[Issue 1223] Support ZeroQueueConsumer (apache#1225)

Fixes apache#1223

### Motivation

Support ZeroQueueConsumer, refer to Java [ZeroQueueConsumerImpl](https://github.com/apache/pulsar/blob/8c50a6c2e91c81dbf187ce5e66cb39e2758a741e/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ZeroQueueConsumerImpl.java#L42)

### Modifications

- The consumer add a new optional parameter `EnableZeroQueueConsumer`
- Add a new `zeroQueueConsumer`

pulsar/consumer.go

@@ -160,6 +160,11 @@ type ConsumerOptions struct {
 	// Default value is `1000` messages and should be good for most use cases.
 	ReceiverQueueSize int
 
+	// EnableZeroQueueConsumer, if enabled, the ReceiverQueueSize will be 0.
+	// Notice: only non-partitioned topic is supported.
+	// Default is false.
+	EnableZeroQueueConsumer bool
+
 	// EnableAutoScaledReceiverQueueSize, if enabled, the consumer receive queue will be auto-scaled
 	// by the consumer actual throughput. The ReceiverQueueSize will be the maximum size which consumer
 	// receive queue can be scaled.

pulsar/consumer_impl.go

@@ -22,9 +22,12 @@ import (
 	"fmt"
 	"math/rand"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
+	"github.com/apache/pulsar-client-go/pulsaradmin/pkg/utils"
+
 	"github.com/apache/pulsar-client-go/pulsar/crypto"
 	"github.com/apache/pulsar-client-go/pulsar/internal"
 	pb "github.com/apache/pulsar-client-go/pulsar/internal/pulsar_proto"
@@ -81,6 +84,10 @@ func newConsumer(client *client, options ConsumerOptions) (Consumer, error) {
 		options.ReceiverQueueSize = defaultReceiverQueueSize
 	}
 
+	if options.EnableZeroQueueConsumer {
+		options.ReceiverQueueSize = 0
+	}
+
 	if options.Interceptors == nil {
 		options.Interceptors = defaultConsumerInterceptors
 	}
@@ -236,7 +243,24 @@ func newConsumer(client *client, options ConsumerOptions) (Consumer, error) {
 }
 
 func newInternalConsumer(client *client, options ConsumerOptions, topic string,
-	messageCh chan ConsumerMessage, dlq *dlqRouter, rlq *retryRouter, disableForceTopicCreation bool) (*consumer, error) {
+	messageCh chan ConsumerMessage, dlq *dlqRouter, rlq *retryRouter, disableForceTopicCreation bool) (Consumer, error) {
+	partitions, err := client.TopicPartitions(topic)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(partitions) > 1 && options.EnableZeroQueueConsumer {
+		return nil, pkgerrors.New("ZeroQueueConsumer is not supported for partitioned topics")
+	}
+
+	if len(partitions) == 1 && options.EnableZeroQueueConsumer &&
+		strings.Contains(partitions[0], utils.PARTITIONEDTOPICSUFFIX) {
+		return nil, pkgerrors.New("ZeroQueueConsumer is not supported for partitioned topics")
+	}
+
+	if len(partitions) == 1 && options.EnableZeroQueueConsumer {
+		return newZeroConsumer(client, options, topic, messageCh, dlq, rlq, disableForceTopicCreation)
+	}
 
 	consumer := &consumer{
 		topic:                     topic,
@@ -253,7 +277,7 @@ func newInternalConsumer(client *client, options ConsumerOptions, topic string,
 		metrics:                   client.metrics.GetLeveledMetrics(topic),
 	}
 
-	err := consumer.internalTopicSubscribeToPartitions()
+	err = consumer.internalTopicSubscribeToPartitions()
 	if err != nil {
 		return nil, err
 	}
@@ -343,10 +367,6 @@ func (c *consumer) internalTopicSubscribeToPartitions() error {
 		consumer  *partitionConsumer
 	}
 
-	receiverQueueSize := c.options.ReceiverQueueSize
-	metadata := c.options.Properties
-	subProperties := c.options.SubscriptionProperties
-
 	startPartition := oldNumPartitions
 	partitionsToAdd := newNumPartitions - oldNumPartitions
 
