[vdr] Re: WaitForPut/WaitForGet (was VDR developer version 1.1.31)

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Stefan Huelswitt wrote:
> 
> On 11 May 2003 Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de> wrote:
> 
> Hi,
> 
> > - Removed the WaitForPut/WaitForGet stuff from cRingBuffer, since it appears to
> >   no longer be necessary due to the implementation of cNonBlockingFileReader in
> >   dvbplayer.c. Also, the long timeout in WaitForPut caused problems with cReceivers
> >   that use a ring buffer and didn't immediately return from their Receive() function
> >   if the buffer runs full (thanks to Sascha Volkenandt for reporting this one).
> 
> With these functions removed, how I'm supposed to wait in a
> non-busy way for data arrival or free buffer space?
> 
> I cannot understand why these have been removed (specialy if we
> are close to a release). This makes the ringbuffer pretty useless
> for most uses and breaks not only my plugins.

There was a problem with cReceivers that used cRingBuffer* to buffer
the data they got in their Receive() function. The Receive() function
is supposed to return _immediately_, but when the ring buffer was full
it waited _inside_ the Put() function for up to a full second - which
broke the data stream for all cReceivers attached to that device.

Therefore I tested what would happen if the WaitForPut/WaitForGet mechanism was
removed and didn't see any difference in recording, replaying or transfer mode.
I wasn't aware that any plugin would explicitly call any of these functions.

So, if any plugin is using such a buffer in a cReceiver it would risk breaking
the data stream if the buffer runs full. And if it uses the buffer in a different
context I wonder why the waiting should be done in the buffer and not where
the actual reading or writing is done. Maybe take a look at how VDR does this
in cDvbPlayer::Action().

Of course I could put these things back into cRingBuffer, but VDR itself
wouldn't be using them any more, and any plugin that implements a cReceiver
also shouldn't do so. If there are other applications that _really_ need
WaitForPut/WaitForGet please let me know.

Klaus 
-- 
_______________________________________________________________

Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
_______________________________________________________________


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