首先，贴一下异步io中用的的一些结构体，因为平常很少用，整理起来方便查看。 aio.h中的struct aiocb
struct aiocb { int aio_fildes; /* file desriptor. */ int aio_lio_opcode; /* operation to be performed. */ int aio_reqprio; /* request priority offset. */ volatile void *aio_buf; /* location of buffer. */ size_t aio_nbytes; /* length of transfer. */ struct sigevent aio_sigevent; /* signal number and value. */ /* internal members. */ struct aiocb *__next_prio; int __abs_prio; int __policy; int __error_code; __ssize_t __return_value; };
siginfo.h中的struct sigevent和union sigval
typedef struct sigevent { sigval_t sigev_value; int sigev_signo; int sigev_notify; union { int _pad[__sigev_pad_size]; /* when sigev_signal and sigev_thread_id set, lwp id of the thread to receive the signal. */ __pid_t _tid; struct { void (*_function) (sigval_t); /* function to start. */ void *_attribute; /* really pthread_attr_t. */ } _sigev_thread; } _sigev_un; } sigevent_t; /* posix names to access some of the members. */ # define sigev_notify_function _sigev_un._sigev_thread._function # define sigev_notify_attributes _sigev_un._sigev_thread._attribute
typedef union sigval { int sival_int; void *sival_ptr; } sigval_t;
例子1：
#include <aio.h> #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <signal.h> void async_read(int s, siginfo_t * info, void * context) { struct aiocb *ptr = (struct aiocb *)info->si_value.sival_ptr; printf("read=%s", (char *)ptr->aio_buf); } int main(void) { struct aiocb cb; char sbuf[100]; int ret; struct sigaction act; sigemptyset(&act.sa_mask); act.sa_flags = sa_restart | sa_siginfo; act.sa_sigaction = async_read; sigaction(sigusr1, &act, null); bzero(&cb, sizeof(cb)); cb.aio_fildes = 0; cb.aio_buf = sbuf; cb.aio_nbytes = 100; cb.aio_offset = 0; cb.aio_sigevent.sigev_value.sival_ptr = &cb; cb.aio_sigevent.sigev_notify = sigev_signal; cb.aio_sigevent.sigev_signo = sigusr1; ret = aio_read(&cb); if (ret == -1) { perror("aio_read"); exit(1); } int i = 0; while (1) { printf("%d/n",i++); sleep(3); } return 0; }
运行结果： 注意：要加相应的库，-lrt
$ ./gcc -o test aio_signal.c -lrt$ ./test 0 1 h2 ell3 o read=hello 4 ^c
例子2：
#include <aio.h> #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> void async_read(sigval_t val) { struct aiocb *ptr = (struct aiocb *)val.sival_ptr; printf("read=%s", (char *)ptr->aio_buf); } int main(void) { struct aiocb cb; char sbuf[100]; int ret; bzero(&cb, sizeof(cb)); cb.aio_fildes = 0; cb.aio_buf = sbuf; cb.aio_nbytes = 100; cb.aio_offset = 0; cb.aio_sigevent.sigev_value.sival_ptr = &cb; cb.aio_sigevent.sigev_notify = sigev_thread; cb.aio_sigevent.sigev_notify_function = async_read; cb.aio_sigevent.sigev_notify_attributes = null; ret = aio_read(&cb); if (ret == -1) { perror("aio_read"); exit(1); } int i = 0; while (1) { printf("%d/n",i++); sleep(1); } return 0; }
运行结果同上。