@@ -364,45 +384,7 @@ func (c *consumer) internalTopicSubscribeToPartitions() error {
 
 		go func(idx int, pt string) {
 			defer wg.Done()
-
-			var nackRedeliveryDelay time.Duration
-			if c.options.NackRedeliveryDelay == 0 {
-				nackRedeliveryDelay = defaultNackRedeliveryDelay
-			} else {
-				nackRedeliveryDelay = c.options.NackRedeliveryDelay
-			}
-			opts := &partitionConsumerOpts{
-				topic:                       pt,
-				consumerName:                c.consumerName,
-				subscription:                c.options.SubscriptionName,
-				subscriptionType:            c.options.Type,
-				subscriptionInitPos:         c.options.SubscriptionInitialPosition,
-				partitionIdx:                idx,
-				receiverQueueSize:           receiverQueueSize,
-				nackRedeliveryDelay:         nackRedeliveryDelay,
-				nackBackoffPolicy:           c.options.NackBackoffPolicy,
-				metadata:                    metadata,
-				subProperties:               subProperties,
-				replicateSubscriptionState:  c.options.ReplicateSubscriptionState,
-				startMessageID:              c.options.startMessageID,
-				startMessageIDInclusive:     c.options.StartMessageIDInclusive,
-				subscriptionMode:            c.options.SubscriptionMode,
-				readCompacted:               c.options.ReadCompacted,
-				interceptors:                c.options.Interceptors,
-				maxReconnectToBroker:        c.options.MaxReconnectToBroker,
-				backoffPolicy:               c.options.BackoffPolicy,
-				keySharedPolicy:             c.options.KeySharedPolicy,
-				schema:                      c.options.Schema,
-				decryption:                  c.options.Decryption,
-				ackWithResponse:             c.options.AckWithResponse,
-				maxPendingChunkedMessage:    c.options.MaxPendingChunkedMessage,
-				expireTimeOfIncompleteChunk: c.options.ExpireTimeOfIncompleteChunk,
-				autoAckIncompleteChunk:      c.options.AutoAckIncompleteChunk,
-				consumerEventListener:       c.options.EventListener,
-				enableBatchIndexAck:         c.options.EnableBatchIndexAcknowledgment,
-				ackGroupingOptions:          c.options.AckGroupingOptions,
-				autoReceiverQueueSize:       c.options.EnableAutoScaledReceiverQueueSize,
-			}
+			opts := newPartitionConsumerOpts(pt, c.consumerName, idx, c.options)
 			cons, err := newPartitionConsumer(c, c.client, opts, c.messageCh, c.dlq, c.metrics)
 			ch <- ConsumerError{
 				err:       err,
@@ -444,6 +426,48 @@ func (c *consumer) internalTopicSubscribeToPartitions() error {
 	return nil
 }
 
+func newPartitionConsumerOpts(topic, consumerName string, idx int, options ConsumerOptions) *partitionConsumerOpts {
+
+	var nackRedeliveryDelay time.Duration
+	if options.NackRedeliveryDelay == 0 {
+		nackRedeliveryDelay = defaultNackRedeliveryDelay
+	} else {
+		nackRedeliveryDelay = options.NackRedeliveryDelay
+	}
+	return &partitionConsumerOpts{
+		topic:                       topic,
+		consumerName:                consumerName,
+		subscription:                options.SubscriptionName,
+		subscriptionType:            options.Type,
+		subscriptionInitPos:         options.SubscriptionInitialPosition,
+		partitionIdx:                idx,
+		receiverQueueSize:           options.ReceiverQueueSize,
+		nackRedeliveryDelay:         nackRedeliveryDelay,
+		nackBackoffPolicy:           options.NackBackoffPolicy,
+		metadata:                    options.Properties,
+		subProperties:               options.SubscriptionProperties,
+		replicateSubscriptionState:  options.ReplicateSubscriptionState,
+		startMessageID:              options.startMessageID,
+		startMessageIDInclusive:     options.StartMessageIDInclusive,
+		subscriptionMode:            options.SubscriptionMode,
+		readCompacted:               options.ReadCompacted,
+		interceptors:                options.Interceptors,
+		maxReconnectToBroker:        options.MaxReconnectToBroker,
+		backoffPolicy:               options.BackoffPolicy,
+		keySharedPolicy:             options.KeySharedPolicy,
+		schema:                      options.Schema,
+		decryption:                  options.Decryption,
+		ackWithResponse:             options.AckWithResponse,
+		maxPendingChunkedMessage:    options.MaxPendingChunkedMessage,
+		expireTimeOfIncompleteChunk: options.ExpireTimeOfIncompleteChunk,
+		autoAckIncompleteChunk:      options.AutoAckIncompleteChunk,
+		consumerEventListener:       options.EventListener,
+		enableBatchIndexAck:         options.EnableBatchIndexAcknowledgment,
+		ackGroupingOptions:          options.AckGroupingOptions,
+		autoReceiverQueueSize:       options.EnableAutoScaledReceiverQueueSize,
+	}
+}
+
 func (c *consumer) Subscription() string {
 	return c.options.SubscriptionName
 }