December 2005 - Boost - lists.boost.org

Some Boost.Test queries
by Daryle Walker 27 Dec '05

27 Dec '05

1. Is there a way to specify that two auto-unit tests must come in a certain order? What about any kind of tests? Or do you have to create a giant test to force a particular order? 2. If the answer to [1] is "yes," then can fixtures be used to carry over changed variables between tests? 3. Can a fixture be a class template, so it can be used with a auto-unit test template such that the fixture changes its class parameter to match the test's parameter? (I worked around this currently by using an inner class template within a non-template class fixture.) -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

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[defer] - new version uploaded
by simon meiklejohn 26 Dec '05

26 Dec '05

New version of the Defer library uploaded to the Boost Vault, Concurrent Programming folder. Main addition is support for a size configurable work item queue provided by Oliver Kowalke (thanks Oliver), from the thread_queue component in the same folder. This library may provide a counterpoint to the Boost.Asio library's related work deferral facilities. Cheers Simon

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Re: [boost] [Review] Boost.Logging: formal review
by Richard Glanmark 26 Dec '05

26 Dec '05

> -----Original Message----- > From: boost-bounces(a)lists.boost.org > [mailto:boost-bounces@lists.boost.org] On Behalf Of Gennadiy Rozental > Sent: den 15 december 2005 22:39 > To: boost(a)lists.boost.org > Subject: Re: [boost] [Review] Boost.Logging: formal review > > > 1. Enabled/disabled logger, logging macros and efficiency > > > > The logging macro BOOST_LOG should accept two arguments > instead of one. > > The logger and the log message. The syntax > > > > (1) BOOST_LOG(some_log) << "my message " << foo() << bar(); > > > > should be replaced with > > > > (2) BOOST_LOG(some_log, "my message " << foo() << bar()); > > > > and the macro being defined something like this > > > > (3) #define BOOST_LOG(logger, msg) \ > > if(logger.isEnabled()) { /* code that logs msg */ ... } > > > > Thus, disabled loggers will never take longer than simple > > if-statement, as long as the isEnabled() method is fast, which IMO > > should take no longer than comparing booleans. > > 1. I think this is also the case in original interface. > > > In the original solution (1) the method foo() will always > be called, > > which is inefficient when the logger is disabled, in solution (2), > > foo() will never be called when the logger is disabled. > > I think you are mistaken Yes, my mistake. > > Further more, the macro could insert extra information such as > > __LINE__, __FILE__ etc. > > This is also true for original interface. Yes true -- my mistake again (I didn't look enough at the implementation of the macro). > All in all I prefer message not be inside brackets. It looks > much more natural and I don't see any theoretical problens to > get the same performance. But I also believe that macro > shouldn't be a primary interface. > So if you prefer message inside the breakets - it's your choice. However, there is one additional benefit of placing the message inside brackets. One can remove the log statement in a build. Other than that, I guess its style preferences. > > 2. Filtering > > > > There has been some discussion about the ability of a library to be > > able to do more filtering than simple log levels, notably > by Gennadiy > > Rozental. > > > > Gennadiy writes: > >> At the bare minimum it should support: > >> > >> entry level - levels set is ordered set of values indication > > importance of > >> information provided. Filtering is based on threshold. Examples: > > DEBUG, INFO, MAJOR > > > >> entry category - categories set is a set of unique values > indicating > > kind of > >> information provided Filtering is based on masking. > >> Examples: ARGS, RETURN_VALUE, ERROR_LOG, DATA_FLOW, PROG_FLOW > > > >> entry keyword - keyword set is set of user defined keywords (most > > frequently strings) > >> identifying area of the program. Filtering is based on match of > > keywords. > >> Keywords usually are used to mark specific part of application. > > > > I agree that it is very important for a logging library to > support this. > > However, I do not think that the solution is for the > logging library > > to be aware of such special values. The library should be as > > simplistic as > > My position that library should be configurable by any class > satisfying Filter concept. > This particular filters could probably be supplied by the > library as an example and as most widely useful. > > > My proposed solution is to basically let loggers be somewhat entry > > (Gennadiy's definition above) unaware. Instead, let the developer be > > I do not see how it's possible. IMO framework should employ > some MPL magic and construct proper entry structure based on > set of Filters passed as template policy parameters. > > > entry aware. By that I mean that the developer should log messages > > that belong to a specific entry category/level to a > specific logger. > > For > > This is never be acceptable IMO. Even with 3 filters, each > ahving 5 possible values you looking into 125 different loggers. Support for log functions on top of a basic framework solution is needed to alleviate this problem. I wouldn't mind that the library provides log funtions that take various filter functions or predicates to determine wether to send a log statement to a logger. In this case, the logger would be enabled and the log filter function would send log statements to the logger if the log statement meets some criteria. Still, the underlying logger framework would be the same; logger object should still be enabled or disabled/enabled, there would still be a few different logger objects for different levels and possible other user defined criteria. IMO it is very important for an administrator/programmer of a system to be able to enable/disable logs, know what loggers and appenders exists and be able to configure said entities. If filter is only done on a per log statement, how do you even know as a administrator of a system what log filters exists? Which filter criteria should be enabled and which filter criteria should be disabled? If all log statements are sent to one logger object, the logger object becomes a monolith of functionality and complexity. Runtime performance might degrade considerable if various filters is to be checked, not only if the log statements should be logged, but also if one wants to send log statements to different appenders/sinks/destinations. Cheers, Richard The content of this e-mail is intended only for the confidential use of the person(s) to whom it is addressed. If the reader of this message is not such a person, you are hereby notified that you have received this communication in error and that reading it, copying it, or in any way disseminating its content to any other person, is strictly prohibited. If you have received this message in error, please notify the author by replying to the e-mail immediately. NeoNet AB and its subsidiaries (NeoNet Securities AB, NeoNet Securities Inc. and NeoNet Technology AB) are unable to exercise control over the content of information contained in transmissions made via the Internet and hereby excludes any warranty as to the quality or accuracy of any information contained in this message and any liability of any kind for the information contained in it, or for its transmission, reception, storage or use in any way whatsoever.

