151 (#99)

* fix #98
wanghenshui · Mar 10, 2024 · a7f44d3 · a7f44d3
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diff --git a/README.md b/README.md
@@ -24,9 +24,9 @@ RSS使用仓库的release RSS [链接](https://github.com/wanghenshui/cppweeklyn
 
 ## 2024
 
-|  |  |  |  | [145](./posts/145.md) | [146](./posts/146.md) | [147](./posts/147.md) | [148](./posts/148.md) | [149](./posts/149.md) | [150](./posts/150.md) |
-| - | - | - | - | ------------------ | ------------------ | ------------------ | ------------------ | ----------------- | - |
-|  |  |  |  |                    |                    |                    |                    |                   |  |
+| [151](./posts/151.md) |  |  |  |                    |                    |                    |                    |                    |                    |
+| ------------------ | - | - | - | ------------------ | ------------------ | ------------------ | ------------------ | ------------------ | ------------------ |
+|                    |  |  |  | [145](./posts/145.md) | [146](./posts/146.md) | [147](./posts/147.md) | [148](./posts/148.md) | [149](./posts/149.md) | [150](./posts/150.md) |
 
 ---
 
@@ -73,7 +73,7 @@ RSS使用仓库的release RSS [链接](https://github.com/wanghenshui/cppweeklyn
 - 杨杰
 - 阿刚
 - MSK
-- 不语 x28
+- 不语 x29
 - ywp
 - 范天泷
 - 罗盛波
@@ -98,9 +98,10 @@ RSS使用仓库的release RSS [链接](https://github.com/wanghenshui/cppweeklyn
 - Captain
 - Anien
 - jerry
-- HNY x6
+- HNY x8
 - CHENL
 - 沧海
 - 彩虹蛇皮虾
 - Tudou
 - kenshin
+- {}
diff --git a/posts/150.md b/posts/150.md
@@ -2,7 +2,7 @@
 layout: post
 title:  第150期
 ---
-# C++ 中文周刊 2024-02-24 第150期
+# C++ 中文周刊 2024-03-03 第150期
 
 [周刊项目地址](https://github.com/wanghenshui/cppweeklynews)
 
@@ -224,7 +224,16 @@ TEST_CASE("UART Construction") {
 - 善用 __builtin_expect
 - 分支改switch
 
