{"id":41,"date":"2021-05-22T21:21:57","date_gmt":"2021-05-22T13:21:57","guid":{"rendered":"https:\/\/blog.cauchyschwarz.com\/?p=41"},"modified":"2021-05-22T21:27:59","modified_gmt":"2021-05-22T13:27:59","slug":"%e6%b7%b1%e5%85%a5%e5%ba%94%e7%94%a8c11%e7%ac%94%e8%ae%b0-%e7%ac%ac5%e7%ab%a0","status":"publish","type":"post","link":"https:\/\/blog.cauchyschwarz.com\/?p=41","title":{"rendered":"\u6df1\u5165\u5e94\u7528C++11\u7b14\u8bb0 \u7b2c5\u7ae0"},"content":{"rendered":"\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 ez-toc-wrap-right counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-69e0aed0de90c\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" 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href=\"https:\/\/blog.cauchyschwarz.com\/?p=41\/#%E4%BD%BF%E7%94%A8C11%E8%AE%A9%E5%A4%9A%E7%BA%BF%E7%A8%8B%E5%BC%80%E5%8F%91%E5%8F%98%E5%BE%97%E7%AE%80%E5%8D%95\" >\u4f7f\u7528C++11\u8ba9\u591a\u7ebf\u7a0b\u5f00\u53d1\u53d8\u5f97\u7b80\u5355<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=41\/#%E7%BA%BF%E7%A8%8B\" >\u7ebf\u7a0b<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=41\/#%E4%BA%92%E6%96%A5%E9%87%8F\" >\u4e92\u65a5\u91cf<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=41\/#%E6%9D%A1%E4%BB%B6%E5%8F%98%E9%87%8F\" >\u6761\u4ef6\u53d8\u91cf<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=41\/#%E5%8E%9F%E5%AD%90%E5%8F%98%E9%87%8F\" >\u539f\u5b50\u53d8\u91cf<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=41\/#call_once%E4%B8%8Eonce_flag\" >call_once\u4e0eonce_flag<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=41\/#%E5%BC%82%E6%AD%A5%E6%93%8D%E4%BD%9C%E7%B1%BB\" >\u5f02\u6b65\u64cd\u4f5c\u7c7b<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=41\/#%E7%BA%BF%E7%A8%8B%E5%BC%82%E6%AD%A5%E6%93%8D%E4%BD%9C%E5%87%BD%E6%95%B0async\" >\u7ebf\u7a0b\u5f02\u6b65\u64cd\u4f5c\u51fd\u6570async<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E4%BD%BF%E7%94%A8C11%E8%AE%A9%E5%A4%9A%E7%BA%BF%E7%A8%8B%E5%BC%80%E5%8F%91%E5%8F%98%E5%BE%97%E7%AE%80%E5%8D%95\"><\/span>\u4f7f\u7528C++11\u8ba9\u591a\u7ebf\u7a0b\u5f00\u53d1\u53d8\u5f97\u7b80\u5355<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E7%BA%BF%E7%A8%8B\"><\/span>\u7ebf\u7a0b<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>\u53ef\u4ee5\u901a\u8fc7<code>std::thread<\/code>\u521b\u5efa\u4e00\u4e2a\u7ebf\u7a0b<\/li><li>\u8981\u8ba9\u7ebf\u7a0b\u51fd\u6570\u7684\u751f\u547d\u5468\u671f\u5728\u7ebf\u7a0b\u5bf9\u8c61\u7684\u751f\u547d\u5468\u671f\u4e4b\u5185\uff0c\u5426\u5219\u4f1a\u51fa\u9519<\/li><li>\u7ebf\u7a0b\u5bf9\u8c61\u9700\u8981join\u6216detach<\/li><li>\u7ebf\u7a0b\u4e0d\u53ef\u4ee5\u590d\u5236\u4f46\u662f\u53ef\u4ee5\u79fb\u52a8(<code>std::move<\/code>)<\/li><li>\u51e0\u4e2a\u7ebf\u7a0b\u76f8\u5173\u7684api\uff1a<ul><li><code>get_id()<\/code>\u83b7\u53d6\u5f53\u524d\u7ebf\u7a0bid<\/li><li><code>