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Re: [Pharo-dev] [Ann] ReadWriteLock

by Ben Coman

On Tue, Jan 5, 2016 at 11:59 PM, Denis Kudriashov <dionisiydk(a)gmail.com> wrote: > > 2016-01-05 16:06 GMT+01:00 Ben Coman <btc(a)openinworld.com>: >> >> btw I have this growing suspicion that we should eliminate >> Semaphore>>critical: and Semaphore>>forMutualExclusion. Semaphores >> on their own should *not* provide a facility for to protect critical >> regions since they suffer from accidental release [1] due to >> *lack*of*ownership*. > > > I have same feeling when analyse problem of critical: implementation. But I > not think that Semaphore>>forMutualExclusion is bad. But Semaphore>>forMutualExclusion *encourages* people to believe semaphores can be used *on*their*own* for mutual exclusion, when they *shouldn't*. You *must* add ownership. If the mutual exclusion object doesnât have ownership then, irrelevant of what it is called, it is not a mutex!!! [1]. "Strictly speaking [2]... -- A mutex is *locking* mechanism used to synchronize access to a resource. Only one task (can be a thread or process based on OS abstraction) can acquire the mutex. It means there is *ownership* associated with mutex, and only the owner can release the lock (mutex). -- A semaphore is *signaling* mechanism (âI am done, you can carry onâ kind of signal). For example, if you are listening songs (assume it as one task) on your mobile and at the same time your friend calls you, an interrupt is triggered upon which an interrupt service routine (ISR) signals the call processing task to wakeup >It is common case that semaphore "free" by default. With an implementation like.. Semaphore>>forMutualExclusion ^self new signal we don't gain a lot, and its a misleading convenience method since its doesn't provide the proper facility for mutual exclusion (and I do conflate mutual exclusion == mutex). Indeed, "Semaphore forMutualExclusion + roll your ownership management + problems since you weren't aware you needed to roll your own ownership management" is not more convenient than "Mutex new" If you want to keep a convenience method for a pre signalled Semaphore, then we could provide something like "Semaphore newSignalled" > And this name is explicitly said about this. Actually no. It explicitly says it provides mutual exclusion - which without ownership, it does not. It only implicitly provides a pre-signalled Semaphore - you have to *know* of look at the source. [1] https://blog.feabhas.com/2009/09/mutex-vs-semaphores-%E2%80%93-part-2-the-m… [2] http://www.geeksforgeeks.org/mutex-vs-semaphore/ cheers -ben

Jan. 5, 2016

Re: [Pharo-dev] Catalog statistics (Who know this projects?)

by Sven Van Caekenberghe

> On 05 Jan 2016, at 17:55, Esteban Lorenzano <estebanlm(a)gmail.com> wrote: > > >> On 05 Jan 2016, at 17:35, phil(a)highoctane.be wrote: >> >> I happen to know quite a number of projects. >> >> So, what's the best path to follow to put a description in them? >> >> Editing configs and saving to MetaRepo is not an issue but will put my name all over upon save, which is not really nice to people making the work. > > it doesnât matterâ¦ your name will be just the config version, not the rest. But they most probably will get overwritten in the future. The original 'source' configs need to be changed. >> >> I can spend a couple hours on it this week. > > +1 > >> >> Please advise. >> >> Phil >> >> On Tue, Jan 5, 2016 at 5:14 PM, Esteban Lorenzano <estebanlm(a)gmail.com> wrote: >> >>> On 05 Jan 2016, at 17:06, Stephan Eggermont <stephan(a)stack.nl> wrote: >>> >>> On 05-01-16 16:56, Esteban Lorenzano wrote: >>>> >>>>> On 05 Jan 2016, at 16:51, Stephan Eggermont <stephan(a)stack.nl> wrote: >>>>> >>>>> On 05-01-16 16:21, Esteban Lorenzano wrote: >>>>>> Soâ¦ I took a couple of minutes to do a small list of project description status: >>>>>> >>>>>> From a total of 379 projects currently in the catalog, just 115 have a description and/or keywords associated. >>>>>> Which means 264 are mysterious projects nobody can guess what are they about. >>>>>> >>>>>> I was thinking most of this projects would be in Unsorted (or Pharo 3), but I found that many are also on Pharo 5 and 4â¦. which is frankly unacceptable :) >>>>>> Even very important projects like Seaside or Garage and Glorp are not documented. >>>>>> >>>>>> So, please peopleâ¦ take a look at your projects and PLEASE, provide a description and proper keywordsâ¦ Nobody can guess what is Aconcagua (besides a cool mountain in south america), or Telescope, etc., etc., etc. >>>>>> >>>>>> Here the list of non-documented projects: >>>>> >>>>> ss3 has no projects? >>>> >>>> catalog just catalogs projects in the MetaRepos >>>> you project can live where he wants, but configuration needs to be copied into MetaRepoForPharoXX >>>> >>>> thatâs how always was, and thatâs what catalog shows :) >>> >>> http://ss3.gemtalksystems.com/ss/MetaRepoForPharo20 >> >> hmmmâ¦ didnât remember that existed :) >> but i was even considering propose you to deprecate the unsorted repository (a lot of obsolete projects there)â¦ >> >> Esteban >> >>> >>> Stephan >> >> >

