Refactoring the core BatchManager to change how it handles batch entry failures.

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/batchmanager/BatchAndSend.java → core/sdk-core/src/main/java/software/amazon/awssdk/core/batchmanager/BatchAndSend.java

@@ -13,11 +13,12 @@
  * permissions and limitations under the License.
  */
 
-package software.amazon.awssdk.core.internal.batchmanager;
+package software.amazon.awssdk.core.batchmanager;
 
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import software.amazon.awssdk.annotations.SdkProtectedApi;
+import software.amazon.awssdk.core.batchmanager.IdentifiableMessage;
 
 /**
  * Takes a list of identified requests in addition to a destination and batches the requests into a batch request.

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/batchmanager/BatchKeyMapper.java → core/sdk-core/src/main/java/software/amazon/awssdk/core/batchmanager/BatchKeyMapper.java

@@ -13,7 +13,7 @@
  * permissions and limitations under the License.
  */
 
-package software.amazon.awssdk.core.internal.batchmanager;
+package software.amazon.awssdk.core.batchmanager;
 
 import software.amazon.awssdk.annotations.SdkProtectedApi;
 

core/sdk-core/src/main/java/software/amazon/awssdk/core/batchmanager/BatchManagerBuilder.java

@@ -17,9 +17,6 @@
 
 import java.util.concurrent.ScheduledExecutorService;
 import software.amazon.awssdk.annotations.SdkProtectedApi;
-import software.amazon.awssdk.core.internal.batchmanager.BatchAndSend;
-import software.amazon.awssdk.core.internal.batchmanager.BatchKeyMapper;
-import software.amazon.awssdk.core.internal.batchmanager.BatchResponseMapper;
 
 @SdkProtectedApi
 public interface BatchManagerBuilder<RequestT, ResponseT, BatchResponseT, B> {

core/sdk-core/src/main/java/software/amazon/awssdk/core/batchmanager/BatchOverrideConfiguration.java

@@ -33,11 +33,15 @@ public final class BatchOverrideConfiguration implements ToCopyableBuilder<Batch
     BatchOverrideConfiguration> {
 
     private final Integer maxBatchItems;
+    private final Integer maxBatchKeys;
+    private final Integer maxBufferSize;
     private final Duration maxBatchOpenInMs;
 
     public BatchOverrideConfiguration(Builder builder) {
         this.maxBatchItems = Validate.isPositiveOrNull(builder.maxBatchItems, "maxBatchItems");
         this.maxBatchOpenInMs = Validate.isPositiveOrNull(builder.maxBatchOpenInMs, "maxBachOpenInMs");
+        this.maxBatchKeys = Validate.isPositiveOrNull(builder.maxBatchKeys, "maxBatchKeys");
+        this.maxBufferSize = Validate.isPositiveOrNull(builder.maxBufferSize, "maxBufferSize");
     }
 
     public static Builder builder() {
@@ -51,6 +55,20 @@ public Optional<Integer> maxBatchItems() {
         return Optional.ofNullable(maxBatchItems);
     }
 
+    /**
+     * @return the optional maximum number of batchKeys to keep track of.
+     */
+    public Optional<Integer> maxBatchKeys() {
+        return Optional.ofNullable(maxBatchKeys);
+    }
+
+    /**
+     * @return the maximum number of items to allow to be buffered for each batchKey.
+     */
+    public Optional<Integer> maxBufferSize() {
+        return Optional.ofNullable(maxBufferSize);
+    }
+
     /**
      * @return the optional maximum amount of time (in milliseconds) that an outgoing call waits to be batched with messages of
      * the same type.
@@ -87,19 +105,29 @@ public boolean equals(Object o) {
         if (maxBatchItems != null ? !maxBatchItems.equals(that.maxBatchItems) : that.maxBatchItems != null) {
             return false;
         }
+        if (maxBatchKeys != null ? !maxBatchKeys.equals(that.maxBatchKeys) : that.maxBatchKeys != null) {
+            return false;
+        }
+        if (maxBufferSize != null ? !maxBufferSize.equals(that.maxBufferSize) : that.maxBufferSize != null) {
+            return false;
+        }
         return maxBatchOpenInMs != null ? maxBatchOpenInMs.equals(that.maxBatchOpenInMs) : that.maxBatchOpenInMs == null;
     }
 
