HHH-18271 Avoid mega-morphic callsites for equals/hashCode with known types

Author: beikov

hibernate-core/src/main/java/org/hibernate/engine/spi/CollectionKey.java

@@ -26,23 +26,23 @@
 public final class CollectionKey implements Serializable {
 	private final String role;
 	private final Object key;
-	private final Type keyType;
+	private final @Nullable Type keyType;
 	private final SessionFactoryImplementor factory;
 	private final int hashCode;
 
 	public CollectionKey(CollectionPersister persister, Object key) {
 		this(
 				persister.getRole(),
 				key,
-				persister.getKeyType(),
+				persister.getKeyType().getTypeForEqualsHashCode(),
 				persister.getFactory()
 		);
 	}
 
 	private CollectionKey(
 			String role,
 			@Nullable Object key,
-			Type keyType,
+			@Nullable Type keyType,
 			SessionFactoryImplementor factory) {
 		this.role = role;
 		if ( key == null ) {
@@ -58,7 +58,7 @@ private CollectionKey(
 	private int generateHashCode() {
 		int result = 17;
 		result = 37 * result + role.hashCode();
-		result = 37 * result + keyType.getHashCode( key, factory );
+		result = 37 * result + ( keyType == null ? key.hashCode() : keyType.getHashCode( key, factory ) );
 		return result;
 	}
 
@@ -90,7 +90,7 @@ public boolean equals(final @Nullable Object other) {
 		final CollectionKey that = (CollectionKey) other;
 		return that.role.equals( role )
 				&& ( this.key == that.key ||
-					keyType.isEqual( this.key, that.key, factory ) );
+					keyType == null ? this.key.equals( that.key ) : keyType.isEqual( this.key, that.key, factory ) );
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/engine/spi/EntityKey.java

@@ -14,6 +14,7 @@
 import org.hibernate.AssertionFailure;
 import org.hibernate.persister.entity.EntityPersister;
 import org.hibernate.pretty.MessageHelper;
+import org.hibernate.type.Type;
 
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -59,7 +60,8 @@ private int generateHashCode() {
 		int result = 17;
 		final String rootEntityName = persister.getRootEntityName();
 		result = 37 * result + rootEntityName.hashCode();
-		result = 37 * result + persister.getIdentifierType().getHashCode( identifier, persister.getFactory() );
+		final Type identifierType = persister.getIdentifierType().getTypeForEqualsHashCode();
+		result = 37 * result + ( identifierType == null ? identifier.hashCode() : identifierType.getHashCode( identifier, persister.getFactory() ) );
 		return result;
 	}
 
@@ -99,8 +101,10 @@ public boolean equals(@Nullable Object other) {
 	}
 
 	private boolean sameIdentifier(final EntityKey otherKey) {
-		return this.identifier == otherKey.identifier ||
-			persister.getIdentifierType().isEqual( otherKey.identifier, this.identifier, persister.getFactory() );
+		final Type identifierType;
+		return this.identifier == otherKey.identifier || (
+				(identifierType = persister.getIdentifierType().getTypeForEqualsHashCode()) == null && identifier.equals( otherKey.identifier )
+						|| identifierType != null && identifierType.isEqual( otherKey.identifier, this.identifier, persister.getFactory() ) );
 	}
 
 	private boolean samePersistentType(final EntityKey otherKey) {

hibernate-core/src/main/java/org/hibernate/type/AbstractStandardBasicType.java

@@ -27,13 +27,14 @@
 import org.hibernate.type.descriptor.ValueBinder;
 import org.hibernate.type.descriptor.ValueExtractor;
 import org.hibernate.type.descriptor.WrapperOptions;
-import org.hibernate.type.descriptor.java.AbstractClassJavaType;
 import org.hibernate.type.descriptor.java.JavaType;
 import org.hibernate.type.descriptor.java.MutabilityPlan;
 import org.hibernate.type.descriptor.java.MutableMutabilityPlan;
 import org.hibernate.type.descriptor.jdbc.JdbcLiteralFormatter;
 import org.hibernate.type.descriptor.jdbc.JdbcType;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 /**
  * Convenience base class for {@link BasicType} implementations.
  * Packages a {@link JavaType} with a {@link JdbcType}.
@@ -50,7 +51,7 @@ public abstract class AbstractStandardBasicType<T>
 	private final ValueBinder<T> jdbcValueBinder;
 	private final ValueExtractor<T> jdbcValueExtractor;
 	private final JdbcLiteralFormatter<T> jdbcLiteralFormatter;
-	private final AbstractClassJavaType<T> javaTypeAsAbstractClassJavaType;
+	private final @Nullable Type typeForEqualsHashCode;
 	private final Class javaTypeClass;
 	private final MutabilityPlan<T> mutabilityPlan;
 	private final Comparator<T> javatypeComparator;
@@ -68,13 +69,7 @@ public AbstractStandardBasicType(JdbcType jdbcType, JavaType<T> javaType) {
 		this.javaTypeClass = javaType.getJavaTypeClass();
 		this.mutabilityPlan = javaType.getMutabilityPlan();
 		this.javatypeComparator = javaType.getComparator();
-		//This is a dispatch optimisation to avoid megamorphic invocations on the most common type:
-		if ( javaType instanceof AbstractClassJavaType ) {
-			this.javaTypeAsAbstractClassJavaType = (AbstractClassJavaType) javaType;
-		}
-		else {
-			this.javaTypeAsAbstractClassJavaType = null;
-		}
+		this.typeForEqualsHashCode = javaType.useObjectEqualsHashCode() ? null : this;
 	}
 
