Hello World
```mermaid
expectations
+———-+ +——————+ +———-+ | producer | –> | [ queue:foobar ] | –> | consumer | +———-+ +——————+ +———-+
reality
+———-+ +——————-+ +——————-+ +———-+ | producer | –> | (exchange:foobar) | –> | [ queue:foobar ] | –> | consumer | +———-+ +——————-+ +——————-+ +———-+
### Connection
```go
import (
"context"
"fmt"
"log"
"time"
"github.com/streadway/amqp"
)
var addr = "amqp://admin:admin@rabbitmq1:5672/"
var (
connect func(addr string) (*amqp.Connection, error)
handle func (addr string, ch chan *amqp.Error, conn *amqp.Connection)
)
connect = func(addr string) (*amqp.Connection, error) {
conn, err := amqp.Dial(addr);
connErrorChan := conn.NotifyClose(make(chan *amqp.Error))
go handle(addr, connErrorChan, conn)
return conn, err
}
handle = func(addr string, ch chan *amqp.Error, conn *amqp.Connection) {
err := <- ch
fmt.Println("connection lost... ")
t1 := time.Now()
for {
c, err := connect(addr)
if err != nil {
break
}
fmt.Printf("reconnected in %s...\n", time.Since(t1))
conn = c
}
}
conn, err := connect(addr);
if err != nil {
log.Fatal(err)
}
#Code
type Queue struct {
Name string
Durable bool
Exclusive bool
AutoDelete bool
NoWait bool
Args amqp.Table
}
type Exchange struct {
Name string
Type string
Durable bool
AutoDelete bool
Internal bool
NoWait bool
Args amqp.Table
}
type PublishOptions struct {
Exchange string
Routing string
Mandatory bool
Immediate bool
}
type ConsumeOptions struct {
Queue string
Name string
NoLocal bool
NoAck bool
Exclusive bool
NoWait bool
Args amqp.Table
}
func QueueDeclare(ch *amqp.Channel, q Queue) (amqp.Queue, error) {
if q.Args == nil {
q.Args = amqp.Table{}
}
return ch.QueueDeclare(q.Name, q.Durable, q.AutoDelete, q.Exclusive, q.NoWait, q.Args)
}
func DeleteQueue(ch *amqp.Channel, name string) (string, error) {
cnt, err := ch.QueueDelete(name, false, false, true)
return fmt.Sprintf("Deleted %d messages", cnt), err
}
func CreateExchange(ch *amqp.Channel, e Exchange) error {
if e.Args == nil {
e.Args = amqp.Table{}
}
return ch.ExchangeDeclare(e.Name, e.Type, e.Durable, e.AutoDelete, e.Internal, e.NoWait, e.Args)
}
func Publish(ch *amqp.Channel, p PublishOptions, m amqp.Publishing) error {
return ch.Publish(p.Exchange, p.Routing, p.Mandatory, p.Immediate, m)
}
func Consume(ch *amqp.Channel, c ConsumeOptions) (<-chan amqp.Delivery, error) {
if c.Args == nil {
c.Args = amqp.Table{}
}
return ch.Consume(c.Queue, c.Name, c.NoAck, c.Exclusive, c.NoLocal, c.NoWait, c.Args)
}
import "math/rand"
import "context"
func Consumer(done chan struct{}, consumer ConsumeOptions, messages <-chan amqp.Delivery) {
fmt.Printf("Start Consumer: %s\n", consumer.Name)
defer fmt.Printf("Exiting consumer: %s\n", consumer.Name)
for {
// random deley helps to switch consumers to other goroutines
time.Sleep(time.Duration(rand.Int63n(10)) * time.Millisecond)
select {
case m, ok := <-messages:
if !ok {
continue
}
if len(m.Body) == 0 {
time.Sleep(time.Second)
continue
}
fmt.Printf("%s > %s\n", consumer.Name, string(m.Body))
case <-done:
return
default:
}
}
}
#Example
done := make(chan struct{})
ch, err := conn.Channel()
if err != nil {
log.Fatal("foo", err)
}
queue, err := QueueDeclare(ch, Queue{Name: "hello-world"})
if err != nil {
log.Fatal("bar", err)
}
queue
result >>> {hello-world 0 0}
options := PublishOptions{
Routing: queue.Name,
}
for i := 0; i < 5; i++ {
Publish(ch, options, amqp.Publishing{
Body: []byte(fmt.Sprintf("Event #%d", i)),
})
}
// --- Consuming --------------------------------------------------------------
cons := ConsumeOptions{
Name: fmt.Sprint("helloworld-reader"),
Queue: queue.Name,
NoAck: true,
}
chMsg, err := Consume(ch, cons)
fmt.Printf("Consumer, %v\n", err)
go Consumer(done, cons, chMsg)
time.Sleep(time.Second)
> Consumer, <nil>
> Start Consumer: helloworld-reader
> helloworld-reader > Event #0
> helloworld-reader > Event #1
> helloworld-reader > Event #2
> helloworld-reader > Event #3
> helloworld-reader > Event #4
// --- Cleanup --------------------------------------------------------------
time.AfterFunc(1*time.Second, func(){
fmt.Println("Cleanup...")
close(done)
i, err := ch.QueueInspect(queue.Name)
fmt.Sprintf("%#v", i)
DeleteQueue(ch, queue.Name)
ch.Close()
})
<-done
time.Sleep(time.Second)
> Cleanup...
> Exiting consumer: helloworld-reader