Kaixuan-Duan commented on code in PR #3132:
URL: https://github.com/apache/fluss/pull/3132#discussion_r3224043187
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fluss-server/src/main/java/org/apache/fluss/server/kv/RemoteLogFetcher.java:
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@@ -333,12 +555,202 @@ private void advance() {
}
}
+ /**
+ * Obtain the local file for {@code segment}, ideally reusing a
prefetched download. On
+ * success the ring head is consumed and a refill is triggered, so the
window stays full as
+ * long as more segments remain.
+ */
+ private File fetchSegmentFile(RemoteLogSegment segment) throws
IOException {
+ // Invariant: fillPrefetchWindow() and advance() walk the same
pre-filtered
+ // `segments` list in strict order with identical skip rules;
consumption is
+ // single-threaded FIFO; prefetchNum >= 1 (Math.max(1, ...) in the
ctor). So
+ // the ring head is *always* the segment advance() is asking for.
+ int headSlot = nextConsumeIndex % prefetchNum;
+ RemoteLogSegment headSegment = prefetchSegments[headSlot];
+ assert isSameSegmentId(segment, headSegment)
+ : "prefetch ring head "
+ + (headSegment == null ? "null" :
headSegment.remoteLogSegmentId())
+ + " does not match requested "
+ + segment.remoteLogSegmentId();
+ Future<File> headFuture = prefetchSlots[headSlot];
+ // Eagerly null the slot refs so the ring never keeps stale
references even if the
+ // consumer throws below — also releases the RemoteLogSegment for
GC early.
+ prefetchSlots[headSlot] = null;
+ prefetchSegments[headSlot] = null;
+ nextConsumeIndex++;
+ try {
+ return headFuture.get();
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ throw new IOException(
+ "Interrupted while waiting for remote log segment
download: "
+ + segment.remoteLogSegmentId(),
+ e);
+ } catch (CancellationException e) {
+ LOG.warn(
+ "Prefetched segment {} was cancelled, fallback to sync
download.",
+ segment.remoteLogSegmentId(),
+ e);
+ return downloadSegmentWithRetry(segment);
+ } catch (ExecutionException e) {
Review Comment:
You're right — the async worker already exhausts retries via
downloadSegmentWithRetry(). Removed the redundant sync retry in catch
(ExecutionException); now propagates directly as IOException.
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