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Forward port r56500.

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61007 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Michael Wetherell 2009-06-12 00:17:37 +00:00
parent f0ceebb7e0
commit 527983315d
1 changed files with 45 additions and 20 deletions
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65
src/common/object.cpp
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@ -206,37 +206,45 @@ wxClassInfo *wxClassInfo::FindClass(const wxString& className)
}
}
// This function wasn't written to be reentrant but there is a possiblity of
// reentrance if something it does causes a shared lib to load and register
// classes. On Solaris this happens when the wxHashTable is newed, so the first
// part of the function has been modified to handle it, and a wxASSERT checks
// against reentrance in the remainder of the function.
// Reentrance can occur on some platforms (Solaris for one), as the use of hash
// and string objects can cause other modules to load and register classes
// before the original call returns. This is handled by keeping the hash table
// local when it is first created and only assigning it to the global variable
// when the function is ready to return.
//
// That does make the assumption that after the function has completed the
// first time the problem will no longer happen; all the modules it depends on
// will have been loaded. The assumption is checked using the 'entry' variable
// as a reentrance guard, it checks that once the hash table is global it is
// not accessed multiple times simulateously.
void wxClassInfo::Register()
{
if ( !sm_classTable )
{
wxHashTable *classTable = new wxHashTable(wxKEY_STRING);
// check for reentrance
if ( sm_classTable )
delete classTable;
else
sm_classTable = classTable;
}
#if wxDEBUG_LEVEL
// reentrance guard - see note above
static int entry = 0;
wxASSERT_MSG(++entry == 1, _T("wxClassInfo::Register() reentrance"));
#endif // wxDEBUG_LEVEL
wxHashTable *classTable;
if ( !sm_classTable )
{
// keep the hash local initially, reentrance is possible
classTable = new wxHashTable(wxKEY_STRING);
}
else
{
// guard againt reentrance once the global has been created
wxASSERT_MSG(++entry == 1, _T("wxClassInfo::Register() reentrance"));
classTable = sm_classTable;
}
// Using IMPLEMENT_DYNAMIC_CLASS() macro twice (which may happen if you
// link any object module twice mistakenly, or link twice against wx shared
// library) will break this function because it will enter an infinite loop
// and eventually die with "out of memory" - as this is quite hard to
// detect if you're unaware of this, try to do some checks here.
wxASSERT_MSG( sm_classTable->Get(m_className) == NULL,
wxASSERT_MSG( classTable->Get(m_className) == NULL,
wxString::Format
(
_T("Class \"%s\" already in RTTI table - have you used IMPLEMENT_DYNAMIC_CLASS() multiple times or linked some object file twice)?"),
@ -244,10 +252,27 @@ void wxClassInfo::Register()
)
);
sm_classTable->Put(m_className, (wxObject *)this);
classTable->Put(m_className, (wxObject *)this);
// if we're using a local hash we need to try to make it global
if ( sm_classTable != classTable )
{
if ( !sm_classTable )
{
// make the hash global
sm_classTable = classTable;
}
else
{
// the gobal hash has already been created by a reentrant call,
// so delete the local hash and try again
delete classTable;
Register();
}
}
#if wxDEBUG_LEVEL
--entry;
entry = 0;
#endif // wxDEBUG_LEVEL
}