{"id":600,"date":"2013-12-05T18:00:15","date_gmt":"2013-12-05T10:00:15","guid":{"rendered":"http:\/\/coderbee.net\/?p=600"},"modified":"2014-02-21T22:17:53","modified_gmt":"2014-02-21T14:17:53","slug":"juc-aqs","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/concurrent\/20131205\/600","title":{"rendered":"JUC AQS"},"content":{"rendered":"<p>AQS \u662f <code>java.util.concurrent.locks.AbstractQueuedSynchronizer<\/code> \u7c7b\u7684\u7b80\u79f0\uff0c\u5b83\u867d\u7136\u53ea\u662f\u4e00\u4e2a\u7c7b\uff0c\u4f46\u4e5f\u662f\u4e00\u4e2a\u5f3a\u5927\u7684\u6846\u67b6\uff0c\u76ee\u7684\u662f\u4e3a\u5b9e\u73b0\u4f9d\u8d56\u4e8e\u5148\u8fdb\u5148\u51fa (FIFO) \u7b49\u5f85\u961f\u5217\u7684\u963b\u585e\u9501\u548c\u76f8\u5173\u540c\u6b65\u5668\uff08\u4fe1\u53f7\u91cf\u3001\u4e8b\u4ef6\uff0c\u7b49\u7b49\uff09\u63d0\u4f9b\u4e00\u4e2a\u6846\u67b6\uff0c\u8fd9\u4e9b\u7c7b\u540c\u6b65\u5668\u90fd\u4f9d\u8d56\u5355\u4e2a\u539f\u5b50 int \u503c\u6765\u8868\u793a\u72b6\u6001\u3002<\/p>\n<p>AQS \u5b9e\u73b0\u4e86\u63a7\u5236\u540c\u6b65\u7684\u6846\u67b6\uff0c\u5e76\u5b9a\u4e49\u62bd\u8c61\u65b9\u6cd5\u7559\u7ed9<strong>\u5b50\u7c7b\u5b9a\u4e49\u54ea\u79cd\u72b6\u6001\u610f\u5473\u7740\u88ab\u83b7\u53d6\u6216\u88ab\u91ca\u653e<\/strong>\uff0c\u662f\u4e2a\u5178\u578b\u7684\u6a21\u677f\u65b9\u6cd5\u5b9e\u73b0\u3002<\/p>\n<h2>\u6982\u8ff0<\/h2>\n<p>\u540c\u6b65\u5668\u4e00\u822c\u5305\u542b\u4e24\u79cd\u65b9\u6cd5\uff0c\u4e00\u79cd\u662facquire\uff0c\u53e6\u4e00\u79cd\u662frelease\u3002acquire\u64cd\u4f5c\u963b\u585e\u8c03\u7528\u7684\u7ebf\u7a0b\uff0c\u76f4\u5230\u6216\u9664\u975e\u540c\u6b65\u72b6\u6001\u5141\u8bb8\u5176\u7ee7\u7eed\u6267\u884c\u3002\u800crelease\u64cd\u4f5c\u5219\u662f\u901a\u8fc7\u67d0\u79cd\u65b9\u5f0f\u6539\u53d8\u540c\u6b65\u72b6\u6001\uff0c\u4f7f\u5f97\u4e00\u6216\u591a\u4e2a\u88abacquire\u963b\u585e\u7684\u7ebf\u7a0b\u7ee7\u7eed\u6267\u884c\u3002<\/p>\n<h3>\u540c\u6b65\u5668\u7684\u57fa\u672c\u601d\u60f3<\/h3>\n<p>acquire\u64cd\u4f5c\uff1a<\/p>\n<pre>\n\/\/ \u5faa\u73af\u91cc\u4e0d\u65ad\u5c1d\u8bd5\uff0c\u5178\u578b\u7684\u5931\u8d25\u540e\u91cd\u8bd5\nwhile (synchronization state does not allow acquire) {\n     \/\/ \u540c\u6b65\u72b6\u6001\u4e0d\u5141\u8bb8\u83b7\u53d6\uff0c\u8fdb\u5165\u5faa\u73af\u4f53\uff0c\u4e5f\u5c31\u662f\u5931\u8d25\u540e\u7684\u5904\u7406\n     enqueue current thread if not already queued;     \/\/ \u5982\u679c\u5f53\u524d\u7ebf\u7a0b\u4e0d\u5728\u7b49\u5f85\u961f\u5217\u91cc\uff0c\u5219\u52a0\u5165\u7b49\u5f85\u961f\u5217\n     possibly block current thread;     \/\/ \u53ef\u80fd\u7684\u8bdd\uff0c\u963b\u585e\u5f53\u524d\u7ebf\u7a0b\n}\n\n\/\/ \u6267\u884c\u5230\u8fd9\u91cc\uff0c\u8bf4\u660e\u5df2\u7ecf\u6210\u529f\u83b7\u53d6\uff0c\u5982\u679c\u4e4b\u524d\u6709\u52a0\u5165\u961f\u5217\uff0c\u5219\u51fa\u961f\u5217\u3002\ndequeue current thread if it was queued; \n<\/pre>\n<p>release\u64cd\u4f5c\uff1a<\/p>\n<pre>\nupdate synchronization state;    \/\/  \u66f4\u65b0\u540c\u6b65\u72b6\u6001\nif (state may permit a blocked thread to acquire) \/\/ \u68c0\u67e5\u72b6\u6001\u662f\u5426\u5141\u8bb8\u4e00\u4e2a\u963b\u585e\u7ebf\u7a0b\u83b7\u53d6\n      unblock one or more queued threads;     \/\/ \u5141\u8bb8\uff0c\u5219\u5524\u9192\u540e\u7ee7\u7684\u4e00\u4e2a\u6216\u591a\u4e2a\u963b\u585e\u7ebf\u7a0b\u3002\n<\/pre>\n<p>\u4e3a\u4e86\u5b9e\u73b0\u4e0a\u8ff0\u64cd\u4f5c\uff0c\u9700\u8981\u4e0b\u9762\u4e09\u4e2a\u57fa\u672c\u7ec4\u4ef6\u7684\u76f8\u4e92\u534f\u4f5c\uff1a<\/p>\n<ul>\n<li>\u540c\u6b65\u72b6\u6001\u7684\u539f\u5b50\u6027\u7ba1\u7406\uff1a\u600e\u4e48\u5224\u65ad\u540c\u6b65\u5668\u662f\u5426\u53ef\u7528\u7684\uff1f\u600e\u4e48\u7ef4\u62a4\u539f\u5b50\u72b6\u6001\u4e0d\u4f1a\u51fa\u73b0\u975e\u6cd5\u72b6\u6001\uff1f\u600e\u4e48\u8ba9\u5176\u4ed6\u7ebf\u7a0b\u770b\u5230\u5f53\u524d\u7ebf\u7a0b\u5bf9\u72b6\u6001\u7684\u4fee\u6539\uff1f<\/li>\n<li>\u7ebf\u7a0b\u7684\u963b\u585e\u4e0e\u89e3\u9664\u963b\u585e\uff1a\u540c\u6b65\u5668\u4e0d\u53ef\u7528\u65f6\uff0c\u600e\u4e48\u6302\u8d77\u7ebf\u7a0b\uff1f\u540c\u6b65\u5668\u53ef\u7528\u65f6\uff0c\u600e\u4e48\u6062\u590d\u6302\u8d77\u7ebf\u7a0b\u7ee7\u7eed\u6267\u884c\uff1f<\/li>\n<li>\u961f\u5217\u7684\u7ba1\u7406\uff1a\u6709\u591a\u4e2a\u7ebf\u7a0b\u88ab\u963b\u585e\u65f6\uff0c\u600e\u4e48\u7ba1\u7406\u8fd9\u4e9b\u88ab\u963b\u585e\u7684\u7ebf\u7a0b\uff1f\u540c\u6b65\u5668\u53ef\u7528\u65f6\uff0c\u5e94\u8be5\u6062\u590d\u54ea\u4e2a\u963b\u585e\u7ebf\u7a0b\u7ee7\u7eed\u6267\u884c\uff1f\u600e\u4e48\u5904\u7406\u53d6\u6d88\u83b7\u53d6\u7684\u7ebf\u7a0b\uff1f<\/li>\n<\/ul>\n<p><!--more--><\/p>\n<h2>\u5b9e\u73b0<\/h2>\n<h3>\u540c\u6b65\u72b6\u6001\u7684\u539f\u5b50\u6027\u7ba1\u7406<\/h3>\n<p>AQS \u7684\u72b6\u6001\u662f\u901a\u8fc7\u4e00\u4e2a <code>int<\/code> \u7c7b\u578b\u7684\u6574\u6570\u6765\u8868\u793a\u7684\uff0c\u8fd9\u4e2a\u5b57\u6bb5\u662f\u7528<code>volatile<\/code>\u5173\u952e\u5b57\u4fee\u9970\u7684\uff0c\u8fd9\u6837\u901a\u8fc7\u7b80\u5355\u7684\u539f\u5b50\u8bfb\u5199\u5c31\u53ef\u4ee5\u8fbe\u5230\u5185\u5b58\u53ef\u89c6\u6027\uff0c\u51cf\u5c11\u4e86\u540c\u6b65\u7684\u9700\u6c42\u3002\u5b50\u7c7b\u53ef\u4ee5\u83b7\u53d6\u548c\u8bbe\u7f6e\u72b6\u6001\u7684\u503c\uff0c\u901a\u8fc7\u5b9a\u4e49\u72b6\u6001\u7684\u503c\u6765\u8868\u793a AQS \u5bf9\u8c61\u662f\u5426\u88ab\u83b7\u53d6\u6216\u88ab\u91ca\u653e\u3002<\/p>\n<h3>\u7ebf\u7a0b\u7684\u963b\u585e\u4e0e\u89e3\u9664\u963b\u585e<\/h3>\n<p>JDK5\u65b0\u589e\u4e86\u4e00\u4e2a\u7c7b <code>java.util.concurrent.locks.LockSupport<\/code> \u7528\u6765\u652f\u6301\u521b\u5efa\u9501\u548c\u5176\u4ed6\u540c\u6b65\u7c7b\u9700\u8981\u7684\u57fa\u672c\u7ebf\u7a0b\u963b\u585e\u3001\u89e3\u9664\u963b\u585e\u539f\u8bed\u3002<\/p>\n<p>\u8fd9\u4e2a\u7c7b\u6700\u4e3b\u8981\u7684\u529f\u80fd\u6709\u4e24\u4e2a\uff1a<\/p>\n<ul>\n<li>park\uff1a\u628a\u7ebf\u7a0b\u963b\u585e\u3002<\/li>\n<li>unpark\uff1a\u8ba9\u7ebf\u7a0b\u6062\u590d\u6267\u884c\u3002<\/li>\n<\/ul>\n<p>\u6b64\u7c7b\u4ee5\u53ca\u6bcf\u4e2a\u4f7f\u7528\u5b83\u7684\u7ebf\u7a0b\u4e0e\u4e00\u4e2a\u8bb8\u53ef\u5173\u8054\u3002\u5982\u679c\u8be5\u8bb8\u53ef\u53ef\u7528\uff0c\u5e76\u4e14\u53ef\u5728\u8fdb\u7a0b\u4e2d\u4f7f\u7528\uff0c\u5219\u8c03\u7528 park \u5c06\u7acb\u5373\u8fd4\u56de\uff1b\u5426\u5219\u53ef\u80fd \u963b\u585e\u3002\u5982\u679c\u8bb8\u53ef\u5c1a\u4e0d\u53ef\u7528\uff0c\u5219\u53ef\u4ee5\u8c03\u7528 unpark \u4f7f\u5176\u53ef\u7528\u3002\uff08\u8bb8\u53ef\u4e0d\u80fd\u7d2f\u79ef\uff0c\u5e76\u4e14\u6700\u591a\u53ea\u80fd\u6709\u4e00\u4e2a\u8bb8\u53ef\u3002\uff09<\/p>\n<p>\u5176API\u7684\u6587\u6863\u5982\u4e0b\uff1a<\/p>\n<pre>\nstatic Object getBlocker(Thread t)\n          \u8fd4\u56de\u63d0\u4f9b\u7ed9\u6700\u8fd1\u4e00\u6b21\u5c1a\u672a\u89e3\u9664\u963b\u585e\u7684 park \u65b9\u6cd5\u8c03\u7528\u7684 blocker \u5bf9\u8c61\uff0c\u5982\u679c\u8be5\u8c03\u7528\u4e0d\u53d7\u963b\u585e\uff0c\u5219\u8fd4\u56de null\u3002\nstatic void park()\n          \u4e3a\u4e86\u7ebf\u7a0b\u8c03\u5ea6\uff0c\u7981\u7528\u5f53\u524d\u7ebf\u7a0b\uff0c\u9664\u975e\u8bb8\u53ef\u53ef\u7528\u3002\nstatic void park(Object blocker)\n          \u4e3a\u4e86\u7ebf\u7a0b\u8c03\u5ea6\uff0c\u5728\u8bb8\u53ef\u53ef\u7528\u4e4b\u524d\u7981\u7528\u5f53\u524d\u7ebf\u7a0b\u3002\nstatic void parkNanos(long nanos)\n          \u4e3a\u4e86\u7ebf\u7a0b\u8c03\u5ea6\u7981\u7528\u5f53\u524d\u7ebf\u7a0b\uff0c\u6700\u591a\u7b49\u5f85\u6307\u5b9a\u7684\u7b49\u5f85\u65f6\u95f4\uff0c\u9664\u975e\u8bb8\u53ef\u53ef\u7528\u3002\nstatic void parkNanos(Object blocker, long nanos)\n          \u4e3a\u4e86\u7ebf\u7a0b\u8c03\u5ea6\uff0c\u5728\u8bb8\u53ef\u53ef\u7528\u524d\u7981\u7528\u5f53\u524d\u7ebf\u7a0b\uff0c\u5e76\u6700\u591a\u7b49\u5f85\u6307\u5b9a\u7684\u7b49\u5f85\u65f6\u95f4\u3002\nstatic void parkUntil(long deadline)\n          \u4e3a\u4e86\u7ebf\u7a0b\u8c03\u5ea6\uff0c\u5728\u6307\u5b9a\u7684\u65f6\u9650\u524d\u7981\u7528\u5f53\u524d\u7ebf\u7a0b\uff0c\u9664\u975e\u8bb8\u53ef\u53ef\u7528\u3002\nstatic void parkUntil(Object blocker, long deadline)\n          \u4e3a\u4e86\u7ebf\u7a0b\u8c03\u5ea6\uff0c\u5728\u6307\u5b9a\u7684\u65f6\u9650\u524d\u7981\u7528\u5f53\u524d\u7ebf\u7a0b\uff0c\u9664\u975e\u8bb8\u53ef\u53ef\u7528\u3002\nstatic void unpark(Thread thread)\n          \u5982\u679c\u7ed9\u5b9a\u7ebf\u7a0b\u7684\u8bb8\u53ef\u5c1a\u4e0d\u53ef\u7528\uff0c\u5219\u4f7f\u5176\u53ef\u7528\u3002\n<\/pre>\n<h3>\u961f\u5217\u7ba1\u7406<\/h3>\n<p><strong>\u6ce8\uff1a\u7ffb\u8bd1\u81eaJDK1.7.10 AQS \u5185\u90e8\u9759\u6001\u7c7bNode\u6e90\u7801\u7684DOC\u3002<\/strong><\/p>\n<p>\u7b49\u5f85\u961f\u5217\u662fCLH\u9501\u961f\u5217\u7684\u4e00\u79cd\u53d8\u4f53\u3002CLH\u9501\uff08\u53ef\u53c2\u8003\uff1a<a href=\"http:\/\/coderbee.net\/index.php\/java\/20131115\/577\">CLH\u9501<\/a>\uff09\u901a\u5e38\u7528\u4e8e\u81ea\u65cb\u9501\uff0c\u6211\u4eec\u53cd\u800c\u7528\u4e8e\u963b\u585e\u540c\u6b65\u5668\uff0c\u4f46\u4f7f\u7528\u76f8\u540c\u7684\u57fa\u672c\u7b56\u7565\uff1a\u5728\uff08\u7ebf\u7a0b\uff09\u5b83\u81ea\u5df1\u7ed3\u70b9\u7684\u524d\u9a71\u6301\u6709\u5173\u4e8e\u7ebf\u7a0b\u7684\u4e00\u4e9b\u63a7\u5236\u4fe1\u606f\u3002\u6bcf\u4e2a\u7ed3\u70b9\u7684 &#8220;status&#8221; \u5b57\u6bb5\u8ddf\u8e2a\u4e00\u4e2a\u7ebf\u7a0b\u662f\u5426\u5e94\u8be5\u963b\u585e\u3002\u4e00\u4e2a\u7ed3\u70b9\u5728\u5b83\u7684\u524d\u9a71\u91ca\u653e\u65f6\u88ab\u901a\u77e5\u3002\u961f\u5217\u7684\u6bcf\u4e2a\u7ed3\u70b9\u4f5c\u4e3a\u4e00\u4e2a\u7279\u5b9a\u901a\u77e5\u98ce\u683c\uff08specific-notification-style\uff09\u7684\u76d1\u89c6\u5668\u670d\u52a1\uff0c\u6301\u6709\u5355\u4e00\u7b49\u5f85\u7ebf\u7a0b\u3002&#8221;status&#8221; \u5b57\u6bb5\u4e0d\u63a7\u5236\u7ebf\u7a0b\u662f\u5426\u6388\u4e88\u3002\u4e00\u4e2a\u7ebf\u7a0b\u53ef\u80fd\u5c1d\u8bd5\u53bb\u83b7\u53d6\u5982\u679c\u5b83\u662f\u7b2c\u4e00\u4e2a\u8fdb\u5165\u961f\u5217\uff0c\u4f46\u6210\u4e3a\u7b2c\u4e00\u4e2a\u4e0d\u4fdd\u8bc1\u5c31\u6210\u529f\uff1b\u5b83\u53ea\u662f\u83b7\u5f97\u6743\u5229\u53bb\u7ade\u4e89\uff0c\u6240\u4ee5\u5f53\u524d\u91ca\u653e\u7684\u7ade\u4e89\u8005\u7ebf\u7a0b\u53ef\u80fd\u9700\u8981\u518d\u6b21\u7b49\u5f85\uff08\u6ce8\uff1a\u8fd9\u662f\u516c\u5e73\u6027\u7684\u95ee\u9898\uff0c\u5b50\u7c7b\u7684\u5b9e\u73b0\u53ef\u4ee5\u8fdb\u884c\u63a7\u5236\uff09\u3002<\/p>\n<p>\u4e3a\u4e86\u8fdb\u5165CLH\u9501\u961f\u5217\uff0c\u4f60\u53ea\u9700\u8981\u539f\u5b50\u5730\u628a\u5b83\u4f5c\u4e3a\u4e00\u4e2a\u65b0\u7684\u5c3e\u7ed3\u70b9\u62fc\u63a5\uff1b\u4e3a\u4e86\u51fa\u961f\u5217\uff0c\u4f60\u53ea\u9700\u8981\u8bbe\u7f6e &#8220;head&#8221; \u5b57\u6bb5\u3002<\/p>\n<pre>\n      +------+  prev +-----+       +-----+\n head |      | <---- |     | <---- |     |  tail\n      +------+         +-----+       +-----+\n<\/pre>\n<p>\u63d2\u5165\u5230CLH\u961f\u5217\u53ea\u8981\u6c42\u5728 \"tail\" \u4e0a\u8fdb\u884c\u4ec5\u4ec5\u4e00\u4e2a\u539f\u5b50\u64cd\u4f5c\uff0c\u6240\u4ee5\u90a3\u5c31\u6709\u4e00\u4e2a\u4ece unqueued \u5230 queued \u5212\u754c\u7684\u539f\u5b50\u70b9\u3002\u7c7b\u4f3c\u5730\uff0c\u51fa\u961f\u5217\u5305\u542b\u4ec5\u66f4\u65b0 \"head\"\u3002\u7136\u800c\uff0c\u9700\u8981\u989d\u5916\u4e00\u70b9\u5de5\u4f5c\u7528\u4e8e\u7ed3\u70b9\u786e\u8ba4\u5b83\u4eec\u7684\u540e\u7ee7\u662f\u8c01\uff0c\u90e8\u5206\u5730\u4e3a\u4e86\u5904\u7406\u53ef\u80fd\u7684\u7531\u4e8e\u8d85\u65f6\u548c\u4e2d\u65ad\u5bfc\u81f4\u7684\u53d6\u6d88\u3002<\/p>\n<p>\"prev\" \u8fde\u63a5\uff08\u539f\u59cbCLH\u9501\u6ca1\u6709\u4f7f\u7528\uff09\u4e3b\u8981\u662f\u51fa\u4e8e\u5904\u7406\u53d6\u6d88\u7684\u9700\u6c42\u3002\u5982\u679c\u4e00\u4e2a\u7ed3\u70b9\u88ab\u53d6\u6d88\uff0c\u5b83\u7684\u540e\u7ee7\uff08\u4e00\u822c\uff09\u662f\u91cd\u65b0\u8fde\u63a5\u5230\u4e00\u4e2a\u975e\u53d6\u6d88\u7684\u524d\u9a71\u3002\u5bf9\u4e8e\u81ea\u65cb\u9501\u5f62\u5f0f\u4e0b\u7684\u7c7b\u4f3c\u7ed3\u6784\u89c1\uff1a<a href=\"http:\/\/www.cs.rochester.edu\/u\/scott\/synchronization\/\">http:\/\/www.cs.rochester.edu\/u\/scott\/synchronization\/<\/a><\/p>\n<p>\u6211\u4eec\u4f7f\u7528 \"next\" \u8fde\u63a5\u6765\u5b9e\u73b0\u963b\u585e\u7ed3\u6784\u3002\u6bcf\u4e2a\u7ed3\u70b9\u7684\u7ebf\u7a0bid\u662f\u4fdd\u5b58\u5728\u5b83\u81ea\u5df1\u7684\u7ed3\u70b9\u5185\uff0c\u8fd9\u6837\u4e00\u4e2a\u524d\u9a71\u901a\u77e5\u4e0b\u4e00\u4e2a\u7ed3\u70b9\u53bb\u5524\u9192\u90a3\u4e2a\u901a\u8fc7\u904d\u5386 \"next\" \u8fde\u63a5\u51b3\u5b9a\u7684\u7ebf\u7a0b\u3002\u51b3\u5b9a\u540e\u7ee7\u7684\u8fc7\u7a0b\u5fc5\u987b\u907f\u514d\u4e0e\u65b0\u5165\u961f\u7ed3\u70b9\u7ade\u4e89\u8bbe\u7f6e\u5b83\u7684\u524d\u9a71\u7684 \"next\" \u5b57\u6bb5\u3002\u8fd9\u662f\u8fd9\u6837\u89e3\u51b3\u7684\uff1a\u5f53\u4e00\u4e2a\u7ed3\u70b9\u7684\u540e\u7ee7\u662f\u7a7a\u65f6\uff0c\u4ece\u539f\u5b50\u5730\u66f4\u65b0\u7684 \"tail\" \u5411\u540e\u68c0\u67e5\u3002\uff08\u6362\u4e00\u79cd\u8bf4\u6cd5\uff0c\"next\" \u8fde\u63a5\u662f\u4f18\u5316\u7684\uff0c\u8fd9\u6837\u6211\u4eec\u4e00\u822c\u4e0d\u9700\u8981\u5411\u540e\u626b\u63cf\u3002\uff09\uff08\u6ce8\uff1a\u8fd9\u4e5f\u5c31\u662f\u8bf4\uff0c\u4ece \"tail\" \u5411\u540e\u68c0\u67e5\u603b\u662f\u5b89\u5168\u7684\uff0c\u4f46\u53ef\u80fd\u9700\u8981\u8fdb\u884c\u6bd4\u8f83\u591a\u7684\u904d\u5386\uff0c\u6240\u4ee5\u5f15\u5165 \"next\" \u6765\u8fdb\u884c\u4f18\u5316\uff0c\u56e0\u4e3a\u901a\u77e5\u662f\u4ece\u5934\u90e8\u5f00\u59cb\uff0c\u63d2\u5165\u662f\u5728\u5c3e\u90e8\u8fdb\u884c\uff0c\u6240\u4ee5\u4e24\u8005\u7684\u7ade\u4e89\u4e00\u822c\u662f\u4e0d\u591a\u7684\uff0c\u5f53\u51fa\u73b0\u7ade\u4e89\uff0c\u5373\u68c0\u6d4b\u5230\u7ed3\u70b9\u7684\u540e\u7ee7\u662f\u7a7a\u65f6\uff0c\u518d\u4ece \"tail\" \u5411\u540e\u68c0\u67e5\u3002\uff09<\/p>\n<p>\u53d6\u6d88\u5f15\u5165\u4e00\u4e9b\u4fdd\u5b88\u5230\u57fa\u672c\u7b97\u6cd5\u3002\u56e0\u4e3a\u6211\u4eec\u5fc5\u987b\u8f6e\u8be2\u5176\u4ed6\u7ed3\u70b9\u7684\u53d6\u6d88\uff0c\u6211\u4eec\u53ef\u4ee5\u9519\u8fc7\u901a\u77e5\uff0c\u4e0d\u7ba1\u88ab\u53d6\u6d88\u7ed3\u70b9\u662f\u5728\u524d\u6216\u5728\u540e\u3002\u8fd9\u662f\u901a\u8fc7\u5728\u53d6\u6d88\u65f6\u603b\u662funparking\u540e\u7ee7\u8282\u70b9\u6765\u5904\u7406\u7684\uff0c\u5141\u8bb8\u5b83\u4eec\u7a33\u5b9a\u5728\u4e00\u4e2a\u65b0\u7684\u524d\u9a71\uff0c\u9664\u975e\u6211\u4eec\u80fd\u591f\u8bc6\u522b\u4e00\u4e2a\u627f\u62c5\u8fd9\u79cd\u8d23\u4efb\u7684\u524d\u9a71\uff08\u6ce8\uff1a\u72b6\u6001\u662f Node.SIGNAL \u7684\uff09\u3002<\/p>\n<p>CLH\u961f\u5217\u9700\u8981\u4e00\u4e2a\u865a\u62df\u5934\u7ed3\u70b9\u4f5c\u4e3a\u5f00\u59cb\u3002\u4f46\u6211\u4eec\u4e0d\u5728\u6784\u9020\u65f6\u521b\u5efa\u5b83\uff0c\u5982\u679c\u4ece\u6765\u6ca1\u6709\u7ade\u4e89\uff0c\u8fd9\u662f\u6d6a\u8d39\u7cbe\u529b\u3002\u5f53\u7b2c\u4e00\u6b21\u7ade\u4e89\u51fa\u73b0\u65f6\uff0c\u6784\u9020\u8fd9\u4e2a\u7ed3\u70b9\u5e76\u8bbe\u7f6e <code>head<\/code> \u548c <code>tail<\/code> \u6307\u9488\u3002\uff08\u6ce8\uff1a\u961f\u5217\u91cc\u7684\u7ed3\u70b9\u5c1d\u8bd5\u83b7\u53d6\u524d\u4e5f\u9996\u5148\u5224\u65ad\u81ea\u5df1\u7684\u524d\u9a71\u662f\u4e0d\u662f\u5934\u7ed3\u70b9\u3002\uff09<\/p>\n<p>\u5728\u4e00\u4e2aConditions\u4e0a\u7b49\u5f85\u7684\u7ebf\u7a0b\u4f7f\u7528\u76f8\u540c\u7684\u7ed3\u70b9\uff0c\u4f46\u7528\u53e6\u5916\u7684\u4e00\u6761\u94fe\u63a5\u3002Conditions\u53ea\u9700\u8981\u4ee5\u7b80\u5355\u961f\u5217\u8fde\u63a5\u7ed3\u70b9\uff0c\u56e0\u4e3a\u5b83\u4eec\u53ea\u5728\u72ec\u5360\u6301\u6709\u65f6\u8bbf\u95ee\u3002\u6839\u636eawait\uff0c\u7ed3\u70b9\u88ab\u63d2\u5165\u5230\u4e00\u4e2a\u6761\u4ef6\u961f\u5217\u3002\u6839\u636esignal\uff0c\u7ed3\u70b9\u88ab\u8f6c\u6362\u5230\u4e3b\u961f\u5217\u3002\u4e00\u4e2a \"status\" \u5b57\u6bb5\u7684\u7279\u6b8a\u503c\uff08Node.CONDITION\uff09\u7528\u4e8e\u6807\u8bb0\u7ed3\u70b9\u5728\u54ea\u4e2a\u961f\u5217\u3002<\/p>\n<h2>AQS \u4f7f\u7528<\/h2>\n<p>AQS\u5b9e\u73b0\u4e86\u6a21\u677f\u65b9\u6cd5\uff0c\u4f7f\u7528\u65f6\u5177\u4f53\u5b9e\u73b0\u7684\u5b50\u7c7b\u53ea\u9700\u8981\u6839\u636e\u9700\u8981\u5b9e\u73b0\u4e0b\u9762\u7684\u65b9\u6cd5\uff1a<\/p>\n<pre><code class=\"java\">tryAcquire(int)      \/\/ \u8bd5\u56fe\u5728\u72ec\u5360\u6a21\u5f0f\u4e0b\u83b7\u53d6\u5bf9\u8c61\u72b6\u6001\u3002\u6b64\u65b9\u6cd5\u5e94\u8be5\u67e5\u8be2\u662f\u5426\u5141\u8bb8\u5b83\u5728\u72ec\u5360\u6a21\u5f0f\u4e0b\u83b7\u53d6\u5bf9\u8c61\u72b6\u6001\uff0c\u5982\u679c\u5141\u8bb8\uff0c\u5219\u83b7\u53d6\u5b83\u3002\ntryRelease(int)       \/\/ \u8bd5\u56fe\u8bbe\u7f6e\u72b6\u6001\u6765\u53cd\u6620\u72ec\u5360\u6a21\u5f0f\u4e0b\u7684\u4e00\u4e2a\u91ca\u653e\u3002\ntryAcquireShared(int)       \/\/ \u8bd5\u56fe\u5728\u5171\u4eab\u6a21\u5f0f\u4e0b\u83b7\u53d6\u5bf9\u8c61\u72b6\u6001\u3002\u6b64\u65b9\u6cd5\u5e94\u8be5\u67e5\u8be2\u662f\u5426\u5141\u8bb8\u5b83\u5728\u5171\u4eab\u6a21\u5f0f\u4e0b\u83b7\u53d6\u5bf9\u8c61\u72b6\u6001\uff0c\u5982\u679c\u5141\u8bb8\uff0c\u5219\u83b7\u53d6\u5b83\u3002\ntryReleaseShared(int)       \/\/ \u8bd5\u56fe\u8bbe\u7f6e\u72b6\u6001\u6765\u53cd\u6620\u5171\u4eab\u6a21\u5f0f\u4e0b\u7684\u4e00\u4e2a\u91ca\u653e\u3002\nisHeldExclusively()      \/\/ \u5982\u679c\u5bf9\u4e8e\u5f53\u524d\uff08\u6b63\u8c03\u7528\u7684\uff09\u7ebf\u7a0b\uff0c\u540c\u6b65\u662f\u4ee5\u72ec\u5360\u65b9\u5f0f\u8fdb\u884c\u7684\uff0c\u5219\u8fd4\u56de true\u3002\u6b64\u65b9\u6cd5\u662f\u5728\u6bcf\u6b21\u8c03\u7528\u975e\u7b49\u5f85 AbstractQueuedSynchronizer.ConditionObject \u65b9\u6cd5\u65f6\u8c03\u7528\u7684\u3002\uff08\u7b49\u5f85\u65b9\u6cd5\u5219\u8c03\u7528 release(int)\u3002\uff09\n<\/code><\/pre>\n<p>\u8fd9\u4e9btry&#42;\u65b9\u6cd5\u7684\u8fd4\u56de\u503c\u90fd\u8868\u793a\u662f\u5426\u6210\u529f\u83b7\u53d6\u4e14\u662f\u5426\u5141\u8bb8\u7ee7\u7eed\u83b7\u53d6\u3002\u5bf9\u4e8e\u72ec\u5360\u6a21\u5f0f\u4e0b\uff0c\u5982\u679c\u6210\u529f\u83b7\u53d6\uff0c\u603b\u662f\u76f4\u63a5\u8fd4\u56de\u4e86\uff1b\u800c\u5728\u5171\u4eab\u6a21\u5f0f\u4e0b\uff0c\u5982\u679c\u6210\u529f\u83b7\u53d6\u4e86\uff0c\u8fd8\u8981\u5224\u65ad\u662f\u5426\u5141\u8bb8\u7ee7\u7eed\u83b7\u53d6\uff0c\u5982\u679c\u5141\u8bb8\u7ee7\u7eed\u83b7\u53d6\uff0c\u5219\u8981\u5524\u9192\u540e\u7ee7\u8fdb\u884c\u83b7\u53d6\u3002<\/p>\n<p>\u8fd9\u4e2a\u5b9e\u73b0\u7c7b\u5e94\u8be5\u4f5c\u4e3a\u5185\u90e8\u7c7b\u4f7f\u7528\uff0c\u907f\u514d\u7528\u6237\u901a\u8fc7\u516c\u6709\u65b9\u6cd5\u6539\u53d8\u4e86\u72b6\u6001\u3002\u8fd9\u4e9b\u65b9\u6cd5\u7684\u5b9e\u73b0\u5fc5\u987b\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u901a\u5e38\u5e94\u8be5\u5f88\u77ed\u5e76\u4e14\u4e0d\u88ab\u963b\u585e\u3002<\/p>\n<p>\u4e0b\u9762\u662f\u4e00\u4e2a\u9501\u7684\u5b9e\u73b0\u793a\u4f8b\uff1a<\/p>\n<pre><code class=\"java\">class Mutex {\n     class Sync extends AbstractQueuedSynchronizer {\n          public boolean tryAcquire(int ignore) {\n               return compareAndSetState(0, 1);\n          }\n          public boolean tryRelease(int ignore) {\n               