Re: DataObjectLockFree: fix facts in doxygen

On Tue, Dec 11, 2012 at 3:50 PM, Herman Bruyninckx <
[email protected]> wrote:

> Anyway, the Lock Free pattern has as pre-condition for its use that there
> are
> maximally N clients of the data, so that it can foresee N+1 buffer spaces
> of the shared data.
> Did you then still find problems with the code in cases where this
> pre-condition is satisfied?


Yes.

Among the N clients there can be only one writer. This additional
precondition is clear from the implementation and even more clear from the
comments at line
119.<http://gitorious.org/orocos-toolchain/rtt/blobs/master/rtt/base/DataObjectLockFree.hpp#line194>
Alas, it was not documented. Worst, the doxygen claimed the contrary (see
the truth table).


> Since that would be a big bug, I guess.
>

I do not know if having several writers for a non-buffered data port is a
common scenario.

But it would be a hard to find one certainly, since there is no lock nor
warning, only random data corruption.

Or are you trying to add more robustness into the implementation in case
> the pre-condition is not satisfied?
>

no, I'm just fixing the doc so that it matches the implementation.

Cheers

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