ivankelly commented on a change in pull request #1861: Cpp client: add
getLastMessageId and hasMessageAvailable in consmer and reader
URL: https://github.com/apache/incubator-pulsar/pull/1861#discussion_r194108495
##########
File path: pulsar-client-cpp/lib/ConsumerImpl.cc
##########
@@ -919,4 +919,65 @@ void ConsumerImpl::seekAsync(const MessageId& msgId,
ResultCallback callback) {
callback(ResultNotConnected);
}
+void ConsumerImpl::hasMessageAvailableAsync(HasMessageAvailableCallback
callback) {
+ if (this->lastMessageIdAvailable()) {
+ callback(ResultOk, true);
+ return;
+ }
+
+ BrokerGetLastMessageIdCallback callback1 = [this, callback](Result result,
MessageId messageId) {
+ if (this->lastMessageIdAvailable()) {
+ callback(ResultOk, true);
+ } else {
+ callback(ResultOk, false);
+ }
+ };
+
+ getLastMessageIdAsync(callback1);
+}
+
+void ConsumerImpl::brokerGetLastMessageIdListener(Result res, MessageId
messageId,
+
BrokerGetLastMessageIdCallback callback) {
+ if (!callback.empty()) {
+ lastMessageInBroker_ = Optional<MessageId>::of(messageId);
Review comment:
what happens if there's two calls to getLastMessageId interleaved like:
- call 1 to server
- response 1 from server
- call 2 to server
- response 2 from server with higher message id
- response 2 reaches client
- response 1 reaches client
The lastMessageInBroker_ in the client will go backwards. You need some sort
of atomic check.
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