ascherbakoff commented on code in PR #4540:
URL: https://github.com/apache/ignite-3/pull/4540#discussion_r1814629644


##########
modules/transactions/src/main/java/org/apache/ignite/internal/tx/impl/HeapLockManager.java:
##########
@@ -328,10 +349,359 @@ private LockState adjustLockState(LockState state, 
LockState v) {
         }
     }
 
+    private void track(UUID txId, Releasable val) {
+        txMap.compute(txId, (k, v) -> {
+            if (v == null) {
+                v = new ConcurrentLinkedQueue<>();
+            }
+
+            v.add(val);
+
+            return v;
+        });
+    }
+
     /**
-     * A lock state.
+     * Create lock exception with given parameters.
+     *
+     * @param locker Locker.
+     * @param holder Lock holder.
+     * @return Lock exception.
      */
-    public class LockState {
+    private static LockException lockException(UUID locker, UUID holder) {
+        return new LockException(ACQUIRE_LOCK_ERR,
+                "Failed to acquire a lock due to a possible deadlock [locker=" 
+ locker + ", holder=" + holder + ']');
+    }
+
+    /**
+     * Create lock exception when lock holder is believed to be missing.
+     *
+     * @param locker Locker.
+     * @param holder Lock holder.
+     * @return Lock exception.
+     */
+    private static LockException abandonedLockException(UUID locker, UUID 
holder) {
+        return new LockException(ACQUIRE_LOCK_ERR,
+                "Failed to acquire an abandoned lock due to a possible 
deadlock [locker=" + locker + ", holder=" + holder + ']');
+    }
+
+    /**
+     * Common interface for releasing transaction locks.
+     */
+    interface Releasable {
+        /**
+         * Tries to release a lock.
+         *
+         * @param txId Tx id.
+         * @return {@code True} if lock state requires cleanup after release.
+         */
+        boolean tryRelease(UUID txId);
+
+        /**
+         * Gets associated lock key.
+         *
+         * @return Lock key.
+         */
+        LockKey key();
+
+        /**
+         * Returns the lock which is requested by given tx.
+         *
+         * @param txId Tx id.
+         * @return The lock or null if no lock exist.
+         */
+        @Nullable Lock lock(UUID txId);
+
+        /**
+         * Returns lock type.
+         *
+         * @return The type.
+         */
+        boolean coarse();
+    }
+
+    /**
+     * Coarse lock.
+     */
+    public class CoarseLockState implements Releasable {
+        private final IgniteStripedReadWriteLock stripedLock = new 
IgniteStripedReadWriteLock(CONCURRENCY);
+
+        private final ConcurrentHashMap<UUID, Lock> ixlockOwners = new 
ConcurrentHashMap<>();
+        private final Map<UUID, IgniteBiTuple<Lock, CompletableFuture<Lock>>> 
slockWaiters = new HashMap<>();
+        private final ConcurrentHashMap<UUID, Lock> slockOwners = new 
ConcurrentHashMap<>();
+
+        private final LockKey lockKey;
+
+        CoarseLockState(LockKey lockKey) {
+            this.lockKey = lockKey;
+        }
+
+        @Override
+        public boolean tryRelease(UUID txId) {
+            Lock lock = lock(txId);
+
+            release(lock);
+
+            return false;
+        }
+
+        @Override
+        public LockKey key() {
+            return lockKey;
+        }
+
+        @Override
+        public Lock lock(UUID txId) {
+            Lock lock = ixlockOwners.get(txId);
+
+            if (lock != null) {
+                return lock;
+            }
+
+            int idx = Math.floorMod(spread(txId.hashCode()), CONCURRENCY);
+
+            stripedLock.readLock(idx).lock();
+
+            try {
+                lock = slockOwners.get(txId);
+
+                if (lock != null) {
+                    return lock;
+                }
+
+                IgniteBiTuple<Lock, CompletableFuture<Lock>> tuple = 
slockWaiters.get(txId);
+
+                if (tuple != null) {
+                    return tuple.get1();
+                }
+            } finally {
+                stripedLock.readLock(idx).unlock();
+            }
+
+            return null;
+        }
+
+        @Override
+        public boolean coarse() {
+            return true;
+        }
+
+        /**
+         * Acquires a lock.
+         *
+         * @param txId Tx id.
+         * @param lockKey Lock key.
+         * @param lockMode Lock mode.
+         * @return The future.
+         */
+        public CompletableFuture<Lock> acquire(UUID txId, LockKey lockKey, 
LockMode lockMode) {
+            switch (lockMode) {
+                case S:
+                    stripedLock.writeLock().lock();
+
+                    try {
+                        // IX-locks can't be modified under the striped write 
lock.
+                        if (!ixlockOwners.isEmpty()) {
+                            if (ixlockOwners.containsKey(txId)) {
+                                if (ixlockOwners.size() == 1) {
+                                    // Safe to upgrade.
+                                    track(txId, this); // Double track.
+                                    Lock lock = new Lock(lockKey, lockMode, 
txId);
+                                    slockOwners.putIfAbsent(txId, lock);
+                                    return completedFuture(lock);
+                                } else {
+                                    // Attempt to upgrade to SIX in the 
presence of concurrent transactions. Deny lock attempt.
+                                    for (Lock lock : ixlockOwners.values()) {
+                                        if (!lock.txId().equals(txId)) {
+                                            return 
failedFuture(lockException(txId, lock.txId()));
+                                        }
+                                    }
+                                }
+
+                                assert false : "Should not reach here";
+                            }
+
+                            UUID holderTx = 
ixlockOwners.keySet().iterator().next();
+                            CompletableFuture<Void> res = 
fireEvent(LOCK_CONFLICT, new LockEventParameters(txId, holderTx));
+                            // TODO: 
https://issues.apache.org/jira/browse/IGNITE-21153
+                            if (res.isCompletedExceptionally()) {
+                                return 
failedFuture(abandonedLockException(txId, holderTx));
+                            }
+
+                            // Validate reordering with IX locks.
+                            for (Lock lock : ixlockOwners.values()) {
+                                // Allow only high priority transactions to 
wait.
+                                if 
(TxIdPriorityComparator.INSTANCE.compare(lock.txId(), txId) < 0) {

Review Comment:
   🆗 



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