{"id":735,"date":"2020-06-24T13:10:29","date_gmt":"2020-06-24T05:10:29","guid":{"rendered":"https:\/\/www.zeroheart.xyz\/wordpress\/?p=735"},"modified":"2022-02-07T15:13:40","modified_gmt":"2022-02-07T07:13:40","slug":"aqs%e7%9a%84%e5%88%9d%e6%ad%a5%e7%90%86%e8%a7%a3","status":"publish","type":"post","link":"https:\/\/www.zeroheart.xyz\/wordpress\/?p=735","title":{"rendered":"AQS\u7684\u521d\u6b65\u7406\u89e3"},"content":{"rendered":"\n<p>AQS-\u62bd\u8c61\u961f\u5217\u5f0f\u540c\u6b65\u5668\uff0c\u5e38\u7528\u7684\u540c\u6b65\u7c7b\uff0cReentrantLock\u3001CountDownLatch\u3001Semaphore\u3001CyclicBarrier\u7b49\u90fd\u7528\u5230AQS<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">\u7531\u4e00\u4e2avolatile\u7684state\uff0c\u548c\u4e00\u4e2aFIFO\u7684\u961f\u5217\u7ec4\u6210<br><br>\u8fd9\u91cc<code>volatile<\/code>\u80fd\u591f\u4fdd\u8bc1\u591a\u7ebf\u7a0b\u4e0b\u7684\u53ef\u89c1\u6027\uff0c\u5f53<code>state=1<\/code>\u5219\u4ee3\u8868\u5f53\u524d\u5bf9\u8c61\u9501\u5df2\u7ecf\u88ab\u5360\u6709\uff0c\u5176\u4ed6\u7ebf\u7a0b\u6765\u52a0\u9501\u65f6\u5219\u4f1a\u5931\u8d25\uff0c\u52a0\u9501\u5931\u8d25\u7684\u7ebf\u7a0b\u4f1a\u88ab\u653e\u5165\u4e00\u4e2a<code>FIFO<\/code>\u7684\u53cc\u5411\u7b49\u5f85\u961f\u5217\u4e2d\uff0c\u6bd4\u5217\u4f1a\u88ab<code>UNSAFE.park()<\/code>\u64cd\u4f5c\u6302\u8d77\uff0c\u7b49\u5f85\u5176\u4ed6\u83b7\u53d6\u9501\u7684\u7ebf\u7a0b\u91ca\u653e\u9501\u624d\u80fd\u591f\u88ab\u5524\u9192\u3002<br><br>state\u72b6\u6001\u4fee\u6539\u662f\u901a\u8fc7cas\u5b9e\u73b0\u7684\u3002<br><br>\u4e0b\u56fe\u53ef\u4ee5\u7b80\u5355\u6982\u62ec<\/pre>\n\n\n\n<figure class=\"wp-block-image\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"450\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2020\/06\/image-5-1024x450.png\" alt=\"\" class=\"wp-image-738\" srcset=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2020\/06\/image-5-1024x450.png 1024w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2020\/06\/image-5-300x132.png 300w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2020\/06\/image-5-768x338.png 768w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2020\/06\/image-5-1200x527.png 1200w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2020\/06\/image-5.png 1372w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<p>\u975e\u516c\u5e73\u7684\u8bbe\u7f6e\u4e0b\uff0c\u5f53\u7ebf\u7a0b\u7ade\u4e89\u7684\u65f6\u5019\uff0c\u9996\u5148\u4fee\u6539state\u4e3a1\u7684\u7ebf\u7a0b\u83b7\u5f97\u9501\uff0c\u5e76\u628ahead\u6307\u5411\u8be5\u7ebf\u7a0b\uff0csetExclusiveOwnerThread\u4e3a\u5f53\u524d\u7ebf\u7a0b\uff0c\u5728\u53ef\u91cd\u5165\u7684\u60c5\u51b5\u4e0b\uff0c\u6bcf\u6b21\u91cd\u5165state+1\u3002\u9501\u91ca\u653e\u7684\u65f6\u5019\uff0c\u4f1a\u5524\u9192head\u8282\u70b9\u7684\u540e\u7eed\u7ebf\u7a0b\uff0c\u5f00\u59cb\u7ade\u4e89\u9501\uff0c\u6210\u529f\u540e\u4f1a\u628a\u539f\u6765\u7684\u7ebf\u7a0bnode\u8282\u70b9\u4ecehead\u548c\u540e\u7eed\u8282\u70b9\u65ad\u5f00\uff0c\u7b49\u5f85\u5783\u573e\u56de\u6536\u3002\u4ee5\u4e0a\u662f\u6ca1\u6709\u5176\u4ed6\u65b0\u7684\u7ade\u4e89\u7684\u60c5\u51b5\uff0c\u5982\u679c\u7b49\u5f85\u8282\u70b9\u88ab\u5524\u9192\uff0c\u540c\u65f6\u4e5f\u6709\u65b0\u7684\u7ebf\u7a0b\u52a0\u5165\u7ade\u4e89\uff0c\u90a3\u4e48\u6b64\u65f6\u83b7\u5f97\u9501\u7684\u4e0d\u4e00\u5b9a\u662f\u6392\u5728\u524d\u9762\u7684\u8282\u70b9\u3002\u8fd9\u662f\u975e\u516c\u5e73\u9501\u7684\u5b9e\u73b0\u3002<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">\u516c\u5e73\u9501\u7684\u8bbe\u7f6e\u4e0b\uff0c\u5982\u679c\u961f\u5217\u4e2d\u6709\u5143\u7d20\u7b49\u5f85\uff0c\u90a3\u4e48\u65b0\u7684\u7ebf\u7a0b\u76f4\u63a5\u8fdb\u5165\u7b49\u5f85\u961f\u5217\u7684\u5c3e\u90e8\uff0c\u5177\u4f53\u7684\u533a\u522b\u5c31\u5728\u4e0etryAcquire()\u65b9\u6cd5\u52a0\u4e86\u5224\u65ad<br><br>if&nbsp;(!hasQueuedPredecessors()&nbsp;&amp;&amp;<br>    