POSIX跨进程的共享内存同步C ++ / C ++ 11 [英] POSIX Shared Memory Sync Across Processes C++/C++11

问题描述

问题（简​​而言之）：
我使用POSIX共享内存，目前只使用POSIX信号量，我需要控制多个读者，多个作者。我需要帮助我使用什么变量/方法来控制访问在下面描述的限制。
我找到了一个我想实现的方法，但我不确定在使用POSIX共享内存时可以使用什么方法来实现它。

Problem (in short): I'm using POSIX Shared Memory and currently just used POSIX semaphores and i need to control multiple readers, multiple writers. I need help with what variables/methods i can use to control access within the limitations described below. I've found an approach that I want to implement but i'm unsure of what methodology i can use to implement it when using POSIX Shared memory.

找到的内容
http://stackoverflow.com/a/28140784
这个链接有我想使用的算法，但我不确定如何实现它与共享内存。我把类存储在共享内存中吗？这是我需要帮助的地方。
我不确定的原因是我的很多研究，指向保持共享内存到基元只是为了避免解决问题，STL对象不能使用。

What I've Found http://stackoverflow.com/a/28140784 This link has the algorithm i'd like to use but i'm unsure how to implement it with shared memory. Do i store the class in shared memory somehow? This is where I need help please. The reason I'm unsure is a lot of my research, points towards keeping shared memory to primitives only to avoid addressing problems and STL objects can't be used.

注意：
对于我的所有多线程，我使用C ++ 11功能。这个共享内存将是使用C ++ 11 std :: threads的完全独立的程序可执行文件，任何进程/可执行文件的任何线程都将从中访问。我已经避免了Linux pthread的任何我的多线程，并将继续这样做（除非它的控制变量不是实际的pThreads）。

NOTE: For all my multi-threading i'm using C++11 features. This shared memory will be completely seperate program executables using C++11 std::threads from which any thread of any process/executable will want access. I have avoided the Linux pthread for any of my multi-threading and will continue to do so (except if its just control variable not actual pThreads).

解决方案的参数

• 必须可以在2+个进程之间共享，这将运行多个C ++ 11 std :: thread可能希望访问。也就是说多个写入器（一次排除一个），同时允许多个同时读取器，无需作者访问。


• 不使用BOOST库。理想情况下，本机C ++ 11或内置的linux库，这将工作，而不需要安装抽象库。


• 不使用pThread实际线程，但可以使用一些对象， with C ++ 11 std :: thread。


• 理想情况下可以在运行时处理进程崩溃。例如。使用POSIX信号量，如果一个进程崩溃，当它有信号量，每个人都被拧。

• Must be shareable between 2+ processes which will be running multiple C++11 std::thread that may wish access. I.e. Multiple Writers (exclusive one at a time) while allowing multiple simultaneous readers when no writer wants access.
• Not using BOOST libraries. Ideally native C++11 or built in linux libraries, something that will work without the need to install abstract libraries.
• Not using pThread actual threads but could use some object from there that will work with C++11 std::thread.
• Ideally can handle a process crash while in operation. E.g. Using POSIX semaphore if a process crashes while it has the semaphore, everyone is screwed. I have seen people using file locks?

提前感谢

推荐答案

将共享内存保存到基元，以避免解决问题

keeping shared memory to primitives only to avoid addressing problems

可以在程序中使用指针和共享内存对象，只要内存 mmap 编译到同一个地址。这实际上是一个直截了当的提议，特别是在64位。请参阅我为实施详细信息写的开源C库： rszshm - 可调整大小的指针安全共享内存。

You can use pointers in and to shared memory objects across programs, so long as the memory is mmaped to the same address. This is actually a straightforward proposition, especially on 64 bit. See this open source C library I wrote for implementation details: rszshm - resizable pointer-safe shared memory.

使用POSIX信号量，如果一个进程崩溃，当它有信号量，每个人都被拧。

Using POSIX semaphore if a process crashes while it has the semaphore, everyone is screwed.

如果你想使用OS中断的信号量，SysV信号量有SEM_UNDO，在这种情况下恢复。 OTOH pthread提供了强大的互斥体，可以在共享内存中嵌入和共享。这可以用于构建更复杂的机制。

If you want to use OS mediated semaphores, the SysV semaphores have SEM_UNDO, which recovers in this case. OTOH pthread offers robust mutexes that can be embedded and shared in shared memory. This can be used to build more sophisticated mechanisms.

在信号集中提供多个信号量的SysV方案，其中一组操作必须全部成功，或者调用块，允许建立复杂的机制。可以用一组三个信号量进行读/写锁定。

The SysV scheme of providing multiple semaphores in a semaphore set, where a group of actions must all succeed, or the call blocks, permits building sophisticated mechanism too. A read/write lock can be made with a set of three semaphores.

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