jacques-n commented on a change in pull request #1849: URL: https://github.com/apache/iceberg/pull/1849#discussion_r533910195
########## File path: api/src/main/java/org/apache/iceberg/catalog/SupportsCatalogTransactions.java ########## @@ -0,0 +1,137 @@ +/* + * 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.catalog; + +import java.util.Collections; +import java.util.Set; + +/** + * Catalog methods for working with catalog-level transactions. + * + * <p>Catalog implementations are not required to support catalog-level transactional state. + * If they do, they may support one or more {@code IsolationLevel}s and one or more + * {@code LockingMode}s. + */ +public interface SupportsCatalogTransactions { + + /** + * The level of isolation for a transaction. + */ + enum IsolationLevel { + + /** + * Only read committed data. Reading the same table multiple times + * may result in different committed reads for each read. + */ + READ_COMMITTED, + + /** + * Only read committed data. Reading the same table multiple times will + * result in the same view of those tables. + */ + REPEATED_READ, + + /** + * Only read committed data. A commit will only succeed if there have + * been no changes to data read during the course of the transaction + * prior to the commit operation. + */ + SERIALIZABLE; + } + + /** + * The type of locking mode used by the transaction. + */ + enum LockingMode { + + /** + * Pessimistically lock tables. In this situation, each table being worked on will grab a lock. + * This mode will typically result in a better chance for transactions to complete at the cost + * of throughput and resource consumption. + */ + PESSIMISTIC, + + /** + * Run the transaction with an optimistic behavior. This assumes that most operations will not + * conflict. It typically increases concurrency and throughput while reducing resource + * consumption. + */ + OPTIMISTIC; + } + + /** + * Get the list of {@link LockingMode}s this Catalog supports. + * @return A set of locking modes supported. + */ + default Set<LockingMode> lockingModes() { + return Collections.emptySet(); + } + + /** + * Get the list of {@link IsolationLevel}s this Catalog supports. + * @return A set of locking modes supported. + */ + default Set<IsolationLevel> isolationLevels() { + return Collections.emptySet(); + } + + /** + * Start a new transaction and return a {@link TransactionalCatalog} that supports + * cross table operations. If a {@link Catalog} supports {@link OPTIMISTIC} + * locking mode, this will use that mode. If it only supports {@link PESSIMISTIC}, + * it will use that mode with default values for lock times. + * + * @param isolationLevel The {@link IsolationLevel} to use for the transaction. + * @return A Catalog with an open transaction. + * @throws IllegalArgumentException If the IsolationLevel is not supported. + */ + TransactionalCatalog createTransaction(IsolationLevel isolationLevel); + + /** + * Start a new transaction that holds locks for the life of the transaction. + * + * <p>If supported, this type of transaction allows a much higher likelihood of + * transaction completion but can also result in more failures, lower concurrency + * and deadlocks. + * + * @param isolationLevel The {@link IsolationLevel} to use for the transaction. + * @param lockWaitInMillis How long to wait in milliseconds when grabbing a pessimistic lock. + * @param maxTimeMillis The maximum amount of time the transaction is allowed to be open. + * @param tables An optional list of tables that should be locked immediately for this + * transaction. Note that this can include tables that exist and tables that do not + * exist as this transaction may be adding new tables and want to grab pessimistic locks + * for those operations. + * + * @return A Catalog with an open transaction. + * + * @throws IllegalArgumentException If the IsolationLevel is not supported. Also throws if + * {@code lockWaitInMillis} or {@code maxTimeMillis} are not within supported limits + * (check specific {@link Catalog} documentation for any limits). + * @throws CommitFailedException If the list of {@code tables} cannot be locked. + * @throws ValidationException If the set of tables names includes tables names that are not + * valid. + */ + TransactionalCatalog createLockingTransaction( + IsolationLevel isolationLevel, + long lockWaitInMillis, + long maxTimeMillis, + TableIdentifier...tables); Review comment: Per the Javadoc, this is an optional list of tables you can grab locks on at the beginning of a transactions. If you provide no tables, then the expectation would be that locks would be acquired as you interacted with tables. This allows you to fail-fast if you can't grab some locks rather than do a bunch of work and then fail to get a last lock later. At least that was the intention with the api. (This is only relevant to the pessimistic api as there is no such thing as acquiring locks in the optimistic api) ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
