Always use try/finally around DfsBlockCache.clockLock
Any RuntimeException or Error in this block will leave the lock held by the caller thread, which can later result in deadlock or just cache requests hanging forever because they cannot get to the lock object. Wrap everything in try/finally to prevent the lock from hanging, even though a RuntimeException or Error should never happen in any of these code paths. Change-Id: Ibb3467f7ee4c06f617b737858b4be17b10d936e0
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@ -389,36 +389,39 @@ DfsBlock getOrLoad(DfsPackFile pack, long position, DfsReader ctx)
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@SuppressWarnings("unchecked")
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private void reserveSpace(int reserve) {
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clockLock.lock();
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long live = liveBytes + reserve;
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if (maxBytes < live) {
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Ref prev = clockHand;
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Ref hand = clockHand.next;
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do {
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if (hand.hot) {
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// Value was recently touched. Clear
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// hot and give it another chance.
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hand.hot = false;
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prev = hand;
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hand = hand.next;
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continue;
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} else if (prev == hand)
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break;
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try {
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long live = liveBytes + reserve;
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if (maxBytes < live) {
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Ref prev = clockHand;
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Ref hand = clockHand.next;
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do {
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if (hand.hot) {
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// Value was recently touched. Clear
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// hot and give it another chance.
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hand.hot = false;
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prev = hand;
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hand = hand.next;
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continue;
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} else if (prev == hand)
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break;
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// No recent access since last scan, kill
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// value and remove from clock.
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Ref dead = hand;
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hand = hand.next;
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prev.next = hand;
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dead.next = null;
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dead.value = null;
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live -= dead.size;
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dead.pack.cachedSize.addAndGet(-dead.size);
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statEvict++;
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} while (maxBytes < live);
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clockHand = prev;
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// No recent access since last scan, kill
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// value and remove from clock.
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Ref dead = hand;
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hand = hand.next;
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prev.next = hand;
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dead.next = null;
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dead.value = null;
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live -= dead.size;
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dead.pack.cachedSize.addAndGet(-dead.size);
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statEvict++;
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} while (maxBytes < live);
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clockHand = prev;
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}
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liveBytes = live;
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} finally {
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clockLock.unlock();
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}
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liveBytes = live;
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clockLock.unlock();
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}
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private void creditSpace(int credit) {
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@ -429,13 +432,16 @@ private void creditSpace(int credit) {
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private void addToClock(Ref ref, int credit) {
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clockLock.lock();
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if (credit != 0)
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liveBytes -= credit;
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Ref ptr = clockHand;
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ref.next = ptr.next;
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ptr.next = ref;
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clockHand = ref;
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clockLock.unlock();
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try {
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if (credit != 0)
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liveBytes -= credit;
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Ref ptr = clockHand;
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ref.next = ptr.next;
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ptr.next = ref;
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clockHand = ref;
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} finally {
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clockLock.unlock();
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}
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}
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void put(DfsBlock v) {
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