Diff: libs/MemoryPool.h

Revision:

2:1df0b61d3b5a

Child:

3:f151d08d335c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libs/MemoryPool.h	Fri Feb 28 18:52:52 2014 -0800
@@ -0,0 +1,78 @@
+#ifndef _MEMORYPOOL_H
+#define _MEMORYPOOL_H
+
+#include <cstdint>
+// #include <cstdio>
+#include <cstdlib>
+
+#ifdef MEMDEBUG
+    #define MDEBUG(...) printf(__VA_ARGS__)
+#else
+    #define MDEBUG(...) do {} while (0)
+#endif
+
+#include "StreamOutput.h"
+
+/*
+ * with MUCH thanks to http://www.parashift.com/c++-faq-lite/memory-pools.html
+ *
+ * test framework at https://gist.github.com/triffid/5563987
+ */
+
+class MemoryPool
+{
+public:
+    MemoryPool(void* base, uint16_t size);
+    ~MemoryPool();
+
+    void* alloc(size_t);
+    void  dealloc(void* p);
+
+    void  debug(StreamOutput*);
+
+    bool  has(void*);
+
+    uint32_t free(void);
+
+    MemoryPool* next;
+
+    static MemoryPool* first;
+
+private:
+    void* base;
+    uint16_t size;
+};
+
+// this overloads "placement new"
+inline void* operator new(size_t nbytes, MemoryPool& pool)
+{
+    return pool.alloc(nbytes);
+}
+
+// this allows placement new to free memory if the constructor fails
+inline void  operator delete(void* p, MemoryPool& pool)
+{
+    pool.dealloc(p);
+}
+
+// this catches all usages of delete blah. The object's destructor is called before we get here
+// it first checks if the deleted object is part of a pool, and uses free otherwise.
+inline void  operator delete(void* p)
+{
+    MemoryPool* m = MemoryPool::first;
+    while (m)
+    {
+        if (m->has(p))
+        {
+            MDEBUG("Pool %p has %p, using dealloc()\n", m, p);
+            m->dealloc(p);
+            return;
+        }
+        m = m->next;
+    }
+
+    MDEBUG("no pool has %p, using free()\n", p);
+    free(p);
+}
+
+#endif /* _MEMORYPOOL_H */