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consumer.go
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consumer.go
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package main
import (
"fmt"
"github.com/streadway/amqp"
"log"
)
type Consumer struct {
connection *amqp.Connection
channel *amqp.Channel
tag string
done chan error
}
func NewConsumer(amqpURI, exchange, exchangeType, queue, key, ctag string) (*Consumer, error) {
c := &Consumer{
connection: nil,
channel: nil,
tag: ctag,
done: make(chan error),
}
var err error
log.Printf("Connecting to %s", amqpURI)
c.connection, err = amqp.Dial(amqpURI)
if err != nil {
return nil, fmt.Errorf("Dial: %s", err)
}
log.Printf("Getting Channel")
c.channel, err = c.connection.Channel()
if err != nil {
return nil, fmt.Errorf("hannel: %s", err)
}
log.Printf("Declaring Exchange (%s)", 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("Declaring Queue (%s)", queue)
state, err := c.channel.QueueDeclare(
queue, // name of the queue
true, // durable
false, // delete when usused
false, // exclusive
false, // noWait
nil, // arguments
)
if err != nil {
return nil, fmt.Errorf("Queue Declare: %s", err)
}
log.Printf("Declared Queue (%d messages, %d consumers), binding to Exchange (key '%s')", state.Messages, state.Consumers, key)
if err = c.channel.QueueBind(
queue, // name of the queue
key, // routingKey
exchange, // sourceExchange
false, // noWait
nil, // arguments
); err != nil {
return nil, fmt.Errorf("Queue Bind: %s", err)
}
log.Printf("Queue bound to Exchange, starting Consume (consumer tag '%s')", c.tag)
deliveries, err := c.channel.Consume(
queue, // name
c.tag, // consumerTag,
true, // autoAck
false, // exclusive
false, // noLocal
false, // noWait
nil, // arguments
)
if err != nil {
return nil, fmt.Errorf("Queue Consume: %s", err)
}
go handle(deliveries, c.done)
return c, nil
}
func (c *Consumer) Shutdown() error {
// will close() the deliveries channel
if err := c.channel.Cancel(c.tag, true); err != nil {
return fmt.Errorf("Consumer cancel failed: %s", err)
}
if err := c.connection.Close(); err != nil {
return fmt.Errorf("AMQP connection close error: %s", err)
}
defer log.Printf("AMQP shutdown OK")
// wait for handle() to exit
return <-c.done
}
func handle(deliveries <-chan amqp.Delivery, done chan error) {
for d := range deliveries {
log.Printf(
"Got %dB delivery: [%v] %s",
len(d.Body),
d.DeliveryTag,
d.Body,
)
}
log.Printf("Handle: deliveries channel closed")
done <- nil
}