compareAndSetState(0, acquires)) {<br>    setExclusiveOwnerThread(current);<br>    return true;<br>}<br><br>\u5982\u679chasQueuedPredecessors()\u8fd4\u56defalse\uff0c\u8868\u793a\u6ca1\u6709\u7b49\u5f85\u7ebf\u7a0b\uff0c\u90a3\u4e48\u624d\u53c2\u4e0e\u7ade\u4e89\u3002<br><br>public&nbsp;final&nbsp;boolean&nbsp;hasQueuedPredecessors()&nbsp;{<br>&nbsp;&nbsp;&nbsp;&nbsp;Node&nbsp;t&nbsp;=&nbsp;tail;<br>&nbsp;&nbsp;&nbsp;&nbsp;Node&nbsp;h&nbsp;=&nbsp;head;<br>&nbsp;&nbsp;&nbsp;&nbsp;Node&nbsp;s;<br> &nbsp;&nbsp;&nbsp;return h != t &amp;&amp;((s = h.next) == null || s.thread != Thread.currentThread());<br>}<br><\/pre>\n\n\n\n<pre class=\"wp-block-preformatted\">\u4e4b\u524d\u5199\u8fc7\u4e00\u7bc7\uff0c\u8fd9\u6b21\u52a0\u4e86\u70b9\u56fe\uff0c\u65b9\u4fbf\u7406\u89e3\u3002<br><a href=\"https:\/\/www.zeroheart.xyz\/wordpress\/?p=283\">https:\/\/www.zeroheart.xyz\/wordpress\/?p=283<\/a><a href=\"https:\/\/www.zeroheart.xyz\/wordpress\/?p=283\"><\/a><\/pre>\n\n\n\n<pre class=\"wp-block-preformatted\">\u66f4\u591a\u7684\u7ec6\u8282\uff0c\u53ef\u4ee5\u53c2\u8003\u4e00\u4e0b\u8fd9\u7bc7<br><a href=\"https:\/\/mp.weixin.qq.com\/s\/trsjgUFRrz40Simq2VKxTA\">https:\/\/mp.weixin.qq.com\/s\/trsjgUFRrz40Simq2VKxTA <\/a><br><\/pre>\n\n\n\n<p>AQS\u4e2d\u7684\u7b49\u5f85\u5524\u9192\uff0c\u662f\u7528locksupport\u6765\u5b9e\u73b0\u7684\uff0cpark-unpark\u66ff\u4ee3\u4e86obj\u7684wait-notify\u673a\u5236<\/p>\n\n\n\n<p><strong><span class=\"has-inline-color has-bright-red-color\">\u4f20\u7edf\u7684wait-notify\u548clock\u7684await\uff0csignal\u90fd\u9700\u8981 1.\u83b7\u53d6\u9501\uff0c\u624d\u80fd\u8c03\u7528\uff0c2.\u90fd\u9700\u8981\u5148wait\u624d\u80fd\u5524\u9192\uff0c\u800clocksupport\u4e0d\u540c<\/span><\/strong>\u53ef\u4ee5\u4e0d\u7528\u5728lock\u5757\u4e2d\u6267\u884c\uff0c\u4e5f\u53ef\u4ee5\u5148\u5524\u9192\u5728\u7b49\u5f85\u3002<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"196\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-17-1024x196.png\" alt=\"\" class=\"wp-image-1883\" srcset=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-17-1024x196.png 1024w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-17-300x57.png 300w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-17-768x147.png 768w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-17-1200x230.png 1200w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-17.png 1326w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>\u8c03\u7528unpark\u5c31\u4f1a\u7ed9permit+1=1\uff0c\u8c03\u7528park\u5c31\u4f1a\u6d88\u8d39\u4e00\u6b211->0\uff0c\u7acb\u523b\u8fd4\u56de\uff0c\u5982\u679c\u539f\u6765\u5c31\u662f0\uff0c\u90a3\u5c31\u963b\u585e\u7b49\u5f85unpark<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"268\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-18-1024x268.png\" alt=\"\" class=\"wp-image-1890\" srcset=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-18-1024x268.png 