std::thread::hardware_concurrency()<\/code>\u83b7\u53d6CPU\u6838\u5fc3\u6570\u91cf<\/li><li><code>std::this_thread::sleep_for<\/code>\u8ba9\u5f53\u524d\u7ebf\u7a0b\u4f11\u7720<\/li><\/ul><\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E4%BA%92%E6%96%A5%E9%87%8F\"><\/span>\u4e92\u65a5\u91cf<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u5176\u5b9e\u6ca1\u5565\u8bb2\u7684\uff0c\u5c31\u662f4\u79cd\u8bed\u4e49\u7684\u4e92\u65a5\u91cf\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><code>std::mutex<\/code><\/li><li><code>std::timed_mutex<\/code><\/li><li><code>std::recursive_mutex<\/code><\/li><li><code>std::recursive_timed_mutex<\/code><\/li><\/ul>\n\n\n\n<p>\u8c03\u7528\u65f6\u9664\u4e86<code>lock<\/code>\uff0c\u8fd8\u53ef\u4ee5\u7528<code>try_lock<\/code>\u975e\u963b\u585e\u5f0f\u8c03\u7528\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%9D%A1%E4%BB%B6%E5%8F%98%E9%87%8F\"><\/span>\u6761\u4ef6\u53d8\u91cf<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u53ef\u4ee5\u4f7f\u7528<code>condition_varialbe<\/code>\u548c<code>condition_variable_any<\/code>\u6765\u5b9e\u73b0\u540c\u6b65\u961f\u5217\u3002\u793a\u4f8b\u4ee3\u7801\u53c2\u8003cppreference\u7f51\u7ad9\u7684<a href=\"https:\/\/en.cppreference.com\/w\/cpp\/thread\/condition_variable\">\u793a\u4f8b<\/a>\u3002<\/p>\n\n\n\n<p>\u6761\u4ef6\u53d8\u91cf\u7684\u8bed\u4e49\u5f88\u597d\u7406\u89e3\uff0c\u6545\u540d\u601d\u4e49\uff0c\u53ea\u662f\u9700\u8981\u6ce8\u610f\u4e24\u70b9\uff0c\u4e00\u662f\u9700\u8981\u6ce8\u610f\u5faa\u73af\u68c0\u67e5predicate\u662f\u5426\u4e3atrue\uff0c<code>condition_variable<\/code>\u88ab\u5524\u9192\u7684\u65f6\u5019\u662f\u4e0d\u4fdd\u8bc1predicate\u4e3atrue\u7684\uff1b\u4e8c\u662f\u6709\u4e00\u4e2a\u7591\u95ee\u4e3a\u4ec0\u4e48\u6761\u4ef6\u53d8\u91cf\u975e\u5f97\u8981\u548cmutex\u914d\u5408\u4f7f\u7528\uff0c\u7b54\u6848\u662f<a href=\"https:\/\/stackoverflow.com\/a\/2763749\/5357784\">\u4e3a\u4e86\u4fdd\u62a4predicate\u7684\u539f\u5b50\u6027<\/a>\uff0c\u53ef\u4ee5\u9605\u8bfb\u4e00\u4e0b\u8fd9\u4e2a\u7b54\u6848\u4e0b\u7684\u8bc4\u8bba\uff1a<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>the mutex is not to protect the condition variable; it is to protect the predicate data, but I think you know that from reading your comment that followed that statement. You can signal a condition variable legally, and fully supported by implementations, post-unlock of the mutex wrapping the predicate, and in fact you&#8217;ll will relieve contention in doing so in some cases.