NativeThread.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * particular file as subject to the "Classpath" exception as provided
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package sun.nio.ch;

/*
 * Socket通道本地线程操作
 *
 * 在一些系统平台上(如linux或mac)上，当某个可阻塞的Socket通道被阻塞时，其所在的native线程无法被另一个线程关闭。
 * 比如A线程阻塞在Socket通道的读操作上，但是B线程却要关闭该Socket通道，此时必须先等A线程结束该阻塞操作。
 * 等待A线程结束其阻塞操作后，会唤醒休眠的B线程，以完成后续的关闭过程。
 */
class NativeThread {
    
    /*
     * 返回当前通道所在的native线程引用
     *
     * 在windows平台上总是返回0，表示可以随意关闭此线程
     */
    static long current() {
        // return 0 to ensure that async close of blocking sockets will close the underlying socket.
        return 0;
    }
    
    /*
     * 唤醒阻塞的nt线程
     *
     * 在windows平台上此方法无任何效果
     */
    static void signal(long nt) {
    }
    
}