ucontext
簡介 ucontext
Example from wiki:
cpp
#include <stdio.h>
#include <ucontext.h>
#include <unistd.h>
int main(){
ucontext_t context;
getcontext(&context);
puts("Hello world");
sleep(1);
setcontext(&context);
return 0;
}會輸出
cpp
$ ./a.out
Hello world
Hello world
Hello world
^C包裝
cpp
#include <ucontext.h>
#include <cstdint>
#include <memory>
#include <functional>
struct coroutine {
coroutine(const std::function<void (coroutine &)> func, size_t stack_size = SIGSTKSZ)
: stack{new unsigned char[stack_size]}, func{func} {
getcontext(&callee);
callee.uc_link = &caller;
callee.uc_stack.ss_size = stack_size;
callee.uc_stack.ss_sp = stack.get();
makecontext(&callee, reinterpret_cast<void (*)()>(&coroutine_call), 2, reinterpret_cast<size_t>(this) >> 32, this);
}
coroutine(const coroutine &) = delete;
coroutine & operator=(const coroutine &) = delete;
coroutine(coroutine &&) = default;
coroutine & operator=(coroutine &&) = default;
void operator()() {
if (returned) return;
swapcontext(&caller, &callee);
}
operator bool() const {
return !returned;
}
void yield() {
swapcontext(&callee, &caller);
}
private:
ucontext_t caller;
ucontext_t callee;
std::unique_ptr<unsigned char[]> stack;
std::function<void (coroutine &)> func;
bool returned = false;
static void coroutine_call(
uint32_t this_pointer_left_half, uint32_t this_pointer_right_half) {
coroutine & this_ = *reinterpret_cast<coroutine *>((static_cast<size_t>(this_pointer_left_half) << 32) + this_pointer_right_half);
this_.func(this_);
this_.returned = true;
}
};使用
cpp
#include <coroutine.h>
#include <iostream>
int main() {
coroutine test{[](coroutine & self) {
for (int i = 0; i < 5; ++i) {
std::cout << "coroutine " << i << std::endl;
self.yield();
}
}};
while(test) {
std::cout << "main" << std::endl;
test();
}
return 0;
}