pvary commented on code in PR #10484:
URL: https://github.com/apache/iceberg/pull/10484#discussion_r1724698190


##########
flink/v1.19/flink/src/main/java/org/apache/iceberg/flink/maintenance/operator/JdbcLockFactory.java:
##########
@@ -0,0 +1,246 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.iceberg.flink.maintenance.operator;
+
+import java.io.IOException;
+import java.sql.DatabaseMetaData;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.SQLNonTransientConnectionException;
+import java.sql.SQLTimeoutException;
+import java.sql.SQLTransientConnectionException;
+import java.util.Map;
+import java.util.UUID;
+import org.apache.iceberg.jdbc.JdbcClientPool;
+import org.apache.iceberg.jdbc.UncheckedInterruptedException;
+import org.apache.iceberg.jdbc.UncheckedSQLException;
+import 
org.apache.iceberg.relocated.com.google.common.annotations.VisibleForTesting;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.util.PropertyUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class JdbcLockFactory implements TriggerLockFactory {
+  private static final Logger LOG = 
LoggerFactory.getLogger(JdbcLockFactory.class);
+  private static final String INIT_LOCK_TABLES_PROPERTY = 
"maintenance.lock.jdbc.init-lock-tables";
+  private static final String LOCK_TABLE_NAME = "maintenance_lock";
+  private static final int MAX_PREFIX_LENGTH = 100;
+  private static final String CREATE_LOCK_TABLE_SQL =
+      "CREATE TABLE "
+          + LOCK_TABLE_NAME
+          + "(LOCK_TYPE CHAR(1) NOT NULL, ISSUER VARCHAR("
+          + MAX_PREFIX_LENGTH
+          + ") NOT NULL, LOCK_ID CHAR(36) NOT NULL, PRIMARY KEY (LOCK_TYPE, 
ISSUER))";
+  private static final String CREATE_LOCK_SQL =
+      "INSERT INTO " + LOCK_TABLE_NAME + " (LOCK_TYPE, ISSUER, LOCK_ID) VALUES 
(?, ?, ?)";
+  private static final String GET_LOCK_SQL =
+      "SELECT LOCK_ID FROM " + LOCK_TABLE_NAME + " WHERE LOCK_TYPE=? AND 
ISSUER=?";
+  private static final String DELETE_LOCK_SQL =
+      "DELETE FROM " + LOCK_TABLE_NAME + " WHERE LOCK_TYPE=? AND ISSUER=? AND 
LOCK_ID=?";
+
+  private final String uri;
+  private final String issuer;
+  private final Map<String, String> properties;
+  private transient JdbcClientPool pool;
+
+  public JdbcLockFactory(String uri, String issuer, Map<String, String> 
properties) {
+    Preconditions.checkNotNull(uri, "JDBC connection URI is required");
+    Preconditions.checkArgument(
+        issuer.length() < MAX_PREFIX_LENGTH,
+        "Invalid prefix length: issuer should be shorter than %s",
+        MAX_PREFIX_LENGTH);
+    this.uri = uri;
+    this.issuer = issuer;
+    this.properties = properties;
+  }
+
+  @Override
+  public void open() {
+    this.pool = new JdbcClientPool(1, uri, properties);
+
+    if (PropertyUtil.propertyAsBoolean(properties, INIT_LOCK_TABLES_PROPERTY, 
false)) {
+      initializeLockTables();
+    }
+  }
+
+  /** Only used in testing to share the jdbc pool */
+  @VisibleForTesting
+  void open(JdbcLockFactory other) {
+    this.pool = other.pool;
+  }
+
+  @Override
+  public Lock createLock() {
+    return new Lock(pool, issuer, Type.MAINTENANCE);
+  }
+
+  @Override
+  public Lock createRecoveryLock() {
+    return new Lock(pool, issuer, Type.RECOVERY);
+  }
+
+  @Override
+  public void close() throws IOException {
+    pool.close();
+  }
+
+  private void initializeLockTables() {
+    LOG.trace("Creating database tables (if missing) to store table 
maintenance locks");
+    try {
+      pool.run(
+          conn -> {
+            DatabaseMetaData dbMeta = conn.getMetaData();
+            ResultSet tableExists =
+                dbMeta.getTables(
+                    null /* catalog name */,
+                    null /* schemaPattern */,
+                    LOCK_TABLE_NAME /* tableNamePattern */,