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ptr_container: ptr_map_adapter interface
by Slawomir Lisznianski 26 Dec '05

26 Dec '05

Hello, I've been using ptr_map lately and have a few questions regarding its interface. Below is a signature of `insert' function as declared in ptr_map_adapter: std::pair<iterator,bool> insert( key_type& k, value_type x ); Why is `k' a non-const reference? To imply ownership transfer, couldn't `x' be of `std::auto_ptr<value_type>' type instead? What happend to std::pair as an argument of insert? Was symmetry with std::map dropped for a reason here? Cheers, Slawomir Lisznianski

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[smart-ptr] no link to enable_shared_from_this docs
by Ronald Garcia 25 Dec '05

25 Dec '05

I just recently discovered the enable_shared_from_this.hpp header file and located its documentation by searching, but there appears to be no link to it from the smart pointer library documentation. Should there be one? Thanks, ron

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Re: [boost] Patch for mingw-tools.jam
by Janusz Piwowarski 24 Dec '05

24 Dec '05

.. and missed patch. -- Regards, Janusz

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[MultiIndex] proposal - delayed index initialisation and maintenance
by Neil Hunt 24 Dec '05

24 Dec '05

I am just sort of throwing this out there as a wild idea. Having a trait on any given index such that it is only initialised upon first access. The motivation being - When displaying a table of rows of fields, the user may not necessarily click on any given column header for sorting, and would only rarely click on the majority of column headers. Therefore it is not required to maintain any given column index unless the user has requested sorting by that index. Neil

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Re: [boost] [Review] Boost.Logging: formal review
by Richard Glanmark 23 Dec '05

