Constant for consumer timeout and doc updates

Documentation to queue argument constants was missing links to the
constant themselves. Go Doc allows to link to a specific symbol using
squared brackets.

Added as well a constant for SAC in CQ and QQ.

Signed-off-by: Aitor Pérez Cedres <acedres@vmware.com>

examples_test.go

@@ -550,8 +550,27 @@ func ExampleChannel_QueueDeclare_classicQueueV2() {
 		false,                 // exclusive
 		false,                 // noWait
 		amqp.Table{
+			amqp.QueueTypeArg:    amqp.QueueTypeClassic,
 			amqp.QueueVersionArg: 2,
 		},
 	)
 	log.Printf("Declared Classic Queue v2: %s", q.Name)
 }
+
+func ExampleChannel_QueueDeclare_consumerTimeout() {
+	conn, _ := amqp.Dial("amqp://localhost")
+	ch, _ := conn.Channel()
+	// this works only with RabbitMQ 3.12+
+	q, _ := ch.QueueDeclare(
+		"my-classic-queue-v2", // queue name
+		true,                  // durable
+		false,                 // auto-delete
+		false,                 // exclusive
+		false,                 // noWait
+		amqp.Table{
+			amqp.QueueTypeArg:       amqp.QueueTypeQuorum, // also works with classic queues
+			amqp.ConsumerTimeoutArg: 600_000,              // 10 minute consumer timeout
+		},
+	)
+	log.Printf("Declared Classic Queue v2: %s", q.Name)
+}

types.go

@@ -11,6 +11,8 @@ import (
 	"time"
 )
 
+// DefaultExchange is the default direct exchange that binds every queue by its
+// name. Applications can route to a queue using the queue name as routing key.
 const DefaultExchange = ""
 
 // Constants for standard AMQP 0-9-1 exchange types.
@@ -214,36 +216,48 @@ type Decimal struct {
 // Most common queue argument keys in queue declaration. For a comprehensive list
 // of queue arguments, visit [RabbitMQ Queue docs].
 //
-// QueueTypeArg queue argument is used to declare quorum and stream queues.
-// Accepted values are QueueTypeClassic (default), QueueTypeQuorum and
-// QueueTypeStream. [Quorum Queues] accept (almost) all queue arguments as their
+// [QueueTypeArg] queue argument is used to declare quorum and stream queues.
+// Accepted values are [QueueTypeClassic] (default), [QueueTypeQuorum] and
+// [QueueTypeStream]. [Quorum Queues] accept (almost) all queue arguments as their
 // Classic Queues counterparts. Check [feature comparison] docs for more
 // information.
 //
-// Queues can define their [max length] using QueueMaxLenArg and
-// QueueMaxLenBytesArg queue arguments. Overflow behaviour is set using
-// QueueOverflowArg. Accepted values are QueueOverflowDropHead (default),
-// QueueOverflowRejectPublish and QueueOverflowRejectPublishDLX.
+// Queues can define their [max length] using [QueueMaxLenArg] and
+// [QueueMaxLenBytesArg] queue arguments. Overflow behaviour is set using
+// [QueueOverflowArg]. Accepted values are [QueueOverflowDropHead] (default),
+// [QueueOverflowRejectPublish] and [QueueOverflowRejectPublishDLX].
 //
-// [Queue TTL] can be defined using QueueTTLArg. That is, the time-to-live for an
-// unused queue. [Queue Message TTL] can be defined using QueueMessageTTLArg.
-// This will set a time-to-live for **messages** in the queue.
+// [Queue TTL] can be defined using [QueueTTLArg]. That is, the time-to-live for an
+// unused queue. [Queue Message TTL] can be defined using [QueueMessageTTLArg].
+// This will set a time-to-live for messages in the queue.
 //
-// [Stream retention] can be configured using StreamMaxLenBytesArg, to set the
+// [Stream retention] can be configured using [StreamMaxLenBytesArg], to set the
 // maximum size of the stream. Please note that stream queues always keep, at
-// least, one segment. [Stream retention] can also be set using StreamMaxAgeArg,
+// least, one segment. [Stream retention] can also be set using [StreamMaxAgeArg],
 // to set time-based retention. Values are string with unit suffix. Valid
 // suffixes are Y, M, D, h, m, s. E.g. "7D" for one week. The maximum segment
-// size can be set using StreamMaxSegmentSizeBytesArg. The default value is
+// size can be set using [StreamMaxSegmentSizeBytesArg]. The default value is
 // 500_000_000 bytes ~= 500 megabytes
 //
+// Starting with RabbitMQ 3.12, consumer timeout can be configured as a queue
+// argument. This is the timeout for a consumer to acknowledge a message. The
+// value is the time in milliseconds. The timeout is evaluated periodically,
+// at one minute intervals. Values lower than one minute are not supported.
+// See the [consumer timeout] guide for more information.
+//
+// [Single Active Consumer] on quorum and classic queues can be configured
+// using [SingleActiveConsumerArg]. This argument expects a boolean value. It is
+// false by default.
+//
 // [RabbitMQ Queue docs]: https://rabbitmq.com/queues.html
 // [Stream retention]: https://rabbitmq.com/streams.html#retention
 // [max length]: https://rabbitmq.com/maxlength.html
 // [Queue TTL]: https://rabbitmq.com/ttl.html#queue-ttl
 // [Queue Message TTL]: https://rabbitmq.com/ttl.html#per-queue-message-ttl
 // [Quorum Queues]: https://rabbitmq.com/quorum-queues.html
 // [feature comparison]: https://rabbitmq.com/quorum-queues.html#feature-comparison
+// [consumer timeout]: https://rabbitmq.com/consumers.html#acknowledgement-timeout
+// [Single Active Consumer]: https://rabbitmq.com/consumers.html#single-active-consumer
 const (
 	QueueTypeArg                 = "x-queue-type"
 	QueueMaxLenArg               = "x-max-length"
@@ -256,6 +270,9 @@ const (
 	StreamMaxSegmentSizeBytesArg = "x-stream-max-segment-size-bytes"
 	// QueueVersionArg declares the Classic Queue version to use. Expects an integer, either 1 or 2.
 	QueueVersionArg = "x-queue-version"
+	// ConsumerTimeoutArg is available in RabbitMQ 3.12+ as a queue argument.
+	ConsumerTimeoutArg      = "x-consumer-timeout"
+	SingleActiveConsumerArg = "x-single-active-consumer"
 )
 
 // Values for queue arguments. Use as values for queue arguments during queue declaration.
@@ -267,6 +284,8 @@ const (
 //		amqp.QueueMaxLenArg: 100,
 //		amqp.QueueTTLArg: 1800000,
 //	}
+//
+// Refer to [Channel.QueueDeclare] for more examples.
 const (
 	QueueTypeClassic              = "classic"
 	QueueTypeQuorum               = "quorum"