<\/p><\/blockquote>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8E%9F%E5%AD%90%E5%8F%98%E9%87%8F\"><\/span>\u539f\u5b50\u53d8\u91cf<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p><code>std::atomic&lt;T&gt;<\/code>\uff0c\u63d0\u4f9b\u4ee5\u4e0bapi\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><code>operator=<\/code><\/li><li><code>is_lock_free<\/code><\/li><li><code>store<\/code><\/li><li><code>load<\/code><\/li><li><code>operator T<\/code><\/li><li><code>exchange<\/code><\/li><li><code>compare_exchange_weak<\/code><\/li><li><code>compare_exchange_strong<\/code><\/li><\/ul>\n\n\n\n<p>\u5bf9\u4e8eint\u8fd9\u4e9b\u5e38\u89c1\u57fa\u7840\u7c7b\u578b\u7684\u539f\u5b50\u53d8\u91cf\u7248\u672c\uff0c\u8fd8\u6709\u76f8\u5e94\u7684\u7279\u5316\u51fd\u6570\u6a21\u677f\u5b9e\u73b0\uff0c\u5177\u4f53\u67e5cppreference\u5c31\u53ef\u4ee5\u4e86\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"call_once%E4%B8%8Eonce_flag\"><\/span>call_once\u4e0eonce_flag<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u4e3a\u4e86\u4fdd\u8bc1\u591a\u7ebf\u7a0b\u4e0b\u67d0\u4e2a\u51fd\u6570\u53ea\u88ab\u8c03\u7528\u4e00\u6b21\uff0c\u53ef\u4ee5\u4f7f\u7528<code>call_once<\/code>\u6765\u5305\u88f9\u8be5\u51fd\u6570\uff0c\u540c\u65f6\u9700\u8981\u58f0\u660e\u4e00\u4e2a<code>once_flag<\/code>\u53d8\u91cf\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%BC%82%E6%AD%A5%E6%93%8D%E4%BD%9C%E7%B1%BB\"><\/span>\u5f02\u6b65\u64cd\u4f5c\u7c7b<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li><code>std::future<\/code><br><code>future<\/code>\u4e0d\u652f\u6301\u62f7\u8d1d\uff0c\u5982\u679c\u9700\u8981\u653e\u8fdb\u5bb9\u5668\u91cc\u9700\u8981\u4f7f\u7528<code>shared_future<\/code>\uff1b<br><code>future<\/code>\u7684api\uff1a<code>get<\/code>\u3001<code>valid<\/code>\u3001<code>wait<\/code>\u3001<code>wait_for<\/code>\u3001<code>wait_until<\/code>\uff1b<\/li><li><code>std::promise<\/code><\/li><li><code>std::package_task<\/code><\/li><\/ul>\n\n\n\n<p>\u76f4\u63a5\u7406\u89e3\u8fd9\u4e09\u4e2a\u6982\u5ff5\u4f3c\u4e4e\u6709\u70b9\u56f0\u96be\uff0c\u6240\u4ee5\u53ef\u4ee5\u5148\u770b\u4e0bcppreference\u7ed9\u7684\u4f8b\u5b50\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>   #include &lt;iostream&gt;\n   #include &lt;future&gt;\n   #include &lt;thread&gt;\n\n   int main()\n   {\n       \/\/ future from a packaged_task\n       std::packaged_task&lt;int()&gt; task(&#91;]{ return 7; }); \/\/ wrap the function\n       std::future&lt;int&gt; f1 = task.get_future();  \/\/ get a future\n       std::thread t(std::move(task)); \/\/ launch on a thread\n\n       \/\/ future from an async()\n       std::future&lt;int&gt; f2 = std::async(std::launch::async, &#91;]{ return 8; });\n\n       \/\/ future from a promise\n       std::promise&lt;int&gt; p;\n       std::future&lt;int&gt; f3 = p.get_future();\n       std::thread( &#91;&amp;p]{ p.set_value_at_thread_exit(9); }).detach();\n\n       std::cout &lt;&lt; \"Waiting...\" &lt;&lt; std::flush;\n       f1.wait();\n       f2.wait();\n       f3.wait();\n       std::cout &lt;&lt; \"Done!