导航:[首页]->[cpp]->[Posix纤程库]

纤程可以认为是用户级线程,切换都在用户态运行,效率较高,不过和线程最大的区别时,纤程必须自己明确地释放执行回话,否则其他人将一直不能被执行.

纤程的特性尤其使用状态机或者小逻辑处理

主要包括makecontext/swapcontext,getcontext/setcontext等几个函数.

#include <ucontext.h>
#include <stdio.h>
#include <stdlib.h>

static ucontext_t uctx_main, uctx_func1, uctx_func2;

#define handle_error(msg) \
    do { perror(msg); exit(EXIT_FAILURE); } while (0)

static void func1(void)
{
    printf("func1: started\n");
    printf("func1: swapcontext(&uctx_func1, &uctx_func2)\n");
    if (swapcontext(&uctx_func1, &uctx_func2) == -1)
        handle_error("swapcontext");
    printf("func1: returning\n");
}

static void func2(void)
{
    printf("func2: started\n");
    printf("func2: swapcontext(&uctx_func2, &uctx_func1)\n");
    if (swapcontext(&uctx_func2, &uctx_func1) == -1)
        handle_error("swapcontext");
    printf("func2: returning\n");
}

int main(int argc, char *argv[])
{
    char func1_stack[16384];
    char func2_stack[16384];

    if (getcontext(&uctx_func1) == -1)
        handle_error("getcontext");
    uctx_func1.uc_stack.ss_sp = func1_stack;
    uctx_func1.uc_stack.ss_size = sizeof(func1_stack);
    uctx_func1.uc_link = &uctx_main;
    makecontext(&uctx_func1, func1, 0);

    if (getcontext(&uctx_func2) == -1)
        handle_error("getcontext");
    uctx_func2.uc_stack.ss_sp = func2_stack;
    uctx_func2.uc_stack.ss_size = sizeof(func2_stack);
    /* Successor context is f1(), unless argc > 1 */
    uctx_func2.uc_link = (argc > 1) ? NULL : &uctx_func1;
    makecontext(&uctx_func2, func2, 0);

    printf("main: swapcontext(&uctx_main, &uctx_func2)\n");
    if (swapcontext(&uctx_main, &uctx_func2) == -1)
        handle_error("swapcontext");

    printf("main: exiting\n");
    exit(EXIT_SUCCESS);
}

由于纤程和Luacoroutine很相似.云风大师搞了一个C 的 coroutine 库

参考

  1. http://blog.csdn.net/cyberlabs/article/details/6920138
  2. http://blog.codingnow.com/2012/07/c_coroutine.html