如何从另一个函数内的随机位置调用C函数？ [英] How to call a C function from random places inside another function?

问题描述

谁能告诉我如何在 C 函数内的随机位置插入函数调用（例如 Yield（）），当代码运行时， Yield（）从代码的不同部分被调用？

Can anyone tell me how to insert a function call (say Yield() ) at random places inside a C function, so that each time the code is run, Yield() gets called from different parts of the code ?

我面临着我在合作线程环境中使用2个线程这样的要求，除非正在运行的线程显式地产生处理器，否则其他（正在等待）的线程将无法开始运行。我不想将 Yield（）调用放在单个点上，因为这会使线程序列具有确定性。在不重新布线整个环境（从协作到抢占）的情况下，这是我能想到的唯一解决方案，其中Thread_1（）在随机位置进行 Yield（）调用

I am faced with such a requirement as I'm using 2 threads in a cooperative threading environment , where unless the running thread yields the processor explicitly , the other (waiting) thread cannot start running. I don't want to place the Yield() call at a single point , since that makes the thread sequence deterministic. Without rewiring the entire environment (from cooperative to pre-emptive) , this is the only solution I can think of in which Thread_1() makes the Yield() call at random places inside it, allowing Thread_2() to take over.

也欢迎对实现相同最终目标的其他解决方案有任何见解！

Any insights into a different solution achieving the same end-goals is also welcome!

推荐答案

我认为需要BFI解决方案

我认为您必须解决该问题明显的方法。您将需要为 Yield（）进行包装，从而对是否调用真实对象做出随机决定。

A BFI solution is called for, I think

I think you will have to solve this the obvious way. You will need to make a wrapper for Yield() that makes a "random" decision on whether to call the real thing.

如果您不关心执行速度，那么我会使其成为真正的C函数，如果您愿意，我建议使用预处理器宏。

If you are not concerned with execution speed then I would make it a real C function, and if you are I might suggest a preprocessor macro.

因此，

#define Yield0() ((random() & 0xf) == 0 && Yield())

为需要的通话机会选择百分比掩码。对于0xf，如果 random（）具有良好的低阶位随机性，则您将在16次调用中看到1 Yield（）。如果可以使用MT或其他高质量的随机数生成器，则低阶位将直接有用，否则您可能需要 random（）>> 3& ...

Choose the mask for the percentage chance of a call you want. For 0xf, and if random() has good low-order bit randomness, then you would see 1 Yield() in 16 calls. If you can use an MT or other high quality random number generator, the low order bits will be directly useful, otherwise you might want to random() >> 3 & ...

您只需要把Yield0（）调用放在任何地方。

And you will just need to put Yield0() calls everywhere.

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