New database setting DEFAULT_CONNECTION (disabled by default) to support…

New database setting DEFAULT_CONNECTION (disabled by default) to support DriverManager.getConnection("jdbc:default:connection"). Please note the Oracle JDBC driver will try to resolve this database URL if it is loaded before the H2 driver.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,10 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>JaQu: the static map Db.TOKENS was not synchronized.
+<ul><li>New database setting DEFAULT_CONNECTION (disabled by default)
+    to support DriverManager.getConnection("jdbc:default:connection").
+    Please note the Oracle JDBC driver will try to resolve this database URL if it is loaded before the H2 driver.
+</li><li>JaQu: the static map Db.TOKENS was not synchronized.
 </li><li>DatabaseMetaData.getProcedureColumns returned the wrong data
     (it also returned the Connection parameter if there was any).
 </li><li>Issue 284: If the query cache was used (enabled by default in version 1.3.x), 

h2/src/main/org/h2/Driver.java

@@ -32,6 +32,9 @@ import org.h2.upgrade.DbUpgrade;
 public class Driver implements java.sql.Driver {
 
     private static final Driver INSTANCE = new Driver();
+    private static final String DEFAULT_URL = "jdbc:default:connection";
+    private static final ThreadLocal<Connection> DEFAULT_CONNECTION = new ThreadLocal<Connection>();
+
     private static volatile boolean registered;
 
     static {
@@ -55,6 +58,9 @@ public class Driver implements java.sql.Driver {
             if (!acceptsURL(url)) {
                 return null;
             }
+            if (url.equals(DEFAULT_URL)) {
+                return DEFAULT_CONNECTION.get();
+            }
             Connection c = DbUpgrade.connectOrUpgrade(url, info);
             if (c != null) {
                 return c;
@@ -73,7 +79,14 @@ public class Driver implements java.sql.Driver {
      * @return if the driver understands the URL
      */
     public boolean acceptsURL(String url) {
-        return url != null && url.startsWith(Constants.START_URL);
+        if (url != null) {
+            if (url.startsWith(Constants.START_URL)) {
+                return true;
+            } else if (url.equals(DEFAULT_URL)) {
+                return DEFAULT_CONNECTION.get() != null;
+            }
+        }
+        return false;
     }
 
     /**
@@ -147,4 +160,11 @@ public class Driver implements java.sql.Driver {
         }
     }
 
+    /**
+     * INTERNAL
+     */
+    public static void setDefaultConnection(Connection c) {
+        DEFAULT_CONNECTION.set(c);
+    }
+
 }

h2/src/main/org/h2/constant/DbSettings.java

@@ -71,6 +71,16 @@ public class DbSettings extends SettingsBase {
      */
     public final boolean dbCloseOnExit = get("DB_CLOSE_ON_EXIT", true);
 
+    /**
+     * Database setting <code>DEFAULT_CONNECTION</code> (default: false).<br />
+     * Whether Java functions can use
+     * <code>DriverManager.getConnection("jdbc:default:connection")</code> to
+     * get a database connection. This feature is disabled by default for
+     * performance reasons. Please note the Oracle JDBC driver will try to
+     * resolve this database URL if it is loaded before the H2 driver.
+     */
+    public boolean defaultConnection = get("DEFAULT_CONNECTION", false);
+
     /**
      * Database setting <code>DEFAULT_ESCAPE</code> (default: \).<br />
      * The default escape character for LIKE comparisons. To select no escape

h2/src/main/org/h2/engine/FunctionAlias.java

@@ -13,6 +13,7 @@ import java.lang.reflect.Modifier;
 import java.sql.Connection;
 import java.util.ArrayList;
 import java.util.Arrays;
+import org.h2.Driver;
 import org.h2.command.Parser;
 import org.h2.constant.ErrorCode;
 import org.h2.constant.SysProperties;
@@ -376,10 +377,14 @@ public class FunctionAlias extends SchemaObjectBase {
             }
             boolean old = session.getAutoCommit();
             Value identity = session.getScopeIdentity();
+            boolean defaultConnection = session.getDatabase().getSettings().defaultConnection;
             try {
                 session.setAutoCommit(false);
                 Object returnValue;
                 try {
+                    if (defaultConnection) {
+                        Driver.setDefaultConnection(session.createConnection(columnList));
+                    }
                     returnValue = method.invoke(null, params);
                     if (returnValue == null) {
                         return ValueNull.INSTANCE;
@@ -401,6 +406,9 @@ public class FunctionAlias extends SchemaObjectBase {
             } finally {
                 session.setScopeIdentity(identity);
                 session.setAutoCommit(old);
+                if (defaultConnection) {
+                    Driver.setDefaultConnection(null);
+                }
             }
         }
 

h2/src/test/org/h2/test/db/TestFunctions.java

@@ -14,6 +14,7 @@ import java.math.BigDecimal;
 import java.sql.Blob;
 import java.sql.Connection;
 import java.sql.DatabaseMetaData;
+import java.sql.DriverManager;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
@@ -47,6 +48,7 @@ public class TestFunctions extends TestBase implements AggregateFunction {
 
     public void test() throws Exception {
         deleteDb("functions");
+        testDefaultConnection();
         testFunctionInSchema();
         testGreatest();
         testSource();
@@ -65,6 +67,19 @@ public class TestFunctions extends TestBase implements AggregateFunction {
         IOUtils.deleteRecursive(TEMP_DIR, true);
     }
 
+    private void testDefaultConnection() throws SQLException {
+        Connection conn = getConnection("functions;DEFAULT_CONNECTION=TRUE");
+        Statement stat = conn.createStatement();
+        stat.execute("create alias test for \""+TestFunctions.class.getName()+".testDefaultConn\"");
+        stat.execute("call test()");
+        stat.execute("drop alias test");
+        conn.close();
+    }
+
+    public static void testDefaultConn() throws SQLException {
+        DriverManager.getConnection("jdbc:default:connection");
+    }
+
     private void testFunctionInSchema() throws SQLException {
         Connection conn = getConnection("functions");
         Statement stat = conn.createStatement();