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amqp.go
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amqp.go
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package amqp
import (
"bytes"
"context"
"encoding/json"
"fmt"
"github.com/pkg/errors"
"github.com/qq992936/machinery/v1/brokers/errs"
"github.com/qq992936/machinery/v1/brokers/iface"
"github.com/qq992936/machinery/v1/common"
"github.com/qq992936/machinery/v1/config"
"github.com/qq992936/machinery/v1/tasks"
"github.com/qq992936/machinery/v2/log"
"github.com/streadway/amqp"
"sync"
"time"
)
type AMQPConnection struct {
queueName string
connection *amqp.Connection
channel *amqp.Channel
queue amqp.Queue
confirmation <-chan amqp.Confirmation
errorchan <-chan *amqp.Error
cleanup chan struct{}
}
// Broker represents an AMQP broker
type Broker struct {
common.Broker
common.AMQPConnector
processingWG sync.WaitGroup // use wait group to make sure task processing completes on interrupt signal
connections map[string]*AMQPConnection
connectionsMutex sync.RWMutex
}
// New creates new Broker instance
func New(cnf *config.Config) iface.Broker {
return &Broker{Broker: common.NewBroker(cnf), AMQPConnector: common.AMQPConnector{}, connections: make(map[string]*AMQPConnection)}
}
// StartConsuming enters a loop and waits for incoming messages
func (b *Broker) StartConsuming(consumerTag string, concurrency int, taskProcessor iface.TaskProcessor) (bool, error) {
b.Broker.StartConsuming(consumerTag, concurrency, taskProcessor)
queueName := taskProcessor.CustomQueue()
if queueName == "" {
queueName = b.GetConfig().DefaultQueue
}
conn, channel, queue, _, amqpCloseChan, err := b.Connect(
b.GetConfig().Broker,
b.GetConfig().MultipleBrokerSeparator,
b.GetConfig().TLSConfig,
b.GetConfig().AMQP.Exchange, // exchange name
b.GetConfig().AMQP.ExchangeType, // exchange type
queueName, // queue name
true, // queue durable
false, // queue delete when unused
b.GetConfig().AMQP.BindingKey, // queue binding key
nil, // exchange declare args
amqp.Table(b.GetConfig().AMQP.QueueDeclareArgs), // queue declare args
amqp.Table(b.GetConfig().AMQP.QueueBindingArgs), // queue binding args
)
if err != nil {
b.GetRetryFunc()(b.GetRetryStopChan())
return b.GetRetry(), err
}
defer b.Close(channel, conn)
if err = channel.Qos(
b.GetConfig().AMQP.PrefetchCount,
0, // prefetch size
false, // global
); err != nil {
return b.GetRetry(), fmt.Errorf("Channel qos error: %s", err)
}
deliveries, err := channel.Consume(
queue.Name, // queue
consumerTag, // consumer tag
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // arguments
)
if err != nil {
return b.GetRetry(), fmt.Errorf("Queue consume error: %s", err)
}
log.INFO.Print("[*] Waiting for messages. To exit press CTRL+C")
if err := b.consume(deliveries, concurrency, taskProcessor, amqpCloseChan); err != nil {
return b.GetRetry(), err
}
// Waiting for any tasks being processed to finish
b.processingWG.Wait()
return b.GetRetry(), nil
}
// StopConsuming quits the loop
func (b *Broker) StopConsuming() {
b.Broker.StopConsuming()
// Waiting for any tasks being processed to finish
b.processingWG.Wait()
}
// GetOrOpenConnection will return a connection on a particular queue name. Open connections
// are saved to avoid having to reopen connection for multiple queues
func (b *Broker) GetOrOpenConnection(queueName string, queueBindingKey string, exchangeDeclareArgs, queueDeclareArgs, queueBindingArgs amqp.Table) (*AMQPConnection, error) {
var err error
b.connectionsMutex.Lock()
defer b.connectionsMutex.Unlock()
conn, ok := b.connections[queueName]
if !ok {
conn = &AMQPConnection{
queueName: queueName,
cleanup: make(chan struct{}),
}
conn.connection, conn.channel, conn.queue, conn.confirmation, conn.errorchan, err = b.Connect(
b.GetConfig().Broker,
b.GetConfig().MultipleBrokerSeparator,
b.GetConfig().TLSConfig,
b.GetConfig().AMQP.Exchange, // exchange name
b.GetConfig().AMQP.ExchangeType, // exchange type
queueName, // queue name
true, // queue durable
false, // queue delete when unused
queueBindingKey, // queue binding key
exchangeDeclareArgs, // exchange declare args
queueDeclareArgs, // queue declare args
queueBindingArgs, // queue binding args
)
if err != nil {
return nil, errors.Wrapf(err, "Failed to connect to queue %s", queueName)
