{"id":5309,"date":"2021-06-09T19:03:05","date_gmt":"2021-06-09T11:03:05","guid":{"rendered":"https:\/\/damogame.cn\/wordpress\/?p=5309"},"modified":"2021-06-09T19:03:05","modified_gmt":"2021-06-09T11:03:05","slug":"%e6%99%ba%e8%83%bd%e6%8c%87%e9%92%88%e6%98%af%e5%90%a6%e7%ba%bf%e7%a8%8b%e5%ae%89%e5%85%a8","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/5309","title":{"rendered":"\u667a\u80fd\u6307\u9488\u662f\u5426\u7ebf\u7a0b\u5b89\u5168"},"content":{"rendered":"
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1.9 \u518d\u8bbashared_ptr \u7684\u7ebf\u7a0b\u5b89\u5168<\/strong><\/div>\n<\/div>\n<\/div>\n<\/div>\n
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\u867d\u7136\u6211\u4eec\u501fshared_ptr \u6765\u5b9e\u73b0\u7ebf\u7a0b\u5b89\u5168\u7684\u5bf9\u8c61\u91ca\u653e\uff0c\u4f46\u662fshared_ptr \u672c\u8eab\u4e0d\u662f100% \u7ebf\u7a0b\u5b89\u5168\u7684\u3002\u5b83\u7684\u5f15\u7528\u8ba1\u6570\u672c\u8eab\u662f\u5b89\u5168\u4e14\u65e0\u9501\u7684\uff0c\u4f46\u5bf9\u8c61\u7684\u8bfb\u5199\u5219\u4e0d\u662f\uff0c\u56e0\u4e3ashared_ptr \u6709\u4e24\u4e2a\u6570\u636e\u6210\u5458\uff0c\u8bfb\u5199\u64cd\u4f5c\u4e0d\u80fd\u539f\u5b50\u5316\u3002\u6839\u636e\u6587\u686311\uff0cshared_ptr \u7684\u7ebf\u7a0b\u5b89\u5168\u7ea7\u522b\u548c\u5185\u5efa\u7c7b\u578b\u3001\u6807\u51c6\u5e93\u5bb9\u5668\u3001std::string \u4e00\u6837\uff0c\u5373\uff1a<\/p>\n

\u4e00\u4e2ashared_ptr \u5bf9\u8c61\u5b9e\u4f53\u53ef\u88ab\u591a\u4e2a\u7ebf\u7a0b\u540c\u65f6\u8bfb\u53d6\uff1b<\/p>\n

\u4e24\u4e2ashared_ptr \u5bf9\u8c61\u5b9e\u4f53\u53ef\u4ee5\u88ab\u4e24\u4e2a\u7ebf\u7a0b\u540c\u65f6\u5199\u5165\uff0c\u201c\u6790\u6784\u201d\u7b97\u5199\u64cd\u4f5c\uff1b<\/p>\n

\u5982\u679c\u8981\u4ece\u591a\u4e2a\u7ebf\u7a0b\u8bfb\u5199\u540c\u4e00\u4e2ashared_ptr \u5bf9\u8c61\uff0c\u90a3\u4e48\u9700\u8981\u52a0\u9501\u3002<\/p>\n

\u8bf7\u6ce8\u610f\uff0c\u4ee5\u4e0a\u662fshared_ptr \u5bf9\u8c61\u672c\u8eab\u7684\u7ebf\u7a0b\u5b89\u5168\u7ea7\u522b\uff0c\u4e0d\u662f\u5b83\u7ba1\u7406\u7684\u5bf9\u8c61\u7684\u7ebf\u7a0b\u5b89\u5168\u7ea7\u522b\u3002<\/p>\n

\u8981\u5728\u591a\u4e2a\u7ebf\u7a0b\u4e2d\u540c\u65f6\u8bbf\u95ee\u540c\u4e00\u4e2ashared_ptr\uff0c\u6b63\u786e\u7684\u505a\u6cd5\u662f\u7528mutex \u4fdd\u62a4\uff1a<\/p>\n

