Re: [Qemu-devel] [PATCH 5/6] main-loop: replace WaitForMultipleObjects with g_poll

[Blue Swirl]

On Tue, Mar 20, 2012 at 09:49, Paolo Bonzini <address@hidden> wrote:
> On w32, glib implements g_poll using WaitForMultipleObjects
> or MsgWaitForMultipleObjects.  This means that we can simplify
> our code by switching to g_poll, and at the same time prepare for
> adding back glib sources.

Unfortunately g_poll does not seem to be available in glib-2.0:
  CC    main-loop.o
/src/qemu/main-loop.c: In function 'os_host_main_loop_wait':
/src/qemu/main-loop.c:438: warning: implicit declaration of function 'g_poll'
/src/qemu/main-loop.c:438: warning: nested extern declaration of 'g_poll'
  LINK  qemu-img.exe
main-loop.o: In function `os_host_main_loop_wait':
/src/qemu/main-loop.c:438: undefined reference to `_g_poll'

>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  main-loop.c |   40 +++++++++++++++++-----------------------
>  1 files changed, 17 insertions(+), 23 deletions(-)
>
> diff --git a/main-loop.c b/main-loop.c
> index 7364074..4d02568 100644
> --- a/main-loop.c
> +++ b/main-loop.c
> @@ -220,9 +220,9 @@ int main_loop_init(void)
>
>  static fd_set rfds, wfds, xfds;
>  static int nfds;
> +static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
>
>  #ifndef _WIN32
> -static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
>  static int n_poll_fds;
>  static int max_priority;
>
> @@ -351,6 +351,7 @@ void qemu_del_polling_cb(PollingFunc *func, void *opaque)
>  /* Wait objects support */
>  typedef struct WaitObjects {
>     int num;
> +    int revents[MAXIMUM_WAIT_OBJECTS + 1];
>     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
>     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
>     void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
> @@ -367,6 +368,7 @@ int qemu_add_wait_object(HANDLE handle, WaitObjectFunc 
> *func, void *opaque)
>     w->events[w->num] = handle;
>     w->func[w->num] = func;
>     w->opaque[w->num] = opaque;
> +    w->revents[w->num] = 0;
>     w->num++;
>     return 0;
>  }
> @@ -385,6 +387,7 @@ void qemu_del_wait_object(HANDLE handle, WaitObjectFunc 
> *func, void *opaque)
>             w->events[i] = w->events[i + 1];
>             w->func[i] = w->func[i + 1];
>             w->opaque[i] = w->opaque[i + 1];
> +            w->revents[i] = w->revents[i + 1];
>         }
>     }
>     if (found) {
> @@ -400,9 +403,8 @@ void qemu_fd_register(int fd)
>
>  static int os_host_main_loop_wait(int timeout)
>  {
> -    int ret, ret2, i;
> +    int ret, i;
>     PollingEntry *pe;
> -    int err;
>     WaitObjects *w = &wait_objects;
>     static struct timeval tv0;
>
> @@ -422,33 +424,25 @@ static int os_host_main_loop_wait(int timeout)
>         }
>     }
>
> +    for (i = 0; i < w->num; i++) {
> +        poll_fds[i].fd = (DWORD) w->events[i];
> +        poll_fds[i].events = G_IO_IN;
> +    }
> +
>     qemu_mutex_unlock_iothread();
> -    ret = WaitForMultipleObjects(w->num, w->events, FALSE, timeout);
> +    ret = g_poll(poll_fds, w->num, timeout);
>     qemu_mutex_lock_iothread();
> -    if (WAIT_OBJECT_0 + 0 <= ret && ret <= WAIT_OBJECT_0 + w->num - 1) {
> -        if (w->func[ret - WAIT_OBJECT_0]) {
> -            w->func[ret - WAIT_OBJECT_0](w->opaque[ret - WAIT_OBJECT_0]);
> +    if (ret > 0) {
> +        for (i = 0; i < w->num; i++) {
> +            w->revents[i] = poll_fds[i].revents;
>         }
> -
> -        /* Check for additional signaled events */
> -        for (i = (ret - WAIT_OBJECT_0 + 1); i < w->num; i++) {
> -            /* Check if event is signaled */
> -            ret2 = WaitForSingleObject(w->events[i], 0);
> -            if (ret2 == WAIT_OBJECT_0) {
> -                if (w->func[i]) {
> -                    w->func[i](w->opaque[i]);
> -                }
> -            } else if (ret2 != WAIT_TIMEOUT) {
> -                err = GetLastError();
> -                fprintf(stderr, "WaitForSingleObject error %d %d\n", i, err);
> +        for (i = 0; i < w->num; i++) {
> +            if (w->revents[i] && w->func[i]) {
> +                w->func[i](w->opaque[i]);
>             }
>         }
> -    } else if (ret != WAIT_TIMEOUT) {
> -        err = GetLastError();
> -        fprintf(stderr, "WaitForMultipleObjects error %d %d\n", ret, err);
>     }
>
> -
>     /* If an edge-triggered socket event occurred, select will return a
>      * positive result on the next iteration.  We do not need to do anything
>      * here.
> --
> 1.7.7.6
>
>
>