Re: [RFC \ WISH] Add -o option to git-rev-list

["Marco Costalba" <mcostalba@gmail.com>]

On 12/11/06, Josef Weidendorfer <Josef.Weidendorfer@gmx.de> wrote:
> On Monday 11 December 2006 01:15, Marco Costalba wrote:
> >               guiUpdateTimer.start(100, true);
>
> What is the result with "guiUpdateTimer.start(0, true);" ?
> There is no need to put in any time interval at all, because
> the timeout is a normal event which will be queued in the GUI
> event queue.
>
> If there were X events in the mean time, they are queued and handled
> before your timeOut function is called again. So the GUI will be
> responsive, even if you have a 0 ms timer.
>

IOW you suggest to use a brute force polling of the pipe.

I'will try this, just to test the pipe, not the application because I
would really need to read data in big chunks.

Data read from pipe/file or something else is read in an array (char*
[]) and do not touched anymore, no more copies are made. For every
read a new array is allocated on the heap.

With chunks of 64KB, because each rev descriptions is about few
hundered bytes only few revs (about 1% with current linux tree) fall
at the boundary of the chunk, half in one and the rest in the next.
This boundary revs require a special handling that at the end involves
an additional copy.

If I get from the pipe very small data (few KB) probably it would be
better to read always in a local array of fixed size and then copy to
final destination in memory. But this imply that all the data work
copy is duplicated: instead of 30MB of data we'll going to move 60MB
(linux tree)

With big chunks of 64KB only about 1% of data (revs that fall at the
array boundary) is duplicated.