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hash set crashing during iteration (boost 1.35.0)
by Julie Larson 20 May '08

20 May '08

Hello, I'm using boost 1.35.0 and found this sample code about the hash set functionality: http://www.boost.org/doc/libs/1_35_0/doc/html/intrusive/advanced_lookups_in… and modified it as shown below. I find that when iterating through the hash table, the thing crashes here (where the get_next function contains an invalid value for n): template<class VoidPointer> struct slist_node_traits { .... static node_ptr get_next(const_node_ptr n) ----------> { return n->next_; } .... }; Should I use an earlier more stable version of boost or am I doing something dreadfully wrong? Thank you for any insights -Julie #include <stdio.h> #include <string> #include <iostream> // for std::cout #include <boost/foreach.hpp> #include <boost/intrusive/unordered_set.hpp> using namespace boost::intrusive; struct CStringHasher { std::size_t operator()(const std::string& str) const { std::size_t seed = 0; const char* sz = str.c_str(); if ( ! sz ) return seed; for(; *sz; ++sz) boost::hash_combine(seed, *sz); return seed; } }; class CWord : public unordered_set_base_hook<> { //This is a derivation hook public: std::string m_strWord; int m_nID; unordered_set_member_hook<> member_hook_; //This is a member hook CWord( const std::string& strWord, int nID ) : m_strWord( strWord ), m_nID( nID ) {} friend bool operator== (const CWord& a, const CWord& b) { return a.m_strWord == b.m_strWord; } friend std::size_t hash_value(const CWord& value) { return CStringHasher()(value.m_strWord.c_str()); } }; class CWordHash { public: typedef unordered_set<CWord> word_hash_set; typedef word_hash_set::bucket_type word_bucket_type; typedef word_hash_set::bucket_traits word_bucket_traits; typedef word_hash_set::iterator word_iter; CWordHash() : m_hWords( word_bucket_traits( m_Buckets, s_nNumBuckets ) ) {} ~CWordHash() { BOOST_FOREACH( CWord& w, m_hWords ) { CWord* pWord = &w; delete pWord; } } struct CStrExpensiveClassEqual { bool operator()(const std::string& str, const CWord &c) const { return str == c.m_strWord; } bool operator()(const CWord& c, const std::string& str) const { return str == c.m_strWord; } }; CWord* get( const std::string& str ) { word_iter it = m_hWords.find( str, CStringHasher(), CStrExpensiveClassEqual()); if( it == m_hWords.end() ) return NULL; return &*it; } bool insert( const std::string& strKey, int nID ) { word_hash_set::insert_commit_data insert_data; bool bSuccess = m_hWords.insert_check( strKey, CStringHasher(), CStrExpensiveClassEqual(), insert_data).second; if ( bSuccess ) { CWord* pWord = new CWord(strKey, nID); m_hWords.insert_commit(*pWord, insert_data); } return bSuccess; } static const int s_nNumBuckets = 10000; word_bucket_type m_Buckets[s_nNumBuckets]; word_hash_set m_hWords; }; extern int main(int argc, char *argv[]) { CWordHash hWords; // hash string to word id int nID = 1; std::string strWord = "hello"; hWords.insert( strWord, nID ); nID = 2; strWord = "world"; hWords.insert( strWord, nID ); for ( CWordHash::word_hash_set::iterator it = hWords.m_hWords.begin(); it != hWords.m_hWords.end(); it++ ) { CWord& w = *it; std::cout << w.m_strWord << "\t" << w.m_nID << "\n"; } return 0; }

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Boost multi-thread issue ---- use macro
by Peisheng Wang 19 May '08

19 May '08

Why #if ISTHREADSAFE boost::mutex::scoped_lock lock(CacheInfo_mutex); # endif functions well , but not if(isThreadSafe) { boost::mutex::scoped_lock lock(CacheInfo_mutex); } -- Peisheng Wang Software Engineer iZENEsoft (Shanghai) Co., Ltd Room 601 Marine Tower, No. 1 Pudong Ave. Tel:86-21-68860698-114 Fax:86-21-68860699 Company Website:<a target="_blank" href="http://www.izenesoft.com/">www.izenesoft.com</a> <a href="../../../../index.php?menuaction=felamimail.uicompose.compose&send_to=Wmhlbi5ZdUBNb3JnYW5TdGFubGV5LmNvbQ==">Zhen.Yu(a)MorganStanley.com</a>

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Egg review result
by dan marsden 19 May '08

