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Bug in random library
by rupp＠stud.uni-frankfurt.de 13 Feb '04

13 Feb '04

I have either overlooked something basic or found a bug in the random library: boost::mt19937 engine_; double result_ = boost::uniform_real<double>(0., 1.) (engine_); std::cout << result_ << std::endl; assert ( (0. <= result_) && (result_ < 1.) ); results in 4.29093e+09 test_boost: test/test_boost.cpp:17: void test_random (): Assertion `(0. <= result_) && (result_ < 1.)' failed. Abort Although the documentation says "The current implementation is buggy, because it may not fill all of the mantissa with random bits." IMHO this is worse than that: I expected the result to satisfy min <= result < max. I'm using boost 1.31.0 and g++ 2.96 as well as g++ 3.3.2 (identical results) on Red Hat Linux. I hope that either someone can explain me my mistake or fix the bug. Matthias Rupp

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RNG, operator<< and VC7.1
by Witz 13 Feb '04

13 Feb '04

I'm trying to save the state of the random number generators to file but for some reason VC7.1 doesn't seem to be able to find operator<< (or operator>> when i need to read it back in). Anyone else had this problem? Is there a solution other than going in to the header file and creating a read and write function that contains the same code as the streaming operators? I.Whittley

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boost_1_31_0 transform_iterator and VC71 ICE - FYI
by Jeff Flinn 12 Feb '04

12 Feb '04

I've begun converting my projects to using the new iterator_adaptor's. I've encountered an ICE with the code below. I've tried to isolate it to a simple console app but of course, the problem does not occur there. The following distillation does ICE, when compiled with the /Gm (Enable Minimal Rebuild) flag, but compiles and runs fine w/out it. This is an MFC multithreaded lib project NOT using precompiled headers. I'll continue to try to isolate the conditions.Any thoughts on how to isolate the problem? VC7.1 error message: C:\boost\boost_1_31_0\boost\mpl\aux_\preprocessed\plain\apply.hpp(50) : fatal error C1001: INTERNAL COMPILER ERROR (compiler file 'msc1.cpp', line 2701) #include <string> #include <algorithm> #include <vector> #include <numeric> #include <boost/bind.hpp> #include <boost/function.hpp> #include <boost/iterator/transform_iterator.hpp> typedef std::pair<int,int> CSize; CSize SizeFromString( const std::string& aString ){ return CSize(1,2); } CSize XUnionStacked ( const CSize& aSz1, const CSize& aSz2 ){ return CSize(1,2); } CSize XSizeMultiLine( const std::string& aString, const CSize& aSize ) { CSize lSize(0,0); boost::function1<CSize,const std::string& > lSizeFromStringFnc = boost::bind( SizeFromString, _1 ); boost::function2<CSize,const CSize&,const CSize& > lSizeUnionStackedFnc = boost::bind( XUnionStacked, _1, _2 ); std::vector<std::string> lStrings(10); lSize = std::accumulate ( boost::make_transform_iterator( lStrings.begin(), lSizeFromStringFnc ) , boost::make_transform_iterator( lStrings. end(), lSizeFromStringFnc ) , lSize , lSizeUnionStackedFnc ); return lSize; } Thanks, Jeff F

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RE: [Boost-users] Threading problem
by Ben Hutchings 12 Feb '04

