unordered_map has no destructor!

[anonymous]

I noticed that the unordered_map has no destructor as one would assume. There should be a destructor that calls clear() so that the content of the map is deleted. (cf. RAII - ​http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization)

I ran into a serious memory leak because of that, when using an unordered_map locally and assuming that it clears its content when being destroyed.

[Daniel James]

The memory management is taken care of by an internal implementation class called hash_table_data_equivalent_keys or hash_table_data_unique_keys. You can see the destructor here:

​https://svn.boost.org/trac/boost/browser/trunk/boost/unordered/detail/hash_table_impl.hpp?rev=51995#L380

The destructor is called BOOST_UNORDERED_TABLE_DATA because I'm using macros to define the two different hash tables with a single implementation.

unordered_map and unordered_set's implicit destructors both call the implementation classes' destructors, so there's no need to define a destructor for those classes.

[anonymous]

But somehow the unordered_map was only cleared if and only if I called clear() manually. I can post you some details if you like.

[Daniel James]

If you send me an example, I'll have a look at it. Let me know which compiler you're using and on which platform.

[anonymous]

Here is the example (I tried to skip the unnecessary stuff):

definitions:

typedef boost::tuple<TPoint, TPoint, TPoint> TEdgeIdentifier; typedef std::pair<PTempPlzEdge, unsigned> TCountedEdge;

typedef boost::unordered_map<TEdgeIdentifier, TCountedEdge, TEdgeIdentifierHash, TEdgeIdentifierEqual> TEdgeCountMap;

method:

---

TEdgeCountMap EdgeCountDifferentMap( 1.5 * List.size() ); for( "it in List" ){

TEdgeCountMap::iterator found = EdgeCountDifferentMap.find( (*it)->GetEdgeIdentifier() );

if( found != EdgeCountDifferentMap.end() ){

if( "some condition" ){

found->second.second ++;

}

}else{

EdgeCountDifferentMap.insert( std::make_pair( (*it)->GetEdgeIdentifier(), std::make_pair( *it , 1 ) ) );

}

}

for( "it in List" ){

TEdgeCountMap::iterator found = EdgeCountDifferentMap.find( (*it)->GetEdgeIdentifier() );

if( found != EdgeCountDifferentMap.end() && found->second.second > 1 ){

continue;

}

"do something with *it"

}

EdgeCountDifferentMap.clear(); if this is uncommented, I have a huge memory leak although this is the end of the method and EdgeCountDifferentMap should be destroyed

Additionally I noticed (using AQtime 6) that the memory that is allocated within the constructor call "TEdgeCountMap EdgeCountDifferentMap( 1.5 * List.size() );" is not freed too.

I am in the unfortunate situation that I have to use Borland C++ Builder 4. I use boost version 1.37.

[Daniel James]

(In [53253]) Add explicit destructors to the unordered containers. Refs #2908.

Isn't really needed but it doesn't hurt.

[anonymous]

Well, guess what? That worked! Strange, as I can comprehend your previous reasoning totaly. Seems like the old Borland C++-Compiler has a serious issue there. :(

[Daniel James]

(In [53465]) Merge latest changes for unordered. Improved compatability and a few tweaks.

Merged revisions 53127,53253,53256,53311,53314,53316-53318 via svnmerge from ​https://svn.boost.org/svn/boost/trunk

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r53127 | danieljames | 2009-05-20 07:43:38 +0100 (Wed, 20 May 2009) | 1 line

Better configuration for boost.unordered.

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r53253 | danieljames | 2009-05-25 20:14:07 +0100 (Mon, 25 May 2009) | 3 lines

Add explicit destructors to the unordered containers. Refs #2908.

Isn't really needed but it doesn't hurt.

........

r53256 | danieljames | 2009-05-25 20:45:23 +0100 (Mon, 25 May 2009) | 1 line

Unordered change log for explicit destructors.

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r53311 | danieljames | 2009-05-27 18:42:01 +0100 (Wed, 27 May 2009) | 1 line

Missing changelog entry.

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r53314 | danieljames | 2009-05-27 18:44:09 +0100 (Wed, 27 May 2009) | 1 line

Use lightweight_test for unordered.

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r53316 | danieljames | 2009-05-27 19:19:32 +0100 (Wed, 27 May 2009) | 1 line

Some workarounds for old versions of Borland.

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r53317 | danieljames | 2009-05-27 19:32:22 +0100 (Wed, 27 May 2009) | 1 line

Fix a change accidentally included in the last commit.

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r53318 | danieljames | 2009-05-27 19:32:38 +0100 (Wed, 27 May 2009) | 1 line

Remove an unused function.

........