // exclusive
false, // noWait
nil, // arguments
)
if err != nil {
return nil, fmt.Errorf("Queue Declare: %s", err)
}
log.Printf("declared Queue (%q %d messages, %d consumers)", queue.Name, queue.Messages, queue.Consumers)
for _, key := range keys {
log.Printf("declared Queue (binding to Exchange (keys %q)", key)
if err = c.channel.QueueBind(
queue.Name, // name of the queue
key, // bindingKey
exchange, // sourceExchange
false, // noWait
nil, // arguments
); err != nil {
return nil, fmt.Errorf("Queue Bind: %s", err)
}
}
return c, nil
}
func (consumer *Consumer) Shutdown() error {
// will close() the deliveries channel
if err := consumer.channel.Cancel(consumer.tag, true); err != nil {
return fmt.Errorf("Consumer cancel failed: %s", err)
}
if err := consumer.conn.Close(); err != nil {
return fmt.Errorf("AMQP connection close error: %s", err)
}
defer log.Printf("AMQP consumer shutdown OK")
return nil
}
func (consumer *Consumer) Consume(queue_name string) (<-chan amqp.Delivery, error) {
log.Printf("starting Consume on queue %q (consumer tag %q)", queue_name, consumer.tag)
deliveries, err := consumer.channel.Consume(
queue_name, // name
consumer.tag, // consumerTag,
true, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
if err != nil {
return deliveries, fmt.Errorf("Queue Consume: %s", err)
}
return deliveries, err
}