65 lines
2.4 KiB
Java
65 lines
2.4 KiB
Java
/*
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* Copyright (c) 2018, 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.management.ManagementFactory;
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import java.lang.management.MonitorInfo;
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import java.lang.management.ThreadInfo;
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import java.nio.channels.Selector;
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public class SelectorUtils {
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/**
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* tell if the monitor of an Object is held by a Thread.
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* @param t the Thread to hold the monitor of the selected-key set
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* @param lock the Object
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* @return
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*/
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public static boolean mightHoldLock(Thread t, Object lock) {
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long tid = t.getId();
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int hash = System.identityHashCode(lock);
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ThreadInfo ti = ManagementFactory.getThreadMXBean().
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getThreadInfo(new long[]{ tid} , true, false, 100)[0];
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if (ti != null) {
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for (MonitorInfo mi : ti.getLockedMonitors()) {
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if (mi.getIdentityHashCode() == hash)
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return true;
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}
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}
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return false;
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}
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/**
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* Spin until the monitor of the selected-key set is likely held
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* as selected operations are specified to synchronize on the
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* selected-key set.
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* @param t the Thread to hold the monitor of the selected-key set
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* @param sel the Selector
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* @throws Exception
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*/
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public static void spinUntilLocked(Thread t, Selector sel) throws Exception {
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while (!mightHoldLock(t, sel.selectedKeys())) {
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Thread.sleep(50);
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}
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}
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}
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