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rabbitmq-tutorials/go/rpc_client.go
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package main | |
import ( | |
"context" | |
"log" | |
"math/rand" | |
"os" | |
"strconv" | |
"strings" | |
"time" | |
amqp "github.com/rabbitmq/amqp091-go" | |
) | |
func failOnError(err error, msg string) { | |
if err != nil { | |
log.Panicf("%s: %s", msg, err) | |
} | |
} | |
func randomString(l int) string { | |
bytes := make([]byte, l) | |
for i := 0; i < l; i++ { | |
bytes[i] = byte(randInt(65, 90)) | |
} | |
return string(bytes) | |
} | |
func randInt(min int, max int) int { | |
return min + rand.Intn(max-min) | |
} | |
func fibonacciRPC(n int) (res int, err error) { | |
conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/") | |
failOnError(err, "Failed to connect to RabbitMQ") | |
defer conn.Close() | |
ch, err := conn.Channel() | |
failOnError(err, "Failed to open a channel") | |
defer ch.Close() | |
q, err := ch.QueueDeclare( | |
"", // name | |
false, // durable | |
false, // delete when unused | |
true, // exclusive | |
false, // noWait | |
nil, // arguments | |
) | |
failOnError(err, "Failed to declare a queue") | |
msgs, err := ch.Consume( | |
q.Name, // queue | |
"", // consumer | |
true, // auto-ack | |
false, // exclusive | |
false, // no-local | |
false, // no-wait | |
nil, // args | |
) | |
failOnError(err, "Failed to register a consumer") | |
corrId := randomString(32) | |
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second) | |
defer cancel() | |
err = ch.PublishWithContext(ctx, | |
"", // exchange | |
"rpc_queue", // routing key | |
false, // mandatory | |
false, // immediate | |
amqp.Publishing{ | |
ContentType: "text/plain", | |
CorrelationId: corrId, | |
ReplyTo: q.Name, | |
Body: []byte(strconv.Itoa(n)), | |
}) | |
failOnError(err, "Failed to publish a message") | |
for d := range msgs { | |
if corrId == d.CorrelationId { | |
res, err = strconv.Atoi(string(d.Body)) | |
failOnError(err, "Failed to convert body to integer") | |
break | |
} | |
} | |
return | |
} | |
func main() { | |
rand.Seed(time.Now().UTC().UnixNano()) | |
n := bodyFrom(os.Args) | |
log.Printf(" [x] Requesting fib(%d)", n) | |
res, err := fibonacciRPC(n) | |
failOnError(err, "Failed to handle RPC request") | |
log.Printf(" [.] Got %d", res) | |
} | |
func bodyFrom(args []string) int { | |
var s string | |
if (len(args) < 2) || os.Args[1] == "" { | |
s = "30" | |
} else { | |
s = strings.Join(args[1:], " ") | |
} | |
n, err := strconv.Atoi(s) | |
failOnError(err, "Failed to convert arg to integer") | |
return n | |
} |