}
// Reconnect to the channel if it disconnects/errors out
go func() {
select {
case err = <-conn.errorchan:
log.INFO.Printf("Error occurred on queue: %s. Reconnecting", queueName)
b.connectionsMutex.Lock()
delete(b.connections, queueName)
b.connectionsMutex.Unlock()
_, err := b.GetOrOpenConnection(queueName, queueBindingKey, exchangeDeclareArgs, queueDeclareArgs, queueBindingArgs)
if err != nil {
log.ERROR.Printf("Failed to reopen queue: %s.", queueName)
}
case <-conn.cleanup:
return
}
}()
b.connections[queueName] = conn
}
return conn, nil
}
func (b *Broker) CloseConnections() error {
b.connectionsMutex.Lock()
defer b.connectionsMutex.Unlock()
for key, conn := range b.connections {
if err := b.Close(conn.channel, conn.connection); err != nil {
log.ERROR.Print("Failed to close channel")
return nil
}
close(conn.cleanup)
delete(b.connections, key)
}
return nil
}
// Publish places a new message on the default queue
func (b *Broker) Publish(ctx context.Context, signature *tasks.Signature) error {
// Adjust routing key (this decides which queue the message will be published to)
b.AdjustRoutingKey(signature)
msg, err := json.Marshal(signature)
if err != nil {
return fmt.Errorf("JSON marshal error: %s", err)
}
// Check the ETA signature field, if it is set and it is in the future,
// delay the task
if signature.ETA != nil {
now := time.Now().UTC()
if signature.ETA.After(now) {
delayMs := int64(signature.ETA.Sub(now) / time.Millisecond)
return b.delay(signature, delayMs)
}
}
queue := b.GetConfig().DefaultQueue
bindingKey := b.GetConfig().AMQP.BindingKey // queue binding key
if b.isDirectExchange() {
queue = signature.RoutingKey
bindingKey = signature.RoutingKey
}
connection, err := b.GetOrOpenConnection(
queue,
bindingKey, // queue binding key
nil, // exchange declare args
amqp.Table(b.GetConfig().AMQP.QueueDeclareArgs), // queue declare args
amqp.Table(b.GetConfig().AMQP.QueueBindingArgs), // queue binding args
)
if err != nil {
return errors.Wrapf(err, "Failed to get a connection for queue %s", queue)
}
channel := connection.channel
confirmsChan := connection.confirmation
if err := channel.Publish(
b.GetConfig().AMQP.Exchange, // exchange name
signature.RoutingKey, // routing key
false, // mandatory
false, // immediate
amqp.Publishing{
Headers: amqp.Table(signature.Headers),
ContentType: "application/json",
Body: msg,
Priority: signature.Priority,
DeliveryMode: amqp.Persistent,
},
); err != nil {
return errors.Wrap(err, "Failed to publish task")
}
confirmed := <-confirmsChan
if confirmed.Ack {
return nil
}
return fmt.Errorf("Failed delivery of delivery tag: %v", confirmed.DeliveryTag)
}
// consume takes delivered messages from the channel and manages a worker pool
// to process tasks concurrently
func (b *Broker) consume(deliveries <-chan amqp.Delivery, concurrency int, taskProcessor iface.TaskProcessor, amqpCloseChan <-chan *amqp.Error) error {
pool := make(chan struct{}, concurrency)
// initialize worker pool with maxWorkers workers
go func() {
for i := 0; i < concurrency; i++ {
pool <- struct{}{}
}
}()
// make channel with a capacity makes it become a buffered channel so that a worker which wants to
// push an error to `errorsChan` doesn't need to be blocked while the for-loop is blocked waiting
// a worker, that is, it avoids a possible deadlock
errorsChan := make(chan error, 1)
for {
select {
case amqpErr := <-amqpCloseChan:
return amqpErr
case err := <-errorsChan:
return err
case d := <-deliveries:
if concurrency > 0 {
// get worker from pool (blocks until one is available)
<-pool
}
b.processingWG.Add(1)
// Consume the task inside a gotourine so multiple tasks
// can be processed concurrently
go func() {
if err := b.consumeOne(d, taskProcessor, true); err != nil {
errorsChan <- err
}
b.processingWG.Done()
if concurrency > 0 {
// give worker back to pool
pool <- struct{}{}
}
}()
case <-b.GetStopChan():
return nil
}
}
}
// consumeOne processes a single message using TaskProcessor
func (b *Broker) consumeOne(delivery amqp.Delivery, taskProcessor iface.TaskProcessor, ack bool) error {
if len(delivery.Body) == 0 {
delivery.Nack(true, false) // multiple, requeue
return errors.New("Received an empty message") // RabbitMQ down?
