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Re: Boost.Threads: Do we need all those mutexes?
by Batov, Vladimir 30 Jun '04

30 Jun '04

>>" Thread-safety should not be a run-time configurable property." > I think this is somewhat incorrect as absolutes usually are. Well, I'll probably lose the fairly abstract discussion of general incorrectness of absolutes. :-) I just think that compile-time vs. run-time is a pragmatic choice. Why give the user an alternative with is dubious and likely incorrect? For that reason std::list does not provide operator[] even though it could. Surely, one could come up with his/her design that would "require" such an operator for std::list. Does it invalidate the decisions STL designers made? I do not think so. That is why I am suspicious of temptations to lump distinctly different functions of scoped_lock, try_lock and timed_lock into one universal blob. V.

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Re: Boost.Threads: Do we need all those mutexes?
by Batov, Vladimir 30 Jun '04

30 Jun '04

> bool foo(bool threadsafe) > { > mutex::scoped_lock l(m, !threadsafe); > } I am not sure if the example above is appropriate and indicative of the problem we are trying to solve. Thread-safety should not be a run-time configurable property. Like we do not decide on the fly (at run-time) if our ref.-counting class is to be thread-safe or not. All that is resolved at compile time. More so, that still can be solved with statically defined lock/nolock constructors: bool foo(bool some_condifion) { mutex::scoped_lock l(m, boost::nolock); if (some_condition) l.lock(); } 2. I feel that our assumptions of try_lock (yes, I know it is try_scoped_lock, I am just lazy) and timed_lock being refinements of scoped_lock are incorrect. At best scoped_lock and try_lock are refinements of timed_lock as scoped_lock is timed_lock with time=infinite and try_lock is timed_lock with time=0. Therefore, we you insist on common lock functionality, it has to be encapsulated in one timed_lock (or maybe some basic_lock or just a lock). Then, all locks would refine that common behavior. That approach has the advantage of covering the case when I do not know what I want :-) -- then I'd simply use the basic_lock. 3. However, I personally feel that our attempts of generalizing locks are misguided. Locks are different, serve different purposes and provide different and distinct functionality. I feel that we should make an effort to keep different locks different and lean. Like try_lock actually tries to lock. Adding blocking (lock()) functionality to such a lock looks like a mistake as IMHO it encourages bad programming style as it allows to use try_lock where scoped_lock is needed. I feel that the situation when I do not know what kind of lock I need when I step into a function shows that the function needs to be-restructured/split so that in every new component I do know what I need. V.

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Boost.Threads proposed change: lock constructors
by Michael Glassford 30 Jun '04

30 Jun '04

Below I detail proposed changes to the Boost.Threads lock class constructors. Comments? Questions? Mike ----------------------------------------------------------------- The Boost.Threads lock concept constructors are currently defined as follows: Definitions ----------- L: lock type l: lock variable (type L) m: mutex variable (appropriate Mutex type) s: initial lock state (type bool, true=locked, false=unlocked) Lock Concept ------------ L l(m,s) //Blocking lock if s L l(m) //Blocking lock TryLock Concept --------------- L l(m,s) //Blocking lock if s L l(m) //Non-blocking lock TimedLock Concept ----------------- L l(m,s) //Blocking lock if s L l(m,t) //Blocking lock, failing if not obtained by time t These definitions have the following drawbacks: 1) That one of the TryLock constructors blocks while the other doesn't is neither obvious nor very consistent. 2) That the single-parameter constructor of Lock blocks while the single-parameter constructor of TryLock doesn't is neither obvious nor very consistent. 3) Part of the reason for the above inconsistencies is that it's not clear whether the constructors of TryLock should block or not. 4) The TimedLock constructors have no way to request a non-blocking lock. To address these problems, I would like to redefine the lock concept constructors as follows (changes indicated with "^"): Definitions ----------- L: lock type l: lock variable (type L) m: mutex variable (appropriate Mutex type) s: initial lock state (enum type {NO_LOCK=0, LOCK=1}) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ b: block? (enum type blocking_state {NON_BLOCKING=0, BLOCKING=1}) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Lock Concept ------------ L l(m,s) //Blocking lock if s L l(m) //Blocking lock TryLock Concept --------------- L l(m,s,b) //Lock if s; blocking if b ^ ^^^^^^^^^^^^^ L l(m,b) //Lock; blocking if b ^ ^^^^^^^^^^^^^ TimedLock Concept ----------------- L l(m,s,b) //Lock if s; blocking if b ^ ^^^^^^^^^^^^^ L l(m,t) //Blocking lock, failing if not obtained by time t Note: s and b are defined as enums rather than bools to prevent existing code from breaking silently: e.g., if s and b were bools, "TryLock l(m, false)", which currently means "construct a lock object but don't obtain a lock", would change with the new definitions to mean "construct a lock and make a non-blocking attempt to obtain a lock". Also, enums are more explicit than bools. Note: these changes will cause some existing code to break by producing compile errors; the compile errors can be fixed by appropriately adding or changing parameters being passed to the changed TryLock and TimedLock constructors. Mike