23 Dec '05

Some thoughts and ideas about some of the topics that has been discussed regarding the proposed Boost.Logging library. 1. Enabled/disabled logger, logging macros and efficiency The logging macro BOOST_LOG should accept two arguments instead of one. The logger and the log message. The syntax (1) BOOST_LOG(some_log) << "my message " << foo() << bar(); should be replaced with (2) BOOST_LOG(some_log, "my message " << foo() << bar()); and the macro being defined something like this (3) #define BOOST_LOG(logger, msg) \ if(logger.isEnabled()) { /* code that logs msg */ ... } Thus, disabled loggers will never take longer than simple if-statement, as long as the isEnabled() method is fast, which IMO should take no longer than comparing booleans. In the original solution (1) the method foo() will always be called, which is inefficient when the logger is disabled, in solution (2), foo() will never be called when the logger is disabled. Further more, the macro could insert extra information such as __LINE__, __FILE__ etc. If needed or wanted, the macro could of course be redefined to leave no trace of the logging. I could also envision a few other macros that for example creates a logger object on the stack that logs upon creation and destruction, a special macro to aid developers that are always compiled out of release code. Perhaps such macros is best left to the user of the library although I do think that there are common set of macros that is useful for most applications and situations and thus are good candidates for being defined in the library. 2. Filtering There has been some discussion about the ability of a library to be able to do more filtering than simple log levels, notably by Gennadiy Rozental. Gennadiy writes: > At the bare minimum it should support: > > entry level - levels set is ordered set of values indication importance of > information provided. Filtering is based on threshold. Examples: DEBUG, INFO, MAJOR > entry category - categories set is a set of unique values indicating kind of > information provided Filtering is based on masking. > Examples: ARGS, RETURN_VALUE, ERROR_LOG, DATA_FLOW, PROG_FLOW > entry keyword - keyword set is set of user defined keywords (most frequently strings) > identifying area of the program. Filtering is based on match of keywords. > Keywords usually are used to mark specific part of application. I agree that it is very important for a logging library to support this. However, I do not think that the solution is for the logging library to be aware of such special values. The library should be as simplistic as possible, with no or few assumptions about its use, at least at the basic "framework level". Only then IMO could the library accodomate various neeeds. Let me explain. If special values are introduced in the library, there will always be applications and users that lack some other special value, perhaps specific to their domain, but even more likely, to their taste and style. My proposed solution is to basically let loggers be somewhat entry (Gennadiy's definition above) unaware. Instead, let the developer be entry aware. By that I mean that the developer should log messages that belong to a specific entry category/level to a specific logger. For example, if there is a need to log and filter a RETUN_VALUE category, then a specific logger, perhaphs named RETURN_VALUE_LOGGER (or whatever), and let the user send log messages to that logger. This could look something like this: BOOST_LOG( RETURN_VALUE_LOGGER, "The return value is: " << value ); This solution also means that you have a different logger for each level, level filtering perhaps being the most common filter. For example: BOOST_LOG( debug, "some debug output " << a << foo() ); BOOST_LOG( error, "Error: " << e.what() ); where 'debug' and 'error' are loggers. Now, the drawback with this approach is that several loggers needs to be defined and configured, but as long as this is simple this should be ok. There should also be default definitions and configurations available from the library, which "sits" on top of the basic library framework. As for entry keywords (see above), I see two interpretations of Gennadiy's idea. (1) A log statement is marked with a keyword. For example: BOOST_LOGX( logger, "user defined keyword", "my log msg " << value ); Or (2), logging is filtered on what strings are contained in the log message. That is, log statements are written in the normal way by the programmer but is filtered by some mechanism where the log message is matched against certain keywords, like the grep command. For interpretation (1): My proposed solution should solve the problem. Declare a specific logger that the programmer send log statements to for the specified keyword. For interpretation (2 ): IMO the filtering mechanism should either sit on top of loggers or possibly in the appenders, or the tools that are used to view logs (e.g. grep and such). The "on top" solution would be to use specicial functions that utilizes the "lower" layer of simple loggers. It should be an extension to the log library and not be part of the core functionality (but could still be provided by a logging library). For example: BOOST_LOGX( logger, Predicate( ... ), "my log msg" << value ); Thus, the approach to filtering, based on Gennadiy's idea of various criteria is to to enable/disable loggers depending on system/users/developers needs'. Hence, enabling/disabling must be simple. Using John Torjo's solution of manipulate_log-functions this ought be relative easy. The programmer should be able to enable/disable loggers on various critiera. One solution for this would be to attach user, as well as common/default library, supplied name-value pairs to loggers and let the manipulate_log functions enable/disable loggers that meet certain criteria for these name-value pairs. For example, when defining which loggers that are available to the programmer (by himself or some other developer), a log level name-value object is attached to the loggers. The logger named 'debug' is attached with a log level of 'debug' (a literal integer value chosen carefully e.g. 0). Later on in the program, the programmer can issue the statement, using the manipulate_log-functions to enable all loggers that have a property name log level with a value greater than 'debug' and so on. Additional benefits of using this clean approach (maybe possible with Johns solution as well (?)) to loggers is that it is quite possible to have debug loggers log in one subsystem while normal logging is done in the rest of the program. Any combination is possible. The major drawback with this clean approach to loggers as I see it is the additional complexity, cognitive burden, for setting up loggers. Part of this problem should be alleviated by the library by providing a default set of loggers for common/simple/I just wanna get started -situations. Cheers, Richard Glanmark The content of this e-mail is intended only for the confidential use of the person(s) to whom it is addressed. If the reader of this message is not such a person, you are hereby notified that you have received this communication in error and that reading it, copying it, or in any way disseminating its content to any other person, is strictly prohibited. If you have received this message in error, please notify the author by replying to the e-mail immediately. NeoNet AB and its subsidiaries (NeoNet Securities AB, NeoNet Securities Inc. and NeoNet Technology AB) are unable to exercise control over the content of information contained in transmissions made via the Internet and hereby excludes any warranty as to the quality or accuracy of any information contained in this message and any liability of any kind for the information contained in it, or for its transmission, reception, storage or use in any way whatsoever.

