Consider max unconfirmed messages in dynamic batch configuration

src/main/java/com/rabbitmq/stream/impl/DynamicBatch.java

@@ -28,17 +28,22 @@
 final class DynamicBatch<T> implements AutoCloseable {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(DynamicBatch.class);
-  private static final int MIN_BATCH_SIZE = 32;
-  private static final int MAX_BATCH_SIZE = 8192;
+  private static final int MIN_BATCH_SIZE = 16;
 
   private final BlockingQueue<T> requests = new LinkedBlockingQueue<>();
   private final BatchConsumer<T> consumer;
-  private final int configuredBatchSize;
+  private final int configuredBatchSize, minBatchSize, maxBatchSize;
   private final Thread thread;
 
-  DynamicBatch(BatchConsumer<T> consumer, int batchSize) {
+  DynamicBatch(BatchConsumer<T> consumer, int batchSize, int maxUnconfirmed) {
     this.consumer = consumer;
-    this.configuredBatchSize = min(max(batchSize, MIN_BATCH_SIZE), MAX_BATCH_SIZE);
+    if (batchSize < maxUnconfirmed) {
+      this.minBatchSize = min(MIN_BATCH_SIZE, batchSize / 2);
+    } else {
+      this.minBatchSize = min(1, maxUnconfirmed / 2);
+    }
+    this.configuredBatchSize = batchSize;
+    this.maxBatchSize = batchSize * 2;
     this.thread = ConcurrencyUtils.defaultThreadFactory().newThread(this::loop);
     this.thread.start();
   }
@@ -104,9 +109,9 @@ private void maybeCompleteBatch(State<T> state, boolean increaseIfCompleted) {
       boolean completed = this.consumer.process(state.items);
       if (completed) {
         if (increaseIfCompleted) {
-          state.batchSize = min(state.batchSize * 2, MAX_BATCH_SIZE);
+          state.batchSize = min(state.batchSize * 2, this.maxBatchSize);
         } else {
-          state.batchSize = max(state.batchSize / 2, MIN_BATCH_SIZE);
+          state.batchSize = max(state.batchSize / 2, this.minBatchSize);
         }
         state.items = new ArrayList<>(state.batchSize);
       }

src/main/java/com/rabbitmq/stream/impl/DynamicBatchMessageAccumulator.java

@@ -38,6 +38,7 @@ final class DynamicBatchMessageAccumulator implements MessageAccumulator {
   DynamicBatchMessageAccumulator(
       int subEntrySize,
       int batchSize,
+      int maxUnconfirmedMessages,
       Codec codec,
       int maxFrameSize,
       ToLongFunction<Message> publishSequenceFunction,
@@ -75,7 +76,8 @@ final class DynamicBatchMessageAccumulator implements MessageAccumulator {
                 }
                 return result;
               },
-              batchSize);
+              batchSize,
+              maxUnconfirmedMessages);
     } else {
       byte compressionCode =
           compressionCodec == null ? Compression.NONE.code() : compressionCodec.code();
@@ -124,7 +126,8 @@ final class DynamicBatchMessageAccumulator implements MessageAccumulator {
                 }
                 return result;
               },
-              batchSize * subEntrySize);
+              batchSize * subEntrySize,
+              maxUnconfirmedMessages);
     }
   }
 

src/main/java/com/rabbitmq/stream/impl/ProducerUtils.java

@@ -30,6 +30,7 @@ static MessageAccumulator createMessageAccumulator(
       boolean dynamicBatch,
       int subEntrySize,
       int batchSize,
+      int maxUnconfirmedMessages,
       CompressionCodec compressionCodec,
       Codec codec,
       ByteBufAllocator byteBufAllocator,
@@ -44,6 +45,7 @@ static MessageAccumulator createMessageAccumulator(
       return new DynamicBatchMessageAccumulator(
           subEntrySize,
           batchSize,
+          maxUnconfirmedMessages,
           codec,
           maxFrameSize,
           publishSequenceFunction,

src/main/java/com/rabbitmq/stream/impl/StreamProducer.java

@@ -180,6 +180,7 @@ public int fragmentLength(Object entity) {
             dynamicBatch,
             subEntrySize,
             batchSize,
+            maxUnconfirmedMessages,
             compressionCodec,
             environment.codec(),
             environment.byteBufAllocator(),

src/test/java/com/rabbitmq/stream/impl/DynamicBatchTest.java

@@ -71,7 +71,7 @@ void itemAreProcessed() {
           sync.down(items.size());
           return true;
         };
-    try (DynamicBatch<String> batch = new DynamicBatch<>(action, 100)) {
+    try (DynamicBatch<String> batch = new DynamicBatch<>(action, 100, 10_000)) {
       RateLimiter rateLimiter = RateLimiter.create(10000);
       IntStream.range(0, itemCount)
           .forEach(
@@ -102,7 +102,7 @@ void failedProcessingIsReplayed() throws Exception {
           }
           return result;
         };
-    try (DynamicBatch<String> batch = new DynamicBatch<>(action, 100)) {
+    try (DynamicBatch<String> batch = new DynamicBatch<>(action, 100, 10_000)) {
       int firstRoundCount = itemCount / 5;
       IntStream.range(0, firstRoundCount)
           .forEach(
@@ -132,7 +132,7 @@ void lowThrottlingValueShouldStillHighPublishingRate() throws Exception {
           return true;
         };
 
-    try (DynamicBatch<Long> batch = new DynamicBatch<>(action, batchSize)) {
+    try (DynamicBatch<Long> batch = new DynamicBatch<>(action, batchSize, 10_000)) {
       MetricRegistry metrics = new MetricRegistry();
       Meter rate = metrics.meter("publishing-rate");
       AtomicBoolean keepGoing = new AtomicBoolean(true);