2 files changed, 24 insertions, 8 deletions
diff --git a/src/client/northstar/utils/Extensions.ts b/src/client/northstar/utils/Extensions.ts
index ad3e06806..8254c775c 100644
--- a/src/client/northstar/utils/Extensions.ts
+++ b/src/client/northstar/utils/Extensions.ts
@@ -31,13 +31,19 @@ type BatchHandlerAsync<I> = (batch: I[], context: BatchContext) => Promise<void>
 type BatchConverter<I, O> = BatchConverterSync<I, O> | BatchConverterAsync<I, O>;
 type BatchHandler<I> = BatchHandlerSync<I> | BatchHandlerAsync<I>;
 type FixedBatcher = { batchSize: number } | { batchCount: number, mode?: Mode };
+interface ExecutorResult<A> {
+    updated: A;
+    makeNextBatch: boolean;
+}
 interface PredicateBatcher<I, A> {
-    executor: (element: I, accumulator: A | undefined) => A | undefined;
+    executor: (element: I, accumulator: A) => ExecutorResult<A>;
     initial: A;
+    persistAccumulator?: boolean;
 }
 interface PredicateBatcherAsync<I, A> {
-    executor: (element: I, accumulator: A | undefined) => Promise<A | undefined>;
+    executor: (element: I, accumulator: A) => Promise<ExecutorResult<A>>;
     initial: A;
+    persistAccumulator?: boolean;
 }
 type Batcher<I, A> = FixedBatcher | PredicateBatcher<I, A>;
 type BatcherAsync<I, A> = Batcher<I, A> | PredicateBatcherAsync<I, A>;
diff --git a/src/client/util/UtilExtensions.ts b/src/client/util/UtilExtensions.ts
index da47fc1bc..1447e37cb 100644
--- a/src/client/util/UtilExtensions.ts
+++ b/src/client/util/UtilExtensions.ts
@@ -17,14 +17,19 @@ module.exports.BatchAsync = async function <T, A>(batcher: BatcherAsync<T, A>):
 module.exports.PredicateBatch = function <T, A>(batcher: PredicateBatcher<T, A>): T[][] {
     const batches: T[][] = [];
     let batch: T[] = [];
-    const { executor, initial } = batcher;
-    let accumulator: A | undefined = initial;
+    const { executor, initial, persistAccumulator } = batcher;
+    let accumulator = initial;
     for (let element of this) {
-        if ((accumulator = executor(element, accumulator)) !== undefined) {
+        const { updated, makeNextBatch } = executor(element, accumulator);
+        accumulator = updated;
+        if (!makeNextBatch) {
             batch.push(element);
         } else {
             batches.push(batch);
             batch = [element];
+            if (!persistAccumulator) {
+                accumulator = initial;
+            }
         }
     }
     batches.push(batch);
@@ -34,14 +39,19 @@ module.exports.PredicateBatch = function <T, A>(batcher: PredicateBatcher<T, A>)
 module.exports.PredicateBatchAsync = async function <T, A>(batcher: PredicateBatcherAsync<T, A>): Promise<T[][]> {
     const batches: T[][] = [];
     let batch: T[] = [];
-    const { executor, initial } = batcher;
-    let accumulator: A | undefined = initial;
+    const { executor, initial, persistAccumulator } = batcher;
+    let accumulator: A = initial;
     for (let element of this) {
-        if ((accumulator = await executor(element, accumulator)) !== undefined) {
+        const { updated, makeNextBatch } = await executor(element, accumulator);
+        accumulator = updated;
+        if (!makeNextBatch) {
             batch.push(element);
         } else {
             batches.push(batch);
             batch = [element];
+            if (!persistAccumulator) {
+                accumulator = initial;
+            }
         }
     }
     batches.push(batch);