    \n
  1. MutexLock\u00a0mutex;\u00a0\/\/\u00a0No\u00a0need\u00a0for\u00a0ReaderWriterLock<\/li>\n
  2. shared_ptr<Foo>\u00a0globalPtr;<\/li>\n
  3. \/\/\u00a0\u6211\u4eec\u7684\u4efb\u52a1\u662f\u628aglobalPtr\u00a0\u5b89\u5168\u5730\u4f20\u7ed9doit()<\/li>\n
  4. void\u00a0doit(const\u00a0shared_ptr<Foo>&\u00a0pFoo);<\/li>\n<\/ol>\n

    globalPtr \u80fd\u88ab\u591a\u4e2a\u7ebf\u7a0b\u770b\u5230\uff0c\u90a3\u4e48\u5b83\u7684\u8bfb\u5199\u9700\u8981\u52a0\u9501\u3002\u6ce8\u610f\u6211\u4eec\u4e0d\u5fc5\u7528\u8bfb\u5199\u9501\uff0c\u800c\u53ea\u7528\u6700\u7b80\u5355\u7684\u4e92\u65a5\u9501\uff0c\u8fd9\u662f\u4e3a\u4e86\u6027\u80fd\u8003\u8651\u3002\u56e0\u4e3a\u4e34\u754c\u533a\u975e\u5e38\u5c0f\uff0c\u7528\u4e92\u65a5\u9501\u4e5f\u4e0d\u4f1a\u963b\u585e\u5e76\u53d1\u8bfb\u3002<\/p>\n

    \u4e3a\u4e86\u62f7\u8d1dglobalPtr\uff0c\u9700\u8981\u5728\u8bfb\u53d6\u5b83\u7684\u65f6\u5019\u52a0\u9501\uff0c\u5373\uff1a<\/p>\n

      \n
    1. void\u00a0read()<\/li>\n
    2. {<\/li>\n
    3. shared_ptr<Foo>\u00a0localPtr;<\/li>\n
    4. {<\/li>\n
    5. MutexLockGuard\u00a0lock(mutex);<\/li>\n
    6. localPtr\u00a0=\u00a0globalPtr;\u00a0\/\/\u00a0read\u00a0globalPtr<\/li>\n
    7. }<\/li>\n
    8. \/\/\u00a0use\u00a0localPtr\u00a0since\u00a0here\uff0c\u8bfb\u5199localPtr\u00a0\u4e5f\u65e0\u987b\u52a0\u9501<\/li>\n
    9. doit(localPtr);<\/li>\n
    10. }<\/li>\n<\/ol>\n

       <\/p>\n

      \u5199\u5165\u7684\u65f6\u5019\u4e5f\u8981\u52a0\u9501\uff1a<\/p>\n

        \n
      1. void\u00a0write()<\/li>\n
      2. {<\/li>\n
      3. shared_ptr<Foo>\u00a0newPtr(new\u00a0Foo);\u00a0\/\/\u00a0\u6ce8\u610f\uff0c\u5bf9\u8c61\u7684\u521b\u5efa\u5728\u4e34\u754c\u533a\u4e4b\u5916<\/li>\n
      4. {<\/li>\n
      5. MutexLockGuard\u00a0lock(mutex);<\/li>\n
      6. globalPtr\u00a0=\u00a0newPtr;\u00a0\/\/\u00a0write\u00a0to\u00a0globalPtr<\/li>\n
      7. }<\/li>\n
      8. \/\/\u00a0use\u00a0newPtr\u00a0since\u00a0here\uff0c\u8bfb\u5199newPtr\u00a0\u65e0\u987b\u52a0\u9501<\/li>\n
      9. doit(newPtr);<\/li>\n
      10. }<\/li>\n<\/ol>\n

