[Spice-devel] [RFC] server: add main_dispatcher

[Yonit Halperin]

On 09/08/2011 02:17 AM, Alon Levy wrote:
Hi,
I think this patch is sufficient for the 0.8 branch (+ the comments 
bellow + locks (for several display channels threads)).
However for master, due to the red_channel refactoring I think we should 
have a more general dispatcher. It would be nice if (1) we could 
register events and their handlers, so that main_dispatcher won't need 
to know about the specific events. (2) the dispatcher will be 
bi-directional and red_dispatcher will reuse it.

Now that we have a main dispatcher, the calls to reds_update_mouse_mode 
should also be done via the red_dispatcher (those that are triggered by 
red_dispatcher_async_complete, and those that are executed from the vcpu 
thread).

<snip>

> +
> +static void main_dispatcher_handle_read(int fd, int event, void *opaque)
> +{
> +    int ret;
> +    MainDispatcher *md = opaque;
> +    MainDispatcherMessage msg;
> +
> +    ret = read(md->main_fd,&msg, sizeof(msg));
> +    if (ret == -1)
> +        if (errno == EAGAIN) {
> +            return;
> +        } else {
> +            red_printf("error reading from main dispatcher: %d\n", errno);
> +            /* TODO: close channel? */
> +            return;
> +        }
> +    }
> +    if (ret != sizeof(msg)) {
Even if it is very rare, I think we should support it and read till we 
get the whole msg.
> +        red_printf("short read in main dispatcher: %d<  %zd\n", ret, sizeof(msg));
> +        /* TODO: close channel?  */
> +        return;
> +    }
> +
> +    switch (msg.type) {
> +        case MAIN_DISPATCHER_CHANNEL_EVENT:
> +            main_dispatcher_handle_channel_event(&msg);
> +            break;
> +        default:
> +            red_printf("error: unhandled main dispatcher message type %d\n",
> +                       msg.type);
> +    }
> +}
> +
> +void main_dispatcher_init(SpiceCoreInterface *core)
> +{
> +    int channels[2];
> +
> +    memset(&main_dispatcher, 0, sizeof(main_dispatcher));
> +    main_dispatcher.core = core;
> +
> +    if (socketpair(AF_LOCAL, SOCK_STREAM, 0, channels) == -1) {
> +        red_error("socketpair failed %s", strerror(errno));
> +        return;
> +    }
> +    main_dispatcher.main_fd = channels[0];
> +    main_dispatcher.other_fd = channels[1];
> +    main_dispatcher.self = pthread_self();
> +
> +    core->watch_add(main_dispatcher.main_fd, SPICE_WATCH_EVENT_READ,
> +                    main_dispatcher_handle_read,&main_dispatcher);
> +}
> diff --git a/server/main_dispatcher.h b/server/main_dispatcher.h
> new file mode 100644
> index 0000000..2c201c7
> --- /dev/null
> +++ b/server/main_dispatcher.h
> @@ -0,0 +1,9 @@
> +#ifndef MAIN_DISPATCHER_H
> +#define MAIN_DISPATCHER_H
> +
> +#include<spice.h>
> +
> +void main_dispatcher_channel_event(int event, SpiceChannelEventInfo *info);
> +void main_dispatcher_init(SpiceCoreInterface *core);
> +
> +#endif //MAIN_DISPATCHER_H
> diff --git a/server/reds.c b/server/reds.c
> index 90779ff..ef9da4f 100644
> --- a/server/reds.c
> +++ b/server/reds.c
> @@ -56,6 +56,7 @@
>   #include "main_channel.h"
>   #include "red_common.h"
>   #include "red_dispatcher.h"
> +#include "main_dispatcher.h"
>   #include "snd_worker.h"
>   #include<spice/stats.h>
>   #include "stat.h"
> @@ -322,7 +323,8 @@ static void reds_stream_channel_event(RedsStream *s, int event)
>   {
>       if (core->base.minor_version<  3 || core->channel_event == NULL)
>           return;
> -    core->channel_event(event,&s->info);
> +
> +    main_dispatcher_channel_event(event,&s->info);
>   }
>
>   static ssize_t stream_write_cb(RedsStream *s, const void *buf, size_t size)
> @@ -3519,6 +3521,7 @@ static int do_spice_init(SpiceCoreInterface *core_interface)
>       init_vd_agent_resources();
>       ring_init(&reds->clients);
>       reds->num_clients = 0;
> +    main_dispatcher_init(core);
>
>       if (!(reds->mig_timer = core->timer_add(migrate_timout, NULL))) {
>           red_error("migration timer create failed");