81 lines
2.8 KiB
Java
81 lines
2.8 KiB
Java
/*
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* Copyright (c) 2019, 2022, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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import java.lang.reflect.Constructor;
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import java.lang.reflect.InvocationTargetException;
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import java.util.concurrent.Executor;
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import java.util.concurrent.Executors;
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/**
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* Helper class for creating Thread buidlers.
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*
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* Tests using this class need to open java.base/java.lang.
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*/
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class ThreadBuilders {
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private ThreadBuilders() { }
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private static final Constructor<?> VTBUILDER_CTOR;
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static {
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try {
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Class<?> clazz = Class.forName("java.lang.ThreadBuilders$VirtualThreadBuilder");
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Constructor<?> ctor = clazz.getDeclaredConstructor(Executor.class);
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ctor.setAccessible(true);
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VTBUILDER_CTOR = ctor;
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} catch (Exception e) {
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throw new InternalError(e);
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}
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}
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/**
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* Returns a builder to create virtual threads that use the given scheduler.
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* @throws UnsupportedOperationException if custom schedulers are not supported
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*/
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static Thread.Builder.OfVirtual virtualThreadBuilder(Executor scheduler) {
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try {
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return (Thread.Builder.OfVirtual) VTBUILDER_CTOR.newInstance(scheduler);
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} catch (InvocationTargetException e) {
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Throwable cause = e.getCause();
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if (cause instanceof RuntimeException re) {
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throw re;
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}
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throw new RuntimeException(e);
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} catch (Exception e) {
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throw new RuntimeException(e);
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}
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}
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/**
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* Return true if custom schedulers are supported.
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*/
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static boolean supportsCustomScheduler() {
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try (var pool = Executors.newCachedThreadPool()) {
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try {
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virtualThreadBuilder(pool);
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return true;
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} catch (UnsupportedOperationException e) {
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return false;
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}
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}
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}
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}
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