}
var multiple, requeue = false, false
// Unmarshal message body into signature struct
signature := new(tasks.Signature)
decoder := json.NewDecoder(bytes.NewReader(delivery.Body))
decoder.UseNumber()
if err := decoder.Decode(signature); err != nil {
delivery.Nack(multiple, requeue)
return errs.NewErrCouldNotUnmarshalTaskSignature(delivery.Body, err)
}
// If the task is not registered, we nack it and requeue,
// there might be different workers for processing specific tasks
if !b.IsTaskRegistered(signature.Name) {
requeue = true
log.INFO.Printf("Task not registered with this worker. Requeing message: %s", delivery.Body)
if !signature.IgnoreWhenTaskNotRegistered {
delivery.Nack(multiple, requeue)
}
return nil
}
log.DEBUG.Printf("Received new message: %s", delivery.Body)
err := taskProcessor.Process(signature)
if ack {
delivery.Ack(multiple)
}
return err
}
// delay a task by delayDuration miliseconds, the way it works is a new queue
// is created without any consumers, the message is then published to this queue
// with appropriate ttl expiration headers, after the expiration, it is sent to
// the proper queue with consumers
func (b *Broker) delay(signature *tasks.Signature, delayMs int64) error {
if delayMs <= 0 {
return errors.New("Cannot delay task by 0ms")
}
message, err := json.Marshal(signature)
if err != nil {
return fmt.Errorf("JSON marshal error: %s", err)
}
// It's necessary to redeclare the queue each time (to zero its TTL timer).
queueName := fmt.Sprintf(
"delay.%d.%s.%s",
delayMs, // delay duration in mileseconds
b.GetConfig().AMQP.Exchange,
signature.RoutingKey, // routing key
)
declareQueueArgs := amqp.Table{
// Exchange where to send messages after TTL expiration.
"x-dead-letter-exchange": b.GetConfig().AMQP.Exchange,
// Routing key which use when resending expired messages.
"x-dead-letter-routing-key": signature.RoutingKey,
// Time in milliseconds
// after that message will expire and be sent to destination.
"x-message-ttl": delayMs,
// Time after that the queue will be deleted.
"x-expires": delayMs * 2,
}
conn, channel, _, _, _, err := b.Connect(
b.GetConfig().Broker,
b.GetConfig().MultipleBrokerSeparator,
b.GetConfig().TLSConfig,
b.GetConfig().AMQP.Exchange, // exchange name
b.GetConfig().AMQP.ExchangeType, // exchange type
queueName, // queue name
true, // queue durable
b.GetConfig().AMQP.AutoDelete, // queue delete when unused
queueName, // queue binding key
nil, // exchange declare args
declareQueueArgs, // queue declare args
amqp.Table(b.GetConfig().AMQP.QueueBindingArgs), // queue binding args
)
if err != nil {
return err
}
defer b.Close(channel, conn)
if err := channel.Publish(
b.GetConfig().AMQP.Exchange, // exchange
queueName, // routing key
false, // mandatory
false, // immediate
amqp.Publishing{
Headers: amqp.Table(signature.Headers),
ContentType: "application/json",
Body: message,
DeliveryMode: amqp.Persistent,
},
); err != nil {
return err
}
return nil
}
func (b *Broker) isDirectExchange() bool {
return b.GetConfig().AMQP != nil && b.GetConfig().AMQP.ExchangeType == "direct"
}
// AdjustRoutingKey makes sure the routing key is correct.
// If the routing key is an empty string:
// a) set it to binding key for direct exchange type
// b) set it to default queue name
func (b *Broker) AdjustRoutingKey(s *tasks.Signature) {
if s.RoutingKey != "" {
return
}
if b.isDirectExchange() {
// The routing algorithm behind a direct exchange is simple - a message goes
// to the queues whose binding key exactly matches the routing key of the message.
s.RoutingKey = b.GetConfig().AMQP.BindingKey
return
}
s.RoutingKey = b.GetConfig().DefaultQueue
}
// Helper type for GetPendingTasks to accumulate signatures
type sigDumper struct {
customQueue string
Signatures []*tasks.Signature
}
func (s *sigDumper) Process(sig *tasks.Signature) error {
s.Signatures = append(s.Signatures, sig)
return nil
}
func (s *sigDumper) CustomQueue() string {
return s.customQueue
}
func (_ *sigDumper) PreConsumeHandler() bool {
return true
}
func (b *Broker) GetPendingTasks(queue string) ([]*tasks.Signature, error) {
if queue == "" {
queue = b.GetConfig().DefaultQueue
}
bindingKey := b.GetConfig().AMQP.BindingKey // queue binding key
conn, err := b.GetOrOpenConnection(
queue,
bindingKey, // queue binding key
nil, // exchange declare args
amqp.Table(b.GetConfig().AMQP.QueueDeclareArgs), // queue declare args
amqp.Table(b.GetConfig().AMQP.QueueBindingArgs), // queue binding args
)
if err != nil {
return nil, errors.Wrapf(err, "Failed to get a connection for queue %s", queue)
}
channel := conn.channel
queueInfo, err := channel.QueueInspect(queue)
if err != nil {
return nil, errors.Wrapf(err, "Failed to get info for queue %s", queue)
}
var tag uint64
defer channel.Nack(tag, true, true) // multiple, requeue
dumper := &sigDumper{customQueue: queue}
for i := 0; i < queueInfo.Messages; i++ {
d, _, err := channel.Get(queue, false)
if err != nil {
return nil, errors.Wrap(err, "Failed to get from queue")
}
tag = d.DeliveryTag
b.consumeOne(d, dumper, false)
}
return dumper.Signatures, nil
}