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forked from mjolk/rabbitmq-cli-consumer
/
consumer.go
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/
consumer.go
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package consumer
import (
"bytes"
"compress/zlib"
"encoding/base64"
"errors"
"fmt"
"github.com/nucleus-be/rabbitmq-cli-consumer/command"
"github.com/nucleus-be/rabbitmq-cli-consumer/config"
"github.com/streadway/amqp"
"io/ioutil"
"log"
"math/rand"
"net/url"
"os/exec"
"strconv"
"time"
"encoding/json"
)
type Consumer struct {
Channel *amqp.Channel
Connection *amqp.Connection
Queue string
Factory *command.CommandFactory
ErrLogger *log.Logger
InfLogger *log.Logger
Executer *command.CommandExecuter
DeadLetter bool
Retry int
Compression bool
WriteToPath string
}
func (c *Consumer) Consume() {
c.InfLogger.Println("Registering consumer... ")
msgs, err := c.Channel.Consume(c.Queue, "", false, false, false, false, nil)
if err != nil {
c.ErrLogger.Fatalf("Failed to register a consumer: %s", err)
}
c.InfLogger.Println("Succeeded registering consumer.")
var sendCh *amqp.Channel
if c.DeadLetter {
var err error
sendCh, err = c.Connection.Channel()
if err != nil {
c.ErrLogger.Println("Could not open channel to republish failed jobs %s", err)
}
defer sendCh.Close()
}
defer c.Connection.Close()
defer c.Channel.Close()
forever := make(chan bool)
go func() {
for d := range msgs {
c.InfLogger.Println("reading deliveries")
input := d.Body
if c.Compression {
var b bytes.Buffer
w, err := zlib.NewWriterLevel(&b, zlib.BestCompression)
if err != nil {
c.ErrLogger.Println("Could not create zlib handler")
d.Nack(true, true)
}
c.InfLogger.Println("Compressed message")
w.Write(input)
w.Close()
input = b.Bytes()
}
if c.DeadLetter {
var retryCount int
if d.Headers == nil {
d.Headers = make(map[string]interface{}, 0)
}
retry, ok := d.Headers["retry_count"]
if !ok {
retry = "0"
}
c.InfLogger.Println(fmt.Sprintf("retry %s", retry))
retryCount, err = strconv.Atoi(retry.(string))
if err != nil {
c.ErrLogger.Fatal("could not parse retry header")
}
c.InfLogger.Println(fmt.Sprintf("retryCount : %d max retries: %d", retryCount, c.Retry))
var cmd *exec.Cmd
if c.WriteToPath != "" {
var filepath string
filepath += c.WriteToPath
filepath += c.Queue
filepath += "-"
filepath += time.Now().Format("20060102150405")
filepath += "-"
filepath += strconv.FormatInt(rand.Int63(), 10) // Convert random int to string
filepath += ".json"
cmd = c.Factory.Create(filepath)
jsonContent := jsonPrettyPrint(input) // Pretty print
err := ioutil.WriteFile(filepath, []byte(jsonContent), 0644)
if err != nil {
c.ErrLogger.Println("Could not write input to file")
d.Nack(true, true)
}
} else {
cmd = c.Factory.Create(base64.StdEncoding.EncodeToString(input))
}
if c.Executer.Execute(cmd, d.Body[:]) {
d.Ack(true)
} else if retryCount >= c.Retry {
d.Nack(true, false)
} else {
//republish message with new retry header
retryCount++
d.Headers["retry_count"] = strconv.Itoa(retryCount)
republish := amqp.Publishing{
ContentType: d.ContentType,
ContentEncoding: d.ContentEncoding,
Timestamp: time.Now(),
Body: d.Body,
Headers: d.Headers,
}
err = sendCh.Publish("", c.Queue, false, false, republish)
if err != nil {
c.ErrLogger.Println("error republish %s", err)
}
d.Ack(true)
}
} else {
cmd := c.Factory.Create(base64.StdEncoding.EncodeToString(input))
if c.Executer.Execute(cmd, d.Body[:]) {
d.Ack(true)
} else {
d.Nack(true, false)
}
}
}
}()
c.InfLogger.Println("Waiting for messages...")
