多個執行緒需要共享同乙份配置，但是配置本身又需要更新，如何處理？比較理想的處理方式是 copy on write，每次更新在原有的資料上拷貝乙份，加上更新，然後再替換全域性的那份配置。這樣做的好處是讀取配置完全不會被後台更新block住。要是用加鎖的方式，萬一後台更新執行緒**不靠譜，前台讀配置的地方就被block住了。但是這樣就帶來了乙個舊的配置物件什麼時候被**的問題。因為舊的配置物件可能被任意個執行緒在讀取著，我們怎麼知道什麼時候這些執行緒都讀完了呢？也許我們會得出乙個結論，這個做法只在有gc的語言裡可以搞。
但是，c++ 14 的 shared_ptr，atomic_load 和 atomic_store 提供了乙個解決辦法
#include #include #include #include #include #include #include using namespace std::chrono_literals;
class config
~config()
};std::shared_ptrglobalcfg;
std::shared_ptrreadcurrentcfg()
void reader()
void updateconfig(int id)
void writer()
}int main()
for (auto& thread : threads)
return 0;
}
/home/xiaoju/.clion2016.2/system/cmake/generated/test2-90d0d4c6/90d0d4c6/debug/test2
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process finished with exit code 0
cmake_minimum_required(version 3.6)
project(test2)
set(cmake_cxx_flags "$ -std=c++1y -stdlib=libc++ -pthread")
set(source_files main.cpp)
add_executable(test2 $)
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