-一个样例
+备注
+
+cmov 描述不对，if简单赋值也能生成cmov，
+cmov是一个值得展开的话题
+
+variant + visit开销部份场景要比虚函数要好，不要因噎废食
+
+感谢 球猫 Anien 指正
+
+一个样例sss
 
 ```cpp
 void processThisString(std::string_view input)

diff --git a/posts/151.md b/posts/151.md
@@ -0,0 +1,236 @@
+---
+layout: post
+title:  第151期
+---
+# C++ 中文周刊 2024-03-09 第151期
+
+
+[周刊项目地址](https://github.com/wanghenshui/cppweeklynews)
+
+公众号
+
+<img src="https://wanghenshui.github.io/cppweeklynews/assets/code.png" alt=""  width="30%">
+
+qq群 [点击进入](https://qm.qq.com/q/6NGizNPyG4)
+
+RSS https://github.com/wanghenshui/cppweeklynews/releases.atom
+
+欢迎投稿，推荐或自荐文章/软件/资源等
+
+请[提交 issue](https://github.com/wanghenshui/cppweeklynews/issues)   或评论区留言
+
+本期文章由 不语 HNY {} 赞助
+
+周末有点忙，内容不多，这周争取双更
+
+话说看到了别人的知识星球真有一种这也能卖钱的感觉
+
+c++知识普及还是很远，无论深度还是广度，优质内容还是太少了，这种稍微懂点就敢开知识星球开课了
+
+---
+
+## 资讯
+
+标准委员会动态/ide/编译器信息放在这里
+
+[编译器信息最新动态推荐关注hellogcc公众号 本周更新 2024-02-28 第243期 ](https://mp.weixin.qq.com/s/lb3T0XyK87c-oawfkjwXkA)
+
+
+## 文章
+
+#### [浅谈侵入式结构的应用](https://zhuanlan.zhihu.com/p/679066486)
+
+总结的的非常好
+
+
+#### [In C++/WinRT, you shouldn’t destroy an object while you’re co_awaiting it](https://devblogs.microsoft.com/oldnewthing/20240307-00/?p=109490)
+
+co_wait对象如果被析构，可能有bug
+
+```c++
+struct MyThing : winrt::implements<MyThing, winrt::IInspectable>
+{
+    winrt::IAsyncAction m_pendingAction{ nullptr };
+
+    winrt::IAsyncAction DoSomethingAsync() {
+        auto lifetime = get_strong();
+        m_pendingAction = LongOperationAsync();
+        co_await m_pendingAction;
+        PostProcessing();
+    }
+
+    void Cancel() {
+        if (m_pendingAction) {
+            m_pendingAction.Cancel();
+            m_pendingAction = nullptr;
+        }
+    }
+};
+```
+
+这段代码， 如果DoSomethingAsync的时候另一个线程Cancel了，pendingAction被析构了，co_await就会挂
+
+解决方案，co_await副本，复制一份或者decay_copy auto{}
+
+这种指针问题和co_await关系不大，但是容易忽略，普通函数也可以触发，比如异步调用lambda，然后lambda里reset指针，这种场景，可能需要copy这个对象
+
+#### [Borrow Checker, Lifetimes and Destructor Arguments in C++ Avanced compile-time validation with stateful](https://a10nw01f.github.io/post/advanced_compile_time_validation/metaprogramming)
+
+看得我眼睛疼 在线演示 https://godbolt.org/z/71qs619Ge
+
+
+#### [LLVM's 'RFC: C++ Buffer Hardening' at Google](https://bughunters.google.com/blog/6368559657254912/llvm-s-rfc-c-buffer-hardening-at-google)
+
+安全加固 c buffer的 google内部测试加固完性能衰退也就%1 希望llvm合了
+
+#### [RAII all the things?](https://biowpn.github.io/bioweapon/2024/03/05/raii-all-the-things.html)
+
+用unique_ptr来搞，以前讲过类似的。直接贴代码
+
+```cpp
+struct fcloser {
+    void operator()(std::FILE* fp) const noexcept {
+        std::fclose(fp);
+    }
+};
+
+using file_ptr = std::unique_ptr<std::FILE, fcloser>;
+
+
+struct mem_unmapper {
+    size_t length{};
+
+    void operator()(void* addr) const noexcept {
+        ::munmap(addr, length);
+    }
+};
+
+using mapped_mem_ptr = std::unique_ptr<void, mem_unmapper>;
+
+[[nodiscard]] inline mapped_mem_ptr make_mapped_mem(void* addr, size_t length, int prot, int flags, int fd, off_t offset) {
+    void* p = ::mmap(addr, length, prot, flags, fd, offset);
+    if (p == MAP_FAILED) { // MAP_FAILED is not NULL
+        return nullptr;
+    }
+    return {p, mem_unmapper{length}}; // unique_ptr owns a deleter, which remembers the length
+}
+
+
+// Intentionally non-RAII
+class file_descriptor {
+    int fd_{-1};
+public:
+    file_descriptor(int fd = -1): fd_(fd) {}
+    file_descriptor(nullptr_t) {}
+    operator int() const { return fd_; }
+    explicit operator bool() const { return fd_ != -1; }
+    friend bool operator==(file_descriptor, file_descriptor) = default; // Since C++20
+};
+
+struct fd_closer {
+    using pointer = file_descriptor; // IMPORTANT
+    void operator()(pointer fd) const noexcept {
+        ::close(int(fd));
+    }
+};
+//using unique_fd = std::unique_ptr<int,             fd_closer>; // Ok
+using unique_fd = std::unique_ptr<file_descriptor, fd_closer>; // Ok
+//using unique_fd = std::unique_ptr<void,            fd_closer>; // Ok
+
+```
+
+其他场景自己拼一个defer或者scope_exit
+
+#### [How do I make an expression non-movable? What’s the opposite of std::move? ](https://devblogs.microsoft.com/oldnewthing/20240306-00/?p=109481)
+
+如何实现强制不move？
+
+```cpp
+template<typename T>
+std::remove_reference_t<T> const& no_move(T&& t)
+{
+    return t;
+}
+
+std::vector<int> v = no_move(make_vector());
+```
+
+#### [Python3.13的JIT是如何实现的](https://zhuanlan.zhihu.com/p/682997904)
+
+这个也有点意思
+
+#### [不用指针实现pimpl](https://github.com/friendlyanon/pimpl-but-the-p-is-silent)
+
+代码很短
+
+
+```c++
+class impl
+{
+public:
+  impl();
+  ~impl();
+
+  int add(int x) const;
+
+private:
+  alignas(private_align) unsigned char buffer[private_size];
+};
+
+class impl_private
+{
+public:
+  explicit impl_private(int y);
+
+  int add(int x) const;
+
+private:
+  int _y;
+};
+
+template<typename T>
+using impl_t = std::conditional_t<std::is_const_v<std::remove_pointer_t<T>>,
+                                  impl_private const,
+                                  impl_private>*;
+
+#define IMPL std::launder(reinterpret_cast<impl_t<decltype(this)>>(buffer))
+
+impl::impl()
+{
+  (void)new (buffer) impl_private(1);
+}
+
+impl::~impl()
+{
+  IMPL->~impl_private();
+}
+
+int impl::add(int x) const
+{
+  return IMPL->add(x);
+}
+```
+
+核心是用buffer存实现类，然后硬转，看一乐
+
+
+## 工作招聘
+
+字节跳动图数据库有个招聘，友情推荐一下 
+
+字节图数据库 ByteGraph 团队招聘数据库研发工程师，参与 ByteGraph 存储引擎、查询引擎、数据库与计算融合引擎的核心代码开发。
+实习、校招、社招均可，base 地北京/成都/杭州/新加坡均可，新加坡由于签证问题对级别有一定要求，细节可私聊。
+
+可以加 微信 Expelidarmas或者邮件 huyingqian@bytedance.com
+
+[详情可以看这个](https://zhuanlan.zhihu.com/p/685211021)
+
+他们vldb发过论文的，字节的业务也很强
+
+## 互动
+
+还是缺少优质内容，大家给给点子
+
+---
+
+[上一期](https://wanghenshui.github.io/cppweeklynews/posts/150.html)