HHH-17005 - Replace monitor with a Java lock to avoid pinning when using virtual threads

This commit replaces a `synchronized` with a ReentrantLock in:

- PooledOptimizer
- PooledLoOptimizer
- LegacyHiLoAlgorithmOptimizer
- HiLoOptimizer

The other implementations do not use a monitor lock.

hibernate-core/src/main/java/org/hibernate/id/enhanced/HiLoOptimizer.java

@@ -9,6 +9,8 @@ package org.hibernate.id.enhanced;
 import java.io.Serializable;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.hibernate.HibernateException;
 import org.hibernate.id.IntegralDataTypeHolder;
@@ -80,7 +82,9 @@ public class HiLoOptimizer extends AbstractOptimizer {
 	}
 
 	@Override
-	public synchronized Serializable generate(AccessCallback callback) {
+	public Serializable generate(AccessCallback callback) {
+		lock.lock();
+		try {
 			final GenerationState generationState = locateGenerationState( callback.getTenantIdentifier() );
 
 			if ( generationState.lastSourceValue == null ) {
@@ -102,7 +106,15 @@ public class HiLoOptimizer extends AbstractOptimizer {
 			}
 			return generationState.value.makeValueThenIncrement();
 		}
+		finally {
+			lock.unlock();
+		}
+	}
 
+	/**
+	 * Use a lock instead of the monitor lock to avoid pinning when using virtual threads.
+	 */
+	private final Lock lock = new ReentrantLock();
 	private GenerationState noTenantState;
 	private Map<String,GenerationState> tenantSpecificState;
 
@@ -139,9 +151,15 @@ public class HiLoOptimizer extends AbstractOptimizer {
 	}
 
 	@Override
-	public synchronized IntegralDataTypeHolder getLastSourceValue() {
+	public IntegralDataTypeHolder getLastSourceValue() {
+		lock.lock();
+		try {
 			return noTenantGenerationState().lastSourceValue;
 		}
+		finally {
+			lock.unlock();
+		}
+	}
 
 	@Override
 	public boolean applyIncrementSizeToSourceValues() {
@@ -155,9 +173,15 @@ public class HiLoOptimizer extends AbstractOptimizer {
 	 *
 	 * @return Value for property 'lastValue'.
 	 */
-	public synchronized IntegralDataTypeHolder getLastValue() {
+	public IntegralDataTypeHolder getLastValue() {
+		lock.lock();
+		try {
 			return noTenantGenerationState().value.copy().decrement();
 		}
+		finally {
+			lock.unlock();
+		}
+	}
 
 	/**
 	 * Getter for property 'upperLimit'.
@@ -166,7 +190,13 @@ public class HiLoOptimizer extends AbstractOptimizer {
 	 *
 	 * @return Value for property 'upperLimit'.
 	 */
-	public synchronized IntegralDataTypeHolder getHiValue() {
+	public IntegralDataTypeHolder getHiValue() {
+		lock.lock();
+		try {
 			return noTenantGenerationState().upperLimit;
 		}
+		finally {
+			lock.unlock();
+		}
+	}
 }

hibernate-core/src/main/java/org/hibernate/id/enhanced/LegacyHiLoAlgorithmOptimizer.java

@@ -9,6 +9,8 @@ package org.hibernate.id.enhanced;
 import java.io.Serializable;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.hibernate.HibernateException;
 import org.hibernate.id.IntegralDataTypeHolder;
@@ -53,7 +55,9 @@ public class LegacyHiLoAlgorithmOptimizer extends AbstractOptimizer {
 	}
 
 	@Override
-	public synchronized Serializable generate(AccessCallback callback) {
+	public Serializable generate(AccessCallback callback) {
+		lock.lock();
+		try {
 			final GenerationState generationState = locateGenerationState( callback.getTenantIdentifier() );
 
 			if ( generationState.lo > generationState.maxLo ) {
@@ -64,7 +68,16 @@ public class LegacyHiLoAlgorithmOptimizer extends AbstractOptimizer {
 			generationState.value = generationState.hi.copy().add( generationState.lo++ );
 			return generationState.value.makeValue();
 		}
+		finally {
+			lock.unlock();
+		}
 
