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Date:      Tue, 10 Apr 2012 15:25:40 +0100
From:      Ben Short <ben@benshort.co.uk>
To:        freebsd-questions@freebsd.org
Subject:   Using kqueue with 2 threads
Message-ID:  <CAOiKr=t3V=MWCc6Z_%2BskZYkS-jrXwXUiOkuOk7N_sBCaKWMZxQ@mail.gmail.com>
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Hi,

I'm trying to use a kqueue to listen for VNODE events on a worker thread. I
want new events  to be registered with the kqueue by a separate thread.

I have been referring to this example [URL="
http://doc.geoffgarside.co.uk/kqueue/file.html"]
http://doc.geoffgarside.co.uk/kqueue/file.html[/URL]

Here are the relevant parts of code as it is at the moment.

In my worker thread:

[CODE]std::cerr << "Started worker" << std::endl;

    struct kevent ke;
    int i;

    while ( !mStopRequested ) {

        memset(&ke, 0x00, sizeof(kevent));

        i = kevent(kq, NULL, 0, &ke, 1, NULL);
        if ( i == -1 ) {
            std::cerr << "kqueue produced error: " << strerror(i) <<
std::endl;
            continue; // todo is this the best thing todo?
        }

        std::cerr << "Beep: " << i << std::endl;

    }

    std::cerr << "Shutting down worker" << std::endl;[/CODE]

Other thread

[CODE]int fd = open(fileName.c_str(), O_RDONLY);
    if ( fd == -1 ) {
        std::cerr << "Failed to open file: " << fileName << " Error: " <<
strerror(errno) << std::endl;
        // todo throw exception
    }

    struct kevent ke;

    EV_SET(&ke, fd, EVFILT_VNODE, EV_ADD, NOTE_DELETE | NOTE_RENAME |
NOTE_EXTEND, 0, NULL);

    if (kevent(kq, &ke, 1, NULL, 0, NULL) == -1) {
        std::cerr << "kevent produced error: " << strerror(errno) <<
std::endl;
    }[/CODE]


When I run my code the kevent call in the worker code doesn't block at all.
Any ideas what I'm missing? or if what I want to do is even possible?

Ben

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