 	@Override
@@ -98,13 +93,7 @@ public Class<T> getJavaType() {
 	}
 
 	public T fromString(CharSequence string) {
-		final AbstractClassJavaType<T> type = this.javaTypeAsAbstractClassJavaType;
-		if ( type != null ) {
-			return type.fromString( string );
-		}
-		else {
-			return javaType.fromString( string );
-		}
+		return javaType.fromString( string );
 	}
 
 	protected MutabilityPlan<T> getMutabilityPlan() {
@@ -196,25 +185,19 @@ public boolean isEqual(Object one, Object another) {
 		else if ( one == null || another == null ) {
 			return false;
 		}
+		else if ( typeForEqualsHashCode == null ) {
+			return one.equals( another );
+		}
 		else {
-			final AbstractClassJavaType<T> type = this.javaTypeAsAbstractClassJavaType;
-			if ( type != null ) {
-				//Optimize for the most common case: avoid the megamorphic call
-				return type.areEqual( (T) one, (T) another );
-			}
-			else {
-				return javaType.areEqual( (T) one, (T) another );
-			}
+			return javaType.areEqual( (T) one, (T) another );
 		}
 	}
 
 	@Override
 	@SuppressWarnings("unchecked")
 	public int getHashCode(Object x) {
-		final AbstractClassJavaType<T> type = this.javaTypeAsAbstractClassJavaType;
-		if ( type != null ) {
-			//Optimize for the most common case: avoid the megamorphic call
-			return type.extractHashCode( (T) x );
+		if ( typeForEqualsHashCode == null ) {
+			return x.hashCode();
 		}
 		else {
 			return javaType.extractHashCode( (T) x );
@@ -226,6 +209,11 @@ public final int getHashCode(Object x, SessionFactoryImplementor factory) {
 		return getHashCode( x );
 	}
 
+	@Override
+	public @Nullable Type getTypeForEqualsHashCode() {
+		return typeForEqualsHashCode;
+	}
+
 	@Override
 	@SuppressWarnings("unchecked")
 	public final int compare(Object x, Object y) {

hibernate-core/src/main/java/org/hibernate/type/Type.java

@@ -219,6 +219,15 @@ default String getReturnedClassName() {
 	 */
 	int getHashCode(Object x, SessionFactoryImplementor factory) throws HibernateException;
 
+	/**
+	 * The type to use for {@code equals()} and {@code hashCode()} computation.
+	 * When {@code null}, use {@link Object#equals(Object)} and {@link Object#hashCode()}.
+	 * This is useful to avoid mega-morphic callsites.
+	 */
+	default @Nullable Type getTypeForEqualsHashCode() {
+		return this;
+	}
+
 	/**
 	 * Perform a {@link java.util.Comparator}-style comparison of the given values.
 	 *

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/BooleanJavaType.java

@@ -47,6 +47,11 @@ public BooleanJavaType(char characterValueTrue, char characterValueFalse) {
 		stringValueFalse = String.valueOf( characterValueFalse );
 	}
 
+	@Override
+	public boolean useObjectEqualsHashCode() {
+		return true;
+	}
+
 	@Override
 	public String toString(Boolean value) {
 		return value == null ? null : value.toString();

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/ByteJavaType.java

@@ -31,6 +31,11 @@ public ByteJavaType() {
 		super( Byte.class );
 	}
 
+	@Override
+	public boolean useObjectEqualsHashCode() {
+		return true;
+	}
+
 	@Override
 	public String toString(Byte value) {
 		return value == null ? null : value.toString();

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/CharacterJavaType.java

@@ -25,6 +25,11 @@ public CharacterJavaType() {
 		super( Character.class );
 	}
 
+	@Override
+	public boolean useObjectEqualsHashCode() {
+		return true;
+	}
+
 	@Override
 	public String toString(Character value) {
 		return value.toString();

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/ClassJavaType.java

@@ -22,6 +22,11 @@ public ClassJavaType() {
 		super( Class.class );
 	}
 
+	@Override
+	public boolean useObjectEqualsHashCode() {
+		return true;
+	}
+
 	public String toString(Class value) {
 		return value.getName();
 	}

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/CurrencyJavaType.java

@@ -24,6 +24,11 @@ public CurrencyJavaType() {
 		super( Currency.class );
 	}
 
+	@Override
+	public boolean useObjectEqualsHashCode() {
+		return true;
+	}
+
 	@Override
 	public String toString(Currency value) {
 		return value.getCurrencyCode();

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/DoubleJavaType.java

@@ -35,6 +35,11 @@ public JdbcType getRecommendedJdbcType(JdbcTypeIndicators indicators) {
 		return DoubleJdbcType.INSTANCE;
 	}
 
+	@Override
+	public boolean useObjectEqualsHashCode() {
+		return true;
+	}
+
 	@Override
 	public String toString(Double value) {
 		return value == null ? null : value.toString();