fix(workflows): make Flowable schema upgrades idempotent to survive partial migrations

openmetadata-service/src/main/java/org/openmetadata/service/governance/workflows/IdempotentDdlDataSource.java

@@ -0,0 +1,112 @@
+/*
+ *  Copyright 2021 Collate
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package org.openmetadata.service.governance.workflows;
+
+import java.io.PrintWriter;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+import javax.sql.DataSource;
+
+/**
+ * A {@link DataSource} wrapper that intercepts every {@link Connection} it vends and ensures
+ * that all {@link Statement} variants created from that connection go through
+ * {@link IdempotentDdlStatement}. Only used in migration context so Flowable upgrade scripts
+ * skip already-existing DDL objects instead of failing.
+ */
+final class IdempotentDdlDataSource implements DataSource {
+
+  private final DataSource delegate;
+
+  IdempotentDdlDataSource(DataSource delegate) {
+    this.delegate = delegate;
+  }
+
+  @Override
+  public Connection getConnection() throws SQLException {
+    return wrapConnection(delegate.getConnection());
+  }
+
+  @Override
+  public Connection getConnection(String username, String password) throws SQLException {
+    return wrapConnection(delegate.getConnection(username, password));
+  }
+
+  private Connection wrapConnection(Connection real) {
+    return (Connection)
+        Proxy.newProxyInstance(
+            real.getClass().getClassLoader(),
+            new Class<?>[] {Connection.class},
+            (proxy, method, args) -> {
+              if ("createStatement".equals(method.getName())) {
+                Statement stmt = (Statement) invokeDelegate(method, real, args);
+                return new IdempotentDdlStatement(stmt, real);
+              }
+              return invokeDelegate(method, real, args);
+            });
+  }
+
+  /**
+   * Invokes a method on the real connection, unwrapping any {@link InvocationTargetException}
+   * so callers receive the original exception type (e.g. {@link SQLException}).
+   */
+  private static Object invokeDelegate(Method method, Object target, Object[] args)
+      throws Throwable {
+    try {
+      return method.invoke(target, args);
+    } catch (InvocationTargetException e) {
+      throw e.getCause();
+    }
+  }
+
+  @Override
+  public PrintWriter getLogWriter() throws SQLException {
+    return delegate.getLogWriter();
+  }
+
+  @Override
+  public void setLogWriter(PrintWriter out) throws SQLException {
+    delegate.setLogWriter(out);
+  }
+
+  @Override
+  public void setLoginTimeout(int seconds) throws SQLException {
+    delegate.setLoginTimeout(seconds);
+  }
+
+  @Override
+  public int getLoginTimeout() throws SQLException {
+    return delegate.getLoginTimeout();
+  }
+
+  @Override
+  public Logger getParentLogger() throws SQLFeatureNotSupportedException {
+    return delegate.getParentLogger();
+  }
+
+  @Override
+  public <T> T unwrap(Class<T> iface) throws SQLException {
+    return delegate.unwrap(iface);
+  }
+
+  @Override
+  public boolean isWrapperFor(Class<?> iface) throws SQLException {
+    return delegate.isWrapperFor(iface);
+  }
+}