     @Override
     public int hashCode() {
         int result = maxBatchItems != null ? maxBatchItems.hashCode() : 0;
+        result = 31 * result + (maxBatchKeys != null ? maxBatchKeys.hashCode() : 0);
+        result = 31 * result + (maxBufferSize != null ? maxBufferSize.hashCode() : 0);
         result = 31 * result + (maxBatchOpenInMs != null ? maxBatchOpenInMs.hashCode() : 0);
         return result;
     }
 
     public static final class Builder implements CopyableBuilder<Builder, BatchOverrideConfiguration> {
 
         private Integer maxBatchItems;
+        private Integer maxBatchKeys;
+        private Integer maxBufferSize;
         private Duration maxBatchOpenInMs;
 
         private Builder() {
@@ -116,6 +144,28 @@ public Builder maxBatchItems(Integer maxBatchItems) {
             return this;
         }
 
+        /**
+         * Define the maximum number of batchKeys to keep track of.
+         *
+         * @param maxBatchKeys the new maxBatchKeys value.
+         * @return This object for method chaining.
+         */
+        public Builder maxBatchKeys(Integer maxBatchKeys) {
+            this.maxBatchKeys = maxBatchKeys;
+            return this;
+        }
+
+        /**
+         * Define the maximum number of items to allow to be buffered for each batchKey.
+         *
+         * @param maxBufferSize the new maxBufferSize value.
+         * @return This object for method chaining.
+         */
+        public Builder maxBufferSize(Integer maxBufferSize) {
+            this.maxBufferSize = maxBufferSize;
+            return this;
+        }
+
         /**
          * The maximum amount of time (in milliseconds) that an outgoing call waits for other requests before sending out a batch
          * request.
@@ -128,6 +178,7 @@ public Builder maxBatchOpenInMs(Duration maxBatchOpenInMs) {
             return this;
         }
 
+
         public BatchOverrideConfiguration build() {
             return new BatchOverrideConfiguration(this);
         }

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/batchmanager/BatchResponseMapper.java → core/sdk-core/src/main/java/software/amazon/awssdk/core/batchmanager/BatchResponseMapper.java

@@ -13,10 +13,12 @@
  * permissions and limitations under the License.
  */
 
-package software.amazon.awssdk.core.internal.batchmanager;
+package software.amazon.awssdk.core.batchmanager;
 
 import java.util.List;
 import software.amazon.awssdk.annotations.SdkProtectedApi;
+import software.amazon.awssdk.core.batchmanager.IdentifiableMessage;
+import software.amazon.awssdk.utils.Either;
 
 /**
  * Unpacks the batch response, then transforms individual entries to the appropriate response type. Each entry's batch ID
@@ -27,5 +29,5 @@
 @FunctionalInterface
 @SdkProtectedApi
 public interface BatchResponseMapper<BatchResponseT, ResponseT> {
-    List<IdentifiableMessage<ResponseT>> mapBatchResponse(BatchResponseT batchResponse);
+    List<Either<IdentifiableMessage<ResponseT>, IdentifiableMessage<Throwable>>> mapBatchResponse(BatchResponseT batchResponse);
 }

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/batchmanager/IdentifiableMessage.java → core/sdk-core/src/main/java/software/amazon/awssdk/core/batchmanager/IdentifiableMessage.java

@@ -13,7 +13,7 @@
  * permissions and limitations under the License.
  */
 
-package software.amazon.awssdk.core.internal.batchmanager;
+package software.amazon.awssdk.core.batchmanager;
 
 import software.amazon.awssdk.annotations.SdkProtectedApi;
 import software.amazon.awssdk.utils.Validate;

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/batchmanager/BatchBuffer.java

@@ -27,9 +27,13 @@
 @SdkInternalApi
 public final class BatchBuffer<RequestT, ResponseT> {
     private final Object flushLock = new Object();
-
     private final Map<String, BatchingExecutionContext<RequestT, ResponseT>> idToBatchContext;
 
+    /**
+     * Maximum number of elements that can be included in the BatchBuffer.
+     */
+    private final int maxBufferSize;
+
     // TODO: Figure out better name for nextId and nextBatchEntry.
     /**
      * Batch entries in a batch request require a unique ID so nextId keeps track of the ID to assign to the next
@@ -50,8 +54,9 @@ public final class BatchBuffer<RequestT, ResponseT> {
      */
     private ScheduledFuture<?> scheduledFlush;
 