Jan. 5, 2016

Re: [Pharo-dev] Catalog statistics (Who know this projects?)

by Esteban Lorenzano

> On 05 Jan 2016, at 17:35, phil(a)highoctane.be wrote: > > I happen to know quite a number of projects. > > So, what's the best path to follow to put a description in them? > > Editing configs and saving to MetaRepo is not an issue but will put my name all over upon save, which is not really nice to people making the work. it doesnât matterâ¦ your name will be just the config version, not the rest. > > I can spend a couple hours on it this week. +1 > > Please advise. > > Phil > > On Tue, Jan 5, 2016 at 5:14 PM, Esteban Lorenzano <estebanlm(a)gmail.com <mailto:estebanlm@gmail.com>> wrote: > >> On 05 Jan 2016, at 17:06, Stephan Eggermont <stephan(a)stack.nl <mailto:stephan@stack.nl>> wrote: >> >> On 05-01-16 16:56, Esteban Lorenzano wrote: >>> >>>> On 05 Jan 2016, at 16:51, Stephan Eggermont <stephan(a)stack.nl <mailto:stephan@stack.nl>> wrote: >>>> >>>> On 05-01-16 16:21, Esteban Lorenzano wrote: >>>>> Soâ¦ I took a couple of minutes to do a small list of project description status: >>>>> >>>>> From a total of 379 projects currently in the catalog, just 115 have a description and/or keywords associated. >>>>> Which means 264 are mysterious projects nobody can guess what are they about. >>>>> >>>>> I was thinking most of this projects would be in Unsorted (or Pharo 3), but I found that many are also on Pharo 5 and 4â¦. which is frankly unacceptable :) >>>>> Even very important projects like Seaside or Garage and Glorp are not documented. >>>>> >>>>> So, please peopleâ¦ take a look at your projects and PLEASE, provide a description and proper keywordsâ¦ Nobody can guess what is Aconcagua (besides a cool mountain in south america), or Telescope, etc., etc., etc. >>>>> >>>>> Here the list of non-documented projects: >>>> >>>> ss3 has no projects? >>> >>> catalog just catalogs projects in the MetaRepos >>> you project can live where he wants, but configuration needs to be copied into MetaRepoForPharoXX >>> >>> thatâs how always was, and thatâs what catalog shows :) >> >> http://ss3.gemtalksystems.com/ss/MetaRepoForPharo20 <http://ss3.gemtalksystems.com/ss/MetaRepoForPharo20> > > hmmmâ¦ didnât remember that existed :) > but i was even considering propose you to deprecate the unsorted repository (a lot of obsolete projects there)â¦ > > Esteban > >> >> Stephan > >

Jan. 5, 2016

Re: [Pharo-dev] Catalog statistics (Who know this projects?)

by phil＠highoctane.be

I happen to know quite a number of projects. So, what's the best path to follow to put a description in them? Editing configs and saving to MetaRepo is not an issue but will put my name all over upon save, which is not really nice to people making the work. I can spend a couple hours on it this week. Please advise. Phil On Tue, Jan 5, 2016 at 5:14 PM, Esteban Lorenzano <estebanlm(a)gmail.com> wrote: > > On 05 Jan 2016, at 17:06, Stephan Eggermont <stephan(a)stack.nl> wrote: > > On 05-01-16 16:56, Esteban Lorenzano wrote: > > > On 05 Jan 2016, at 16:51, Stephan Eggermont <stephan(a)stack.nl> wrote: > > On 05-01-16 16:21, Esteban Lorenzano wrote: > > Soâ¦ I took a couple of minutes to do a small list of project description > status: > > From a total of 379 projects currently in the catalog, just 115 have a > description and/or keywords associated. > Which means 264 are mysterious projects nobody can guess what are they > about. > > I was thinking most of this projects would be in Unsorted (or Pharo 3), > but I found that many are also on Pharo 5 and 4â¦. which is frankly > unacceptable :) > Even very important projects like Seaside or Garage and Glorp are not > documented. > > So, please peopleâ¦ take a look at your projects and PLEASE, provide a > description and proper keywordsâ¦ Nobody can guess what is Aconcagua > (besides a cool mountain in south america), or Telescope, etc., etc., etc. > > Here the list of non-documented projects: > > > ss3 has no projects? > > > catalog just catalogs projects in the MetaRepos > you project can live where he wants, but configuration needs to be copied > into MetaRepoForPharoXX > > thatâs how always was, and thatâs what catalog shows :) > > > http://ss3.gemtalksystems.com/ss/MetaRepoForPharo20 > > > hmmmâ¦ didnât remember that existed :) > but i was even considering propose you to deprecate the unsorted > repository (a lot of obsolete projects there)â¦ > > Esteban > > > Stephan > > >

