merlimat commented on a change in pull request #6362: [ClientAPI]Fix
hasMessageAvailable()
URL: https://github.com/apache/pulsar/pull/6362#discussion_r386619487
##########
File path:
pulsar-broker/src/main/java/org/apache/pulsar/broker/service/ServerCnx.java
##########
@@ -1396,22 +1401,83 @@ protected void
handleGetLastMessageId(CommandGetLastMessageId getLastMessageId)
Topic topic = consumer.getSubscription().getTopic();
Position position = topic.getLastMessageId();
int partitionIndex = TopicName.getPartitionIndex(topic.getName());
- if (log.isDebugEnabled()) {
- log.debug("[{}] [{}][{}] Get LastMessageId {} partitionIndex
{}", remoteAddress,
- topic.getName(), consumer.getSubscription().getName(),
position, partitionIndex);
- }
- MessageIdData messageId = MessageIdData.newBuilder()
- .setLedgerId(((PositionImpl)position).getLedgerId())
- .setEntryId(((PositionImpl)position).getEntryId())
- .setPartition(partitionIndex)
- .build();
- ctx.writeAndFlush(Commands.newGetLastMessageIdResponse(requestId,
messageId));
+ getLargestBatchIndexWhenPossible(
+ topic,
+ (PositionImpl) position,
+ partitionIndex,
+ requestId,
+ consumer.getSubscription().getName());
+
} else {
ctx.writeAndFlush(Commands.newError(getLastMessageId.getRequestId(),
ServerError.MetadataError, "Consumer not found"));
}
}
+ private void getLargestBatchIndexWhenPossible(
+ Topic topic,
+ PositionImpl position,
+ int partitionIndex,
+ long requestId,
+ String subscriptionName) {
+
+ PersistentTopic persistentTopic = (PersistentTopic) topic;
+ ManagedLedgerImpl ml = (ManagedLedgerImpl)
persistentTopic.getManagedLedger();
+
+ // If it's not pointing to a valid entry, respond messageId of the
current position.
+ if (position.getEntryId() == -1) {
+ MessageIdData messageId = MessageIdData.newBuilder()
+ .setLedgerId(position.getLedgerId())
+ .setEntryId(position.getEntryId())
+ .setPartition(partitionIndex).build();
+
+ ctx.writeAndFlush(Commands.newGetLastMessageIdResponse(requestId,
messageId));
+ }
+
+ // For a valid position, we read the entry out and parse the batch
size from its metadata.
+ CompletableFuture<Entry> entryFuture = new CompletableFuture<>();
+ ml.asyncReadEntry(position, new AsyncCallbacks.ReadEntryCallback() {
Review comment:
Ideally we should be avoiding this read by just recording the number of
messages in the last batch, along with the current position.
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