MemoryPool.h

00001 #ifndef _MEMORYPOOL_H
00002 #define _MEMORYPOOL_H
00003 
00004 #include <stdint.h>
00005 // #include <cstdio>
00006 #include <stdlib.h>
00007 
00008 #ifdef MEMDEBUG
00009     #define MDEBUG(...) printf(__VA_ARGS__)
00010 #else
00011     #define MDEBUG(...) do {} while (0)
00012 #endif
00013 
00014 #include "StreamOutput.h"
00015 
00016 /*
00017  * with MUCH thanks to http://www.parashift.com/c++-faq-lite/memory-pools.html
00018  *
00019  * test framework at https://gist.github.com/triffid/5563987
00020  */
00021 
00022 class MemoryPool
00023 {
00024 public:
00025     MemoryPool(void* base, uint16_t size);
00026     ~MemoryPool();
00027 
00028     void* alloc(size_t);
00029     void  dealloc(void* p);
00030 
00031     void  debug(StreamOutput*);
00032 
00033     bool  has(void*);
00034 
00035     uint32_t free(void);
00036 
00037     MemoryPool* next;
00038 
00039     static MemoryPool* first;
00040 
00041 private:
00042     void* base;
00043     uint16_t size;
00044 };
00045 
00046 // this overloads "placement new"
00047 inline void* operator new(size_t nbytes, MemoryPool& pool)
00048 {
00049     return pool.alloc(nbytes);
00050 }
00051 
00052 // this allows placement new to free memory if the constructor fails
00053 inline void  operator delete(void* p, MemoryPool& pool)
00054 {
00055     pool.dealloc(p);
00056 }
00057 
00058 // this catches all usages of delete blah. The object's destructor is called before we get here
00059 // it first checks if the deleted object is part of a pool, and uses free otherwise.
00060 inline void  operator delete(void* p)
00061 {
00062     MemoryPool* m = MemoryPool::first;
00063     while (m)
00064     {
00065         if (m->has(p))
00066         {
00067             MDEBUG("Pool %p has %p, using dealloc()\n", m, p);
00068             m->dealloc(p);
00069             return;
00070         }
00071         m = m->next;
00072     }
00073 
00074     MDEBUG("no pool has %p, using free()\n", p);
00075     free(p);
00076 }
00077 
00078 #endif /* _MEMORYPOOL_H */