在用 C 编写线程代码时,我首先必须创建一些 struct
,其中包括所有参数和一个包装函数。这会导致大量代码膨胀并且不易阅读。见:
struct some_function_args {
int arg1;
int arg2;
int arg3;
};
void some_function_wrapper(struct some_function_args* args) {
some_function(args->arg1, args->arg2, args->arg3);
}
int main() {
struct my_args;
my_args.arg1 = 1;
my_args.arg2 = 2;
my_args.arg3 = 3;
pthread_create(..., some_function_wrapper, &my_args);
pthread_join(...);
}
是否有某种宏或库(可能使用 varargs
)自动为我创建所需的结构和包装函数,就像这样?或者这在 C 中根本不可能吗?
int main() {
MY_THREAD thread = IN_THREAD {
some_function(1, 2, 3);
}
JOIN_THREAD(thread);
}
最佳答案
EDIT: I released some code. See threadify.h.
使用下面的宏你可以做这样的事情:
char a = 'A';
int b = 23;
char[] c = "Example";
pthread_t thread;
// THREAD3 because it takes 3 arguments of variable type.
THREAD3(thread, a, b, c, {
printf("test: %c %d %s\n", a, b, c);
});
JOIN(thread);
在 GCC 中是可能的,因为 GCC 有两个非标准扩展:
- 嵌套函数
typeof()
运算符
这个庞大的宏有一些缺点:
- 您不能传递右值(因为不可能创建指向它们的指针)
您需要根据参数的数量使用适当的
THREAD0
、THREAD1
... 宏(不确定是否可以解决此问题使用可变参数宏)。#include <stdio.h> #include <pthread.h> // Nested definition to work around preprocessor prescan #define __CAT(arg1, arg2) arg1 ## arg2 #define CAT(arg1, arg2) __CAT(arg1, arg2) // Use the current line number to create a unique name for objects #define NAME(arg1) CAT(arg1, __LINE__) // Creates a thread without any arguments #define THREAD0(thread, code) \ void NAME(__pthread_wrapper)(void) {\ do {code;} while(0); \ }; \ pthread_create(&thread, NULL, (void*)NAME(__pthread_wrapper), NULL); // Creates a thread with one argument by creating a struct // and passing all values via this struct. #define THREAD1(thread, arg1, code) \ typedef struct { \ typeof(arg1)* NAME(__pthread_arg1); \ } NAME(__pthread_struct); \ void NAME(__pthread_wrapper)(NAME(__pthread_struct)* data) {\ do {code;} while(0); \ }; \ NAME(__pthread_struct) NAME(__data); \ NAME(__data).NAME(__pthread_arg1) = &arg1; \ pthread_create(&thread, NULL, (void*)NAME(__pthread_wrapper), &NAME(__data)); #define THREAD2(thread, arg1, arg2, code) \ typedef struct { \ typeof(arg1)* NAME(__pthread_arg1); \ typeof(arg2)* NAME(__pthread_arg2); \ } NAME(__pthread_struct); \ void NAME(__pthread_wrapper)(NAME(__pthread_struct)* data) {\ do {code;} while(0); \ }; \ NAME(__pthread_struct) NAME(__data); \ NAME(__data).NAME(__pthread_arg1) = &arg1; \ NAME(__data).NAME(__pthread_arg2) = &arg2; \ pthread_create(&thread, NULL, (void*)NAME(__pthread_wrapper), &NAME(__data)); #define THREAD3(thread, arg1, arg2, arg3, code) \ typedef struct { \ typeof(arg1)* NAME(__pthread_arg1); \ typeof(arg2)* NAME(__pthread_arg2); \ typeof(arg3)* NAME(__pthread_arg3); \ } NAME(__pthread_struct); \ void NAME(__pthread_wrapper)(NAME(__pthread_struct)* data) {\ do {code;} while(0); \ }; \ NAME(__pthread_struct) NAME(__data); \ NAME(__data).NAME(__pthread_arg1) = &arg1; \ NAME(__data).NAME(__pthread_arg2) = &arg2; \ NAME(__data).NAME(__pthread_arg3) = &arg3; \ pthread_create(&thread, NULL, (void*)NAME(__pthread_wrapper), &NAME(__data)); /* THREAD4, THREAD5, ... */ #define JOIN(thread) pthread_join(thread, NULL);
关于c - 在 C 中使用 pthreads 时如何避免代码膨胀?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28330956/