refactor by centralizing change in FindOptions#getBatchSize()

Author: NathanQingyangXu

driver-core/src/main/com/mongodb/internal/client/model/FindOptions.java

@@ -215,7 +215,9 @@ public FindOptions maxAwaitTime(final long maxAwaitTime, final TimeUnit timeUnit
      * @mongodb.driver.manual reference/method/cursor.batchSize/#cursor.batchSize Batch Size
      */
     public int getBatchSize() {
-        return batchSize;
+        return batchSize > 0 && batchSize == limit
+                ? (batchSize + 1)
+                : batchSize;
     }
 
     /**

driver-core/src/main/com/mongodb/internal/operation/Operations.java

@@ -188,18 +188,11 @@ <TResult> FindOperation<TResult> find(final MongoNamespace findNamespace, @Nulla
 
     private <TResult> FindOperation<TResult> createFindOperation(final MongoNamespace findNamespace, @Nullable final Bson filter,
                                                                  final Class<TResult> resultClass, final FindOptions options) {
-        final int effectiveBatchSize;
-        if (options.getBatchSize() > 0 && options.getBatchSize() == options.getLimit()) {
-            // Eliminate unnecessary killCursors command when batchSize == limit
-            effectiveBatchSize = options.getBatchSize() + 1;
-        } else {
-            effectiveBatchSize = options.getBatchSize();
-        }
         FindOperation<TResult> operation = new FindOperation<>(
                 findNamespace, codecRegistry.get(resultClass))
                 .retryReads(retryReads)
                 .filter(filter == null ? new BsonDocument() : filter.toBsonDocument(documentClass, codecRegistry))
-                .batchSize(effectiveBatchSize)
+                .batchSize(options.getBatchSize())
                 .skip(options.getSkip())
                 .limit(options.getLimit())
                 .projection(toBsonDocument(options.getProjection()))

driver-reactive-streams/src/main/com/mongodb/reactivestreams/client/internal/FindPublisherImpl.java

@@ -233,13 +233,6 @@ Function<AsyncOperations<?>, TimeoutSettings> getTimeoutSettings() {
 
     @Override
     AsyncReadOperation<AsyncBatchCursor<T>> asAsyncFirstReadOperation() {
-        final FindOptions effectiveFindOptions;
-        if (findOptions.getBatchSize() > 0 && findOptions.getBatchSize() == findOptions.getLimit()) {
-            // Eliminate unnecessary killCursors command when batchSize == limit
-            effectiveFindOptions = findOptions.withBatchSize(findOptions.getBatchSize() + 1);
-        } else {
-            effectiveFindOptions = findOptions;
-        }
-        return getOperations().findFirst(filter, getDocumentClass(), effectiveFindOptions);
+        return getOperations().findFirst(filter, getDocumentClass(), findOptions);
     }
 }

driver-sync/src/main/com/mongodb/client/internal/FindIterableImpl.java

@@ -245,14 +245,7 @@ private <E> E executeExplain(final Class<E> explainResultClass, @Nullable final
     }
 
     public ExplainableReadOperation<BatchCursor<TResult>> asReadOperation() {
-        final FindOptions effectiveFindOptions;
-        if (findOptions.getBatchSize() > 0 && findOptions.getBatchSize() == findOptions.getLimit()) {
-            // Eliminate unnecessary killCursors command when batchSize == limit
-            effectiveFindOptions = findOptions.withBatchSize(findOptions.getBatchSize() + 1);
-        } else {
-            effectiveFindOptions = findOptions;
-        }
-        return operations.find(filter, resultClass, effectiveFindOptions);
+        return operations.find(filter, resultClass, findOptions);
     }
 
 }