Re: [fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
Vinzent Höfler wrote: Graeme Geldenhuys grae...@opensoft.homeip.net: I have a corrected TMultiReadExclusiveWriteSynchronizer implementation (don't worry, not based on Delphi implementation) that I can donate to FPC. I hope it isn't based on the Delphi one. Last time I heard the Delphi implementation suffers from occasional dead locks. If you read my mail (as quoted above), I clearly stated that it is NOT based on the Delphi one. After all, I brought to attention the Delphi similarities in the FPC code a while back - so I would not introduce copyright code into FPC. I just need confirmation that the current implementation in FPC is incorrect though. It's not incorrect, just inefficient. I have to disagree. The currently class name is TMultiReadExclusiveWriteSynchronizer. The currently implementation does NOT allow multi-read (so the class name totally misleading). It uses a simple Critical Section to block any other threads while reading or writing. At least, the FPC team needs to rename the class to TSimpleRWSync (to be Delphi compatible with the same functionality). Regards, - Graeme - -- fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
In our previous episode, Graeme Geldenhuys said: I just need confirmation that the current implementation in FPC is incorrect though. It's not incorrect, just inefficient. I have to disagree. The currently class name is TMultiReadExclusiveWriteSynchronizer. The currently implementation does NOT allow multi-read (so the class name totally misleading). It uses a simple Critical Section to block any other threads while reading or writing. This is already known since the beginning. It is just an initial implementation to ease porting. At least, the FPC team needs to rename the class to TSimpleRWSync (to be Delphi compatible with the same functionality). Sure. I didn't know TSimple*, otherwise i'd suggest to simply delete it, it was always meant as a placeholder. But only when there is a validated, portable substitute. Since though limited and inefficient, the current implementation keeps codebases running. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
Florian Klaempfl flor...@freepascal.org: If you have a better for unix this will be fine. IIRC it is not easy (if possible after all?) to implement TMultiReadExclusiveWriteSynchronizer for unix systems. It's possible, yes. If it's possible in an efficient way, is another question. Vinzent. -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01 ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
In our previous episode, Florian Klaempfl said: (don't worry, not based on Delphi implementation) that I can donate to FPC. I just need confirmation that the current implementation in FPC is incorrect though. If you have a better for unix this will be fine. IIRC it is not easy (if possible after all?) to implement TMultiReadExclusiveWriteSynchronizer for unix systems. Afaik there is a document on the net about an implementation on Solaris. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
Graeme Geldenhuys grae...@opensoft.homeip.net: I have a corrected TMultiReadExclusiveWriteSynchronizer implementation (don't worry, not based on Delphi implementation) that I can donate to FPC. I hope it isn't based on the Delphi one. Last time I heard the Delphi implementation suffers from occasional dead locks. So any such implementation should be reviews very thouroughly. ;) I just need confirmation that the current implementation in FPC is incorrect though. It's not incorrect, just inefficient. Vinzent. -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01 ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
Hi, The current TMultiReadExclusiveWriteSynchronizer as implemented in FPC 2.3.1 is wrong. It use Critical Sections in a standard way which means it blocks all other threads while one thread is doing a Read. This is wrong. It is a MULTI read, SINGLE write synchronizer. So it must only block other thread is a Write is in progress. But allow multiple reads while no Write is in progress. The TMultiReadExclusiveWriteSynchronizer is currently equivalent to the Delphi 7 TSimpleRWSync class, not the Delphi TMultiReadExclusiveWriteSynchronizer class. I have a corrected TMultiReadExclusiveWriteSynchronizer implementation (don't worry, not based on Delphi implementation) that I can donate to FPC. I just need confirmation that the current implementation in FPC is incorrect though. Regards, - Graeme - -- fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
Graeme Geldenhuys schrieb: Hi, The current TMultiReadExclusiveWriteSynchronizer as implemented in FPC 2.3.1 is wrong. It use Critical Sections in a standard way which means it blocks all other threads while one thread is doing a Read. This is wrong. It is a MULTI read, SINGLE write synchronizer. So it must only block other thread is a Write is in progress. But allow multiple reads while no Write is in progress. It is on the safe side but it is not optimal. The TMultiReadExclusiveWriteSynchronizer is currently equivalent to the Delphi 7 TSimpleRWSync class, not the Delphi TMultiReadExclusiveWriteSynchronizer class. I have a corrected TMultiReadExclusiveWriteSynchronizer implementation (don't worry, not based on Delphi implementation) that I can donate to FPC. I just need confirmation that the current implementation in FPC is incorrect though. If you have a better for unix this will be fine. IIRC it is not easy (if possible after all?) to implement TMultiReadExclusiveWriteSynchronizer for unix systems. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
On 28 Aug 2009, at 10:35, Florian Klaempfl wrote: If you have a better for unix this will be fine. IIRC it is not easy (if possible after all?) to implement TMultiReadExclusiveWriteSynchronizer for unix systems. What's wrong with these routines: pthread_rwlock_init, pthread_rwlock_rdlock/pthread_rwlock_wrlock, pthread_rwlock_unlock, pthread_rwlock_destroy? Jonas ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] TMultiReadExclusiveWriteSynchronizer is wrongly implemented
Jonas Maebe schrieb: On 28 Aug 2009, at 10:35, Florian Klaempfl wrote: If you have a better for unix this will be fine. IIRC it is not easy (if possible after all?) to implement TMultiReadExclusiveWriteSynchronizer for unix systems. What's wrong with these routines: pthread_rwlock_init, pthread_rwlock_rdlock/pthread_rwlock_wrlock, pthread_rwlock_unlock, pthread_rwlock_destroy? I simply don't know but I thought there was a reason it could have been also something like kylix compatibility. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