+	}
+
+	/**
+	 * Use a lock instead of the monitor lock to avoid pinning when using virtual threads.
+	 */
+	private final Lock lock = new ReentrantLock();
 	private GenerationState noTenantState;
 	private Map<String,GenerationState> tenantSpecificState;
 
@@ -108,9 +121,15 @@ public class LegacyHiLoAlgorithmOptimizer extends AbstractOptimizer {
 	}
 
 	@Override
-	public synchronized IntegralDataTypeHolder getLastSourceValue() {
+	public IntegralDataTypeHolder getLastSourceValue() {
+		lock.lock();
+		try {
 			return noTenantGenerationState().lastSourceValue.copy();
 		}
+		finally {
+			lock.unlock();
+		}
+	}
 
 	@Override
 	public boolean applyIncrementSizeToSourceValues() {
@@ -124,7 +143,13 @@ public class LegacyHiLoAlgorithmOptimizer extends AbstractOptimizer {
 	 *
 	 * @return Value for property 'lastValue'.
 	 */
-	public synchronized IntegralDataTypeHolder getLastValue() {
+	public IntegralDataTypeHolder getLastValue() {
+		lock.lock();
+		try {
 			return noTenantGenerationState().value;
 		}
+		finally {
+			lock.unlock();
+		}
+	}
 }

hibernate-core/src/main/java/org/hibernate/id/enhanced/PooledLoOptimizer.java

@@ -9,6 +9,8 @@ package org.hibernate.id.enhanced;
 import java.io.Serializable;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.concurrent.locks.Lock;
 
 import org.hibernate.HibernateException;
 import org.hibernate.id.IntegralDataTypeHolder;
@@ -53,7 +55,9 @@ public class PooledLoOptimizer extends AbstractOptimizer {
 	}
 
 	@Override
-	public synchronized Serializable generate(AccessCallback callback) {
+	public Serializable generate(AccessCallback callback) {
+		lock.lock();
+		try {
 			final GenerationState generationState = locateGenerationState( callback.getTenantIdentifier() );
 
 			if ( generationState.lastSourceValue == null
@@ -68,7 +72,15 @@ public class PooledLoOptimizer extends AbstractOptimizer {
 			}
 			return generationState.value.makeValueThenIncrement();
 		}
+		finally {
+			lock.unlock();
+		}
+	}
 
+	/**
+	 * Use a lock instead of the monitor lock to avoid pinning when using virtual threads.
+	 */
+	private final Lock lock = new ReentrantLock();
 	private GenerationState noTenantState;
 	private Map<String,GenerationState> tenantSpecificState;
 

hibernate-core/src/main/java/org/hibernate/id/enhanced/PooledOptimizer.java

@@ -9,6 +9,8 @@ package org.hibernate.id.enhanced;
 import java.io.Serializable;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.hibernate.HibernateException;
 import org.hibernate.id.IntegralDataTypeHolder;
@@ -65,7 +67,9 @@ public class PooledOptimizer extends AbstractOptimizer implements InitialValueAw
 
 
 	@Override
-	public synchronized Serializable generate(AccessCallback callback) {
+	public Serializable generate(AccessCallback callback) {
+		lock.lock();
+		try {
 			final GenerationState generationState = locateGenerationState( callback.getTenantIdentifier() );
 
 			if ( generationState.hiValue == null ) {
@@ -94,7 +98,15 @@ public class PooledOptimizer extends AbstractOptimizer implements InitialValueAw
 
 			return generationState.value.makeValueThenIncrement();
 		}
+		finally {
+			lock.unlock();
+		}
+	}
 
+	/**
+	 * Use a lock instead of the monitor lock to avoid pinning when using virtual threads.
+	 */
+	private final Lock lock = new ReentrantLock();
 	private GenerationState noTenantState;
 	private Map<String,GenerationState> tenantSpecificState;