FSEvents C++示例

Question

我需要为Mac中的文件夹创建FSEvents观察器.我对C++感到满意,有没有办法用C++代码而不是Objective-C来获取FSEvents通知.是否有一些示例代码开始和我需要包含的任何库..？

我已经在这个页面上了. http://developer.apple.com/library/mac/#featuredarticles/FileSystemEvents/_index.html

但似乎只有Objective C,我可以有它的CPP版本

Answer 1

是的,它可以用C.你应该寻找内核队列.

这是一个观察目录的小样本:

#include <errno.h>       // for errno
#include <fcntl.h>       // for O_RDONLY
#include <stdio.h>       // for fprintf()
#include <stdlib.h>      // for EXIT_SUCCESS
#include <string.h>      // for strerror()
#include <sys/event.h>   // for kqueue() etc.
#include <unistd.h>      // for close()

int main (int argc, const char *argv[])
{
   int kq = kqueue ();
   // dir name is in argv[1], NO checks for errors here
   int dirfd = open (argv[1], O_RDONLY);

   struct kevent direvent;
    EV_SET (&direvent, dirfd, EVFILT_VNODE, EV_ADD | EV_CLEAR | EV_ENABLE,
            NOTE_WRITE, 0, (void *)dirname);

   kevent(kq, &direvent, 1, NULL, 0, NULL);

   // Register interest in SIGINT with the queue.  The user data
   // is NULL, which is how we'll differentiate between
   // a directory-modification event and a SIGINT-received event.
   struct kevent sigevent;
   EV_SET (&sigevent, SIGINT, EVFILT_SIGNAL, EV_ADD | EV_ENABLE, 0, 0, NULL);
   // kqueue event handling happens after the legacy API, so make
   // sure it doesn eat the signal before the kqueue can see it.
   signal (SIGINT, SIG_IGN);

   // Register the signal event.
   kevent(kq, &sigevent, 1, NULL, 0, NULL);

   while (1) {
       // camp on kevent() until something interesting happens
       struct kevent change;
       if (kevent(kq, NULL, 0, &change, 1, NULL) == -1) { exit(1); }
       // The signal event has NULL in the user data.  Check for that first.
       if (change.udata == NULL) {
           break;
       } else {
        // udata is non-null, so it's the name of the directory
        printf ("%s\n", (char*)change.udata);
       }
   }
   close (kq);
   return 0;
}

细节可以在ch中找到.Mark Dalrymple的"高级Mac OSX编程"16(kqueues和FSEvents).其他信息可以在*BSD文档中找到kqueues.

或者使用FSEvents中的这个API(它主要是基于C的).

FSEventStreamRef FSEventStreamCreate (CFAllocatorRef allocator,
                                  FSEventStreamCallback callback,
                                  FSEventStreamContext *context,
                                  CFArrayRef pathsToWatch,
                                  FSEventStreamEventId sinceWhen,
                                  CFTimeInterval latency,
                                  FSEventStreamCreateFlags flags);

使用pure-C回调创建FSEvents事件流.

然后使用.将此事件流附加到您的runloop

void FSEventStreamScheduleWithRunLoop (FSEventStreamRef streamRef,
                                   CFRunLoopRef runLoop,
                                   CFStringRef runLoopMode);

是的,在这里你可能应该使用一行Obj-C来获取RunLoop句柄:使用-getCFRunLoop从NSRunLoop获取CFRunLoop

CFRunLoop* loopRef = [[NSRunLoop currentRunLoop] getCFRunLoop];

或使用纯C调用

CFRunLoop* loopRef =  CFRunLoopGetCurrent();

使用启动事件流

Boolean FSEventStreamStart (FSEventStreamRef streamRef);

使用停止事件流

void FSEventStreamStop (FSEventStreamRef streamRef);

然后使用以下方法从runloop中取消计划:

void FSEventStreamUnscheduleFromRunLoop (FSEventStreamRef streamRef,
                                     CFRunLoopRef runLoop,
                                     CFStringRef runLoopMode);

使流无效(清理):

void FSEventStreamInvalidate (FSEventStreamRef streamRef);

希望这会让你开始.