add isValid() to database API

gradle.properties

@@ -1,5 +1,5 @@
 group = org.xbib
 name = database
-version = 1.4.2
+version = 1.4.3
 
 org.gradle.warning.mode = ALL

jdbc-query/src/main/java/org/xbib/jdbc/query/Database.java

@@ -121,6 +121,12 @@ public interface Database extends Supplier<Database> {
      */
     Connection underlyingConnection();
 
+    /**
+     * Probe the underlying connection.
+     * @return true if database has executed a probe query successfully, false if not
+     */
+    boolean probe() throws SQLException;
+
     Options options();
 
     /**

jdbc-query/src/main/java/org/xbib/jdbc/query/DatabaseImpl.java

@@ -139,6 +139,12 @@ public class DatabaseImpl implements Database {
         return connection;
     }
 
+    @Override
+    public boolean probe() throws SQLException {
+        // use a standard timeout of 5 seconds
+        return connection != null && connection.isValid(5);
+    }
+
     @Override
     public Options options() {
         return options;

jdbc-query/src/main/java/org/xbib/jdbc/query/DatabaseProvider.java

@@ -7,7 +7,6 @@ import org.xbib.jdbc.query.util.Metric;
 import javax.sql.DataSource;
 import java.io.Closeable;
 import java.io.IOException;
-import java.lang.reflect.InvocationTargetException;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
@@ -313,14 +312,37 @@ public final class DatabaseProvider implements Supplier<Database>, Closeable {
         } finally {
             metric.done();
             if (logger.isLoggable(Level.FINE)) {
-                StringBuilder buf = new StringBuilder("Get ").append(builder.options.flavor()).append(" database: ");
-                metric.printMessage(buf);
-                logger.fine(buf.toString());
+                StringBuilder sb = new StringBuilder("Get ").append(builder.options.flavor()).append(" database: ");
+                metric.printMessage(sb);
+                logger.fine(sb.toString());
             }
         }
         return database;
     }
 
+    public boolean check() {
+        Metric metric = new Metric(logger.isLoggable(Level.FINE));
+        boolean probe = false;
+        try {
+            if (database != null) {
+                probe = database.probe();
+            } else {
+                get();
+                probe = database.probe();
+            }
+        } catch (SQLException | RuntimeException e) {
+            metric.checkpoint("fail", e.getMessage());
+        } finally {
+            metric.done();
+            if (logger.isLoggable(Level.FINE)) {
+                StringBuilder sb = new StringBuilder("Probe ").append(builder.options.flavor()).append(" database: ");
+                metric.printMessage(sb);
+                logger.log(Level.FINE, sb.toString());
+            }
+        }
+        return probe;
+    }
+
     public void commit() {
         if (connection != null) {
             try {

jdbc-test/src/main/java/org/xbib/jdbc/test/CommonTest.java

@@ -77,6 +77,9 @@ public abstract class CommonTest {
         dbp = createDatabaseProvider(new OptionsOverride() {
         });
         db = dbp.get();
+        if (!db.probe()) {
+            fail();
+        }
         db.dropTableQuietly(TEST_TABLE_NAME);
     }