amqp.go

/*
Copyright (c) 2014 Ashley Jeffs

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

package input

import (
	"fmt"
	"sync/atomic"
	"time"

	"github.com/jeffail/benthos/lib/types"
	"github.com/jeffail/util/log"
	"github.com/jeffail/util/metrics"
	"github.com/streadway/amqp"
)

//--------------------------------------------------------------------------------------------------

func init() {
	constructors["amqp"] = typeSpec{
		constructor: NewAMQP,
		description: `
AMQP is the underlying messaging protocol that is used my RabbitMQ. Support is
currently rather limited, but more configuration options are on the way.

Exchange type options are: direct|fanout|topic|x-custom`,
	}
}

//--------------------------------------------------------------------------------------------------

// AMQPConfig - Configuration for the AMQP input type.
type AMQPConfig struct {
	URI           string `json:"uri" yaml:"uri"`
	Exchange      string `json:"exchange" yaml:"exchange"`
	ExchangeType  string `json:"exchange_type" yaml:"exchange_type"`
	Queue         string `json:"queue" yaml:"queue"`
	BindingKey    string `json:"key" yaml:"key"`
	ConsumerTag   string `json:"consumer_tag" yaml:"consumer_tag"`
	PrefetchCount int    `json:"prefetch_count"`
	PrefetchSize  int    `json:"prefetch_size"`
}

// NewAMQPConfig - Creates a new AMQPConfig with default values.
func NewAMQPConfig() AMQPConfig {
	return AMQPConfig{
		URI:           "amqp://guest:guest@localhost:5672/",
		Exchange:      "benthos-exchange",
		ExchangeType:  "direct",
		Queue:         "benthos-queue",
		BindingKey:    "benthos-key",
		ConsumerTag:   "benthos-consumer",
		PrefetchCount: 1,
		PrefetchSize:  0,
	}
}

//--------------------------------------------------------------------------------------------------

// AMQP - An input type that serves Scalability Protocols messages.
type AMQP struct {
	running int32

	conn         *amqp.Connection
	amqpChan     *amqp.Channel
	consumerChan <-chan amqp.Delivery

	conf  Config
	stats metrics.Type
	log   log.Modular

	messages  chan types.Message
	responses <-chan types.Response

	closeChan  chan struct{}
	closedChan chan struct{}
}

// NewAMQP - Create a new AMQP input type.
func NewAMQP(conf Config, log log.Modular, stats metrics.Type) (Type, error) {
	a := AMQP{
		running:    1,
		conf:       conf,
		stats:      stats,
		log:        log.NewModule(".input.amqp"),
		messages:   make(chan types.Message),
		responses:  nil,
		closeChan:  make(chan struct{}),
		closedChan: make(chan struct{}),
	}

	if err := a.connect(); err != nil {
		return nil, err
	}

	return &a, nil
}

//--------------------------------------------------------------------------------------------------

// connect - Establish a connection to an AMQP server.
func (a *AMQP) connect() (err error) {
	a.conn, err = amqp.Dial(a.conf.AMQP.URI)
	if err != nil {
		return fmt.Errorf("AMQP Connect: %s", err)
	}

	a.amqpChan, err = a.conn.Channel()
	if err != nil {
		return fmt.Errorf("AMQP Channel: %s", err)
	}

	if err = a.amqpChan.ExchangeDeclare(
		a.conf.AMQP.Exchange,     // name of the exchange
		a.conf.AMQP.ExchangeType, // type
		true,  // durable
		false, // delete when complete
		false, // internal
		false, // noWait
		nil,   // arguments
	); err != nil {
		return fmt.Errorf("Exchange Declare: %s", err)
	}

	if _, err = a.amqpChan.QueueDeclare(
		a.conf.AMQP.Queue, // name of the queue
		true,              // durable
		false,             // delete when usused
		false,             // exclusive
		false,             // noWait
		nil,               // arguments
	); err != nil {
		return fmt.Errorf("Queue Declare: %s", err)
	}

	if err = a.amqpChan.QueueBind(
		a.conf.AMQP.Queue,      // name of the queue
		a.conf.AMQP.BindingKey, // bindingKey
		a.conf.AMQP.Exchange,   // sourceExchange
		false,                  // noWait
		nil,                    // arguments
	); err != nil {
		return fmt.Errorf("Queue Bind: %s", err)
	}

	if err = a.amqpChan.Qos(
		a.conf.AMQP.PrefetchCount, a.conf.AMQP.PrefetchSize, false,
	); err != nil {
		return fmt.Errorf("Qos: %s", err)
	}

	if a.consumerChan, err = a.amqpChan.Consume(
		a.conf.AMQP.Queue,       // name
		a.conf.AMQP.ConsumerTag, // consumerTag,
		false, // noAck
		false, // exclusive
		false, // noLocal
		false, // noWait
		nil,   // arguments
	); err != nil {
		return fmt.Errorf("Queue Consume: %s", err)
	}

	return
}

// disconnect - Safely close a connection to an AMQP server.
func (a *AMQP) disconnect() error {
	if a.amqpChan != nil {
		if err := a.amqpChan.Cancel(a.conf.AMQP.ConsumerTag, true); err != nil {
			return fmt.Errorf("Consumer cancel failed: %s", err)
		}
		a.amqpChan = nil
	}
	if a.conn != nil {
		if err := a.conn.Close(); err != nil {
			return fmt.Errorf("AMQP connection close error: %s", err)
		}
		a.conn = nil
	}
	return nil
}

//--------------------------------------------------------------------------------------------------

func (a *AMQP) loop() {
	defer func() {
		atomic.StoreInt32(&a.running, 0)
		a.disconnect()

		close(a.messages)
		close(a.closedChan)
	}()

	var data *amqp.Delivery

	for atomic.LoadInt32(&a.running) == 1 {
		// If no bytes then read a message
		if data == nil {
			select {
			case msg := <-a.consumerChan:
				data = &msg
			case <-a.closeChan:
				return
			}
		}

		// If bytes are read then try and propagate.
		if data != nil {
			select {
			case a.messages <- types.Message{Parts: [][]byte{data.Body}}:
			case <-a.closeChan:
				return
			}
			res, open := <-a.responses
			if !open {
				return
			}
			if resErr := res.Error(); resErr == nil {
				a.stats.Incr("input.amqp.count", 1)
				data.Ack(false)
				data = nil
			} else if resErr == types.ErrMessageTooLarge {
				a.stats.Incr("input.amqp.send.rejected", 1)
				data = nil
			} else {
				a.stats.Incr("input.amqp.send.error", 1)
			}
		}
	}

}

// StartListening - Sets the channel used by the input to validate message receipt.
func (a *AMQP) StartListening(responses <-chan types.Response) error {
	if a.responses != nil {
		return types.ErrAlreadyStarted
	}
	a.responses = responses
	go a.loop()
	return nil
}

// MessageChan - Returns the messages channel.
func (a *AMQP) MessageChan() <-chan types.Message {
	return a.messages
}

// CloseAsync - Shuts down the AMQP input and stops processing requests.
func (a *AMQP) CloseAsync() {
	if atomic.CompareAndSwapInt32(&a.running, 1, 0) {
		close(a.closeChan)
	}
}

// WaitForClose - Blocks until the AMQP input has closed down.
func (a *AMQP) WaitForClose(timeout time.Duration) error {
	select {
	case <-a.closedChan:
	case <-time.After(timeout):
		return types.ErrTimeout
	}
	return nil
}

//--------------------------------------------------------------------------------------------------