Jan. 5, 2016

Re: [Pharo-dev] [Ann] ReadWriteLock

by Henrik Johansen

> On 05 Jan 2016, at 5:10 , Denis Kudriashov <dionisiydk(a)gmail.com> wrote: > > > 2016-01-05 16:54 GMT+01:00 Denis Kudriashov <dionisiydk(a)gmail.com <mailto:dionisiydk@gmail.com>>: > 2016-01-05 16:06 GMT+01:00 Ben Coman <btc(a)openinworld.com <mailto:btc@openinworld.com>>: > This is really strange! Why does the copied class Semaphore2 behave > differently to the original class Semaphore? This was in build 50510. > > It is so frustrating. > I add tests for your cases which is red now. And one for Semaphore (inside ReadWriteLockTests) which is green > > It is really crazy. I just try two experiments: > 1) I move semaphore critical: logic to Mutex. Our test with mutex become red. > 2) I copy Semaphore>>critical: to #critical2:. And with it Semaphore test become red. > > So somebody definitely know about #critical: selector and it receiver Yes, check Process >> #terminate, there's special code for skipping a context if the suspended process was waiting for Semaphore. The way I see it, the purpose of the caught variable in Semaphore is to not execute the ensure: if the process was suspended (and then terminated)*in* the ensure: method, before block ever executes and one starts waiting on the semaphore. If one has made it to the wait call, caught is already true, and the ensure block would be executed on termination unwind.. That part is, as I said above, handled directly in Process >> #terminate (near the bottom) AFAICT, both parts would be need to be reflected for Monitor >> #critical: to work correctly under termination. At which point, it would seem to me a better idea (if possible) if the terminated context was culled into the ensure block, instead of muddying up Process >> #terminate further, one could then write a few ugly, but localized: ensure: [:unwoundContext | (caught and: [unwoundContext isWaitContext notl]) ifTrue: [sem signal]] instead of having to keep adding special case handling to Process >> #terminate. Cheers, Henry

Jan. 5, 2016

Re: [Pharo-dev] [Ann] ReadWriteLock

by Denis Kudriashov

2016-01-05 17:25 GMT+01:00 Denis Kudriashov <dionisiydk(a)gmail.com>: > Comment inside #critical: method said that we should signal in any case. I think I not correctly understand this point when read it. Process terminating case is not mention in comment.

Jan. 5, 2016

Re: [Pharo-dev] [Ann] ReadWriteLock

by Denis Kudriashov

I found problem. Look at Process>>terminate. There is special place: "Figure out if we are terminating the process while waiting in > Semaphore>>critical: > In this case, pop the suspendedContext so that we leave the ensure: block > inside > Semaphore>>critical: without signaling the semaphore." > (oldList class == Semaphore and: [ > self halt. > suspendedContext method == (Semaphore compiledMethodAt: #critical:) ]) > ifTrue: [ > suspendedContext := suspendedContext home ]. Really crazy. Comment inside #critical: method said that we should signal in any case. But #terminate method said that we should not allow signalling in that case. Why it is not implemented inside #critical: method by #ifCurtailed: logic? 2016-01-05 17:10 GMT+01:00 Denis Kudriashov <dionisiydk(a)gmail.com>: > > 2016-01-05 16:54 GMT+01:00 Denis Kudriashov <dionisiydk(a)gmail.com>: > >> 2016-01-05 16:06 GMT+01:00 Ben Coman <btc(a)openinworld.com>: >> >>> This is really strange! Why does the copied class Semaphore2 behave >>> differently to the original class Semaphore? This was in build 50510. >>> >> >> It is so frustrating. >> I add tests for your cases which is red now. And one for Semaphore >> (inside ReadWriteLockTests) which is green >> > > It is really crazy. I just try two experiments: > 1) I move semaphore critical: logic to Mutex. Our test with mutex become > red. > 2) I copy Semaphore>>critical: to #critical2:. And with it Semaphore test > become red. > > So somebody definitely know about #critical: selector and it receiver >

