{"id":565,"date":"2019-10-09T17:32:00","date_gmt":"2019-10-09T09:32:00","guid":{"rendered":"http:\/\/weitaoc.com\/?p=565"},"modified":"2019-10-09T17:32:08","modified_gmt":"2019-10-09T09:32:08","slug":"aqsabstractqueuedsynchronized-%e6%8a%bd%e8%b1%a1%e7%9a%84%e9%98%9f%e5%88%97%e5%90%8c%e6%ad%a5%e5%99%a8","status":"publish","type":"post","link":"http:\/\/weitaoc.com\/?p=565","title":{"rendered":"AQS(AbstractQueuedSynchronized)-\u62bd\u8c61\u7684\u961f\u5217\u540c\u6b65\u5668"},"content":{"rendered":"\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p> \u62bd\u8c61\u7684\u961f\u5217\u5f0f\u7684\u540c\u6b65\u5668\uff0cAQS\u5b9a\u4e49\u4e86\u4e00\u5957\u591a\u7ebf\u7a0b\u8bbf\u95ee\u5171\u4eab\u8d44\u6e90\u7684\u540c\u6b65\u5668\u6846\u67b6\uff0c\u8bb8\u591a\u540c\u6b65\u7c7b\u5b9e\u73b0\u90fd\u4f9d\u8d56\u4e8e\u5b83\uff0c\u5982\u5e38\u7528\u7684ReentrantLock\/Semaphore\/CountDownLatch&#8230; <\/p><\/blockquote>\n\n\n\n<p>ReentrantLock\u7684\u9501\u5b9e\u73b0\u662f\u57fa\u4e8eAbstractQueuedSynchronizer\u5b9e\u73b0\u7684\uff0c\u5176\u5185\u90e8\u5b9e\u73b0\u7c7bSync\u7ee7\u627f\u4e86AbstractQueuedSynchronizer\uff0c\u540c\u65f6\u6d3e\u751f\u51fa\u4e24\u4e2a\u5b50\u7c7bNonfairSync(\u975e\u516c\u5e73\u9501)\u548cFairSync(\u516c\u5e73\u9501)\u3002<\/p>\n\n\n\n<p>\u975e\u516c\u5e73\u9501\u5728\u6bcf\u6b21\u8fdb\u6765\u65f6\u4f1a\u5148\u7528CAS\u53bb\u5360\u6709\u9501\uff0c\u83b7\u53d6\u4e0d\u5230\u518d\u4f7f\u7528\u72ec\u5360\u9501\uff0c\u90fd\u83b7\u53d6\u4e0d\u5230\u9501\u624d\u4f1a\u8fdb\u5165\u961f\u5217\u672b\u5c3e\u7b49\u5f85\u3002\u516c\u5e73\u9501\u4f1a\u76f4\u63a5\u4f7f\u7528\u72ec\u5360\u9501\u53bb\u83b7\u53d6\u9501\uff0c\u5982\u679c\u83b7\u53d6\u4e0d\u5230\u5c31\u80fd\u8fdb\u53bb\u961f\u5217\u7b49\u5f85\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\">\n\n<div class=\"codecolorer-container text geshi\" style=\"overflow:auto;white-space:nowrap;width:100%;\"><table cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td class=\"line-numbers\"><div>1<br \/>2<br \/>3<br \/>4<br \/>5<br \/>6<br \/>7<br \/>8<br \/>9<br \/>10<br \/>11<br \/>12<br \/>13<br \/>14<br \/>15<br \/>16<br \/><\/div><\/td><td><div class=\"text codecolorer\" style=\"white-space:nowrap\">&nbsp; &nbsp; public void lock() {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; sync.lock();<br \/>\n&nbsp; &nbsp; }<br \/>\n<br \/>\n&nbsp; &nbsp; \/\/ FairSync \u516c\u5e73\u9501\u8c03\u7528\u65b9\u5f0f<br \/>\n&nbsp; &nbsp; final void lock() {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; acquire(1); \/\/ \u5c1d\u8bd5\u83b7\u53d6\u72ec\u5360\u9501<br \/>\n&nbsp; &nbsp; }<br \/>\n<br \/>\n&nbsp; &nbsp; \/\/ NonfairSync \u975e\u516c\u5e73\u9501\u8c03\u7528\u65b9\u5f0f<br \/>\n&nbsp; &nbsp; final void lock() {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; if (compareAndSetState(0, 1)) \/\/ \u9996\u5148\u5224\u65adstate\u8d44\u6e90\u662f\u5426\u4e3a0\uff0c\u5982\u679c\u6070\u5de7\u4e3a0\u5219\u8868\u660e\u76ee\u524d\u6ca1\u6709\u7ebf\u7a0b\u5360\u7528\u9501\uff0c\u5219\u5229\u7528CAS\u5360\u6709\u9501<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setExclusiveOwnerThread(Thread.currentThread()); \/\/ \u5f53\u72ec\u5360\u9501\u4e4b\u540e\u5219\u5c06\u8bbe\u7f6eexclusiveOwnerThread\u4e3a\u5f53\u524d\u7ebf\u7a0b<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; else<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; acquire(1); \/\/ \u82e5CAS\u5360\u7528\u9501\u5931\u8d25\u7684\u8bdd\uff0c\u5219\u518d\u5c1d\u8bd5\u83b7\u53d6\u72ec\u5360\u9501<br \/>\n&nbsp; &nbsp; }<\/div><\/td><\/tr><\/tbody><\/table><\/div>\n\n<\/pre>\n\n\n\n<p>\u516c\u5e73\u9501tryAcquire\u6e90\u7801\uff1a <\/p>\n\n\n\n<pre class=\"wp-block-code\">\n\n<div class=\"codecolorer-container text geshi\" style=\"overflow:auto;white-space:nowrap;width:100%;\"><table cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td class=\"line-numbers\"><div>1<br \/>2<br \/>3<br \/>4<br \/>5<br \/>6<br \/>7<br \/>8<br \/>9<br \/>10<br \/>11<br \/>12<br \/>13<br \/>14<br \/>15<br \/>16<br \/>17<br \/>18<br \/>19<br \/>20<br \/>21<br \/>22<br \/><\/div><\/td><td><div class=\"text codecolorer\" style=\"white-space:nowrap\">\/\/ FairSync \u516c\u5e73\u9501\u7684 tryAcquire \u65b9\u6cd5<br \/>\n&nbsp; &nbsp; protected final boolean tryAcquire(int acquires) {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; final Thread current = Thread.currentThread();<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; int c = getState(); \/\/ \u83b7\u53d6\u9501\u8d44\u6e90\u7684\u6700\u65b0\u5185\u5b58\u503c<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; if (c == 0) { \/\/ \u5f53state=0\uff0c\u8bf4\u660e\u9501\u8d44\u6e90\u76ee\u524d\u8fd8\u6ca1\u6709\u88ab\u4efb\u4f55\u7ebf\u7a0b\u88ab\u5360\u7528<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (!hasQueuedPredecessors() &amp;amp;&amp;amp; \/\/ \u68c0\u67e5\u7ebf\u7a0b\u662f\u5426\u6709\u963b\u585e\u961f\u5217<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; compareAndSetState(0, acquires)) { \/\/ \u5982\u679c\u6ca1\u6709\u963b\u585e\u961f\u5217\uff0c\u5219\u901a\u8fc7CAS\u64cd\u4f5c\u83b7\u53d6\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setExclusiveOwnerThread(current); \/\/ \u6ca1\u6709\u963b\u585e\u961f\u5217\uff0c\u4e14CAS\u53c8\u6210\u529f\u83b7\u53d6\u9501\u8d44\u6e90\uff0c\u5219\u8bbe\u7f6e\u72ec\u5360\u7ebf\u7a0b\u5bf9\u8c61\u4e3a\u5f53\u524d\u7ebf\u7a0b<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return true; \/\/ \u8fd4\u56de\u6807\u5fd7\uff0c\u544a\u8bc9\u4e0a\u5c42\u8be5\u7ebf\u7a0b\u5df2\u7ecf\u83b7\u53d6\u5230\u4e86\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u6267\u884c\u5230\u6b64\uff0c\u9501\u8d44\u6e90\u503c\u4e0d\u4e3a0\uff0c\u8bf4\u660e\u5df2\u7ecf\u6709\u7ebf\u7a0b\u6b63\u5728\u5360\u7528\u8fd9\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; else if (current == getExclusiveOwnerThread()) { \/\/ \u65e2\u7136\u9501\u5df2\u7ecf\u88ab\u5360\u7528\uff0c\u5219\u770b\u770b\u5360\u7528\u9501\u7684\u7ebf\u7a0b\u662f\u4e0d\u662f\u5f53\u524d\u7ebf\u7a0b<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int nextc = c + acquires; \/\/ \u5982\u679c\u5360\u7528\u7684\u9501\u7684\u7ebf\u7a0b\u662f\u5f53\u524d\u7ebf\u7a0b\u7684\u8bdd\uff0c\u5219\u4e3a\u91cd\u5165\u9501\u6982\u5ff5\uff0c\u72b6\u6001\u503c\u505a\u52a01\u64cd\u4f5c<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ int\u7c7b\u578b\u503c\u5c0f\u4e8e0\uff0c\u662f\u56e0\u4e3a\u8be5int\u7c7b\u578b\u7684state\u72b6\u6001\u503c\u6ea2\u51fa\u4e86\uff0c\u6ea2\u51fa\u4e86\u7684\u8bdd\u90a3\u5f97\u8bf4\u660e\u8fd9\u4e2a\u9501\u6709\u591a\u96be\u83b7\u53d6\u554a\uff0c\u53ef\u80fd\u51fa\u95ee\u9898\u4e86<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (nextc &amp;lt; 0)<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; throw new Error(&quot;Maximum lock count exceeded&quot;);<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setState(nextc);<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return true; \/\/ \u8fd4\u56de\u6210\u529f\u6807\u5fd7\uff0c\u544a\u8bc9\u4e0a\u5c42\u8be5\u7ebf\u7a0b\u5df2\u7ecf\u83b7\u53d6\u5230\u4e86\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; return false; \/\/ \u8fd4\u56de\u5931\u8d25\u6807\u5fd7\uff0c\u544a\u8bc9\u4e0a\u5c42\u8be5\u7ebf\u7a0b\u6ca1\u6709\u83b7\u53d6\u5230\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; }<\/div><\/td><\/tr><\/tbody><\/table><\/div>\n\n<\/pre>\n\n\n\n<p>\u975e\u516c\u5e73\u9501tryAcquire\u6e90\u7801<\/p>\n\n\n\n<pre class=\"wp-block-code\">\n\n<div class=\"codecolorer-container text geshi\" style=\"overflow:auto;white-space:nowrap;width:100%;\"><table cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td class=\"line-numbers\"><div>1<br \/>2<br \/>3<br \/>4<br \/>5<br \/>6<br \/>7<br \/>8<br \/>9<br \/>10<br \/>11<br \/>12<br \/>13<br \/>14<br \/>15<br \/>16<br \/>17<br \/>18<br \/>19<br \/>20<br \/>21<br \/>22<br \/>23<br \/>24<br \/>25<br \/>26<br \/><\/div><\/td><td><div class=\"text codecolorer\" style=\"white-space:nowrap\">\/\/ NonfairSync \u975e\u516c\u5e73\u9501\u7684 tryAcquire \u65b9\u6cd5<br \/>\n&nbsp; &nbsp; protected final boolean tryAcquire(int acquires) {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; return nonfairTryAcquire(acquires); \/\/ \u8c03\u7528\u7236\u7c7b\u7684\u975e\u516c\u5e73\u83b7\u53d6\u9501\u8d44\u6e90\u65b9\u6cd5<br \/>\n&nbsp; &nbsp; }<br \/>\n<br \/>\n&nbsp; &nbsp; \/\/ NonfairSync \u975e\u516c\u5e73\u9501\u7236\u7c7b Sync \u7c7b\u7684 nonfairTryAcquire \u65b9\u6cd5 &nbsp; &nbsp;<br \/>\n&nbsp; &nbsp; final boolean nonfairTryAcquire(int acquires) {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; final Thread current = Thread.currentThread();<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; int c = getState(); \/\/ \u83b7\u53d6\u9501\u8d44\u6e90\u7684\u6700\u65b0\u5185\u5b58\u503c<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; if (c == 0) { \/\/ \u5f53state=0\uff0c\u8bf4\u660e\u9501\u8d44\u6e90\u76ee\u524d\u8fd8\u6ca1\u6709\u88ab\u4efb\u4f55\u7ebf\u7a0b\u88ab\u5360\u7528<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (compareAndSetState(0, acquires)) { \/\/ \u5148\u4e0d\u7ba1\u4e09\u4e03\u4e8c\u5341\u4e00\uff0c\u5148\u5c1d\u8bd5\u901a\u8fc7CAS\u64cd\u4f5c\u83b7\u53d6\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setExclusiveOwnerThread(current); \/\/ CAS\u4e00\u65e6\u6210\u529f\u83b7\u53d6\u9501\u8d44\u6e90\uff0c\u5219\u8bbe\u7f6e\u72ec\u5360\u7ebf\u7a0b\u5bf9\u8c61\u4e3a\u5f53\u524d\u7ebf\u7a0b<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return true;\/\/ \u8fd4\u56de\u6210\u529f\u6807\u5fd7\uff0c\u544a\u8bc9\u4e0a\u5c42\u8be5\u7ebf\u7a0b\u5df2\u7ecf\u83b7\u53d6\u5230\u4e86\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u6267\u884c\u5230\u6b64\uff0c\u9501\u8d44\u6e90\u503c\u4e0d\u4e3a0\uff0c\u8bf4\u660e\u5df2\u7ecf\u6709\u7ebf\u7a0b\u6b63\u5728\u5360\u7528\u8fd9\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; else if (current == getExclusiveOwnerThread()) { \/\/ \u65e2\u7136\u9501\u5df2\u7ecf\u88ab\u5360\u7528\uff0c\u5219\u770b\u770b\u5360\u7528\u9501\u7684\u7ebf\u7a0b\u662f\u4e0d\u662f\u5f53\u524d\u7ebf\u7a0b<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int nextc = c + acquires; \/\/ \u5982\u679c\u5360\u7528\u7684\u9501\u7684\u7ebf\u7a0b\u662f\u5f53\u524d\u7ebf\u7a0b\u7684\u8bdd\uff0c\u5219\u4e3a\u91cd\u5165\u9501\u6982\u5ff5\uff0c\u72b6\u6001\u503c\u505a\u52a01\u64cd\u4f5c<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ int\u7c7b\u578b\u503c\u5c0f\u4e8e0\uff0c\u662f\u56e0\u4e3a\u8be5int\u7c7b\u578b\u7684state\u72b6\u6001\u503c\u6ea2\u51fa\u4e86\uff0c\u6ea2\u51fa\u4e86\u7684\u8bdd\u90a3\u5f97\u8bf4\u660e\u8fd9\u4e2a\u9501\u6709\u591a\u96be\u83b7\u53d6\u554a\uff0c\u53ef\u80fd\u51fa\u95ee\u9898\u4e86<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (nextc &amp;lt; 0) \/\/ overflow<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; throw new Error(&quot;Maximum lock count exceeded&quot;);<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setState(nextc); \/\/<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return true; \/\/ \u8fd4\u56de\u6210\u529f\u6807\u5fd7\uff0c\u544a\u8bc9\u4e0a\u5c42\u8be5\u7ebf\u7a0b\u5df2\u7ecf\u83b7\u53d6\u5230\u4e86\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; return false; \/\/ \u8fd4\u56de\u5931\u8d25\u6807\u5fd7\uff0c\u544a\u8bc9\u4e0a\u5c42\u8be5\u7ebf\u7a0b\u6ca1\u6709\u83b7\u53d6\u5230\u9501\u8d44\u6e90<br \/>\n&nbsp; &nbsp; }(<\/div><\/td><\/tr><\/tbody><\/table><\/div>\n\n<\/pre>\n\n\n\n<p>\u83b7\u53d6\u9501\u5931\u8d25\u540e\uff0c\u7ebf\u7a0b\u8bf7\u6c42\u4f1a\u653e\u5165\u961f\u5217\u7b49\u5f85\u5524\u9192\uff0c\u6b64\u5904\u662f\u7528\u81ea\u65cb\u7684\u65b9\u5f0f\u5b9e\u73b0(\u6b7b\u5faa\u73af)<\/p>\n\n\n\n<pre class=\"wp-block-code\">\n\n<div class=\"codecolorer-container text geshi\" style=\"overflow:auto;white-space:nowrap;width:100%;\"><table cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td