DATAJDBC-493 - Avoids deadlocks by acquiring lock on aggregate root table.

Introduces infrastructure to obtain locks and uses them to acquire locks on the table of the aggregate root before deleting references.
Without this lock deletes access non root entities before the aggregate root, which is the opposite order of updates and thus may cause deadlocks.

Original pull request: #196.

Author: mhyeon-lee

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/AggregateChangeExecutor.java

@@ -27,6 +27,7 @@
  * Executes an {@link MutableAggregateChange}.
  *
  * @author Jens Schauder
+ * @author Myeonghyeon Lee
  * @since 2.0
  */
 class AggregateChangeExecutor {
@@ -77,6 +78,10 @@ private void execute(DbAction<?> action, JdbcAggregateChangeExecutionContext exe
 				executionContext.executeDeleteRoot((DbAction.DeleteRoot<?>) action);
 			} else if (action instanceof DbAction.DeleteAllRoot) {
 				executionContext.executeDeleteAllRoot((DbAction.DeleteAllRoot<?>) action);
+			} else if (action instanceof DbAction.AcquireLockRoot) {
+				executionContext.executeAcquireLock((DbAction.AcquireLockRoot<?>) action);
+			} else if (action instanceof DbAction.AcquireLockAllRoot) {
+				executionContext.executeAcquireLockAllRoot((DbAction.AcquireLockAllRoot<?>) action);
 			} else {
 				throw new RuntimeException("unexpected action");
 			}

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateChangeExecutionContext.java

@@ -42,13 +42,15 @@
 import org.springframework.data.relational.core.mapping.PersistentPropertyPathExtension;
 import org.springframework.data.relational.core.mapping.RelationalPersistentEntity;
 import org.springframework.data.relational.core.mapping.RelationalPersistentProperty;
+import org.springframework.data.relational.core.sql.LockMode;
 import org.springframework.data.util.Pair;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
  * @author Jens Schauder
  * @author Umut Erturk
+ * @author Myeonghyeon Lee
  */
 class JdbcAggregateChangeExecutionContext {
 
@@ -164,6 +166,14 @@ <T> void executeMerge(DbAction.Merge<T> merge) {
 		}
 	}
 
+	<T> void executeAcquireLock(DbAction.AcquireLockRoot<T> acquireLock) {
+		accessStrategy.acquireLockById(acquireLock.getId(), LockMode.PESSIMISTIC_WRITE, acquireLock.getEntityType());
+	}
+
+	<T> void executeAcquireLockAllRoot(DbAction.AcquireLockAllRoot<T> acquireLock) {
+		accessStrategy.acquireLockAll(LockMode.PESSIMISTIC_WRITE, acquireLock.getEntityType());
+	}
+
 	private void add(DbActionExecutionResult result) {
 		results.put(result.getAction(), result);
 	}

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateTemplate.java

@@ -50,6 +50,7 @@
  * @author Thomas Lang
  * @author Christoph Strobl
  * @author Milan Milanov
+ * @author Myeonghyeon Lee
  */
 public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/CascadingDataAccessStrategy.java

@@ -24,6 +24,7 @@
 import org.springframework.data.domain.Sort;
 import org.springframework.data.mapping.PersistentPropertyPath;
 import org.springframework.data.relational.core.mapping.RelationalPersistentProperty;
+import org.springframework.data.relational.core.sql.LockMode;
 
 /**
  * Delegates each methods to the {@link DataAccessStrategy}s passed to the constructor in turn until the first that does
@@ -33,6 +34,7 @@
  * @author Mark Paluch
  * @author Tyler Van Gorder
  * @author Milan Milanov
+ * @author Myeonghyeon Lee
  * @since 1.1
  */
 public class CascadingDataAccessStrategy implements DataAccessStrategy {
@@ -115,6 +117,24 @@ public void deleteAll(PersistentPropertyPath<RelationalPersistentProperty> prope
 		collectVoid(das -> das.deleteAll(propertyPath));
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#acquireLockById(java.lang.Object, org.springframework.data.relational.core.sql.LockMode, java.lang.Class)
+	 */
+	@Override
+	public <T> void acquireLockById(Object id, LockMode lockMode, Class<T> domainType) {
+		collectVoid(das -> das.acquireLockById(id, lockMode, domainType));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#acquireLockAll(org.springframework.data.relational.core.sql.LockMode, java.lang.Class)
+	 */
+	@Override
+	public <T> void acquireLockAll(LockMode lockMode, Class<T> domainType) {
+		collectVoid(das -> das.acquireLockAll(lockMode, domainType));
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#count(java.lang.Class)

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/DataAccessStrategy.java

@@ -23,6 +23,7 @@
 import org.springframework.data.jdbc.core.JdbcAggregateOperations;
 import org.springframework.data.mapping.PersistentPropertyPath;
 import org.springframework.data.relational.core.mapping.RelationalPersistentProperty;
+import org.springframework.data.relational.core.sql.LockMode;
 import org.springframework.lang.Nullable;
 
