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v0.4.19: fix post-move publish race in VideoCache.download
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Reviewer-flagged: v0.4.18 only checked epoch BEFORE Files.move. The window
between the move completing and READY.put / "완료" chat was still racy —
if /videoCache clear landed in that window, clearAll would epoch++ +
clear READY + delete files on disk, then the download thread would do
READY.put(url, finalPath) anyway, resurrecting a cleared entry and emitting
a stale "완료" message.

Add a second epoch check immediately AFTER Files.move(): if the epoch
changed, delete finalPath and return without publishing. The pre-move
check is kept too — it lets the common cancel-during-read case skip the
wasted move/delete round-trip.
This commit is contained in:
tkrmagid
2026-05-16 22:51:32 +09:00
parent de723fd0b4
commit d11289309b
2 changed files with 19 additions and 5 deletions
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22
src/main/java/com/ejclaw/videoplayer/client/playback/VideoCache.java
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@@ -340,11 +340,10 @@ public final class VideoCache {
return;
}
// Final cancellation check before publishing. If clearAll ran during the read
// loop's last iteration (after the loop check, before this point), we still
// refuse to publish — otherwise we'd resurrect a cache entry post-clear.
// Pre-move cancellation check. If clearAll ran during the read loop, abort
// before promoting .part to final — saves a wasted move + delete.
if (CACHE_EPOCH.get() != startEpoch) {
VideoPlayerMod.LOG.info("[{}] preload: cancelled at publish (clearAll ran) — {}",
VideoPlayerMod.LOG.info("[{}] preload: cancelled before move (clearAll ran) — {}",
VideoPlayerMod.MOD_ID, url);
try { Files.deleteIfExists(partPath); } catch (Throwable ignored) {}
return;
@@ -352,6 +351,21 @@ public final class VideoCache {
Files.move(partPath, finalPath, StandardCopyOption.REPLACE_EXISTING,
StandardCopyOption.ATOMIC_MOVE);
// Post-move cancellation check. clearAll() may have run between the pre-move
// check above and the move itself — in that case clearAll's directory scan
// either missed our file (it didn't exist yet) or saw the .part and skipped /
// failed to delete it. Either way, finalPath now exists on disk but the
// user-visible cache state is "cleared", so we must delete the file and skip
// both the READY.put and the "완료" chat. Without this check, a clear right at
// this window leaves a resurrected file in READY and a stale "완료" message.
if (CACHE_EPOCH.get() != startEpoch) {
VideoPlayerMod.LOG.info("[{}] preload: cancelled after move (clearAll ran) — {}",
VideoPlayerMod.MOD_ID, url);
try { Files.deleteIfExists(finalPath); } catch (Throwable ignored) {}
return;
}
READY.put(url, finalPath);
VideoPlayerMod.LOG.info("[{}] preload: cached {} ({} bytes) -> {}",
VideoPlayerMod.MOD_ID, url, total, finalPath.getFileName());