Jan. 5, 2016

Re: [Pharo-dev] Catalog statistics (Who know this projects?)

by Esteban Lorenzano

> On 05 Jan 2016, at 17:06, Stephan Eggermont <stephan(a)stack.nl> wrote: > > On 05-01-16 16:56, Esteban Lorenzano wrote: >> >>> On 05 Jan 2016, at 16:51, Stephan Eggermont <stephan(a)stack.nl> wrote: >>> >>> On 05-01-16 16:21, Esteban Lorenzano wrote: >>>> Soâ¦ I took a couple of minutes to do a small list of project description status: >>>> >>>> From a total of 379 projects currently in the catalog, just 115 have a description and/or keywords associated. >>>> Which means 264 are mysterious projects nobody can guess what are they about. >>>> >>>> I was thinking most of this projects would be in Unsorted (or Pharo 3), but I found that many are also on Pharo 5 and 4â¦. which is frankly unacceptable :) >>>> Even very important projects like Seaside or Garage and Glorp are not documented. >>>> >>>> So, please peopleâ¦ take a look at your projects and PLEASE, provide a description and proper keywordsâ¦ Nobody can guess what is Aconcagua (besides a cool mountain in south america), or Telescope, etc., etc., etc. >>>> >>>> Here the list of non-documented projects: >>> >>> ss3 has no projects? >> >> catalog just catalogs projects in the MetaRepos >> you project can live where he wants, but configuration needs to be copied into MetaRepoForPharoXX >> >> thatâs how always was, and thatâs what catalog shows :) > > http://ss3.gemtalksystems.com/ss/MetaRepoForPharo20 <http://ss3.gemtalksystems.com/ss/MetaRepoForPharo20> hmmmâ¦ didnât remember that existed :) but i was even considering propose you to deprecate the unsorted repository (a lot of obsolete projects there)â¦ Esteban > > Stephan

Jan. 5, 2016

Re: [Pharo-dev] [Ann] ReadWriteLock

by Denis Kudriashov

2016-01-05 16:54 GMT+01:00 Denis Kudriashov <dionisiydk(a)gmail.com>: > 2016-01-05 16:06 GMT+01:00 Ben Coman <btc(a)openinworld.com>: > >> This is really strange! Why does the copied class Semaphore2 behave >> differently to the original class Semaphore? This was in build 50510. >> > > It is so frustrating. > I add tests for your cases which is red now. And one for Semaphore (inside > ReadWriteLockTests) which is green > It is really crazy. I just try two experiments: 1) I move semaphore critical: logic to Mutex. Our test with mutex become red. 2) I copy Semaphore>>critical: to #critical2:. And with it Semaphore test become red. So somebody definitely know about #critical: selector and it receiver

Jan. 5, 2016

Re: [Pharo-dev] Catalog statistics (Who know this projects?)

by Stephan Eggermont

On 05-01-16 16:56, Esteban Lorenzano wrote: > >> On 05 Jan 2016, at 16:51, Stephan Eggermont <stephan(a)stack.nl> wrote: >> >> On 05-01-16 16:21, Esteban Lorenzano wrote: >>> Soâ¦ I took a couple of minutes to do a small list of project description status: >>> >>> From a total of 379 projects currently in the catalog, just 115 have a description and/or keywords associated. >>> Which means 264 are mysterious projects nobody can guess what are they about. >>> >>> I was thinking most of this projects would be in Unsorted (or Pharo 3), but I found that many are also on Pharo 5 and 4â¦. which is frankly unacceptable :) >>> Even very important projects like Seaside or Garage and Glorp are not documented. >>> >>> So, please peopleâ¦ take a look at your projects and PLEASE, provide a description and proper keywordsâ¦ Nobody can guess what is Aconcagua (besides a cool mountain in south america), or Telescope, etc., etc., etc. >>> >>> Here the list of non-documented projects: >> >> ss3 has no projects? > > catalog just catalogs projects in the MetaRepos > you project can live where he wants, but configuration needs to be copied into MetaRepoForPharoXX > > thatâs how always was, and thatâs what catalog shows :) http://ss3.gemtalksystems.com/ss/MetaRepoForPharo20 Stephan

Jan. 5, 2016