-    public BatchBuffer(ScheduledFuture<?> scheduledFlush) {
+    public BatchBuffer(int maxBufferSize, ScheduledFuture<?> scheduledFlush) {
         this.idToBatchContext = new ConcurrentHashMap<>();
+        this.maxBufferSize = maxBufferSize;
         this.nextId = 0;
         this.nextBatchEntry = 0;
         this.scheduledFlush = scheduledFlush;
@@ -94,13 +99,18 @@ public CompletableFuture<ResponseT> getResponse(String key) {
         return idToBatchContext.get(key).response();
     }
 
-    public BatchingExecutionContext<RequestT, ResponseT> put(RequestT request, CompletableFuture<ResponseT> response) {
+    public void put(RequestT request, CompletableFuture<ResponseT> response)
+            throws IndexOutOfBoundsException {
         synchronized (this) {
+            if (idToBatchContext.size() == maxBufferSize) {
+                throw new IndexOutOfBoundsException("MaxBufferSize reached");
+            }
+
             if (nextId == Integer.MAX_VALUE) {
                 nextId = 0;
             }
             String id = Integer.toString(nextId++);
-            return idToBatchContext.put(id, new BatchingExecutionContext<>(request, response));
+            idToBatchContext.put(id, new BatchingExecutionContext<>(request, response));
         }
     }
 

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/batchmanager/BatchConfiguration.java

@@ -25,13 +25,20 @@ public final class BatchConfiguration {
 
     // TODO: Update these default values.
     private static final int DEFAULT_MAX_BATCH_ITEMS = 5;
+    private static final int DEFAULT_MAX_BATCH_KEYS = 100;
+    private static final int DEFAULT_MAX_BUFFER_SIZE = 500;
     private static final Duration DEFAULT_MAX_BATCH_OPEN_IN_MS = Duration.ofMillis(200);
+
     private final Integer maxBatchItems;
+    private final Integer maxBatchKeys;
+    private final Integer maxBufferSize;
     private final Duration maxBatchOpenInMs;
 
     public BatchConfiguration(BatchOverrideConfiguration overrideConfiguration) {
         Optional<BatchOverrideConfiguration> configuration = Optional.ofNullable(overrideConfiguration);
         this.maxBatchItems = configuration.flatMap(BatchOverrideConfiguration::maxBatchItems).orElse(DEFAULT_MAX_BATCH_ITEMS);
+        this.maxBatchKeys = configuration.flatMap(BatchOverrideConfiguration::maxBatchKeys).orElse(DEFAULT_MAX_BATCH_KEYS);
+        this.maxBufferSize = configuration.flatMap(BatchOverrideConfiguration::maxBufferSize).orElse(DEFAULT_MAX_BUFFER_SIZE);
         this.maxBatchOpenInMs = configuration.flatMap(BatchOverrideConfiguration::maxBatchOpenInMs)
                                              .orElse(DEFAULT_MAX_BATCH_OPEN_IN_MS);
     }
@@ -43,4 +50,12 @@ public Duration maxBatchOpenInMs() {
     public int maxBatchItems() {
         return maxBatchItems;
     }
+
+    public int getMaxBatchKeys() {
+        return maxBatchKeys;
+    }
+
+    public int getMaxBufferSize() {
+        return maxBufferSize;
+    }
 }

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/batchmanager/BatchingMap.java

@@ -30,20 +30,32 @@
 @SdkInternalApi
 public final class BatchingMap<RequestT, ResponseT> {
 
+    private final int maxBatchKeys;
+    private final int maxBufferSize;
     private final Map<String, BatchBuffer<RequestT, ResponseT>> batchContextMap;
 
-    public BatchingMap() {
+    public BatchingMap(int maxBatchKeys, int maxBufferSize) {
         this.batchContextMap = new ConcurrentHashMap<>();
+        this.maxBatchKeys = maxBatchKeys;
+        this.maxBufferSize = maxBufferSize;
     }
 
+    // put has a happens-before relation with removeBufferIfNeeded which is called by flushableRequests() and
+    // flushableScheduledRequests. This is done because removeBufferIfNeeded removes the underlying buffer and so we want to
+    // guarantee that we don't try to put items into a buffer that is removed.
     public void put(String batchKey, Supplier<ScheduledFuture<?>> scheduleFlush, RequestT request,
-                     CompletableFuture<ResponseT> response) {
-        batchContextMap.computeIfAbsent(batchKey, k -> new BatchBuffer<>(scheduleFlush.get()))
+                     CompletableFuture<ResponseT> response) throws IndexOutOfBoundsException {
+        batchContextMap.computeIfAbsent(batchKey, k -> {
+            if (batchContextMap.size() == maxBatchKeys) {
+                throw new IndexOutOfBoundsException("MaxBatchKeys reached");
+            }
+            return new BatchBuffer<>(maxBufferSize, scheduleFlush.get());
+        })
                        .put(request, response);
     }
 
