gemini-code-assist[bot] commented on code in PR #37691:
URL: https://github.com/apache/beam/pull/37691#discussion_r2843507744
##########
sdks/java/harness/src/main/java/org/apache/beam/fn/harness/state/StateFetchingIterators.java:
##########
@@ -669,12 +675,23 @@ static class LazyBlockingStateFetchingIterator implements
PrefetchableIterator<B
private final StateRequest stateRequestForFirstChunk;
private ByteString continuationToken;
private CompletableFuture<StateResponse> prefetchedResponse;
+ private boolean hasNoState;
LazyBlockingStateFetchingIterator(
BeamFnStateClient beamFnStateClient, StateRequest
stateRequestForFirstChunk) {
this.beamFnStateClient = beamFnStateClient;
this.stateRequestForFirstChunk = stateRequestForFirstChunk;
this.continuationToken =
stateRequestForFirstChunk.getGet().getContinuationToken();
+ this.hasNoState = false;
+ }
+
+ LazyBlockingStateFetchingIterator(
+ BeamFnStateClient beamFnStateClient, StateRequest
stateRequestForFirstChunk,
+ boolean hasNoState) {
+ this.beamFnStateClient = beamFnStateClient;
+ this.stateRequestForFirstChunk = stateRequestForFirstChunk;
+ this.continuationToken =
stateRequestForFirstChunk.getGet().getContinuationToken();
+ this.hasNoState = hasNoState;
}
Review Comment:
There's a potential `NullPointerException` here. If `hasNoState` is true,
`continuationToken` can still be non-null (e.g., `ByteString.EMPTY` for a new
read). This would cause `hasNext()` to return `true`. However, `prefetch()`
will do nothing due to the `!hasNoState` check. Consequently, when `next()` is
called, it will attempt to call `.get()` on a `null` `prefetchedResponse`,
leading to an NPE.
To fix this, the iterator should be made empty when `hasNoState` is true.
The cleanest way to achieve this is by setting `continuationToken` to `null` in
the constructor if `hasNoState` is true. This will cause `hasNext()` to return
`false` from the beginning.
```java
LazyBlockingStateFetchingIterator(
BeamFnStateClient beamFnStateClient, StateRequest
stateRequestForFirstChunk,
boolean hasNoState) {
this.beamFnStateClient = beamFnStateClient;
this.stateRequestForFirstChunk = stateRequestForFirstChunk;
this.hasNoState = hasNoState;
if (hasNoState) {
this.continuationToken = null;
} else {
this.continuationToken =
stateRequestForFirstChunk.getGet().getContinuationToken();
}
}
```
##########
sdks/java/harness/src/main/java/org/apache/beam/fn/harness/state/StateFetchingIterators.java:
##########
@@ -713,7 +730,7 @@ public boolean isReady() {
@Override
public void prefetch() {
- if (continuationToken != null && prefetchedResponse == null) {
+ if (continuationToken != null && prefetchedResponse == null &&
!hasNoState) {
Review Comment:
If the constructor is updated to nullify `continuationToken` when
`hasNoState` is true (as suggested in another comment), this `!hasNoState`
check becomes redundant because `continuationToken != null` will already be
false in that case. You could simplify this condition for better readability.
```java
if (continuationToken != null && prefetchedResponse == null) {
```
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