setState(0);\n               return true;\n          }\n     }\n     private final Sync sync = new Sync();\n     public void lock() { sync.acquire(0); }\n     public void unlock() { sync.release(0); }\n}\n<\/code><\/pre>\n<h2>\u4e00\u70b9\u8bf4\u660e<\/h2>\n<p>AQS \u7684\u5b9e\u73b0\u662f\u5efa\u7acb\u5728Java\u5185\u5b58\u6a21\u578b\u7684\u57fa\u7840\u4e0a\u7684\uff0c\u7279\u522b\u662f volatile \u53d8\u91cf\u7684\u5185\u5b58\u8bed\u4e49\u53ca\u5176 happens-before \u89c4\u5219\uff0c\u540e\u7eed\u7684\u6587\u7ae0\u4f1a\u5bf9 AQS \u7684\u6e90\u7801\u8fdb\u884c\u6ce8\u91ca\u3001\u5206\u6790\uff0c\u5982\u679c\u60f3\u660e\u767d\u4e3a\u4ec0\u4e48\u90a3\u4e48\u505a\uff0c\u5efa\u8bae\u5148\u9605\u8bfb <a href=\"http:\/\/coderbee.net\/index.php\/concurrent\/20131219\/650\">Java\u5185\u5b58\u6a21\u578b<\/a> \u548c <a href=\"http:\/\/coderbee.net\/index.php\/concurrent\/20131211\/624\">\u5185\u5b58\u5c4f\u969c<\/a> \u8fd9\u4e24\u7bc7\u6587\u7ae0\u3002<\/p>\n<h2>\u53c2\u8003\u8d44\u6599<\/h2>\n<ul>\n<li>AQS\u7684\u8bba\u6587\uff1a<a href=\"http:\/\/gee.cs.oswego.edu\/dl\/papers\/aqs.pdf\">http:\/\/gee.cs.oswego.edu\/dl\/papers\/aqs.pdf<\/a><\/li>\n<li>\u8bba\u6587\u7ffb\u8bd1\uff1a<a href=\"http:\/\/my.oschina.net\/clopopo\/blog\/121920\">http:\/\/my.oschina.net\/clopopo\/blog\/121920<\/a><\/li>\n<\/ul>\n<hr\/>\n<p>\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u5fae\u4fe1\u516c\u4f17\u53f7: <strong>coderbee\u7b14\u8bb0<\/strong>\uff0c\u53ef\u4ee5\u66f4\u53ca\u65f6\u56de\u590d\u4f60\u7684\u8ba8\u8bba\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"258\" height=\"258\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/coderbee-note.jpg\" class=\"alignnone size-full wp-image-1707\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>AQS \u662f java.util.concurrent.locks.Abstrac &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/concurrent\/20131205\/600\">\u7ee7\u7eed\u9605\u8bfb <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[121],"tags":[122,231,110,123],"_links":{"self":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/600"}],"collection":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/comments?post=600"}],"version-history":[{"count":10,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/600\/revisions"}],"predecessor-version":[{"id":812,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/600\/revisions\/812"}],"wp:attachment":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/media?parent=600"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/categories?post=600"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/tags?post=600"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}