上下文切换 – ucontext_t和makecontext()

makecontext()将一个函数及其参数附加到一个上下文,该函数是否一直坚持上下文,直到更改提交给它为止？

1 #include <stdio.h>
  2 #include <stdlib.h>
  3 #include <ucontext.h>
  4 #define MEM 64000
  5 
  6 ucontext_t T1,T2,Main;
  7 ucontext_t a;
  8 
  9 int fn1()
 10 {
 11   printf("this is from 1n");
 12   setcontext(&Main);
 13 }
 14 
 15 void fn2()
 16 {
 17   printf("this is from 2n");
 18   setcontext(&a);
 19   printf("finished 1n");
 20 }
 21 
 22 void start()
 23 {
 24   getcontext(&a);
 25   a.uc_link=0;
 26   a.uc_stack.ss_sp=malloc(MEM);
 27   a.uc_stack.ss_size=MEM;
 28   a.uc_stack.ss_flags=0;
 29   makecontext(&a,(void*)&fn1,0);
 30 }
 31 
 32 int main(int argc,char *argv[])
 33 {
 34   start();
 35   getcontext(&Main);
 36   getcontext(&T1);
 37   T1.uc_link=0;
 38   T1.uc_stack.ss_sp=malloc(MEM);
 39   T1.uc_stack.ss_size=MEM;
 40   makecontext(&T1,0);
 41   swapcontext(&Main,&T1);
 42   getcontext(&T2);
 43   T2.uc_link=0;
 44   T2.uc_stack.ss_sp=malloc(MEM);
 45   T2.uc_stack.ss_size=MEM;
 46   T2.uc_stack.ss_flags=0;
 47   makecontext(&T2,(void*)&fn2,0);
 48   swapcontext(&Main,&T2);
 49   printf("completedn");
 50   exit(0);
 51 }