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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.yolean.concurrent;
import org.junit.Test;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.Phaser;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Supplier;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertThrows;
import static org.junit.Assert.fail;
/**
* @author jonmv
*/
public class MemoizedTest {
final Phaser phaser = new Phaser();
final int threads = 128;
@Test
public void test() throws ExecutionException, InterruptedException {
var lazy = new Memoized<>(new OnceSupplier(), OnceCloseable::close);
phaser.register(); // test thread
phaser.register(); // whoever calls the factory
Phaser latch = new Phaser(threads + 1);
ExecutorService executor = Executors.newFixedThreadPool(threads);
List<Future<?>> futures = new ArrayList<>();
for (int i = 0; i < 128; i++) {
futures.add(executor.submit(() -> {
latch.arriveAndAwaitAdvance();
lazy.get().rendezvous();
while (true) lazy.get();
}));
}
// All threads waiting for latch, will race to factory
latch.arriveAndAwaitAdvance();
// One thread waiting in factory, the others are blocked, will go to rendezvous
phaser.arriveAndAwaitAdvance();
// All threads waiting in rendezvous, will repeatedly get until failure
phaser.arriveAndAwaitAdvance();
// Unsynchronized close should be detected by all threads
lazy.close();
// Close should carry through only once
lazy.close();
assertEquals("already closed",
assertThrows(IllegalStateException.class, lazy::get).getMessage());
for (Future<?> future : futures)
assertEquals("java.lang.IllegalStateException: already closed",
assertThrows(ExecutionException.class, future::get).getMessage());
executor.shutdown();
}
@Test
public void closeBeforeFirstGet() throws Exception {
OnceSupplier supplier = new OnceSupplier();
Memoized<OnceCloseable, ?> lazy = Memoized.of(supplier);
lazy.close();
assertEquals("already closed",
assertThrows(IllegalStateException.class, lazy::get).getMessage());
lazy.close();
assertFalse(supplier.initialized.get());
}
class OnceSupplier implements Supplier<OnceCloseable> {
final AtomicBoolean initialized = new AtomicBoolean();
@Override public OnceCloseable get() {
phaser.arriveAndAwaitAdvance();
if ( ! initialized.compareAndSet(false, true)) fail("initialized more than once");
phaser.bulkRegister(threads - 1); // register all the threads who didn't get the factory
return new OnceCloseable();
}
}
class OnceCloseable implements AutoCloseable {
final AtomicBoolean closed = new AtomicBoolean();
@Override public void close() {
if ( ! closed.compareAndSet(false, true)) fail("closed more than once");
}
void rendezvous() {
phaser.arriveAndAwaitAdvance();
}
}
}
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