 /**
@@ -33,6 +34,7 @@
  * @author Jens Schauder
  * @author Tyler Van Gorder
  * @author Milan Milanov
+ * @author Myeonghyeon Lee
  */
 public interface DataAccessStrategy extends RelationResolver {
 
@@ -129,6 +131,23 @@ public interface DataAccessStrategy extends RelationResolver {
 	 */
 	void deleteAll(PersistentPropertyPath<RelationalPersistentProperty> propertyPath);
 
+	/**
+	 * Acquire Lock
+	 *
+	 * @param id the id of the entity to load. Must not be {@code null}.
+	 * @param lockMode the lock mode for select. Must not be {@code null}.
+	 * @param domainType the domain type of the entity. Must not be {@code null}.
+	 */
+	<T> void acquireLockById(Object id, LockMode lockMode, Class<T> domainType);
+
+	/**
+	 * Acquire Lock entities of the given domain type.
+	 *
+	 * @param lockMode the lock mode for select. Must not be {@code null}.
+	 * @param domainType the domain type of the entity. Must not be {@code null}.
+	 */
+	<T> void acquireLockAll(LockMode lockMode, Class<T> domainType);
+
 	/**
 	 * Counts the rows in the table representing the given domain type.
 	 *

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/DefaultDataAccessStrategy.java

@@ -18,17 +18,16 @@
 import static org.springframework.data.jdbc.core.convert.SqlGenerator.*;
 
 import java.sql.JDBCType;
+import java.sql.ResultSet;
+import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Predicate;
 
-import org.springframework.dao.DataRetrievalFailureException;
-import org.springframework.dao.EmptyResultDataAccessException;
-import org.springframework.dao.InvalidDataAccessApiUsageException;
-import org.springframework.dao.OptimisticLockingFailureException;
+import org.springframework.dao.*;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.jdbc.support.JdbcUtil;
@@ -41,7 +40,9 @@
 import org.springframework.data.relational.core.mapping.RelationalPersistentEntity;
 import org.springframework.data.relational.core.mapping.RelationalPersistentProperty;
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
+import org.springframework.data.relational.core.sql.LockMode;
 import org.springframework.data.relational.core.sql.SqlIdentifier;
+import org.springframework.jdbc.core.ResultSetExtractor;
 import org.springframework.jdbc.core.RowMapper;
 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcOperations;
 import org.springframework.jdbc.core.namedparam.SqlParameterSource;
@@ -62,6 +63,7 @@
  * @author Tom Hombergs
  * @author Tyler Van Gorder
  * @author Milan Milanov
+ * @author Myeonghyeon Lee
  * @since 1.1
  */
 public class DefaultDataAccessStrategy implements DataAccessStrategy {
@@ -237,6 +239,27 @@ public void deleteAll(PersistentPropertyPath<RelationalPersistentProperty> prope
 				.update(sql(propertyPath.getBaseProperty().getOwner().getType()).createDeleteAllSql(propertyPath));
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#acquireLockById(java.lang.Object, org.springframework.data.relational.core.sql.LockMode, java.lang.Class)
+	 */
+	@Override
+	public <T> void acquireLockById(Object id, LockMode lockMode, Class<T> domainType) {
+		String acquireLockByIdSql = sql(domainType).getAcquireLockById(lockMode);
+		SqlIdentifierParameterSource parameter = createIdParameterSource(id, domainType);
+		operations.queryForObject(acquireLockByIdSql, parameter, Object.class);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#acquireLockAll(org.springframework.data.relational.core.sql.LockMode, java.lang.Class)
+	 */
+	@Override
+	public <T> void acquireLockAll(LockMode lockMode, Class<T> domainType) {
+		String acquireLockAllSql = sql(domainType).getAcquireLockAll(lockMode);
+		operations.query(acquireLockAllSql, Collections.emptyMap(), new NoMappingResultSetExtractor());
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#count(java.lang.Class)
@@ -582,4 +605,14 @@ public T getBean() {
 			return null;
 		}
 	}
+
+	/**
+	 * The type No mapping result set extractor.
+	 */
+	static class NoMappingResultSetExtractor implements ResultSetExtractor<Object> {
+		@Override
+		public Object extractData(ResultSet resultSet) throws SQLException, DataAccessException {
+			return null;
+		}
+	}
 }

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/DelegatingDataAccessStrategy.java

@@ -19,6 +19,7 @@
 import org.springframework.data.domain.Sort;
 import org.springframework.data.mapping.PersistentPropertyPath;
 import org.springframework.data.relational.core.mapping.RelationalPersistentProperty;
+import org.springframework.data.relational.core.sql.LockMode;
 import org.springframework.util.Assert;
 