19 May '08

This is a summary of the review of the Egg library by Shunsuke Sogame. The main issue with this review was the low number of reviews submitted, despite a reasonable amount of discussion on the list. In total only 1 review was received, from Giovanni Piero Deretta. This review was a yes vote, contingent on a mini review of improved documentation. Given this extremely low review count, unfortunately Egg cannot be accepted into Boost at this time. The remainder of this summary will cover some of the themes relating to lack of reviews, and also other highlights of the review. I'll start with some positive notes. Several comments on the list suggested that functionality in Egg was wanted by users, and that they would like to see Egg in Boost in some form in the future. Several writers also pointed out the high quality of the implementation of Egg, and technical issues were not really a focus of the discussions. During discussions on the developer several reviewers comments on the quality / style of the documentation for Egg. Motivation seemed to be a big issue in these comments, questions of the form "why should I use Egg versus Boost.XXX" were common. There typically were good reasons to use Egg, but these were not apparent to readers of the documentation. A related issue that cropped up was the sheer scale of Egg, one potential review was withdrawn as the scale of Egg was so large that the reviewer felt he could not do it justice. A couple of reviews pointed out that the documentation could be hard to follow, sometimes as the assumed expertise of the readers was possibly too high, and also for other reasons, such as the __ prefixed notation used in a lot of the documentation. Both Giovanni and Daniel Walker generously offered to provide assistance with the documentation for Egg. Joel de Guzman pointed out that that the timing of the review was poor, as it was in the immediate run up to Boostcon, and many potential reviewers would be busy with preparation for that event. This comment was supported by several people I discussed this with at Boostcon. There was much incredibly detailed technical discussion, which I cannot do justice to here. Those interested will be able to find the discussion on the mailing list archives. In summary I believe key points of the review were: * The number of reviews was insufficient to accept the library in its current form. This seemed to be due to documentation issues making reviews difficult, and the poor timing of the review before Boostcon. * The library was of high technical quality, and the functionality was needed by Boost users in some form. * Documentation issues would definitely need to be addressed before the library could be satisfactorily reviewed and accepted into Boost. I'd like to thank Shunsuke Sogame for submitting the library, and the hard work that he has put in so far. I'd like to encourage him to continue his efforts, and to take up the offers of assistance with documentation if he feels it appropriate. I personally would like to see many parts of Egg in Boost in some form in the future, and other reviewers seemed to agree. I would also like to thank the reviewer, and the many people that contributed discussion on the list, hopefully this will lead to an improved Egg returning in future. Thanks Dan Marsden Review Manager __________________________________________________________ Sent from Yahoo! Mail. A Smarter Email http://uk.docs.yahoo.com/nowyoucan.html

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Boost 1.35 TR1?
by Sohail Somani 19 May '08

19 May '08

Hi, Is there a TR1 package for Boost 1.35? -- Sohail Somani http://uint32t.blogspot.com

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[interprocess] move semantics for shared objects, regions?
by Bryan Green 19 May '08

19 May '08

Hello, In the interprocess library, move semantics are provided for all the container types using boost::interprocess::move(). The code for move semantics is (mostly) present in the shared object types and shared_region, but something is missing for it to actually work for these classes: the necessary specialization of the 'is_movable' trait, and the correct signature on the copy constructor and assignment operators. For example, this does not compile: //---------------- file_mapping m_file; { file_mapping f("file.bin", ipc::read_write); m_file = move(f); } //---------------- But this workaround compiles and works as expected: //---------------- file_mapping m_file; { file_mapping f("file.bin", ipc::read_write); detail::moved_object<file_mapping> mf(f); m_file = mf; } //---------------- Given a simple patch that mirrors what is done for move semantics for the containers, the first example above will work. Is there a reason this was left out? If it is an oversight, would a bug report with a patch file be welcome? Thanks, -bryan --------------------------------------- Bryan Green Visualization Group NASA Advanced Supercomputing Division NASA Ames Research Center email: bryan.d.green(a)nasa.gov ---------------------------------------

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how to sleep a thread for specified milliseconds and/or nanoseconds
by Victor Whiskey Yankee 19 May '08

19 May '08

Hello, I'm using boost 1.35. Would someone please give example of best way to sleep for a specified duration of milliseconds or nanoseconds? It seems that xtime is being deprecated in the thread library, but the sleep function still wants an xtime? Thanks, Victor

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Include Question
by brad＠16systems.com 19 May '08

19 May '08

Hi Guys, I'm new to boost. Just a quick question about the include. I download and untar 1.35.0 to /usr/include then I ran ./configure and make install which for the most part were a success. After this, a dir named boost-1_35 is created under /usr/local/include. Here's where the confusion (for me) comes in... I may do includes this way: g++ -static -I/usr/include/boost_1_35_0 test.cpp -o test.cpp Or this way: g++ -static -I/usr/local.include/boost-1_35 test.cpp -o test.cpp Does it matter? Compiled stuff would fail for the first example (I think), but header only stuff should be OK in the first example or second, right? Just curious. Thanks, Brad

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[python] Function with const wchar_t* arguments/return values
by Dan Fike 19 May '08

19 May '08

[Boost.Python] Anybody have a suggestion for the best way to expose a class's member function that accepts const wchar_t* as an argument, or returns a const wchar_t*? I'm trying to find a way to do it that does not involve writing a thin wrapper function around each of my member functions that convert to/from std:wstring or something. If it balloons up into 100 functions that interact with const wchar_t*, that's a pretty big handful of tiny wrapper functions. I apologize if this is a dumb question, but I haven't found any useful info. It all works implicitly for const char*. Any ideas? Thanks, Dan Fike

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proper way to wait for threads ends
by Axel 19 May '08

19 May '08

Hello I m writting a program which create threads following commands received on a socket connection. When exiting, I'd like to wait that all dynamically created threads have ended their jobs. I thought about using a shared variable (with mutual exclusion) that threads would increment at start and decrement at end. And then the program would stop, loop on sleep() while this shared variable is still > 0. Is there a better way to wait for the end of threads ?

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[date_time] time_periodS subtraction
by Igor R. 19 May '08

19 May '08

Hi, As far as I see, the time_period class does not support any subtraction operation. Is it possible to add it to the "wishlist"? It would be very useful addition for the further releases of the library. I mean the following operation: ----[123456789)----- -----period1 -------[3456789abcdef)---period2 ---[0123456789abc)------perod3 period2 - period1: -----------------[abcdef) period3 - period1: ---[0)----------[abc) Igor'. _________________________________________________________________ News, entertainment and everything you care about at Live.com. Get it now! http://www.live.com/getstarted.aspx

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