Avoid getLastMessageId RPC when calling hasMessageAvailable after seek by timestamp (#491)

(cherry picked from commit 15e0b00)

Author: BewareMyPower

lib/ConsumerImpl.cc

@@ -1561,6 +1561,10 @@ void ConsumerImpl::seekAsync(uint64_t timestamp, ResultCallback callback) {
 bool ConsumerImpl::isReadCompacted() { return readCompacted_; }
 
 void ConsumerImpl::hasMessageAvailableAsync(HasMessageAvailableCallback callback) {
+    if (!incomingMessages_.empty()) {
+        callback(ResultOk, true);
+        return;
+    }
     bool compareMarkDeletePosition;
     {
         std::lock_guard<std::mutex> lock{mutexForMessageId_};
@@ -1726,6 +1730,7 @@ void ConsumerImpl::seekAsyncInternal(long requestId, SharedBuffer seek, const Se
         hasSoughtByTimestamp_.store(true, std::memory_order_release);
     } else {
         seekMessageId_ = *boost::get<MessageId>(&seekArg);
+        hasSoughtByTimestamp_.store(false, std::memory_order_release);
     }
     seekStatus_ = SeekStatus::IN_PROGRESS;
     seekCallback_ = std::move(callback);

tests/ReaderTest.cc

@@ -21,7 +21,9 @@
 #include <pulsar/Reader.h>
 #include <time.h>
 
+#include <future>
 #include <string>
+#include <thread>
 
 #include "HttpHelper.h"
 #include "PulsarFriend.h"
@@ -850,7 +852,7 @@ TEST_P(ReaderSeekTest, testHasMessageAvailableAfterSeekToEnd) {
     ASSERT_FALSE(hasMessageAvailable);
 }
 
-TEST_P(ReaderSeekTest, testHasMessageAvailableAfterSeekTimestamp) {
+TEST_F(ReaderSeekTest, testHasMessageAvailableAfterSeekTimestamp) {
     using namespace std::chrono;
     const auto topic = "test-has-message-available-after-seek-timestamp-" + std::to_string(time(nullptr));
     Producer producer;
@@ -862,12 +864,10 @@ TEST_P(ReaderSeekTest, testHasMessageAvailableAfterSeekTimestamp) {
 
     auto createReader = [this, &topic](Reader& reader, const MessageId& msgId) {
         ASSERT_EQ(ResultOk, client.createReader(topic, msgId, {}, reader));
-        if (GetParam()) {
-            if (msgId == MessageId::earliest()) {
-                EXPECT_HAS_MESSAGE_AVAILABLE(reader, true);
-            } else {
-                EXPECT_HAS_MESSAGE_AVAILABLE(reader, false);
-            }
+        if (msgId == MessageId::earliest()) {
+            EXPECT_HAS_MESSAGE_AVAILABLE(reader, true);
+        } else {
+            EXPECT_HAS_MESSAGE_AVAILABLE(reader, false);
         }
     };
 
@@ -886,6 +886,22 @@ TEST_P(ReaderSeekTest, testHasMessageAvailableAfterSeekTimestamp) {
         ASSERT_EQ(ResultOk, reader.seek(timestampBeforeSend));
         EXPECT_HAS_MESSAGE_AVAILABLE(reader, true);
     }
+
+    // Test `hasMessageAvailableAsync` will complete immediately if the incoming message queue is non-empty
+    Reader reader;
+    ASSERT_EQ(ResultOk, client.createReader(topic, MessageId::latest(), {}, reader));
+    reader.seek(timestampBeforeSend);
+    std::promise<std::thread::id> threadIdPromise;
+
+    waitUntil(seconds(3),
+              [&reader] { return PulsarFriend::getConsumer(reader)->getNumOfPrefetchedMessages() > 0; });
+    reader.hasMessageAvailableAsync([&threadIdPromise](Result result, bool hasMessageAvailable) {
+        ASSERT_EQ(ResultOk, result);
+        ASSERT_TRUE(hasMessageAvailable);
+        threadIdPromise.set_value(std::this_thread::get_id());
+    });
+    auto threadId = threadIdPromise.get_future().get();
+    ASSERT_EQ(threadId, std::this_thread::get_id());
 }
 
 TEST_F(ReaderSeekTest, testSeekInclusiveChunkMessage) {