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fix: park contended area locks without losing wakeups #13

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Merged
Spottedleaf merged 1 commit into from
Oct 20, 2026
Merged

fix: park contended area locks without losing wakeups #13

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8 changes: 5 additions & 3 deletions concurrentutil/src/main/java/ca/spottedleaf/concurrentutil/lock/ReentrantAreaLock.java
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Original file line number Diff line number Diff line change
Expand Up @@ -185,7 +185,7 @@ public Node lock(final int fromX, final int fromY, final int toX, final int toY)
final long[] areaAffected = new long[(toSectionX - fromSectionX + 1) * (toSectionY - fromSectionY + 1)];
int areaAffectedLen = 0;

final Node ret = new Node(this, areaAffected, currThread);
Node ret = new Node(this, areaAffected, currThread);

for (;;) {
Node park = null;
Expand Down Expand Up @@ -228,8 +228,9 @@ public Node lock(final int fromX, final int fromY, final int toX, final int toY)

areaAffectedLen = 0;

// since we inserted, we need to drain waiters
ret.notifier.notifyThreadsAndBlock();
// A contender may start waiting after this notification, so do not reuse the node.
ret.notifier.notifyThreads();
ret = new Node(this, areaAffected, currThread);
}

if (park == null) {
Expand All @@ -242,6 +243,7 @@ public Node lock(final int fromX, final int fromY, final int toX, final int toY)
}

// failed
park.notifier.waitUntilReady();
}
}

Expand Down