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Re: [boost] [Review] Boost.Logging: formal review
by Martin Bonner 23 Dec '05

23 Dec '05

----Original Message---- From: Richard Glanmark [mailto:Richard.Glanmark@neonet.biz] Sent: 15 December 2005 08:33 To: boost(a)lists.boost.org Subject: Re: [boost] [Review] Boost.Logging: formal review > Some thoughts and ideas about some of the topics that has been > discussed regarding the proposed Boost.Logging library. > > > 1. Enabled/disabled logger, logging macros and efficiency > > The logging macro BOOST_LOG should accept two arguments instead of > one. The logger and the log message. The syntax > > (1) BOOST_LOG(some_log) << "my message " << foo() << bar(); > > should be replaced with > > (2) BOOST_LOG(some_log, "my message " << foo() << bar()); > > and the macro being defined something like this > > (3) #define BOOST_LOG(logger, msg) \ > if(logger.isEnabled()) { /* code that logs msg */ ... } The current definition is (I believe) #define BOOST_LOG(logger) \ if(!logger.isEnabled()) {} else logger Which achieves the same ends. In particular, foo() is not called unless logging occurs. -- Martin Bonner Martin.Bonner(a)Pitechnology.com Pi Technology, Milton Hall, Ely Road, Milton, Cambridge, CB4 6WZ, ENGLAND Tel: +44 (0)1223 441434

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reactor versus proactor
by Arkadiy Vertleyb 23 Dec '05

23 Dec '05

Hi all, This is a question to networking gurus, and is on the edge of being off topic, but I am asking it here because I hope it will help me to better understand rationale behind the asio design... As was stated before, asio is based on the proactor pattern. This pattern is known for its scalability, but is difficult to port since it's based on asynchronous calls which are implemented differently (or not implemented at all) on diferent OSs. OTOH, reactor (the one based on select) seems to be easily portable, and also scalable, but its only real problem is that it doesn't utilise threads, and so it can't take an advantage of multi-processor systems. So my question is, isn't this drawback easily remedied by just placing select-ed sockets into a queue, and having multiple threads (from a thread pool) pick them up and performing the work? Wouldn't this provide comparable performance on multiple processors, with much better portability, than proactor? Thanks, Arkadiy

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