[ http://issues.apache.org/jira/browse/XERCESC-1334?page=comments#action_58517 ] xuerong tang commented on XERCESC-1334: ---------------------------------------
The affected version should be 2.5.0 and 2.6.0, instead of 1.5, 1.6 > XMLTransService::makeNewTranscoderFor(...) does not have a corresponding > method to release the memory it allocates. Once a new XMLTranscoder is > created, no other feasible way to clear up the memory except for calling > XMLTranscoder destructor explicitly > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ > > Key: XERCESC-1334 > URL: http://issues.apache.org/jira/browse/XERCESC-1334 > Project: Xerces-C++ > Type: Improvement > Components: Utilities > Versions: 1.5, 1.5.1, 1.5.2, 1.6.0 > Environment: WinXP/VC7.1 > Reporter: xuerong tang > Priority: Critical > > a)Problem description: > Once TransService is used to create a new XMLTranscoder, no other feasible > way to clear up the memory except for calling XMLTranscoder destructor > explicitly. The signature of the creation function is as follows: > XMLTranscoder* XMLTransService::makeNewTranscoderFor > b)Analyzed the problem: > i.The class tree is XMemory --> XMLTranscoder --> XMLUTF8Transcoder. The > delete/new operators in the base class were overloaded with pluggable memory > manager (default is Xerces’ MemoryManager class implementation, which > currently uses global operators ::operator delete, ::operator new in a > straightforward manner). The function signature is like this: > void* XMemory::operator new(size_t size, MemoryManager* manager) > void XMemory::operator delete(void* p, MemoryManager* manager) > ii.Although the definitions for the above new/delete appeared symmetric, they > are actually not. In C++, there is a way of calling this overloaded new > operator using “replacement new” syntax: e.g., new (manager) > XMLTranscoder(…), which will call the overloaded new operator (do some memory > allocation in this case) first and then call the class constructor (do some > further memory allocation in this case). Unfortunately, there is no such a > “replacement delete” that will “undo” these things automatically. As a > result, whenever “placement new” was used, for releasing the memory, the > destructor should be called explicitly first, then the overloaded delete > should be called (so that the corresponding memory manager is used) to free > up the memory. See BJARNE’s C++ Programming Language (3rd Edition) Page 256 > for detailed explanation. > iii.Debugging into method makeNewTranscoderFor(…) reveals that it called > “replacement new” to do the memory allocation: > template <class TType> XMLTranscoder* > ENameMapFor<TType>::makeNew(const unsigned int blockSize, > MemoryManager* const manager) const > { > return new (manager) TType(getKey(), blockSize, manager); > } > but it seemed to me that Xerces did not provide a corresponding method to > release&clean up objects (at lease in current releases 2.5.0 and 2.6.0) > iv.Without a corresponding destroyTranscoder(...) to hide the detail of > releasing the memory for me, I have to use the following “messy” code: > //create a new transcoder > XMLTranscoder* aTranscoder = XMLPlatformUtils::fgTransService-> > makeNewTranscoderFor(encodingName, resCode, 16*maxBufferSize, > XMLPlatformUtils::fgMemoryManager); > //do some work with the transcoder > ... > //messy code for releasing all the memory > aTranscoder->~XMLTranscoder(); //release the memory allocated in constructor > aTranscoder->operator delete(aTranscoder, XMLPlatformUtils::fgMemoryManager); > //release the memory allocated by replacment new > c) Proposed improvement > XMLTransService should provide a corresponding DestroyTranscoder(...) method > that will internally call the above two lines of code so that the > implementation detail is hidden to the Xerces users. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - If you want more information on JIRA, or have a bug to report see: http://www.atlassian.com/software/jira --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