1024w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-18-300x78.png 300w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-18-768x201.png 768w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-18-1200x314.png 1200w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-18.png 1246w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<figure class=\"wp-block-image\" id=\"block-46c4b5a5-2518-4a61-8399-4072c0a02f09\"><img decoding=\"async\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-22-1024x383.png\" alt=\"\u6b64\u56fe\u7247\u7684alt\u5c5e\u6027\u4e3a\u7a7a\uff1b\u6587\u4ef6\u540d\u4e3aimage-22-1024x383.png\"\/><\/figure>\n\n\n\n<p id=\"block-2e523021-48a8-4b94-acb5-a5c44f3d848d\">\ufeff<\/p>\n\n\n\n<figure class=\"wp-block-image\" id=\"block-4e424a52-9f54-4b59-adf1-355f948ce872\"><img decoding=\"async\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-19.png\" alt=\"\u6b64\u56fe\u7247\u7684alt\u5c5e\u6027\u4e3a\u7a7a\uff1b\u6587\u4ef6\u540d\u4e3aimage-19.png\"\/><\/figure>\n\n\n\n<figure class=\"wp-block-image\" id=\"block-7cdf098f-c026-438c-a77b-bd4db667fb45\"><img decoding=\"async\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-20-1024x242.png\" alt=\"\u6b64\u56fe\u7247\u7684alt\u5c5e\u6027\u4e3a\u7a7a\uff1b\u6587\u4ef6\u540d\u4e3aimage-20-1024x242.png\"\/><figcaption>\u6bcf\u4e2a\u6392\u961f\u7684\u7ebf\u7a0b\u4e5f\u6709\u4e00\u4e2a\u72b6\u6001<br>\ufeff<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image\" id=\"block-8ed702e6-17e9-49c8-846d-58999c143c33\"><img decoding=\"async\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-21-1024x546.png\" alt=\"\u6b64\u56fe\u7247\u7684alt\u5c5e\u6027\u4e3a\u7a7a\uff1b\u6587\u4ef6\u540d\u4e3aimage-21-1024x546.png\"\/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"479\" height=\"317\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-23.png\" alt=\"\" class=\"wp-image-1904\" srcset=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-23.png 479w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-23-300x199.png 300w\" sizes=\"(max-width: 479px) 100vw, 479px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"876\" height=\"415\" src=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-24.png\" alt=\"\" class=\"wp-image-1908\" srcset=\"https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-24.png 876w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-24-300x142.png 300w, https:\/\/www.zeroheart.xyz\/wordpress\/wp-content\/uploads\/2022\/02\/image-24-768x364.png 768w\" sizes=\"(max-width: 876px) 100vw, 876px\" \/><figcaption>\u961f\u5217\u4e3a\u7a7a\u7684\u65f6\u5019\uff0c\u7b2c\u4e00\u4e2a\u7b49\u5f85\u7ebf\u7a0b\u5165\u961f\uff0c\u4f1a\u5148\u589e\u52a0\u4e00\u4e2a\u7a7a\u7684\u8282\u70b9\u4f5c\u4e3a\u5934\u90e8<\/figcaption><\/figure>\n\n\n\n<p><a href=\"https:\/\/www.bilibili.com\/video\/BV1zb411M7NQ?p=147&amp;spm_id_from=333.788.b_6d756c74695f70616765.147\">\u5c1a\u7845\u8c37Java\u5927\u5382\u9762\u8bd5\u9898\u5168\u96c6(java\u9762\u8bd5\uff0c\u5468\u9633\u4e3b\u8bb2)-Java\u9762\u8bd5_\u5927\u5382\u9ad8\u9891\u9762\u8bd5\u9898_\u9633\u54e5_\u54d4\u54e9\u54d4\u54e9_bilibili<\/a><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>AQS-\u62bd\u8c61\u961f\u5217\u5f0f\u540c\u6b65\u5668\uff0c\u5e38\u7528\u7684\u540c\u6b65\u7c7b\uff0cReentrantLock\u3001CountDownLatch\u3001Semaph 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