1 Basic Hazard Pointer Algorithm read pointer A from SRC remove A from SRC 1 5 4 Safe to use pointer A SRC A hazard pointer is a single-writer multi-reader pointer. set HP to A if SRC == A clear ACCESS If a hazard pointer points to an object before its removal, then the object will not be reclaimed as long as the hazard pointer remains unchanged unchanged. *A Hazard Pointer Synchronous Reclamation Beyond Concurrency TS2 – Maged Michael Protector Remover / Reclaimer Hazard pointers protect access to objects that may be removed concurrently. SAFE RECLAMATION

(thankfully) not used by either implementation • Both use the lowest-order bits on the control_block pointer as a lock26 Daniel Anderson -- danielanderson.net Solution #2: The split reference count • Used project on GitHub by Vladislav Tyulbashev Key idea: If we could atomically load the control_block pointer and increment the reference count at the same time, we would avoid the race to zero27 Daniel Anderson Big idea: local_ref_count counts the number of in- flight atomic loads on the currently stored pointer atomic> control_block28 Daniel Anderson -- danielanderson.net Solution #2: The

实现稀疏的方法有： • hash 哈希（本例中的 unordered_map ） • pointer 指针（本例中的 Block1 ） • dense 稠密（本例中的 Block ） • 他们之间可以相互组合，形成更复杂的稀疏数据结构。 • 下面这个例子中的稀疏数据结构，用这种语言可以表示为 hash().pointer(11).dense(8) 。 封装起来，方便多层解耦 封装起来，方便多层解耦 封装起来，方便多层解耦 封装起来，方便多层解耦 封装起来，方便多层解耦 封装起来，方便多层解耦 • 这样就封装好了，通过模板的方式实现了 自定义的稀疏数据结构： • hash().pointer(11).dense(8) 开源的体素处理库： OpenVDB • OpenVDB 的稀疏体积，可以存储符号距 离场 (SDF) ，也可以存储烟雾仿真的结果 等。 • 据张心欣说， OpenVDB 赢得了奥斯卡奖 赢得了奥斯卡奖 。 • 因为他经常用在影视特效中，主要是符号 距离场有时比 mesh 处理起来方便很多。 OpenVDB 的设计：如果用 SNode 来表示 • hash().pointer(5).pointer(4).dense(3) ZENO 中就大量使用了 OpenVDB ，并且以节点的形式提供给用户调用 • github.com/zenustech/zeno ZENO 中的流体仿真，就是基于

accessing pointer not thread-safe, one thread could be reading pointer, while another thread could be storing new pointer  Make it thread-safe?  Manually use mutex to protect access to smart pointer  Use

而函数指针也是无条件跳转指令： jmp [pointer] 或者说 call [pointer] ，区别在于他的地址 不是写死的，而是动态从内存中读取出来的。 • 普通函数调用的目的地址（或偏移量）写死在指令里， CPU 可以自动预取这个地址的指令。 • 但是函数指针的调用，因为这个目的地址是需要计算得出的，或者说他存在内存中，随时可 能被改写， CPU 难以预判执行到 call [pointer] 的时候这个指针会指向哪里，无法预取。

dereference • more to come.. Flow-sensitive • Coroutine lifetime checks • Most of CppCoreChecks • Pointer safety analysis • Ownership analysis • Lifetime analysis (preview) • more to come…Looking under analysis – Gabor Horvath (online 29th)Thanks!Fourier-Motzkin eliminationResourcesImproved Null Pointer Dereference Detection in Visual Studio 2 022 version 17.0 Preview 4 - C++ Team Blog (microsoft.com)

Neargye) • P0595R2 is_constant_evaluated() (GH-353, Jennifer Yao – MSVC compiler) • P1006R1 constexpr pointer_to() (GH-397, AdamBucior) • P1023R0 constexpr array Comparisons (GH-599, Weheineman) • P1032R1 spans are implicitly constructible from arrays and vectors • Avoids ownership confusion, accidental pointer arithmetic • span  span; span 🐞 span • Shallow const, like T* •

bridging the CPU-GPU divide. Managed memory is accessible to both the CPU and GPU using a single pointer. The key is that the system automatically migrates data allocated in Unified Memory between host bridging the CPU-GPU divide. Managed memory is accessible to both the CPU and GPU using a single pointer. The key is that the system automatically migrates data allocated in Unified Memory between host

 undeclare_reachable()  declare_no_pointers()  undeclare_no_pointers()  get_pointer_safety()  enum pointer_safety  Available since C++11  Not aware of any use of this API  Removed from

conntrack? • Ingress • Move IPVS Netfilter hook from local-in to PREROUTING • The challenges • Skb’s pointer to route is NULL during PREROUTING • No de-fragment is done during PREROUTING IPVS bypass conntrack