12 Feb '04

Damien McGivern <d_mcgivern(a)yahoo.com> wrote: > (First post) > Hi, > I've just started working with boost and have come > into some trouble with the thread class. I've included > the test code that I'm having the problem with in the > hope that someone could point out to me where I'm > going wrong. > > The code tests the QueueAccessor class > (CommandQueue.hpp) with the test code in > CommandQueueTest.hpp. I created a base class > (Runnable) to aid in creating a thread that runs an > object's method rather than a function. The code > compiles OK and seems to run OK too at first until I > realised that the main thread has somehow become one > of the threads that I created and is in a continuous > loop after the first join() is called > > _writer_thread1->join(); // line 21 join() waits for the thread to *end*. This should be done after the threads have been told to Stop(). > As you can probably guess from my code my background > is in Java so I'm not entirely sure if I'm using the > boost::thread correctly. I thought Java's join() was exactly the same. > I tested the QueueAccessor > using threads that use a static worker function > instead of an object's method and it seemed to run OK > so I'm assuming that the problem lies with the > Runnable base class. > > I'm using boost version 1.31.0 running Windows XP and > using VS.Net 2003 to compile/run the code. > > Any help will be very much appreciated Here are the bugs I found: - Runnable::_running is read and written from multiple threads without use of a mutex. - The result of QueueAccessor::Pop is undefined if the queue is empty. Perhaps it should throw in this case? - The return type of QueueAccessor::Size should be std::queue<QueueItem>::size_type (which I think is std::size_t). - QueueAccessor::Size doesn't lock the mutex for the queue. - Reader::Do busy-waits for input. It should wait on a condition variable instead. (Condition variables provide functions equivalent to the wait, notify and notifyAll methods that Object has in Java.) Worse, when the reader is asked to stop, Reader::Do may never return to Worker::Run and so the thread will never stop. - CommandQueueTest.hpp doesn't include <iostream>. - #include <name> is reserved for use with system headers. You should use #include "name" for including your own headers. - Identifiers that include "__" are reserved for the use of the implementation. You must not use them. - Many member variables are protected when they should be private. I have fixed most of the above and the program now works. Ben.

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boost_1_31_0 documentation - "Getting Started"
by Jeff Flinn 12 Feb '04

12 Feb '04

First the nit - The examples for running bjam include the arguments in double quotes as in: bjam "-sTOOLS=gcc" install Being bjam and generally makefile(and generally command line) impaired I tried: bjam "-sTOOLS=VC71" "-sVC71_ROOT=C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7" Which results in: VC71-tools.jam: No such file or directory C:\boost\boost_1_31_0\tools/build/v1\allyourbase.jam:630: in C++ rule C++-action unknown in module C:\boost\boost_1_31_0\tools/build/v1\allyourbase.jam:1097: in Object C:\boost\boost_1_31_0\tools/build/v1\allyourbase.jam:1162: in Objects C:\boost\boost_1_31_0\tools/build/v1\boost-base.jam:130: in dll-files C:\boost\boost_1_31_0\tools/build/v1\boost-base.jam:1934: in subvariant-target C:\boost\boost_1_31_0\tools/build/v1\boost-base.jam:2361: in stage Jamfile:144: in load-jamfiles C:\boost\boost_1_31_0\tools\build\v1\bootstrap.jam:15: in boost-build C:\boost\boost_1_31_0\boost-build.jam:16: in module scope Of course the following works great! bjam -sTOOLS=VC71 -sVC71_ROOT="C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7" So I'm not sure of the purpose of the "" in the documentation, but they are misleading, at least to me. The Praise - Awesome improvement in the completeness and organization of the built libs and dlls! Thanks, Jeff

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RE: [Boost-users] Threading problem
by Geert Pante 12 Feb '04

12 Feb '04

There's nothing wrong with your runnable class, but with your use of thread::join(). Boost::threads start as soon as they are constructed, join() means: wait until they are finished. In your test code, it doesn't make sense to join() your threads before you Stop() them. Probably the next is what you meant: Threading::boost_thread_starter starter3((Threading::Runnable *)&writer2); boost::thread* _writer_thread2 = new boost::thread(starter3); // pause for 5 secs boost::xtime xt; boost::xtime_get(&xt, boost::TIME_UTC); xt.sec += 5; boost::thread::sleep(xt); writer2.Stop(); _writer_thread2->join(); Cya, Geert.