-    public void putScheduledFlush(String key, ScheduledFuture<?> scheduledFlush) {
-        batchContextMap.get(key).putScheduledFlush(scheduledFlush);
+    public void putScheduledFlush(String batchKey, ScheduledFuture<?> scheduledFlush) {
+        batchContextMap.get(batchKey).putScheduledFlush(scheduledFlush);
     }
 
     public void forEach(BiConsumer<String, BatchBuffer<RequestT, ResponseT>> action) {

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/batchmanager/DefaultBatchManager.java

@@ -24,14 +24,18 @@
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import software.amazon.awssdk.annotations.SdkInternalApi;
+import software.amazon.awssdk.core.batchmanager.BatchAndSend;
+import software.amazon.awssdk.core.batchmanager.BatchKeyMapper;
 import software.amazon.awssdk.core.batchmanager.BatchManager;
 import software.amazon.awssdk.core.batchmanager.BatchOverrideConfiguration;
+import software.amazon.awssdk.core.batchmanager.BatchResponseMapper;
+import software.amazon.awssdk.core.batchmanager.IdentifiableMessage;
+import software.amazon.awssdk.utils.Either;
 import software.amazon.awssdk.utils.Validate;
 
 @SdkInternalApi
 public final class DefaultBatchManager<RequestT, ResponseT, BatchResponseT> implements BatchManager<RequestT, ResponseT,
     BatchResponseT> {
-
     private final int maxBatchItems;
     private final Duration maxBatchOpenInMs;
 
@@ -65,7 +69,8 @@ public final class DefaultBatchManager<RequestT, ResponseT, BatchResponseT> impl
 
     private DefaultBatchManager(DefaultBuilder<RequestT, ResponseT, BatchResponseT> builder) {
         BatchConfiguration batchConfiguration = new BatchConfiguration(builder.overrideConfiguration);
-        this.requestsAndResponsesMaps = new BatchingMap<>();
+        this.requestsAndResponsesMaps = new BatchingMap<>(batchConfiguration.getMaxBatchKeys(),
+                                                          batchConfiguration.getMaxBufferSize());
         this.maxBatchItems = batchConfiguration.maxBatchItems();
         this.maxBatchOpenInMs = batchConfiguration.maxBatchOpenInMs();
         this.batchFunction = Validate.notNull(builder.batchFunction, "Null batchFunction");
@@ -116,7 +121,6 @@ private void flushBuffer(String batchKey, Map<String, BatchingExecutionContext<R
         List<IdentifiableMessage<RequestT>> requestEntries = new ArrayList<>();
         flushableRequests.forEach((contextId, batchExecutionContext) ->
                                       requestEntries.add(new IdentifiableMessage<>(contextId, batchExecutionContext.request())));
-
         if (!requestEntries.isEmpty()) {
             batchFunction.batchAndSend(requestEntries, batchKey)
                          .whenComplete((result, ex) -> handleAndCompleteResponses(result, ex, flushableRequests));
@@ -129,13 +133,17 @@ private void handleAndCompleteResponses(BatchResponseT batchResult, Throwable ex
             requests.forEach((contextId, batchExecutionContext) -> batchExecutionContext.response()
                                                                                         .completeExceptionally(exception));
         } else {
-            List<IdentifiableMessage<ResponseT>> identifiedResponses = responseMapper.mapBatchResponse(batchResult);
-            for (IdentifiableMessage<ResponseT> identifiedResponse : identifiedResponses) {
-                String id = identifiedResponse.id();
-                ResponseT response = identifiedResponse.message();
-                requests.get(id)
-                        .response()
-                        .complete(response);
+            List<Either<IdentifiableMessage<ResponseT>, IdentifiableMessage<Throwable>>> identifiedResponses =
+                responseMapper.mapBatchResponse(batchResult);
+            for (Either<IdentifiableMessage<ResponseT>, IdentifiableMessage<Throwable>> response : identifiedResponses) {
+                response.map(
+                    actualResponse -> requests.get(actualResponse.id())
+                                              .response()
+                                              .complete(actualResponse.message()),
+                    throwable -> requests.get(throwable.id())
+                                         .response()
+                                         .completeExceptionally(throwable.message())
+                );
             }
         }
         requests.clear();