ascherbakoff commented on code in PR #4540: URL: https://github.com/apache/ignite-3/pull/4540#discussion_r1812144291
########## modules/core/src/main/java/org/apache/ignite/internal/util/IgniteStripedReadWriteLock.java: ########## @@ -0,0 +1,222 @@ +/* + * 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.ignite.internal.util; + +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.concurrent.locks.Condition; +import java.util.concurrent.locks.Lock; +import java.util.concurrent.locks.ReadWriteLock; +import java.util.concurrent.locks.ReentrantReadWriteLock; + +/** + * ReadWriteLock with striping mechanics. Compared to {@link ReentrantReadWriteLock} it has slightly improved performance of + * {@link ReadWriteLock#readLock()} operations at the cost of {@link ReadWriteLock#writeLock()} operations and memory consumption. It also + * supports reentrancy semantics like {@link ReentrantReadWriteLock}. + */ +public class IgniteStripedReadWriteLock implements ReadWriteLock { + /** Index generator. */ + private static final AtomicInteger IDX_GEN = new AtomicInteger(); + + /** Index. */ + private static final ThreadLocal<Integer> IDX = ThreadLocal.withInitial(() -> IDX_GEN.incrementAndGet()); + + /** Locks. */ + private final ReentrantReadWriteLock[] locks; + + /** Composite write lock. */ + private final WriteLock writeLock; + + /** + * Creates a new instance with given concurrency level. + * + * @param concurrencyLvl Number of internal read locks. + */ + public IgniteStripedReadWriteLock(int concurrencyLvl) { + locks = new ReentrantReadWriteLock[concurrencyLvl]; + + for (int i = 0; i < concurrencyLvl; i++) { + locks[i] = new ReentrantReadWriteLock(); + } + + writeLock = new WriteLock(); + } + + /** + * Gets current index. + * + * @return Index of current thread stripe. + */ + private int curIdx() { + int idx = IDX.get(); + + return idx % locks.length; + } + + /** {@inheritDoc} */ + @Override + public Lock readLock() { + return locks[curIdx()].readLock(); + } + + /** + * Get a lock by stripe. + * + * @param idx Stripe index. + * @return The lock. + */ + public Lock readLock(int idx) { + return locks[idx].readLock(); Review Comment: This method corresponds to the javadoc description - get a lock by stripe index. And number of striped is known on lock creation. -- 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. To unsubscribe, e-mail: notifications-unsubscr...@ignite.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
