[vlc-devel] [PATCH]Win32 screensaver disable change part II

[Juha Jeronen]

Hi,

On 05/03/2011 10:20 AM, Kaarlo Räihä wrote:
>
>
> 2011/5/2 Rémi Denis-Courmont <remi at remlab.net <mailto:remi at remlab.net>>
>
>     ----- Message d'origine -----
>     > It isn't perfect code wise, since I have NO clue how to create
>     thread
>     > without parameters using vlc thread functions.
>
>     That is impossible. If you do not need any parameter, the
>     convention is to pass NULL. That being said, there is almost
>     always need to pass a parameter, some kind of context.
>
>     > kill_thread(id)
>
>     Killing a thread makes no sense. Every thread has to be joined,
>     before the plugin is unloaded and before its context data gets
>     invalidated.
>
>
> Problem with join is that 50 seconds long sleep function I have since
> AFAIK join needs selfterminating threads. But in Win32 (according to
> MSDN) you are allowed to use ExitThread or similar function to
> terminate threads since VLC is C code.

Suggestion:

- Have an instance data struct for the thread, containing only an exit
flag (initialized to false in the main thread, just before it starts the
new thread). Malloc it, and pass a pointer as the thread argument. The
flag will be used for signaling.
- When the main thread wants to shut down the screensaver prevention
thread, it sets the exit flag to true.
- When the thread notices that its exit flag has been set to true, it joins.
- Finally, we need to take care of the 50-second sleep. How about,
instead of

for( ; ; )
{
    PreventScreensaver();
    sleep(50);
}

having

for( ; ; )
{
    PreventScreensaver();

    for(int i = 0; i < 100; ++i)
    {
        sleep(0.5); /* this is what I meant by pseudocode ;) */
        if( p_data->b_exited )
            goto _terminated; /* "doublebreak;" :) */
    }
}

_terminated:
/* ...clean up, join... */


This is not ideal, as it relies on polling, but it should get the job
done without a need to kill the thread from the outside.

 -J

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