C++ What's wrong with these functions? - c++

Question

This is a class I'm doing to organize every memory block I allocate using malloc/calloc, so I can easily dispose of them later. The following is the definition of this class:
#include "memmanager.h"
std::vector<void*> MemoryManager::GarbageCollector(0);
void MemoryManager::AddToGC(void* myThing)
{
if(__DEBUG__MODE__)
MainDebugger.Log("Adding 1 element to GC: %p", "Info", myThing);
MemoryManager::GarbageCollector.push_back(myThing);
return;
}
void MemoryManager::MultiAddToGC(int args, void* myThing, ...)
{
if(args < 1)
return;
#ifdef _DEBUG
MainDebugger.Log("Adding %i element to GC", "Info", args);
#endif
va_list chrstr;
va_start(chrstr, args);
for(int x = 0; x < args; x++)
MemoryManager::GarbageCollector.push_back(va_arg(chrstr, void*));
va_end(chrstr);
return;
}
void MemoryManager::Flush()
{
int lasterror = 0;
#ifdef _DEBUG
MainDebugger.Log("Call to MemoryManager::Flush() with %i items in the GC", "Info", MemoryManager::GarbageCollector.size());
#endif
for(unsigned int x = 0; x < MemoryManager::GarbageCollector.size(); x++)
{
errno = lasterror = 0;
free(GarbageCollector[x]);
lasterror = errno;
if(lasterror > 0)
MainDebugger.Log("MemoryManager::Flush() Error: %s (%i : %p)", "Error", strerror(lasterror), x, GarbageCollector[x]);
}
GarbageCollector.clear();
return;
}
The problem seems to be with the function "MultiAddToGC". When I do this in my main file:
MemoryManager::MultiAddToGC(3,tst,mfile,testfile);
MemoryManager::Flush();
It works fine if I'm in Debug mode (I'm doing this in VC++ 2010). But if I change to Release mode, it gives me an error inside MemoryManager::Flush() while calling the free() function (something about the stack being corrupted). I can continue, if I continue, I get the following in my log:
15:12:26 f 00 (0 fps) | Error > MemoryManager::Flush() Error: Invalid
argument (2 : 00D44784)
However, if I do this:
MemoryManager::AddToGC(tst);
MemoryManager::AddToGC(mfile);
MemoryManager::AddToGC(testfile);
MemoryManager::Flush();
It works both in Debug, and release. No errors. So I'm assuming the error is in MultiAddToGC(), but I can't find it. The following code is the header, "memmanager.h":
#ifndef __MEMMANAGER_H__
#define __MEMMANAGER_H__
#include <vector>
#include <malloc.h>
#include <stdarg.h>
#include "..\core.h"
#include "..\DEBUGGER\debugger.h"
extern bool __DEBUG__MODE__;
extern GameDebugger MainDebugger;
class MemoryManager {
public:
static void MemoryManager::AddToGC(void*);
static void MemoryManager::MultiAddToGC(int, void*,...);
static void MemoryManager::Flush();
private:
static std::vector<void*> GarbageCollector;
protected:
};
#endif
Any help/tips/advise is wellcome.

Answer 1

In va_start(chrstr, args);, the second parameter should be the last named parameter, so myThing (but you probably want to remove myThing in fact).
but I would write
template <typename...Ts>
void MemoryManager::MultiAddToGC(Ts*... myThings)
{
if(sizeof...(myThings) < 1)
return;
#ifdef _DEBUG
MainDebugger.Log("Adding %i elements to GC", "Info", sizeof...(myThings));
#endif
int dummy[] = {(MemoryManager::GarbageCollector.push_back(myThings), 0)...};
(void) dummy; // avoid warning for unused variable
}
or simply
void MemoryManager::MultiAddToGC(const std::initializer_list<void*>& myThings)
{
if(myThings.size() < 1)
return;
#ifdef _DEBUG
MainDebugger.Log("Adding %i elements to GC", "Info", myThings.size());
#endif
MemoryManager::GarbageCollector.insert(MemoryManager::GarbageCollector.begin(),
myThings.begin(), myThings.end());
}