src/java.base/unix/classes/sun/nio/ch/NativeThread.java
author alanb
Tue, 05 Feb 2019 18:53:19 +0000
branchniosocketimpl-branch
changeset 57148 1a13164f3f4f
parent 47216 71c04702a3d5
child 57301 66c3aaf31f2b
permissions -rw-r--r--
Cache native thread id to avoid call to JNI in blocking I/O ops
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/*
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 * Copyright (c) 2002, 2013, 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.  Oracle designates this
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 * particular file as subject to the "Classpath" exception as provided
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 * by Oracle in the LICENSE file that accompanied this code.
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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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package sun.nio.ch;
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// Signalling operations on native threads
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//
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// On some operating systems (e.g., Linux), closing a channel while another
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// thread is blocked in an I/O operation upon that channel does not cause that
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// thread to be released.  This class provides access to the native threads
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// upon which Java threads are built, and defines a simple signal mechanism
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// that can be used to release a native thread from a blocking I/O operation.
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import jdk.internal.access.JavaLangAccess;
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import jdk.internal.access.SharedSecrets;
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public class NativeThread {
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    private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
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    /**
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     * Returns the current thread's ID.
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     */
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    public static long current() {
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        long tid = JLA.nativeTid();
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        if (tid == 0) {
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            tid = current0();
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            JLA.setNativeTid(tid);
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        }
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        return tid;
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    }
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    /**
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     * Signals the given thread.
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     */
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    public static void signal(long tid) {
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        signal0(tid);
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    }
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    private static native long current0();
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    private static native void signal0(long tid);
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    private static native void init();
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    static {
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        IOUtil.load();
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        init();
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    }
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}