merlimat commented on a change in pull request #1066: Issue 937: add
CommandGetLastMessageId to make reader know the end of topic
URL: https://github.com/apache/incubator-pulsar/pull/1066#discussion_r167382938
##########
File path:
pulsar-client/src/main/java/org/apache/pulsar/client/impl/ConsumerImpl.java
##########
@@ -1248,6 +1254,77 @@ public void seek(MessageId messageId) throws
PulsarClientException {
return seekFuture;
}
+ public boolean hasMessageAvailable() throws PulsarClientException {
+ try {
+ return hasMessageAvailableAsync().get();
+ } catch (ExecutionException | InterruptedException e) {
+ throw new PulsarClientException(e);
+ }
+ }
+
+ public CompletableFuture<Boolean> hasMessageAvailableAsync() {
+ final CompletableFuture<Boolean> booleanFuture = new
CompletableFuture<>();
+
+ if (lastMessageIdInBroker.compareTo(lastDequeuedMessage) > 0 &&
+ ((MessageIdImpl)lastMessageIdInBroker).getEntryId() != -1) {
+ booleanFuture.complete(true);
+ } else {
+ getLastMessageIdAsync().thenAccept(messageId -> {
+ lastMessageIdInBroker = messageId;
+ if (lastMessageIdInBroker.compareTo(lastDequeuedMessage) > 0 &&
+ ((MessageIdImpl)lastMessageIdInBroker).getEntryId() != -1)
{
+ booleanFuture.complete(true);
+ } else {
+ booleanFuture.complete(false);
+ }
+ }).exceptionally(e -> {
+ log.error("[{}][{}] Failed getLastMessageId command", topic,
subscription);
+ booleanFuture.completeExceptionally(e.getCause());
+ return null;
+ });
+ }
+ return booleanFuture;
+ }
+
+ private CompletableFuture<MessageId> getLastMessageIdAsync() {
+ if (getState() == State.Closing || getState() == State.Closed) {
+ return FutureUtil
+ .failedFuture(new
PulsarClientException.AlreadyClosedException("Consumer was already closed"));
+ }
+
+ if (cnx().getRemoteEndpointProtocolVersion() <
ProtocolVersion.v11.getNumber()) {
+ return FutureUtil
+ .failedFuture(new PulsarClientException
+ .NotSupportedException("GetLastMessageId Not supported for
ProtocolVersion: " +
+ cnx().getRemoteEndpointProtocolVersion()));
+ }
+
+ if (!isConnected()) {
Review comment:
If it's currently not connected, we should try to mask the exception from
the user if the failure is transient.
There is already an `operationTimeout` defined in client, it would be good
to have a way to retry internally with backoff up to that amount of time.
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