jerrypeng commented on a change in pull request #221: Auto update the client to
handle changes in number of partitions
URL: https://github.com/apache/pulsar-client-go/pull/221#discussion_r408421517
##########
File path: pulsar/consumer_impl.go
##########
@@ -130,56 +136,108 @@ func internalTopicSubscribe(client *client, options
ConsumerOptions, topic strin
log: log.WithField("topic", topic),
}
- partitions, err := client.TopicPartitions(topic)
+ if options.Name != "" {
+ consumer.consumerName = options.Name
+ } else {
+ consumer.consumerName = generateRandomName()
+ }
+
+ err := consumer.internalTopicSubscribeToPartitions()
if err != nil {
return nil, err
}
- numPartitions := len(partitions)
- consumer.consumers = make([]*partitionConsumer, numPartitions)
+ // set up timer to monitor for new partitions being added
+ duration := options.AutoDiscoveryPeriod
+ if duration <= 0 {
+ duration = defaultAutoDiscoveryDuration
+ }
+ consumer.ticker = time.NewTicker(duration)
+
+ go func() {
+ for range consumer.ticker.C {
+ consumer.log.Debug("Auto discovering new partitions")
+ consumer.internalTopicSubscribeToPartitions()
+ }
+ }()
+
+ return consumer, nil
+}
+
+func (c *consumer) internalTopicSubscribeToPartitions() error {
+ partitions, err := c.client.TopicPartitions(c.topic)
+ if err != nil {
+ return err
+ }
+
+ oldNumPartitions := 0
+ newNumPartitions := len(partitions)
+
+ c.Lock()
+ oldConsumers := c.consumers
+ c.Unlock()
+
+ if oldConsumers != nil {
+ oldNumPartitions = len(oldConsumers)
+ if oldNumPartitions == newNumPartitions {
+ c.log.Debug("Number of partitions in topic has not
changed")
+ return nil
+ }
+
+ c.log.WithField("old_partitions", oldNumPartitions).
+ WithField("new_partitions", newNumPartitions).
+ Info("Changed number of partitions in topic")
+ }
+
+ consumers := make([]*partitionConsumer, newNumPartitions)
+
+ // Copy over the existing consumer instances
+ for i := 0; i < oldNumPartitions; i++ {
Review comment:
Why isn't there a mutex here when we are setting new consumers to old
consumers? Shouldn't this whole block be in a mutux to prevent race conditions?
https://github.com/apache/pulsar-client-go/pull/221/files#diff-8b65201e8d71d0f36fdcbdfc7b5d5f0aR176-R197
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