<-forever
}
func New(cfg *config.Config, factory *command.CommandFactory, errLogger, infLogger *log.Logger) (*Consumer, error) {
uri := fmt.Sprintf(
"amqp://%s:%s@%s:%s%s",
url.QueryEscape(cfg.RabbitMq.Username),
url.QueryEscape(cfg.RabbitMq.Password),
cfg.RabbitMq.Host,
cfg.RabbitMq.Port,
cfg.RabbitMq.Vhost,
)
infLogger.Println("Connecting RabbitMQ...")
conn, err := amqp.Dial(uri)
if nil != err {
return nil, errors.New(fmt.Sprintf("Failed connecting RabbitMQ: %s", err.Error()))
}
infLogger.Println("Connected.")
infLogger.Println("Opening channel...")
ch, err := conn.Channel()
if nil != err {
return nil, errors.New(fmt.Sprintf("Failed to open a channel: %s", err.Error()))
}
infLogger.Println("Done.")
infLogger.Println("Setting QoS... ")
// Attempt to preserve BC here
if cfg.Prefetch.Count == 0 {
cfg.Prefetch.Count = 3
}
if err := ch.Qos(cfg.Prefetch.Count, 0, cfg.Prefetch.Global); err != nil {
return nil, errors.New(fmt.Sprintf("Failed to set QoS: %s", err.Error()))
}
infLogger.Println("Succeeded setting QoS.")
// Check for missing exchange settings to preserve BC
if "" == cfg.Exchange.Name && "" == cfg.Exchange.Type && !cfg.Exchange.Durable && !cfg.Exchange.Autodelete {
cfg.Exchange.Type = "direct"
}
var table map[string]interface{}
deadLetter := false
if "" != cfg.Deadexchange.Name {
infLogger.Printf("Declaring deadletter exchange \"%s\"...", cfg.Deadexchange.Name)
err = ch.ExchangeDeclare(cfg.Deadexchange.Name, cfg.Deadexchange.Type, cfg.Deadexchange.Durable, cfg.Deadexchange.AutoDelete, false, false, amqp.Table{})
if nil != err {
return nil, errors.New(fmt.Sprintf("Failed to declare exchange: %s", err.Error()))
}
table = make(map[string]interface{}, 0)
table["x-dead-letter-exchange"] = cfg.Deadexchange.Name
table["x-dead-letter-routing-key"] = cfg.Queue.Key
infLogger.Printf("Declaring error queue \"%s\"...", cfg.Deadexchange.Queue)
_, err = ch.QueueDeclare(cfg.Deadexchange.Queue, true, false, false, false, amqp.Table{})
// Bind queue
infLogger.Printf("Binding error queue \"%s\" to dead letter exchange \"%s\"...", cfg.Deadexchange.Queue, cfg.Deadexchange.Name)
err = ch.QueueBind(cfg.Deadexchange.Queue, cfg.Queue.Key, cfg.Deadexchange.Name, false, amqp.Table{})
if nil != err {
return nil, errors.New(fmt.Sprintf("Failed to bind queue to dead-letter exchange: %s", err.Error()))
}
deadLetter = true
}
// Empty Exchange name means default, no need to declare
if "" != cfg.Exchange.Name {
infLogger.Printf("Declaring exchange \"%s\"...", cfg.Exchange.Name)
err = ch.ExchangeDeclare(cfg.Exchange.Name, cfg.Exchange.Type, cfg.Exchange.Durable, cfg.Exchange.Autodelete, false, false, amqp.Table{})
if nil != err {
return nil, errors.New(fmt.Sprintf("Failed to declare exchange: %s", err.Error()))
}
if 0 != cfg.Queue.Max_Length {
table["x-max-length"] = cfg.Queue.Max_Length
}
//binding to exchange
infLogger.Printf("Declaring queue \"%s\"...with args: %+v", cfg.Queue.Name, table)
_, err = ch.QueueDeclare(cfg.Queue.Name, true, false, false, false, table)
if nil != err {
return nil, errors.New(fmt.Sprintf("Failed to declare queue: %s", err.Error()))
}
// Bind queue with key
infLogger.Printf("Binding queue \"%s\" to exchange \"%s\"...", cfg.Queue.Name, cfg.Exchange.Name)
err = ch.QueueBind(cfg.Queue.Name, cfg.Queue.Key, cfg.Exchange.Name, false, table)
if nil != err {
return nil, errors.New(fmt.Sprintf("Failed to bind queue exchange: %s", err.Error()))
}
}
return &Consumer{
Channel: ch,
Connection: conn,
Queue: cfg.Queue.Name,
Factory: factory,
ErrLogger: errLogger,
InfLogger: infLogger,
Executer: command.New(errLogger, infLogger),
Compression: cfg.RabbitMq.Compression,
DeadLetter: deadLetter,
Retry: cfg.Deadexchange.Retry,
WriteToPath: cfg.Output.Path,
}, nil
}
func jsonPrettyPrint(in []byte) string {
var out bytes.Buffer
err := json.Indent(&out, in, "", "\t")
if err != nil {
return string(bytes.IndexByte(in, 0))
}
return out.String()
}