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[1.32 release] Boost.Test plan
by Rozental, Gennadiy 30 Jun '04

30 Jun '04

I plan to add one more big feature and several small one into this release. I should be able to finish all of this within 3 weeks. I mostly worry about some regression on old compilers. I will try to address most of it before committing. Gennadiy.

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two thread libs? [was: Re: [boost] Re: logging library]
by John Torjo 30 Jun '04

30 Jun '04

> [snip] > Static-link build option added > > The option to link Boost.Threads as a static library has been added back with some limitations. This feature was originally removed because boost::thread_specific_ptr required that Boost.Threads be dynamically linked in order for its cleanup functionality to work on Win32 platforms. Several options are currently being explored to resolve this issue. In the meantime, the ability to link Boost.Threads statically has been added back with boost::thread_specific_ptr support removed from the statically linked version. The decision to add it back was made because its lack is one of the most frequent complaints about Boost.Threads and because the other approaches that are being investigated to deal with boost::thread_specific_ptr cleanup look fairly promising. so if I get the latest boost.thread I'll have all this (ability to use it as a static lib)? > > Note > Boost.Threads is still dynamically linked by default. In order to force it to be statically linked, it is necessary to #define BOOST_THREAD_USE_LIB before any of the Boost.Threads header files are #included. I'm not sure this is ok with me. I think it should still be statically linked by default (see below). > > Note > If the boost::thread_specific_ptr cleanup issue cannot be resolved by some other means, it is highly likely that the option to statically link Boost.Threads will be removed again in a future version of Boost, at least for Win32 platforms. This is because the boost::thread_specific_ptr functionality will be increasingly used by Boost.Threads itself, so that proper cleanup will become essential in future versions of Boost.Threads. Again, I don't understand why you need thread_specific_ptr within boost.threads so much. Anyway, if you need thread_specific_ptr so much, maybe we could do away with two libraries, something like: 'thread' and 'thread_ext' or so. In the thread, we should keep what was roughly before: - mutexes (don't tell me they need TLS) and scoped locks - thread class (no cleanup support) - xtime In the thread_ext, include whatever needs thread_specific_ptr, and extra goodies - this will have the statically/dynamically linked issue. I think this would be quite good in the long run, since there are so many libs/applications that only need basic thread support, and who really don't want an extra DLL added to the maintenance list. Best, John -- John Torjo Freelancer -- john(a)torjo.com -- http://www.torjo.com/logview/ - viewing/filtering logs is just too easy!

