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client.go
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client.go
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package rabbitmq
import (
"context"
"sync"
"time"
amqp "github.com/rabbitmq/amqp091-go"
)
type ClientConfig struct {
// this callback will be invoked whenever network failure happens or node shuts down
NetworkErrCallback func(*amqp.Error)
// note that this interval is taken into account when on reconnecting multiple times in row
AutoRecoveryInterval time.Duration
// this callback will be invoked whenever connection retry fails or resource freeing returns error
// returning value as bool should indicate whether to keep retrying recovery or not
AutoRecoveryErrCallback func(error) bool
// this callback will be called if restoring a consumer fails after recovery procedure
ConsumerAutoRecoveryErrCallback func(AMQPConsumer, error)
// configurations for setting up dial and new connection
DialCfg DialConfig
PublisherConfirmEnabled bool
PublisherConfirmNowait bool
ConsumerQos int
ConsumerPrefetchSize int
ConsumerGlobal bool
}
type Client struct {
cfg ClientConfig
consumers []AMQPConsumer
connection *amqp.Connection
publisherChan *amqp.Channel
consumerChan *amqp.Channel
mx sync.RWMutex
wg sync.WaitGroup
}
func NewClient(cfg ClientConfig) (*Client, error) {
client := Client{
cfg: cfg,
}
if err := client.connect(); err != nil {
return nil, err
}
return &client, nil
}
// Consume makes all necessary housekeeping stuff for creating an exchange, queue, queue-binding
// then starts new goroutine (if IConsumer is set) which starts receiving messages from rabbitmq-server
// safe for concurrent usage
func (c *Client) Consume(consumer AMQPConsumer) error {
c.mx.Lock()
defer c.mx.Unlock()
c.consumers = append(c.consumers, consumer)
return c.consume(consumer)
}
// Publish wrapper for amqp091-go PublishWithContext
func (c *Client) Publish(ctx context.Context, exchange, key string, mandatory, immediate bool, msg amqp.Publishing) error {
return c.publisherChan.PublishWithContext(ctx, exchange, key, mandatory, immediate, msg)
}
// PublishConfirm publishes message and waits for confirmation
// make sure `PublisherConfirmEnabled` is true in configuration
func (c *Client) PublishConfirm(ctx context.Context, exchange, key string, mandatory, immediate bool, msg amqp.Publishing) error {
defConfirm, err := c.publisherChan.PublishWithDeferredConfirmWithContext(ctx, exchange, key, mandatory, immediate, msg)
if err != nil {
return err
}
success := defConfirm.Wait()
if !success {
return NewErrPublishNotAcked(exchange, key, msg)
}
return nil
}
func (c *Client) Close() error {
var err error
if !c.connection.IsClosed() {
err = c.publisherChan.Close()
for _, consumer := range c.consumers {
err = c.consumerChan.Cancel(consumer.ConsumerID, false)
}
c.wg.Wait()
err = c.consumerChan.Close()
err = c.connection.Close()
}
return err
}
func (c *Client) connect() error {
conn, err := Dial(c.cfg.DialCfg)
if err != nil {
return err
}
// it's recommended to separate publisher and consumer channels in order to avoid heavy control-flows
// https://www.rabbitmq.com/channels.html#flow-control
publisherChannel, err := conn.Channel()
if err != nil {
return err
}
if c.cfg.PublisherConfirmEnabled {
if err := publisherChannel.Confirm(c.cfg.PublisherConfirmNowait); err != nil {
return err
}
}
// create new channel for consumer
consumerChannel, err := conn.Channel()
if err != nil {
return err
}
if err := consumerChannel.Qos(
c.cfg.ConsumerQos,
c.cfg.ConsumerPrefetchSize,
c.cfg.ConsumerGlobal,
); err != nil {
return err
}
// reassign
c.connection = conn
c.publisherChan = publisherChannel
c.consumerChan = consumerChannel
go func() {
errNotifyChan := c.connection.NotifyClose(make(chan *amqp.Error))
for connectionErr := range errNotifyChan {
c.cfg.NetworkErrCallback(connectionErr)
c.reconnect()
}
}()
return nil
}
func (c *Client) reconnect() {
if err := c.Close(); err != nil {
shouldContinue := c.cfg.AutoRecoveryErrCallback(err)
if !shouldContinue {
return
}
}
// try to connect
if err := c.connect(); err != nil {
shouldContinue := c.cfg.AutoRecoveryErrCallback(err)
if shouldContinue {
// when instant reconnect fails, try again after some time
time.AfterFunc(c.cfg.AutoRecoveryInterval, func() {
c.reconnect()
})
}
} else {
// connection was successful, so restore consumers
for _, consumerParam := range c.consumers {
if err := c.consume(consumerParam); err != nil {
c.cfg.ConsumerAutoRecoveryErrCallback(consumerParam, err)
}
}
}
}
func (c *Client) consume(consumer AMQPConsumer) error {
if err := c.consumerChan.ExchangeDeclare(
consumer.ExchangeParams.Name,
consumer.ExchangeParams.Type,
consumer.ExchangeParams.Durable,
consumer.ExchangeParams.AutoDelete,
consumer.ExchangeParams.Internal,
consumer.ExchangeParams.Nowait,
consumer.ExchangeParams.Args,
); err != nil {
return err
}
queue, err := c.consumerChan.QueueDeclare(
consumer.QueueParams.Name,
consumer.QueueParams.Durable,
consumer.QueueParams.AutoDelete,
consumer.QueueParams.Exclusive,
consumer.QueueParams.Nowait,
consumer.QueueParams.Args,
)
if err != nil {
return err
}
for _, key := range consumer.RoutingKeys {
// The default exchange is a `direct type` with no name (empty string) pre-declared by the broker.
// It has one special property that makes it very useful for simple applications:
// every queue that is created is automatically bound to it with a routing event which is the same as the queue name.
if consumer.ExchangeParams.Name != "" {
if err := c.consumerChan.QueueBind(
queue.Name,
key,
consumer.ExchangeParams.Name,
consumer.QueueBindParams.Nowait,
consumer.QueueBindParams.Args,
); err != nil {
return err
}
}
}
if consumer.IConsumer != nil {
deliveries, err := c.consumerChan.Consume(
consumer.QueueParams.Name,
consumer.ConsumerParams.ConsumerID,
consumer.ConsumerParams.AutoAck,
consumer.ConsumerParams.Exclusive,
consumer.ConsumerParams.NoLocal,
consumer.ConsumerParams.Nowait,
consumer.ConsumerParams.Args,
)
if err != nil {
return err
}
c.wg.Add(1)
go func() {
defer c.wg.Done()
for msg := range deliveries {
consumer.Consume(context.Background(), msg)
}
}()
}
return nil
}