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一 JDK层

1 AbstractQueuedSynchronizer

                        代码节选自：java.util.concurrent.locks.ReentrantLock.java
                         /** Synchronizer providing all implementation mechanics */
                            private final Sync sync;
                            /**
                             * Base of synchronization control for this lock. Subclassed
                             * into fair and nonfair versions below. Uses AQS state to
                             * represent the number of holds on the lock.
                             */
                            abstract static class Sync extends AbstractQueuedSynchronizer {
                        ......
                        }
                        

                            public void lock() {
                                sync.lock();
                            }
                    

                    

                        

                        
                                /**
                                 * Acquires in exclusive mode, ignoring interrupts.  Implemented
                                 * by invoking at least once {@link #tryAcquire},
                                 * returning on success.  Otherwise the thread is queued, possibly
                                 * repeatedly blocking and unblocking, invoking {@link
                                 * #tryAcquire} until success.  This method can be used
                                 * to implement method {@link Lock#lock}.
                                 *
                                 * @param arg the acquire argument.  This value is conveyed to
                                 *        {@link #tryAcquire} but is otherwise uninterpreted and
                                 *        can represent anything you like.
                                 */
                                public final void acquire(int arg) {
                                    if (!tryAcquire(arg) &&
                                        acquireQueued(addWaiter(Node.EXCLUSIVE), arg))
                                        selfInterrupt();
                                }