GODOT IS OPEN SOURCE

core/pool_allocator.h

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+/*************************************************************************/
+/*  pool_allocator.h                                                     */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                    http://www.godotengine.org                         */
+/*************************************************************************/
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                 */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+#ifndef POOL_ALLOCATOR_H
+#define POOL_ALLOCATOR_H
+
+#include "typedefs.h"
+
+/**
+	@author Juan Linietsky <reduzio@gmail.com>
+ * Generic Pool Allocator.
+ * This is a generic memory pool allocator, with locking, compacting and alignment. (@TODO alignment)
+ * It used as a standard way to manage alloction in a specific region of memory, such as texture memory,
+ * audio sample memory, or just any kind of memory overall.
+ * (@TODO) abstraction should be greater, because in many platforms, you need to manage a nonreachable memory.
+*/
+
+enum {
+	
+	POOL_ALLOCATOR_INVALID_ID=-1 ///< default invalid value. use INVALID_ID( id ) to test
+};
+
+class PoolAllocator {
+public:	
+	typedef int ID;
+private:	
+	enum {
+		CHECK_BITS=8,
+  		CHECK_LEN=(1<<CHECK_BITS),
+		CHECK_MASK=CHECK_LEN-1
+	
+	};
+	
+	
+	struct Entry {
+		
+		unsigned int pos;
+		unsigned int len;
+		unsigned int lock;
+		unsigned int check;		
+		
+		inline void clear() { pos=0; len=0; lock=0; check=0; }
+		Entry() { clear(); }
+	};
+	
+	
+	typedef int EntryArrayPos;
+	typedef int EntryIndicesPos;
+	
+	Entry *entry_array;
+	int *entry_indices;
+	int entry_max;
+	int entry_count;
+	
+	uint8_t *pool;
+	void *mem_ptr;
+	int pool_size;
+	
+	int free_mem;
+	int free_mem_peak;
+
+	unsigned int check_count;
+	int align;
+	
+	bool needs_locking;
+	
+	inline int entry_end(const Entry& p_entry) const { 
+		return p_entry.pos+aligned(p_entry.len); 
+	}
+	inline int aligned(int p_size) const {
+			
+		int rem=p_size%align;
+		if (rem)
+			p_size+=align-rem;
+			
+		return p_size;
+	}
+	
+	void compact(int p_up_to=-1);
+	void compact_up(int p_from=0);
+	bool get_free_entry(EntryArrayPos* p_pos);
+	bool find_hole(EntryArrayPos *p_pos, int p_for_size);
+	bool find_entry_index(EntryIndicesPos *p_map_pos,Entry *p_entry);
+	Entry* get_entry(ID p_mem);
+	const Entry* get_entry(ID p_mem) const;
+	
+	void create_pool(void * p_mem,int p_size,int p_max_entries);
+protected:	
+	virtual void mt_lock() const; ///< Reimplement for custom mt locking
+	virtual void mt_unlock() const; ///< Reimplement for custom mt locking
+	
+public:
+	
+	enum {
+		DEFAULT_MAX_ALLOCS=4096,
+	};
+
+	ID alloc(int p_size); ///< Alloc memory, get an ID on success, POOL_ALOCATOR_INVALID_ID on failure
+	void free(ID p_mem); ///< Free allocated memory
+	Error resize(ID p_mem,int p_new_size); ///< resize a memory chunk
+	int get_size(ID p_mem) const;
+	
+	int get_free_mem(); ///< get free memory
+	int get_used_mem() const;
+	int get_free_peak(); ///< get free memory
+
+	Error lock(ID p_mem); //@todo move this out
+	void *get(ID p_mem);
+	const void *get(ID p_mem) const;
+	void unlock(ID p_mem);
+	bool is_locked(ID p_mem) const;
+		
+	PoolAllocator(int p_size,bool p_needs_locking=false,int p_max_entries=DEFAULT_MAX_ALLOCS);
+	PoolAllocator(void * p_mem,int p_size, int p_align = 1, bool p_needs_locking=false,int p_max_entries=DEFAULT_MAX_ALLOCS);
+	PoolAllocator(int p_align,int p_size,bool p_needs_locking=false,int p_max_entries=DEFAULT_MAX_ALLOCS);
+		
+	virtual ~PoolAllocator();
+	
+};
+
+#endif