Add BatchedMessageIdImpl to acknowledge batched messages

lib/BatchMessageAcker.h

@@ -0,0 +1,71 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+#pragma once
+
+#include <atomic>
+#include <memory>
+#include <mutex>
+
+#include "BitSet.h"
+#include "ProtoApiEnums.h"
+
+namespace pulsar {
+
+class BatchMessageAcker;
+using BatchMessageAckerPtr = std::shared_ptr<BatchMessageAcker>;
+
+class BatchMessageAcker {
+   public:
+    using Lock = std::lock_guard<std::mutex>;
+
+    static BatchMessageAckerPtr create(int32_t batchSize) {
+        return std::make_shared<BatchMessageAcker>(batchSize);
+    }
+
+    BatchMessageAcker(int32_t batchSize) : bitSet_(batchSize) { bitSet_.set(0, batchSize); }
+
+    bool ackIndividual(int32_t batchIndex) {
+        Lock lock{mutex_};
+        bitSet_.clear(batchIndex);
+        return bitSet_.isEmpty();
+    }
+
+    bool ackCumulative(int32_t batchIndex) {
+        Lock lock{mutex_};
+        // The range of cumulative acknowledgment is closed while BitSet::clear accepts a left-closed
+        // right-open range.
+        bitSet_.clear(0, batchIndex + 1);
+        return bitSet_.isEmpty();
+    }
+
+    bool shouldAckPreviousMessageId() noexcept {
+        bool expectedValue = false;
+        return prevBatchCumulativelyAcked_.compare_exchange_strong(expectedValue, true);
+    }
+
+   private:
+    BitSet bitSet_;
+    // When a batched message is acknowledged cumulatively, the previous message id will be acknowledged
+    // without batch index ACK enabled. However, it should be acknowledged only once. Use this flag to
+    // determine whether to acknowledge the previous message id.
+    std::atomic_bool prevBatchCumulativelyAcked_{false};
+    mutable std::mutex mutex_;
+};
+
+}  // namespace pulsar