class=\"line-numbers\"><div>1<br \/>2<br \/>3<br \/>4<br \/>5<br \/>6<br \/>7<br \/>8<br \/>9<br \/>10<br \/>11<br \/>12<br \/>13<br \/>14<br \/>15<br \/>16<br \/>17<br \/>18<br \/>19<br \/>20<br \/>21<br \/><\/div><\/td><td><div class=\"text codecolorer\" style=\"white-space:nowrap\">private Node enq(final Node node) {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; for (;;) { \/\/ \u81ea\u65cb\u7684\u6b7b\u5faa\u73af\u64cd\u4f5c\u65b9\u5f0f<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Node t = tail;<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u56e0\u4e3a\u662f\u81ea\u65cb\u65b9\u5f0f\uff0c\u9996\u6b21\u94fe\u8868\u961f\u5217tail\u80af\u5b9a\u4e3a\u7a7a\uff0c\u4f46\u662f\u540e\u7eed\u94fe\u8868\u6709\u6570\u636e\u540e\u5c31\u4e0d\u4f1a\u4e3a\u7a7a\u4e86<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (t == null) { \/\/ Must initialize<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (compareAndSetHead(new Node())) \/\/ \u961f\u5217\u4e3a\u7a7a\u65f6\uff0c\u5219\u521b\u5efa\u4e00\u4e2a\u7a7a\u5bf9\u8c61\u7ed3\u70b9\u4f5c\u4e3a\u5934\u7ed3\u70b9\uff0c\u65e0\u610f\u601d\uff0c\u53ef\u8ba4\u4e3a\u5080\u5121\u7ed3\u70b9<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; tail = head; \/\/ \u7a7a\u961f\u5217\u7684\u8bdd\uff0c\u5934\u5c3e\u90fd\u6307\u5411\u540c\u4e00\u4e2a\u5bf9\u8c61<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; } else {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u8fdb\u5165 else \u65b9\u6cd5\u91cc\u9762\uff0c\u8bf4\u660e\u94fe\u8868\u961f\u5217\u5df2\u7ecf\u6709\u7ed3\u70b9\u4e86<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; node.prev = t;<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u56e0\u4e3a\u5b58\u5728\u5e76\u53d1\u64cd\u4f5c\uff0c\u901a\u8fc7CAS\u5c1d\u8bd5\u5c06\u65b0\u52a0\u5165\u7684node\u7ed3\u70b9\u8bbe\u7f6e\u4e3a\u961f\u5c3e\u7ed3\u70b9<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (compareAndSetTail(t, node)) {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u5982\u679cnode\u8bbe\u7f6e\u961f\u5c3e\u7ed3\u70b9\u6210\u529f\uff0c\u5219\u5c06\u4e4b\u524d\u7684\u65e7\u7684\u5bf9\u8c61\u5c3e\u7ed3\u70b9t\u7684\u540e\u7ee7\u7ed3\u70b9\u6307\u5411node,node\u7684\u524d\u9a71\u7ed3\u70b9\u4e5f\u8bbe\u7f6e\u4e3at<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; t.next = node;<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return t;<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u5982\u679c\u6267\u884c\u5230\u8fd9\u91cc\uff0c\u8bf4\u660e\u4e0a\u8ff0\u4e24\u4e2aCAS\u64cd\u4f5c\u4efb\u4f55\u4e00\u4e2a\u5931\u8d25\u7684\u8bdd\uff0c\u8be5\u65b9\u6cd5\u662f\u4e0d\u4f1a\u653e\u5f03\u7684\uff0c\u56e0\u4e3a\u662f\u81ea\u65cb\u64cd\u4f5c\uff0c\u518d\u6b21\u5faa\u73af\u7ee7\u7eed\u5165\u961f<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; }<\/div><\/td><\/tr><\/tbody><\/table><\/div>\n\n<\/pre>\n\n\n\n<p>acquireQueued\u4e5f\u662f\u91c7\u7528\u4e00\u4e2a\u81ea\u65cb\u7684\u6b7b\u5faa\u73af\u64cd\u4f5c\u65b9\u5f