 /**
@@ -28,6 +29,7 @@
  * @author Jens Schauder
  * @author Tyler Van Gorder
  * @author Milan Milanov
+ * @author Myeonghyeon Lee
  * @since 1.1
  */
 public class DelegatingDataAccessStrategy implements DataAccessStrategy {
@@ -107,6 +109,24 @@ public void deleteAll(PersistentPropertyPath<RelationalPersistentProperty> prope
 		delegate.deleteAll(propertyPath);
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#acquireLockById(java.lang.Object, org.springframework.data.relational.core.sql.LockMode, java.lang.Class)
+	 */
+	@Override
+	public <T> void acquireLockById(Object id, LockMode lockMode, Class<T> domainType) {
+		delegate.acquireLockById(id, lockMode, domainType);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#acquireLockAll(org.springframework.data.relational.core.sql.LockMode, java.lang.Class)
+	 */
+	@Override
+	public <T> void acquireLockAll(LockMode lockMode, Class<T> domainType) {
+		delegate.acquireLockAll(lockMode, domainType);
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#count(java.lang.Class)

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/SqlGenerator.java

@@ -258,6 +258,26 @@ String getFindOne() {
 		return findOneSql.get();
 	}
 
+	/**
+	 * Create a {@code SELECT count(id) FROM … WHERE :id = … (LOCK CLAUSE)} statement.
+	 *
+	 * @param lockMode Lock clause mode.
+	 * @return the statement as a {@link String}. Guaranteed to be not {@literal null}.
+	 */
+	String getAcquireLockById(LockMode lockMode) {
+		return this.createAcquireLockById(lockMode);
+	}
+
+	/**
+	 * Create a {@code SELECT count(id) FROM … (LOCK CLAUSE)} statement.
+	 *
+	 * @param lockMode Lock clause mode.
+	 * @return the statement as a {@link String}. Guaranteed to be not {@literal null}.
+	 */
+	String getAcquireLockAll(LockMode lockMode) {
+		return this.createAcquireLockAll(lockMode);
+	}
+
 	/**
 	 * Create a {@code INSERT INTO … (…) VALUES(…)} statement.
 	 *
@@ -359,6 +379,33 @@ private String createFindOneSql() {
 		return render(select);
 	}
 
+	private String createAcquireLockById(LockMode lockMode) {
+
+		Table table = this.getTable();
+
+		Select select = StatementBuilder //
+			.select(getIdColumn()) //
+			.from(table) //
+			.where(getIdColumn().isEqualTo(getBindMarker(ID_SQL_PARAMETER))) //
+			.lock(lockMode) //
+			.build();
+
+		return render(select);
+	}
+
+	private String createAcquireLockAll(LockMode lockMode) {
+
+		Table table = this.getTable();
+
+		Select select = StatementBuilder //
+			.select(getIdColumn()) //
+			.from(table) //
+			.lock(lockMode) //
+			.build();
+
+		return render(select);
+	}
+
 	private String createFindAllSql() {
 		return render(selectBuilder().build());
 	}

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/mybatis/MyBatisDataAccessStrategy.java

@@ -26,6 +26,7 @@
 import org.mybatis.spring.SqlSessionTemplate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.jdbc.core.convert.CascadingDataAccessStrategy;
@@ -41,6 +42,7 @@
 import org.springframework.data.relational.core.mapping.RelationalMappingContext;
 import org.springframework.data.relational.core.mapping.RelationalPersistentProperty;
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
+import org.springframework.data.relational.core.sql.LockMode;
 import org.springframework.data.relational.core.sql.SqlIdentifier;
 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcOperations;
 import org.springframework.util.Assert;
@@ -60,6 +62,7 @@
  * @author Mark Paluch
  * @author Tyler Van Gorder
  * @author Milan Milanov
+ * @author Myeonghyeon Lee
  */
 public class MyBatisDataAccessStrategy implements DataAccessStrategy {
 
@@ -248,6 +251,34 @@ public void deleteAll(PersistentPropertyPath<RelationalPersistentProperty> prope
 		sqlSession().delete(statement, parameter);
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#acquireLockById(java.lang.Object, org.springframework.data.relational.core.sql.LockMode, java.lang.Class)
+	 */
+	@Override
+	public <T> void acquireLockById(Object id, LockMode lockMode, Class<T> domainType) {
+		String statement = namespace(domainType) + ".acquireLockById";
+		MyBatisContext parameter = new MyBatisContext(id, null, domainType, Collections.emptyMap());
+
+		long result = sqlSession().selectOne(statement, parameter);
+		if (result < 1) {
+			throw new EmptyResultDataAccessException(
+				String.format("The lock target does not exist. id: %s, statement: %s", id, statement), 1);
+		}
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#acquireLockAll(org.springframework.data.relational.core.sql.LockMode, java.lang.Class)
+	 */
+	@Override
+	public <T> void acquireLockAll(LockMode lockMode, Class<T> domainType) {
+		String statement = namespace(domainType) + ".acquireLockAll";
+		MyBatisContext parameter = new MyBatisContext(null, null, domainType, Collections.emptyMap());
+
+		sqlSession().selectOne(statement, parameter);
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#findById(java.lang.Object, java.lang.Class)