Cyrill commented on code in PR #7970:
URL: https://github.com/apache/ignite-3/pull/7970#discussion_r3109121460
##########
modules/transactions/src/main/java/org/apache/ignite/internal/tx/impl/HeapLockManager.java:
##########
@@ -903,6 +917,52 @@ public int waitersCount() {
}
}
+ /**
+ * Checks if any currently held lock mode is incompatible with the
intended mode.
+ * Runs in O(1) time (constant number of lock modes). Must be called
under {@code synchronized (waiters)}.
+ */
+ private boolean hasAnyIncompatibleHolder(LockMode intended) {
+ for (LockMode held : LOCK_MODES) {
+ if (lockModeHeldCount[held.ordinal()] > 0 &&
!held.isCompatible(intended)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /** Adjusts {@code lockModeHeldCount} for a mode transition. Must be
called under {@code synchronized (waiters)}. */
+ private void updateHeldCount(@Nullable LockMode oldMode, @Nullable
LockMode newMode) {
+ if (oldMode == newMode) {
+ return;
+ }
+ if (oldMode != null) {
+ lockModeHeldCount[oldMode.ordinal()]--;
+ }
+ if (newMode != null) {
+ lockModeHeldCount[newMode.ordinal()]++;
+ }
+ }
+
+ /** Locks the waiter and updates {@code lockModeHeldCount}. Must be
called under {@code synchronized (waiters)}. */
+ private void lockOnWaiter(WaiterImpl waiter) {
+ LockMode oldMode = waiter.lockMode();
+ waiter.lock();
+ updateHeldCount(oldMode, waiter.lockMode());
+ }
+
+ /** Validates lockModeHeldCount is consistent with actual waiter
state. Must be called under {@code synchronized (waiters)}. */
+ private void assertLockModeHeldCount() {
+ int[] expected = new int[LOCK_MODES.length];
+ for (WaiterImpl w : waiters.values()) {
+ if (w.lockMode != null) {
+ expected[w.lockMode.ordinal()]++;
+ }
+ }
Review Comment:
Benchmarks (LockManagerBenchmark, 1 fork, default JMH settings):
| bench | main
| this PR | Δ |
|------------------------------------------------------|---------------------|---------------------|------|
| contendedSharedKeyS (16 threads, shared key, S-mode) | 6.100 ± 0.271
µs/op | 4.809 ± 0.362 µs/op | −21% |
| lockCommit (1 thread, 200 unique X keys) | 22.757 µs/op
| 19.022 µs/op | −16% |
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