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/*
* Copyright (c) 2022, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* @test
* @summary Test Thread.getStackTrace to examine the stack trace of a virtual
* thread and its carrier
* @requires vm.continuations
* @modules java.base/java.lang:+open
* @run main GetStackTrace
*/
import java.util.Objects;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedTransferQueue;
import java.util.stream.Stream;
public class GetStackTrace {
private static final Object LOCK = new Object();
public static void main(String[] args) throws Exception {
try (var scheduler = new Scheduler()) {
Thread vthread = scheduler.startVirtualThread(() -> {
synchronized (LOCK) {
try {
LOCK.wait();
} catch (InterruptedException e) { }
}
});
try {
// wait for virtual thread to wait
while (vthread.getState() != Thread.State.WAITING) {
Thread.sleep(10);
}
// bottom-most frame of virtual thread should be VirtualThread.run
System.out.println(vthread);
StackTraceElement[] vthreadStack = vthread.getStackTrace();
Stream.of(vthreadStack).forEach(System.out::println);
assertEquals("run", vthreadStack[vthreadStack.length - 1].getMethodName());
System.out.println();
// top-most frame of carrier thread should be Continuation.run
// bottom-most frame of carrier thread should be Thread.run
var carrier = scheduler.thread();
System.out.println(carrier);
StackTraceElement[] carrierStack = carrier.getStackTrace();
Stream.of(carrierStack).forEach(System.out::println);
assertEquals("run", carrierStack[0].getMethodName());
assertEquals("run", carrierStack[carrierStack.length - 1].getMethodName());
} finally {
vthread.interrupt();
}
}
}
/**
* A scheduler with one thread.
*/
private static class Scheduler implements AutoCloseable, Executor {
private final BlockingQueue<Runnable> tasks = new LinkedTransferQueue<>();
private final Thread thread;
private volatile boolean done;
Scheduler() {
this.thread = Thread.ofPlatform().start(() -> {
try {
while (!done) {
Runnable task = tasks.take();
task.run();
}
} catch (InterruptedException e) { }
});
}
Thread thread() {
return thread;
}
@Override
public void close() throws InterruptedException {
done = true;
thread.interrupt();
thread.join();
}
@Override
public void execute(Runnable task) {
tasks.add(task);
}
Thread startVirtualThread(Runnable task) {
return ThreadBuilders.virtualThreadBuilder(this).start(task);
}
}
private static void assertTrue(boolean e) {
if (!e) throw new RuntimeException();
}
private static void assertEquals(Object x, Object y) {
if (!Objects.equals(x, y))
throw new RuntimeException();
}
}
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