AbstractOwnableSynchronizer

概述

可能由线程独占拥有的同步器。此类为创建锁和相关同步器提供了基础，这些同步器可能需要所有权的概念。类本身不管理或使用此信息。但是，子类和工具可以使用适当维护的值来帮助控制和监视访问并提供诊断。java中以下类继承了该类

源码

public abstract class AbstractOwnableSynchronizer
    implements java.io.Serializable {

    /** Use serial ID even though all fields transient. */
    private static final long serialVersionUID = 3737899427754241961L;

    /**
     * Empty constructor for use by subclasses.
     */
    protected AbstractOwnableSynchronizer() { }

    /**
     * The current owner of exclusive mode synchronization.
     */
    private transient Thread exclusiveOwnerThread;

    /**
     * Sets the thread that currently owns exclusive access.
     * A {@code null} argument indicates that no thread owns access.
     * This method does not otherwise impose any synchronization or
     * {@code volatile} field accesses.
     * @param thread the owner thread
     */
    protected final void setExclusiveOwnerThread(Thread thread) {
        exclusiveOwnerThread = thread;
    }

    /**
     * Returns the thread last set by {@code setExclusiveOwnerThread},
     * or {@code null} if never set.  This method does not otherwise
     * impose any synchronization or {@code volatile} field accesses.
     * @return the owner thread
     */
    protected final Thread getExclusiveOwnerThread() {
        return exclusiveOwnerThread;
    }
}

维护了一个transient的线程，用来标记独占模式下的拥有线程，并提供set和get方法