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[1.32 Plan] multi_index
by Joaquín Mª López Muñoz 30 Jun '04

30 Jun '04

This is the plan for release of Boost.MultiIndex. This is a newly added library. Current status: commited in the CVS since 6 weeks or so. Regression tests are OK for all the compilers that I intend to support. If someone is interested in some other compiler being supported, please contact me. Pending issues: #1 Minor updates to the docs. No big deal. #2 Some changes related to the new defect macro BOOST_NO_POINTER_TO_MEMBER_TEMPLATE_PARAMETERS These issues will be resolved way before the branching date, I hope. Questions: #1 Dave talked about Aleksey going to merge a new version of MPL in the main trunk. When will that happen? How disruptive do you expect it to be wrt to the rest of libraries? #2 Should I update the additional stuff right away (links in the main and libraries pages, uploading of bio and picture etc.)? Or is anybody else taking care of that stuff? #3 Vladimir just talked about "adding markup for the failures". What is this? Is this something required as part of the regression fixing process? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Explicit markup notes
by Aleksey Gurtovoy 30 Jun '04

30 Jun '04

Could I ask that every time we are adding an explicit failure to "status\explicit-failures-markup.xml" or, even more so, marking up a library as unusable, we also provide a note explaining the markup? We don't have to come up with a specific wording for every single failure -- there are a few standard notes at the end of the document that fit many common situations, and can be simply referenced by their ID (e.g. <note refid="3"/>), but not saying anything at all significantly defeats reports' usefullness. -- Aleksey Gurtovoy MetaCommunications Engineering

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Library doc link is broken
by Jeff Garland 30 Jun '04

30 Jun '04

The current CVS doc link seems to have gone down... Not Found The requested URL /regression-logs/cs-win32_metacomm/doc/html/libraries.html was not found on this server. Jeff

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[Formal review result] Tribool
by Thomas Witt 30 Jun '04

30 Jun '04

Hi, I am happy to report that the "Tribool" library by Doug Gregor has been ACCEPTED into boost. Other than this there is very little to be said. Reviews were generally in favour of the library and the issues surfaced during the review have been addressed by Doug. There were some comments regarding the scope of the library. While I agree that an broader coverage of 3-valued logic might be good to have, I do not think it justifies delaying acceptance of the library. Regards Thomas Review Manager Tribool -- Thomas Witt witt(a)acm.org

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Bug in token_functions.hpp
by Joe Gottman 30 Jun '04

30 Jun '04

I have found a bug in token_functions.hpp. I have a hello-world program that looks like this: ----------begin file #include <boost/token_functions.hpp> int main(int argc, char* argv[]) { boost::char_separator<char> sep; printf("Hello World!\n"); return 0; } ----------end file It fails under MSVC 6.0 with the following error messages: c:\jobs\boost\token_functions.hpp(261) : error C2065: 'is_pointer' : undeclared identifier c:\jobs\boost\token_functions.hpp(267) : see reference to class template instantiation 'boost::tokenizer_detail::get_iterator_category<Iterator>' being compiled c:\jobs\boost\token_functions.hpp(261) : error C2275: 'Iterator' : illegal use of this type as an expression c:\jobs\boost\token_functions.hpp(267) : see reference to class template instantiation 'boost::tokenizer_detail::get_iterator_category<Iterator>' being compiled c:\jobs\boost\token_functions.hpp(261) : error C2059: syntax error : ',' c:\jobs\boost\token_functions.hpp(267) : see reference to class template instantiation 'boost::tokenizer_detail::get_iterator_category<Iterator>' being compiled c:\jobs\boost\token_functions.hpp(264) : error C2238: unexpected token(s) preceding ';' c:\jobs\boost\token_functions.hpp(267) : see reference to class template instantiation 'boost::tokenizer_detail::get_iterator_category<Iterator>' being compiled c:\jobs\boost\token_functions.hpp(266) : error C2653: 'cat' : is not a class or namespace name c:\jobs\boost\token_functions.hpp(267) : see reference to class template instantiation 'boost::tokenizer_detail::get_iterator_category<Iterator>' being compiled I believe the problem is that we need to add the line #include <boost/type_traits/is_pointer.hp> to token_functions.hpp. If I add this line to my program before including token_functions.hpp, everything compiles fine. Joe Gottman

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