0f\uff0c\u53ea\u6709\u5934\u7ed3\u70b9\u624d\u80fd\u5c1d\u8bd5\u83b7\u53d6\u9501\u8d44\u6e90\uff0c\u5176\u4f59\u7684\u7ed3\u70b9\u6328\u4e2a\u6328\u4e2a\u5728\u90a3\u91cc\u7b49\u5f85\u4fee\u6539\uff0c\u7b49\u5f85\u88ab\u5524\u9192\uff0c\u7b49\u5f85\u673a\u4f1a\u6210\u4e3a\u5934\u7ed3\u70b9\uff1b\u800c\u65b0\u6dfb\u52a0\u7684node\u7ed3\u70b9\u4e5f\u81ea\u7136\u9003\u4e0d\u8fc7\u5982\u6b64\u547d\u8fd0\uff0c\u5148\u770b\u770b\u662f\u5426\u5934\u7ed3\u70b9\uff0c\u7136\u540e\u518d\u770b\u770b\u662f\u5426\u80fd\u4f11\u606f\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\">\n\n<div class=\"codecolorer-container text geshi\" style=\"overflow:auto;white-space:nowrap;width:100%;\"><table cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td class=\"line-numbers\"><div>1<br \/>2<br \/>3<br \/>4<br \/>5<br \/>6<br \/>7<br \/>8<br \/>9<br \/>10<br \/>11<br \/>12<br \/>13<br \/>14<br \/>15<br \/>16<br \/>17<br \/>18<br \/>19<br \/>20<br \/>21<br \/>22<br \/>23<br \/>24<br \/>25<br \/><\/div><\/td><td><div class=\"text codecolorer\" style=\"white-space:nowrap\">final boolean acquireQueued(final Node node, int arg) {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; boolean failed = true;<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; try {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; boolean interrupted = false;<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for (;;) { \/\/ \u81ea\u65cb\u7684\u6b7b\u5faa\u73af\u64cd\u4f5c\u65b9\u5f0f<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; final Node p = node.predecessor(); \/\/ \u5982\u679c\u65b0\u5efa\u7ed3\u70b9\u7684\u524d\u9a71\u7ed3\u70b9\u662f\u5934\u7ed3\u70b9<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u5982\u679c\u524d\u9a71\u7ed3\u70b9\u4e3a\u5934\u7ed3\u70b9\uff0c\u90a3\u4e48\u8be5\u7ed3\u70b9\u5219\u662f\u8001\u4e8c\uff0c\u4ec5\u6b21\u4e8e\u8001\u5927\uff0c\u4e5f\u5e0c\u671b\u5c1d\u8bd5\u53bb\u83b7\u53d6\u4e00\u4e0b\u9501\uff0c\u4e07\u4e00\u5934\u7ed3\u70b9\u6070\u5de7\u521a\u521a\u91ca\u653e\u5462\uff1f\u5e0c\u671b\u8fd8\u662f\u8981\u6709\u7684\uff0c\u4e07\u4e00\u5b9e\u73b0\u4e86\u5462\u3002\u3002\u3002<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (p == head &amp;amp;&amp;amp; tryAcquire(arg)) {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setHead(node);<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; p.next = null; \/\/ help GC<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u62ff\u5230\u9501\u8d44\u6e90\u540e\uff0c\u5219\u8be5node\u7ed3\u70b9\u5347\u7ea7\u505a\u5934\u7ed3\u70b9\uff0c\u4e14\u8bbe\u7f6e\u540e\u7ee7\u7ed3\u70b9\u6307\u9488\u4e3a\u7a7a\uff0c\u4fbf\u4e8eGC\u56de\u6536<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; failed = false;<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return interrupted;<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (shouldParkAfterFailedAcquire(p, node) &amp;amp;&amp;amp; \/\/ \u6839\u636e\u524d\u9a71\u7ed3\u70b9\u770b\u770b\u662f\u5426\u9700\u8981\u4f11\u606f\u4e00\u4f1a\u513f<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; parkAndCheckInterrupt()) \/\/ \u963b\u585e\u64cd\u4f5c\uff0c\u6b63\u5e38\u60c5\u51b5\u4e0b\uff0c\u83b7\u53d6\u4e0d\u5230\u9501\uff0c\u4ee3\u7801\u5c31\u5728\u8be5\u65b9\u6cd5\u505c\u6b62\u4e86\uff0c\u76f4\u5230\u88ab\u5524\u9192<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; interrupted = true;<br \/>\n<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \/\/ \u5982\u679c\u6267\u884c\u5230\u8fd9\u91cc\uff0c\u8bf4\u660e\u5c1d\u8bd5\u4f11\u606f\u5931\u8d25\u4e86\uff0c\u56e0\u4e3a\u662f\u81ea\u65cb\u64cd\u4f5c\uff0c\u6240\u4ee5\u8fd8\u4f1a\u518d\u6b21\u5faa\u73af\u7ee7\u7eed\u64cd\u4f5c\u5224\u65ad<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; } finally {<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (failed)<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; cancelAcquire(node);<br \/>\n&nbsp; &nbsp; &nbsp; &nbsp; }<br \/>\n&nbsp; &nbsp; }<\/div><\/td><\/tr><\/tbody><\/table><\/div>\n\n<\/pre>\n<p>\u8f6c\u8f7d\u8bf7\u6ce8\u660e\uff1a<a href=\"http:\/\/weitaoc.com\">\u8ff7\u8def\u7684\u8001\u9f20<\/a> &raquo; <a href=\"http:\/\/weitaoc.com\/?p=565\">AQS(AbstractQueuedSynchronized)-\u62bd\u8c61\u7684\u961f\u5217\u540c\u6b65\u5668<\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>\u62bd\u8c61\u7684\u961f\u5217\u5f0f\u7684\u540c\u6b65\u5668\uff0cAQS\u5b9a\u4e49\u4e86\u4e00\u5957\u591a\u7ebf\u7a0b\u8bbf\u95ee\u5171\u4eab\u8d44\u6e90\u7684\u540c\u6b65\u5668\u6846\u67b6\uff0c\u8bb8\u591a\u540c\u6b65\u7c7b\u5b9e\u73b0\u90fd\u4f9d\u8d56\u4e8e\u5b83\uff0c\u5982\u5e38\u7528\u7684ReentrantLock\/Semaphore\/CountDownLatch&#8230; ReentrantLock\u7684\u9501\u5b9e\u73b0\u662f\u57fa\u4e8eAbstrac [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[57],"tags":[59,62],"class_list":["post-565","post","type-post","status-publish","format-standard","hentry","category-java","tag-java","tag-62"],"views":8230,"_links":{"self":[{"href":"http:\/\/weitaoc.com\/index.php?rest_route=\/wp\/v2\/posts\/565","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/weitaoc.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/weitaoc.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/weitaoc.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/weitaoc.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=565"}],"version-history":[{"count":1,"href":"http:\/\/weitaoc.com\/index.php?rest_route=\/wp\/v2\/posts\/565\/revisions"}],"predecessor-version":[{"id":566,"href":"http:\/\/weitaoc.com\/index.php?rest_route=\/wp\/v2\/posts\/565\/revisions\/566"}],"wp:attachment":[{"href":"http:\/\/weitaoc.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=565"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/weitaoc.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=565"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/weitaoc.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=565"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}