[GitHub] [ignite-3] rpuch commented on a change in pull request #414: IGNITE-15536 Use VarHandle to replace UNSAFE in IgniteSpinReadWriteLock

[GitBox <gi...@apache.org>]

rpuch commented on a change in pull request #414:
URL: https://github.com/apache/ignite-3/pull/414#discussion_r738059046



##########
File path: modules/core/src/test/java/org/apache/ignite/internal/util/IgniteSpinReadWriteLockTest.java
##########
@@ -0,0 +1,530 @@
+/*
+ * 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.time.Duration;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Tests for {@link IgniteSpinReadWriteLock}.
+ */
+@Timeout(20)
+class IgniteSpinReadWriteLockTest {
+    /** The lock under test. */
+    private final IgniteSpinReadWriteLock lock = new IgniteSpinReadWriteLock();
+
+    /** Poller used to poll for 10 seconds. */
+    private final Poller poller10Sec = new Poller(Duration.ofSeconds(10), Duration.ofMillis(10));
+
+    /** Executor service used to run tasks in threads different from the main test thread. */
+    private final ExecutorService executor = Executors.newCachedThreadPool();
+
+    /**
+     * Cleans up after a test.
+     *
+     * @throws Exception if something goes wrong
+     */
+    @AfterEach
+    void cleanup() throws Exception {
+        releaseReadLockHeldByCurrentThread();
+        releaseWriteLockHeldByCurrentThread();
+
+        executor.shutdownNow();
+        executor.awaitTermination(3, TimeUnit.SECONDS);
+    }
+
+    /***/
+    private void releaseReadLockHeldByCurrentThread() {
+        while (true) {
+            try {
+                lock.readUnlock();
+            }
+            catch (IllegalMonitorStateException e) {
+                // released our read lock completely
+                break;
+            }
+        }
+    }
+
+    /***/
+    private void releaseWriteLockHeldByCurrentThread() {
+        while (lock.writeLockedByCurrentThread())
+            lock.writeUnlock();
+    }
+
+    /**
+     *
+     */
+    @Test
+    void readLockDoesNotAllowWriteLockToBeAcquired() {
+        lock.readLock();
+
+        assertThatWriteLockAcquireAttemptBlocksForever();
+
+        lock.readUnlock();
+    }
+
+    /***/
+    private void assertThatWriteLockAcquireAttemptBlocksForever() {
+        Future<?> future = executor.submit(lock::writeLock);
+
+        assertThrows(TimeoutException.class, () -> future.get(500, TimeUnit.MILLISECONDS));
+    }
+
+    /**
+     *
+     */
+    @Test
+    void readLockDoesNotAllowWriteLockWithoutSleepsToBeAcquired() {
+        lock.readLock();
+
+        assertThatWriteLockAcquireAttemptWithoutSleepsBlocksForever();
+
+        lock.readUnlock();
+    }
+
+    /**
+     *
+     */
+    @Test
+    void readLockDoesNotAllowWriteLockToBeAcquiredWithTimeout() throws Exception {
+        lock.readLock();
+
+        Boolean acquired = callWithTimeout(() -> lock.tryWriteLock(1, TimeUnit.MILLISECONDS));
+        assertThat(acquired, is(false));
+
+        lock.readUnlock();
+    }
+
+    /**
+     *
+     */
+    @Test
+    void readLockAllowsReadLockToBeAcquired() throws Exception {
+        lock.readLock();
+
+        assertThatReadLockCanBeAcquired();
+    }
+
+    /***/
+    private void assertThatReadLockCanBeAcquired() throws InterruptedException, ExecutionException, TimeoutException {
+        Future<?> readLockAttemptFuture = executor.submit(lock::readLock);
+        getWithTimeout(readLockAttemptFuture);
+    }
+
+    /***/
+    private <T> T callWithTimeout(Callable<T> call) throws ExecutionException, InterruptedException, TimeoutException {
+        Future<T> future = executor.submit(call);
+        return getWithTimeout(future);
+    }
+
+    /***/
+    private void runWithTimeout(Runnable runnable) throws ExecutionException, InterruptedException, TimeoutException {
+        Future<?> future = executor.submit(runnable);
+        getWithTimeout(future);
+    }
+
+    /***/
+    private <T> T getWithTimeout(Future<? extends T> future) throws ExecutionException,

Review comment:
       Why make a method static when we never use it in a static context?
   
   Generally, I think we should have method applicability (non-static over static; private over package-local/protected/public, etc) as low as possible to make sure that someone thinks twice before using it in a broader context.
   
   In this case, it doesn't matter much, it's a private method, but I would still like to hear motivation behind this suggestion :)




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