[GitHub] [pulsar] phemmer opened a new issue #6901: HasNext incorrectly reports next value available.

[GitBox <gi...@apache.org>]

phemmer opened a new issue #6901:
URL: https://github.com/apache/pulsar/issues/6901


   **Describe the bug**
   Whenever a topic has messages on it, using `HasNext()` reports `true`, even if there are no messages at or after the cursor position.
   
   Not sure if this is limited to Go, but I doubt it since it's just a thin layer on top of the C client.
   
   **To Reproduce**
   Run:
   ```
   pulsar-admin namespaces create public/test
   pulsar-admin namespaces set-retention public/test --time -1 --size -1
   ```
   ```go
   package main
   
   import (
   	"context"
   	"fmt"
   	"os"
   	"time"
   
   	"github.com/apache/pulsar/pulsar-client-go/pulsar"
   )
   
   func main() {
   	if err := Main(); err != nil {
   		fmt.Fprintf(os.Stderr, "Error: %s\n", err)
   		os.Exit(1)
   	}
   	os.Exit(0)
   }
   
   func Main() error {
   	client, err := pulsar.NewClient(pulsar.ClientOptions{
   		URL: "pulsar://localhost:6650",
   	})
   	if err != nil { return err }
   
   	producer, err := client.CreateProducer(pulsar.ProducerOptions{
   		Topic: "persistent://public/test/test",
   	})
   	if err != nil { return err }
   
   	err = producer.Send(context.Background(), pulsar.ProducerMessage{Payload: []byte("test")})
   	if err != nil { return err }
   
   	consumer, err := client.CreateReader(pulsar.ReaderOptions{
   		Topic: "persistent://public/test/test",
   		StartMessageID: pulsar.LatestMessage,
   	})
   
   	hasnext, err := consumer.HasNext()
   	if err != nil { return err }
   	fmt.Printf("HasNext: %v\n", hasnext)
   
   	deadline, _ := context.WithDeadline(context.Background(), time.Now().Add(time.Second))
   	next, err := consumer.Next(deadline)
   	if err != nil { return err }
   	fmt.Printf("Next: %+v\n", next)
   
   	return nil
   }
   ```
   
   **Expected behavior**
   Should output `HasNext: false`
   
   **Screenshots**
   ```
   2020/05/06 14:29:17.854 c_client.go:68: [info] INFO  | ConnectionPool:85 | Created connection for pulsar://localhost:6650
   2020/05/06 14:29:17.856 c_client.go:68: [info] INFO  | ClientConnection:330 | [127.0.0.1:50238 -> 127.0.0.1:6650] Connected to broker
   2020/05/06 14:29:17.865 c_client.go:68: [info] INFO  | HandlerBase:53 | [persistent://public/test/test, ] Getting connection from pool
   2020/05/06 14:29:17.871 c_client.go:68: [info] INFO  | ProducerImpl:151 | [persistent://public/test/test, ] Created producer on broker [127.0.0.1:50238 -> 127.0.0.1:6650] 
   2020/05/06 14:29:17.874 c_client.go:68: [info] INFO  | HandlerBase:53 | [persistent://public/test/test, reader-d7bf639c4c, 0] Getting connection from pool
   2020/05/06 14:29:17.878 c_client.go:68: [info] INFO  | ConsumerImpl:170 | [persistent://public/test/test, reader-d7bf639c4c, 0] Created consumer on broker [127.0.0.1:50238 -> 127.0.0.1:6650] 
   HasNext: true
   Error: context deadline exceeded
   ```
   
   **Desktop (please complete the following information):**
    - OS: Linux - Fedora 31
   
   **Additional context**
   Add any other context about the problem here.
   


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