+                    null /* types */);
+            if (tableExists.next()) {
+              return true;
+            }
+
+            LOG.debug("Creating table {} to store iceberg catalog tables", 
LOCK_TABLE_NAME);
+            return conn.prepareStatement(CREATE_LOCK_TABLE_SQL).execute();
+          });
+
+    } catch (SQLTimeoutException e) {
+      throw new UncheckedSQLException(
+          e, "Cannot initialize JDBC table maintenance lock: Query timed out");
+    } catch (SQLTransientConnectionException | 
SQLNonTransientConnectionException e) {
+      throw new UncheckedSQLException(
+          e, "Cannot initialize JDBC table maintenance lock: Connection 
failed");
+    } catch (SQLException e) {
+      throw new UncheckedSQLException(e, "Cannot initialize JDBC table 
maintenance lock");
+    } catch (InterruptedException e) {
+      Thread.currentThread().interrupt();
+      throw new UncheckedInterruptedException(e, "Interrupted in call to 
initialize");
+    }
+  }
+
+  public static class Lock implements TriggerLockFactory.Lock {
+    private final JdbcClientPool pool;
+    private final String issuer;
+    private final Type type;
+
+    public Lock(JdbcClientPool pool, String issuer, Type type) {
+      this.pool = pool;
+      this.issuer = issuer;
+      this.type = type;
+    }
+
+    @Override
+    public boolean tryLock() {
+      if (isHeld()) {
+        LOG.info("Lock is already held");
+        return false;
+      }
+
+      try {
+        return pool.run(
+            conn -> {
+              try (PreparedStatement sql = 
conn.prepareStatement(CREATE_LOCK_SQL)) {
+                sql.setString(1, type.key);
+                sql.setString(2, issuer);
+                sql.setString(3, UUID.randomUUID().toString());
+                return sql.executeUpdate() == 1;
+              }
+            });
+      } catch (InterruptedException e) {
+        Thread.currentThread().interrupt();
+        throw new UncheckedInterruptedException(e, "Interrupted during 
tryLock");
+      } catch (SQLException e) {
+        // SQL exception happened when creating the lock
+        throw new UncheckedSQLException(e, "Failed to create %s lock", type);
+      }
+    }
+
+    @SuppressWarnings("checkstyle:NestedTryDepth")
+    @Override
+    public boolean isHeld() {
+      try {
+        return pool.run(
+            conn -> {
+              try (PreparedStatement sql = 
conn.prepareStatement(GET_LOCK_SQL)) {
+                sql.setString(1, type.key);
+                sql.setString(2, issuer);
+                try (ResultSet rs = sql.executeQuery()) {
+                  return rs.next();
+                }
+              }
+            });
+      } catch (InterruptedException e) {
+        Thread.currentThread().interrupt();
+        throw new UncheckedInterruptedException(e, "Interrupted during 
isHeld");
+      } catch (SQLException e) {
+        // SQL exception happened when getting lock information
+        throw new UncheckedSQLException(e, "Failed to get lock information for 
%s", type);
+      }
+    }
+
+    @SuppressWarnings("checkstyle:NestedTryDepth")
+    @Override
+    public void unlock() {
+      try {
+        pool.run(
+            conn -> {
+              String lockId;
+              try (PreparedStatement sql = 
conn.prepareStatement(GET_LOCK_SQL)) {
+                sql.setString(1, type.key);
+                sql.setString(2, issuer);
+                try (ResultSet rs = sql.executeQuery()) {
+                  if (rs.next()) {
+                    lockId = rs.getString(1);

Review Comment:
   The `tryLock` and the `unlock` will happen on a different object instance, 
possibly on a different JVM even. So that doesn't help. We need to fetch the id 
in the `unlock` method



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