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Threading problem
by Damien McGivern 12 Feb '04

12 Feb '04

(First post) Hi, I've just started working with boost and have come into some trouble with the thread class. I've included the test code that I'm having the problem with in the hope that someone could point out to me where I'm going wrong. The code tests the QueueAccessor class (CommandQueue.hpp) with the test code in CommandQueueTest.hpp. I created a base class (Runnable) to aid in creating a thread that runs an object's method rather than a function. The code compiles OK and seems to run OK too at first until I realised that the main thread has somehow become one of the threads that I created and is in a continuous loop after the first join() is called _writer_thread1->join(); // line 21 As you can probably guess from my code my background is in Java so I'm not entirely sure if I'm using the boost::thread correctly. I tested the QueueAccessor using threads that use a static worker function instead of an object's method and it seemed to run OK so I'm assuming that the problem lies with the Runnable base class. I'm using boost version 1.31.0 running Windows XP and using VS.Net 2003 to compile/run the code. Any help will be very much appreciated Cheers mcgiv ___________________________________________________________ BT Yahoo! Broadband - Free modem offer, sign up online today and save £80 http://btyahoo.yahoo.co.uk #ifndef __TEST_COMMANDQUEUE2__ #define __TEST_COMMANDQUEUE2__ #include <Universal/CommandQueue.hpp> #include <Threading/Runnable.hpp> using namespace Universal; boost::mutex _iomutex; class Worker : public Threading::Runnable { public: Worker(QueueAccessor* q):Threading::Runnable(), _queue(q), _pause_sec(0){} void Run() { while(this->_running) { this->Do(); if(this->_pause_sec > 0) this->Pause(this->_pause_sec); } } virtual void Do() = 0; protected: QueueAccessor* _queue; int _pause_sec; }; class Writer : public Worker { public: Writer(QueueAccessor* q):Worker(q),_index(0){ this->_pause_sec = 2; } void Do() { boost::mutex::scoped_lock scoped_lock(_iomutex); QueueItem item("hi there", this->_index++); this->_queue->Push(item); std::cout << "Add" << std::endl; } short _index; void Stop() { boost::mutex::scoped_lock scoped_lock(_iomutex); this->_running = false;//Threading::Runnable::Stop(); std::cout << "Stopped Writer" << std::endl; } }; class Reader : public Worker { public: Reader(QueueAccessor* q):Worker(q){} void Do() { while(this->_queue->Size() == 0){} boost::mutex::scoped_lock scoped_lock(_iomutex); QueueItem item = this->_queue->Pop(); std::cout << "Removed id=" << item._data_len << " Data=" << item._data << std::endl; } void Stop() { boost::mutex::scoped_lock scoped_lock(_iomutex); this->_running = false;//Threading::Runnable::Stop(); std::cout << "Stopped Reader" << std::endl; } }; void test() { QueueAccessor* q = new QueueAccessor(); Reader reader(q); Writer writer1(q); Writer writer2(q); // set up threads Threading::boost_thread_starter starter((Threading::Runnable *)&reader); boost::thread* _reader_thread = new boost::thread(starter); Threading::boost_thread_starter starter2((Threading::Runnable *)&writer1); boost::thread* _writer_thread1 = new boost::thread(starter2); Threading::boost_thread_starter starter3((Threading::Runnable *)&writer2); boost::thread* _writer_thread2 = new boost::thread(starter3); // start threads _writer_thread1->join(); _writer_thread2->join(); _reader_thread->join(); // pause for 5 secs boost::xtime xt; boost::xtime_get(&xt, boost::TIME_UTC); xt.sec += 5; boost::thread::sleep(xt); reader.Stop(); writer1.Stop(); writer2.Stop(); delete q; char c; std::cin >> c; } #endif __TEST_COMMANDQUEUE2__ #ifndef __IRUNNABLE__ #define __IRUNNABLE__ #include <boost/thread/thread.hpp> #include <boost/thread/xtime.hpp> namespace Threading { class Runnable { public: Runnable():_running(true){} virtual void Run() = 0; virtual void Stop(){_running = false;} protected: bool _running; // sleeps thread for x sec void Pause(int sec) { boost::xtime xt; boost::xtime_get(&xt, boost::TIME_UTC); xt.sec += sec; boost::thread::sleep(xt); } void Pause(int sec, int ns) { boost::xtime xt; boost::xtime_get(&xt, boost::TIME_UTC); xt.sec += sec; xt.nsec += ns*1000; boost::thread::sleep(xt); } }; // used to pass the Runnable object to the thread's start function struct boost_thread_starter { boost_thread_starter(Runnable* runnable):_runnable(runnable){} // function is called when boost::thread starts void operator()() { // start the Runnable's run method _runnable->Run(); } Runnable* _runnable; }; }// end Threading namespace #endif // __IRUNNABLE__ #ifndef __COMMANDQUEUE__ #define __COMMANDQUEUE__ #include <boost/thread/mutex.hpp> #include <queue> namespace Universal { struct QueueItem { /* QueueItem(int thread, int value):_thread(thread), _value(value){} int _thread; int _value; //*/ QueueItem(char *data, short data_len):_data(data), _data_len(data_len){} char *_data; short _data_len; //*/ }; // used to sync access to the queue class QueueAccessor { public: QueueAccessor(){} void Push(QueueItem item) { boost::mutex::scoped_lock scoped_lock(_mutex); _queue.push(item); } QueueItem Pop() { boost::mutex::scoped_lock scoped_lock(_mutex); if( _queue.size() > 0 ) { QueueItem tmp = _queue.front(); _queue.pop(); return tmp; } } int Size() { return _queue.size(); } protected: std::queue<QueueItem> _queue; boost::mutex _mutex; }; }// Universal namespace #endif // __COMMANDQUEUE__