         <\/p>\n

        \u6ce8\u610f\u5230\u4e0a\u9762\u7684read() \u548cwrite() \u5728\u4e34\u754c\u533a\u4e4b\u5916\u90fd\u6ca1\u6709\u518d\u8bbf\u95eeglobalPtr\uff0c\u800c\u662f\u7528\u4e86\u4e00\u4e2a\u6307\u5411\u540c\u4e00Foo \u5bf9\u8c61\u7684\u6808\u4e0ashared_ptr local copy\u3002\u4e0b\u9762\u4f1a\u8c08\u5230\uff0c\u53ea\u8981\u6709\u8fd9\u6837\u7684local copy \u5b58\u5728\uff0cshared_ptr \u4f5c\u4e3a\u51fd\u6570\u53c2\u6570\u4f20\u9012\u65f6\u4e0d\u5fc5\u590d\u5236\uff0c\u7528reference to const \u4f5c\u4e3a\u53c2\u6570\u7c7b\u578b\u5373\u53ef\u3002\u53e6\u5916\u6ce8\u610f\u5230\u4e0a\u9762\u7684new Foo \u662f\u5728\u4e34\u754c\u533a\u4e4b\u5916\u6267\u884c\u7684\uff0c\u8fd9\u79cd\u5199\u6cd5\u901a\u5e38\u6bd4\u5728\u4e34\u754c\u533a\u5185\u5199globalPtr.reset(new Foo) \u8981\u597d\uff0c\u56e0\u4e3a\u7f29\u77ed\u4e86\u4e34\u754c\u533a\u957f\u5ea6\u3002\u5982\u679c\u8981\u9500\u6bc1\u5bf9\u8c61\uff0c\u6211\u4eec\u56fa\u7136\u53ef\u4ee5\u5728\u4e34\u754c\u533a\u5185\u6267\u884cglobalPtr.reset()\uff0c\u4f46\u662f\u8fd9\u6837\u5f80\u5f80\u4f1a\u8ba9\u5bf9\u8c61\u6790\u6784\u53d1\u751f\u5728\u4e34\u754c\u533a\u4ee5\u5185\uff0c\u589e\u52a0\u4e86\u4e34\u754c\u533a\u7684\u957f\u5ea6\u3002\u4e00\u79cd\u6539\u8fdb\u529e\u6cd5\u662f\u50cf\u4e0a\u9762\u4e00\u6837\u5b9a\u4e49\u4e00\u4e2alocalPtr\uff0c\u7528\u5b83\u5728\u4e34\u754c\u533a\u5185\u4e0eglobalPtr \u4ea4\u6362\uff08swap()\uff09\uff0c\u8fd9\u6837\u80fd\u4fdd\u8bc1\u628a\u5bf9\u8c61\u7684\u9500\u6bc1\u63a8\u8fdf\u5230\u4e34\u754c\u533a\u4e4b\u5916\u3002\u7ec3\u4e60\uff1a\u5728write() \u51fd\u6570\u4e2d\uff0cglobalPtr = newPtr; \u8fd9\u4e00\u53e5\u6709\u53ef\u80fd\u4f1a\u5728\u4e34\u754c\u533a\u5185\u9500\u6bc1\u539f\u6765globalPtr \u6307\u5411\u7684Foo \u5bf9\u8c61\uff0c\u8bbe\u6cd5\u5c06\u9500\u6bc1\u884c\u4e3a\u79fb\u51fa\u4e34\u754c\u533a\u3002<\/p>\n

         <\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

        1.9 \u518d\u8bbashared_ptr \u7684\u7ebf\u7a0b<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"colormag_page_container_layout":"default_layout","colormag_page_sidebar_layout":"default_layout","footnotes":""},"categories":[],"tags":[119],"class_list":["post-5309","post","type-post","status-publish","format-standard","hentry","tag-03-"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/5309","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/comments?post=5309"}],"version-history":[{"count":0,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/5309\/revisions"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=5309"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=5309"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=5309"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}