Add support for partitioned topic consumer seek by time. (#5435)

### Motivation

Add support for partitioned topic consumer seek by time.

### Modifications

Call each partition consumer seekAsync() while call partitioned consumer seekAsync()

### Verifying this change

Update unit tests for consumer.seek().

pulsar-broker/src/test/java/org/apache/pulsar/broker/service/SubscriptionSeekTest.java

@@ -31,6 +31,7 @@ import org.apache.pulsar.broker.service.persistent.PersistentTopic;
 import org.apache.pulsar.client.api.MessageId;
 import org.apache.pulsar.client.api.Producer;
 import org.apache.pulsar.client.api.PulsarClientException;
+import org.apache.pulsar.common.naming.TopicName;
 import org.apache.pulsar.common.util.RelativeTimeUtil;
 import org.testng.annotations.AfterClass;
 import org.testng.annotations.BeforeClass;
@@ -145,18 +146,58 @@ public class SubscriptionSeekTest extends BrokerTestBase {
     @Test
     public void testSeekTimeOnPartitionedTopic() throws Exception {
         final String topicName = "persistent://prop/use/ns-abc/testSeekTimePartitions";
-        long timestamp = 1550479732;
-
-        admin.topics().createPartitionedTopic(topicName, 2);
+        final String resetTimeStr = "100s";
+        final int partitions = 2;
+        long resetTimeInMillis = TimeUnit.SECONDS
+                .toMillis(RelativeTimeUtil.parseRelativeTimeInSeconds(resetTimeStr));
+        admin.topics().createPartitionedTopic(topicName, partitions);
+        Producer<byte[]> producer = pulsarClient.newProducer().topic(topicName).create();
+        // Disable pre-fetch in consumer to track the messages received
         org.apache.pulsar.client.api.Consumer<byte[]> consumer = pulsarClient.newConsumer().topic(topicName)
                 .subscriptionName("my-subscription").subscribe();
 
-        try {
-            consumer.seek(timestamp);
-            fail("Should not have succeeded");
-        } catch (PulsarClientException e) {
-            // Expected
+        List<PersistentSubscription> subs = new ArrayList<>();
+
+        for (int i = 0; i < partitions; i++) {
+            PersistentTopic topicRef = (PersistentTopic) pulsar.getBrokerService()
+                    .getTopicReference(topicName + TopicName.PARTITIONED_TOPIC_SUFFIX + i).get();
+            assertNotNull(topicRef);
+            assertEquals(topicRef.getProducers().size(), 1);
+            assertEquals(topicRef.getSubscriptions().size(), 1);
+            PersistentSubscription sub = topicRef.getSubscription("my-subscription");
+            assertNotNull(sub);
+            subs.add(sub);
+        }
+
+        for (int i = 0; i < 10; i++) {
+            String message = "my-message-" + i;
+            producer.send(message.getBytes());
+        }
+
+        long backlogs = 0;
+        for (PersistentSubscription sub : subs) {
+            backlogs += sub.getNumberOfEntriesInBacklog();
+        }
+
+        assertEquals(backlogs, 10);
+
+        backlogs = 0;
+        long currentTimestamp = System.currentTimeMillis();
+        consumer.seek(currentTimestamp);
+        for (PersistentSubscription sub : subs) {
+            backlogs += sub.getNumberOfEntriesInBacklog();
+        }
+        assertEquals(backlogs, 2);
+
+        // Wait for consumer to reconnect
+        Thread.sleep(1000);
+        consumer.seek(currentTimestamp - resetTimeInMillis);
+        backlogs = 0;
+
+        for (PersistentSubscription sub : subs) {
+            backlogs += sub.getNumberOfEntriesInBacklog();
         }
+        assertEquals(backlogs, 10);
     }
 
 }

pulsar-client-api/src/main/java/org/apache/pulsar/client/api/Consumer.java

@@ -321,9 +321,6 @@ public interface Consumer<T> extends Closeable {
     /**
      * Reset the subscription associated with this consumer to a specific message publish time.
      *
-     * <p>Note: this operation can only be done on non-partitioned topics. For these, one can rather perform
-     * the seek() on the individual partitions.
-     *
      * @param timestamp
      *            the message publish time where to reposition the subscription
      */
@@ -350,9 +347,6 @@ public interface Consumer<T> extends Closeable {
     /**
      * Reset the subscription associated with this consumer to a specific message publish time.
      *
-     * <p>Note: this operation can only be done on non-partitioned topics. For these, one can rather
-     * perform the seek() on the individual partitions.
-     *
      * @param timestamp
      *            the message publish time where to reposition the subscription
      * @return a future to track the completion of the seek operation

pulsar-client/src/main/java/org/apache/pulsar/client/impl/MultiTopicsConsumerImpl.java

@@ -595,7 +595,9 @@ public class MultiTopicsConsumerImpl<T> extends ConsumerBase<T> {
 
     @Override
     public CompletableFuture<Void> seekAsync(long timestamp) {
-        return FutureUtil.failedFuture(new PulsarClientException("Seek operation not supported on topics consumer"));
+        List<CompletableFuture<Void>> futures = new ArrayList<>(consumers.size());
+        consumers.values().forEach(consumer -> futures.add(consumer.seekAsync(timestamp)));
+        return FutureUtil.waitForAll(futures);
     }
 
     @Override