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[BGL] adjacency_list: edge_descriptor ordering
by Ded Panas 12 Feb '04

12 Feb '04

Hi boost! How to store edge descriptors in a sorted container? There is no operator< for this type. Is it considered useless? In my graph building code I first build graph structure, and than calculate properties. So I need to remember edge descriptors between that stages... Also, about the docs: there is no link from Table of Contents to AdjacencyMatrix.html, where edge() function is described. TIA dedpanas

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VTL question (sorry if this is slightly off-topic)
by Matt Verona 11 Feb '04

11 Feb '04

Hello, I was reviewing the View Template Library (VTL) - see http://www.zib.de/weiser/vtl/ ... and have a few questions regarding Views as applied to STL Maps. I was also wondering if Boost was planning to eventually provide a VTL-like framework? I'm looking for a type of View that provides read-only access to an STL map, with only const iterators, but also provides limited insertion and removal access as well (as shown below): This new limited View-like map will only allow clients to iterate using const iterators, and also provides only one public insert(const key&) and one erase(const key&) method. These insert and erase member functions need to be implemented as "Template Method Functions", as follows: (see Design Patterns) * Note: these are shown using the latest SGI STL implementation (i.e., the _M_t.insert_unique and _M_t.erase calls) virtual bool preInsert(const value_type&) { return true; } pair<iterator, bool> insert(const value_type& x) { if(preInsert(x) { return _M_t.insert_unique(x); } return make_pair(end(), false); // make compiler happy } virtual bool preErase(const key_type&) { return true; } size_type erase(const key_type& x) { if(preErase(x) { return _M_t.erase(x); } return 0; // make compiler happy } The preInsert and preErase methods are virtual Hook Methods, and derived classes override these to add behavior to the (non-virtual) insert and erase functions.. Another nice addition to this map view would be a const _Tp& operator[](const key_type& k) const function, implemented something like this: const _Tp& operator[](const key_type& k) const { const_iterator i = lower_bound(k); if(i == end() || key_comp(k, (*i).first)) // if i->first is >= k throw SearchError(k); return (*i).second; } * Note: this simple implementation assumes that the key can be converted to a string in the constructor of the SearchError exception object. I have at least three Manager-like (Mediator) classes that can use this pattern (i.e., derived from this Map View class) as well as others that need a vector view with a similar filtered design... Thanks in advance, ~Matt Verona Houston, Texas USA

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[BGL] adjacency_list: OutEdgeList and EdgeList
by Ded Panas 11 Feb '04

11 Feb '04

I'm somewhat unclear about the difference between OutEdgeListS and EdgeListS selectors of adjacency_list. My questions is: 1. Why EdgeListS defaults to listS, while OutEdgeListS to vecS (BTW, doc says that EdgeListS defaults to vecS also) ? 2. In the docs ("Choosing the Edgelist and VertexList"), what is Edgelist: OutEdgeListS or EdgeListS? It is unclear (seems it is OutEdgeListS). TIA dedpanas

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