Issue helidon-io#6991 - Blocking DB Client: Lazy statement preparatio…

…n and execution

Signed-off-by: Tomáš Kraus <tomas.kraus@oracle.com>

dbclient/dbclient/src/main/java/io/helidon/dbclient/DbExecute.java

@@ -40,7 +40,7 @@
  * The last two methods directly execute the statement and provide appropriate response for future processing.
  * All the methods are non-blocking.
  */
-public interface DbExecute extends AutoCloseable {
+public interface DbExecute {
 
     /*
      * QUERY
@@ -361,9 +361,8 @@ default long dml(String statement, Object... parameters) {
      * Unwrap database executor internals.
      * Only database connection is supported. This connection instance is being used to execute
      * all statements in current database executor context.
-     * <p>When {@code java.sql.Connection} is requested for JDBC provider, this connection life cycle
-     * is bound to this {@link DbExecute} instance life cycle. Explicit {@code close()} method call
-     * on returned connection instance is not required.
+     * <p>When {@code java.sql.Connection} is requested for JDBC provider, this connection must be closed
+     * by user code using {@code close()} method on returned {@code Connection} instance.
      *
      * @param <C> target class to be unwrapped
      * @param cls target class to be unwrapped

dbclient/dbclient/src/main/java/io/helidon/dbclient/DbStatementQuery.java

@@ -19,6 +19,9 @@
 
 /**
  * Database query statement.
+ * <p><b>Important:</b> Method {@link #execute()} returns {@link Stream} of {@link DbRow}. This {@link Stream} must
+ * always be closed because it holds database resources ({@code java.sql.Connection}, {@code java.sql.Statement}
+ * and {@code java.sql.ResultSet}).
  */
 public interface DbStatementQuery extends DbStatement<DbStatementQuery, Stream<DbRow>> {
 }

dbclient/dbclient/src/main/java/io/helidon/dbclient/DbStatementType.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2022 Oracle and/or its affiliates.
+ * Copyright (c) 2023 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

dbclient/dbclient/src/main/java/io/helidon/dbclient/DbStatements.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2022 Oracle and/or its affiliates.
+ * Copyright (c) 2023 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

dbclient/jdbc/src/main/java/io/helidon/dbclient/jdbc/HikariConnectionPool.java

@@ -27,7 +27,7 @@
 /**
  * Hikari Connection Pool integration.
  */
-public class HikariConnectionPool implements JdbcConnectionPool {
+class HikariConnectionPool implements JdbcConnectionPool {
     /** Hikari Connection Pool instance. */
     private final HikariDataSource dataSource;
 

dbclient/jdbc/src/main/java/io/helidon/dbclient/jdbc/JdbcClient.java

@@ -37,7 +37,7 @@ class JdbcClient extends CommonClient implements DbClient {
 
     @Override
     public JdbcExecute execute() {
-        return JdbcExecute.create(context(), connectionPool.connection());
+        return JdbcExecute.create(context(), connectionPool);
     }
 
     @Override
@@ -54,4 +54,4 @@ public <C> C unwrap(Class<C> cls) {
         }
     }
 
-}
+}