Hi Hans, not that we know of. Contribution wlecome. Cheers, Fons. On Wed, 2002-03-13 at 18:51, Essel Dr.Hans-Georg wrote: > Hi Rooters, > I found this interesting, but maybe out dated dialog. Has anybody > implemented in the mean time ring buffers (in memory only)? > Thanks for hints > Hans > > > Jens Paetzold wrote: > > > > Hello, > > > > I would like to change for an online analyzer from paw to root. > > We have the HBOOK ring buffer for row wise ntuples used up to now. > > I have already managed to use TMapFile for the shared memory section with > > histogramms. Now I would like to use also TTrees. > > My question: Is there a simple way to implement a feature like this ring > > buffer for TTrees on a TMapFile? Maybe I have not discovered it yet? > > Or is there some idea for the implementation of this? > > > > Thanks, Jens > > The ring buffer technique is not implemented in TTree. > One of the reasons is that the TMapFile class is not real shared > memory. A copy from the real object via TObject::Streamer is necessary > to update the shared memory area. > I think it would be far more efficient to implement a new class > to support a ring buffer in real shared memory with no copy at all > on the producer and consumer(s). > This class would support only simple types (chars, shorts, ints, floats > and doubles). The class could be a variant of the exsiting TNtuple > class. > > Rene Brun -- Org: CERN, European Laboratory for Particle Physics. Mail: 1211 Geneve 23, Switzerland E-Mail: Fons.Rademakers@cern.ch Phone: +41 22 7679248 WWW: http://root.cern.ch/~rdm/ Fax: +41 22 7679480
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