COMMON: Added a new ObjectPool class, with matching operator new/delete overloads

svn-id: r34785

common/hashmap.h

@@ -37,15 +37,6 @@
 #define USE_HASHMAP_MEMORY_POOL
 #ifdef USE_HASHMAP_MEMORY_POOL
 #include "common/memorypool.h"
-// FIXME: we sadly can't assume standard C++ to be present
-// on every system we support, so we should get rid of this.
-// The solution should be to write a simple placement new
-// on our own.
-
-// Symbian does not have <new> but the new operator 
-#if !defined(__SYMBIAN32__) 
-#include <new>
-#endif
 #endif
 
 namespace Common {
@@ -100,27 +91,15 @@ public:
 	};
 
 
-#ifdef USE_HASHMAP_MEMORY_POOL
-	FixedSizeMemoryPool<sizeof(Node), HASHMAP_MEMORYPOOL_SIZE> _nodePool;
+	ObjectPool<Node, HASHMAP_MEMORYPOOL_SIZE> _nodePool;
 
 	Node *allocNode(const Key &key) {
-		void* mem = _nodePool.malloc();
-		return new (mem) Node(key);
+		return new (_nodePool) Node(key);
 	} 
 
 	void freeNode(Node *node) {
-		node->~Node();
-		_nodePool.free(node);
+		_nodePool.deleteChunk(node);
 	}
-#else
-	Node* allocNode(const Key &key) {
-		return new Node(key);
-	} 
-
-	void freeNode(Node *node) {
-		delete node;
-	}
-#endif
 
 	Node **_storage;	// hashtable of size arrsize.
 	uint _mask;		/**< Capacity of the HashMap minus one; must be a power of two of minus one */

common/memorypool.cpp

@@ -79,7 +79,7 @@ void MemoryPool::addPageToPool(const Page &page) {
 	_next = page.start;
 }
 
-void *MemoryPool::malloc() {
+void *MemoryPool::allocChunk() {
 	if (!_next)	// No free chunks left? Allocate a new page
 		allocPage();
 
@@ -89,7 +89,7 @@ void *MemoryPool::malloc() {
 	return result;
 }
 
-void MemoryPool::free(void* ptr) {
+void MemoryPool::freeChunk(void *ptr) {
 	// Add the chunk back to (the start of) the list of free chunks
 	*(void**)ptr = _next;
 	_next = ptr;

common/memorypool.h

@@ -29,6 +29,7 @@
 #include "common/scummsys.h"
 #include "common/array.h"
 
+
 namespace Common {
 
 class MemoryPool {
@@ -54,10 +55,12 @@ public:
 	MemoryPool(size_t chunkSize);
 	~MemoryPool();
 
-	void 	*malloc();
-	void 	free(void *ptr);
+	void 	*allocChunk();
+	void 	freeChunk(void *ptr);
 
 	void	freeUnusedPages();
+	
+	size_t	getChunkSize() const { return _chunkSize; }
 };
 
 template<size_t CHUNK_SIZE, size_t NUM_INTERNAL_CHUNKS = 32>
@@ -83,6 +86,33 @@ public:
 	FixedSizeMemoryPool() : MemoryPool(CHUNK_SIZE) {}
 };
 
+
+template<class T, size_t NUM_INTERNAL_CHUNKS = 32>
+class ObjectPool : public FixedSizeMemoryPool<sizeof(T), NUM_INTERNAL_CHUNKS> {
+public:
+	void deleteChunk(T *ptr) {
+		ptr->~T();
+		freeChunk(ptr);
+	}
+};
+
 }	// End of namespace Common
 
+// Provide a custom placement new operator, using an arbitrary
+// MemoryPool.
+//
+// This *should* work with all C++ implementations, but may not.
+//
+// For details on using placement new for custom allocators, see e.g.
+// <http://www.parashift.com/c++-faq-lite/dtors.html#faq-11.14>
+
+inline void* operator new(size_t nbytes, Common::MemoryPool& pool) {
+	assert(nbytes <= pool.getChunkSize());
+	return pool.allocChunk();
+}
+
+inline void operator delete(void* p, Common::MemoryPool& pool) {
+	pool.freeChunk(p);
+}
+
 #endif

common/str.cpp

@@ -193,7 +193,7 @@ void String::incRefCount() const {
 		if (g_refCountPool == 0)
 			g_refCountPool = new MemoryPool(sizeof(int));
 
-		_extern._refCount = (int *)g_refCountPool->malloc();
+		_extern._refCount = (int *)g_refCountPool->allocChunk();
 		*_extern._refCount = 2;
 	} else {
 		++(*_extern._refCount);
@@ -212,7 +212,7 @@ void String::decRefCount(int *oldRefCount) {
 		// and the ref count storage.
 		if (oldRefCount) {
 			assert(g_refCountPool);
-			g_refCountPool->free(oldRefCount);
+			g_refCountPool->freeChunk(oldRefCount);
 		}
 		free(_str);
 

common/xmlparser.h

@@ -51,7 +51,7 @@ namespace Common {
 #define MAX_XML_DEPTH 8
 			
 #define XML_KEY(keyName) {\
-		lay =  new CustomXMLKeyLayout;\
+		lay = new CustomXMLKeyLayout;\
 		lay->callback = (&kLocalParserName::parserCallback_##keyName);\
 		layout.top()->children[#keyName] = lay;\
 		layout.push(lay); \
@@ -169,16 +169,14 @@ public:
 		XMLKeyLayout *layout;
 	};
 	
-	FixedSizeMemoryPool<sizeof(ParserNode), MAX_XML_DEPTH> _nodePool;
+	ObjectPool<ParserNode, MAX_XML_DEPTH> _nodePool;
 
 	ParserNode *allocNode() {
-		void* mem = _nodePool.malloc();
-		return new (mem) ParserNode;
+		return new (_nodePool) ParserNode;
 	} 
 
 	void freeNode(ParserNode *node) {
-		node->~ParserNode();
-		_nodePool.free(node);
+		_nodePool.deleteChunk(node);
 	}
 
 	/**