\\nResults are: \"\n                 &lt;&lt; f1.get() &lt;&lt; ' ' &lt;&lt; f2.get() &lt;&lt; ' ' &lt;&lt; f3.get() &lt;&lt; '\\n';\n       t.join();\n   }<\/code><\/pre>\n\n\n\n<p>\u53ef\u4ee5\u770b\u51fa\uff0c<code>future<\/code>\u662f\u7528\u6765\u4fdd\u5b58\u51fd\u6570\u7684\u8fd4\u56de\u503c\u7684\uff0c<code>package_task<\/code>\u548c<code>async<\/code>\u51fd\u6570\u90fd\u53ef\u4ee5\u8fd4\u56de<code>future<\/code>\uff1b<code>promise<\/code>\u5219\u662f\u7c7b\u4f3c\u4e8e\u591a\u4e2a\u7ebf\u7a0b\u5171\u4eab\u7684\u53d8\u91cf\uff0c\u5176\u4ed6\u7ebf\u7a0b\u901a\u8fc7\u4fee\u6539\u8fd9\u4e2a\u5171\u4eab\u7684\u53d8\u91cf\u6765\u8fd4\u56de\u8ba1\u7b97\u7ed3\u679c\uff0c\u800c\u5728<code>promise<\/code>\u5185\u90e8\u8fd8\u662f\u7528\u4e86<code>future<\/code>\u6765\u4fdd\u5b58\u8fd9\u4e2a\u8ba1\u7b97\u7ed3\u679c\uff1b<code>package_task<\/code>\u5219\u662f\u53ef\u8c03\u7528\u5bf9\u8c61\u7684\u5305\u88c5\u7c7b\uff0c\u8fd4\u56de\u4e00\u4e2a<code>future<\/code>\uff0c\u4f46<code>package_task<\/code>\u81ea\u8eab\u4e0d\u4f1a\u521b\u5efa\u7ebf\u7a0b\uff0c\u9700\u8981\u501f\u52a9thread\u7c7b\u6765\u8fd0\u884c\uff1b<code>async<\/code>\u5219\u662f\u53ef\u4ee5\u521b\u5efa\u7ebf\u7a0b\u8fd0\u884c\u51fd\u6570\uff0c\u5e76\u4e14\u8fd4\u56de<code>future<\/code>\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E7%BA%BF%E7%A8%8B%E5%BC%82%E6%AD%A5%E6%93%8D%E4%BD%9C%E5%87%BD%E6%95%B0async\"><\/span>\u7ebf\u7a0b\u5f02\u6b65\u64cd\u4f5c\u51fd\u6570async<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u51fd\u6570\u539f\u578b<code>async(std::launch::async|std::launch::deferred, f, args...)<\/code>\uff0c\u4f7f\u7528async\u65f6\u4f1a\u7acb\u5373\u521b\u5efa\u7ebf\u7a0b\uff0c\u4f7f\u7528deferred\u7684\u65f6\u5019\u8c03\u7528future\u7684get\/wait\u65b9\u6cd5\u624d\u521b\u5efa\u7ebf\u7a0b\uff1b<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4f7f\u7528C++11\u8ba9\u591a\u7ebf\u7a0b\u5f00\u53d1\u53d8\u5f97\u7b80\u5355 \u7ebf\u7a0b \u53ef\u4ee5\u901a\u8fc7std::thread\u521b\u5efa\u4e00\u4e2a\u7ebf\u7a0b \u8981\u8ba9\u7ebf\u7a0b\u51fd\u6570\u7684\u751f\u547d\u5468\u671f\u5728\u7ebf\u7a0b\u5bf9\u8c61\u7684\u751f\u547d\u5468\u671f\u4e4b\u5185\uff0c\u5426\u5219\u4f1a\u51fa\u9519 \u7ebf\u7a0b\u5bf9\u8c61\u9700\u8981join\u6216detach \u7ebf\u7a0b\u4e0d\u53ef\u4ee5\u590d\u5236\u4f46\u662f&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[8,7,9],"class_list":["post-41","post","type-post","status-publish","format-standard","hentry","category-10","tag-c","tag-c11","tag-9"],"_links":{"self":[{"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/posts\/41","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=41"}],"version-history":[{"count":2,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/posts\/41\/revisions"}],"predecessor-version":[{"id":43,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/posts\/41\/revisions\/43"}],"wp:attachment":[{"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=41"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}