genode/repos/base/include/base/heap.h

/*
 * \brief  Heap partition
 * \author Norman Feske
 * \date   2006-05-15
 */

/*
 * Copyright (C) 2006-2013 Genode Labs GmbH
 *
 * This file is part of the Genode OS framework, which is distributed
 * under the terms of the GNU General Public License version 2.
 */

#ifndef _INCLUDE__BASE__HEAP_H_
#define _INCLUDE__BASE__HEAP_H_

#include <util/list.h>
#include <ram_session/ram_session.h>
#include <rm_session/rm_session.h>
#include <base/allocator_avl.h>
#include <base/lock.h>

namespace Genode {

	/**
	 * Heap that uses dataspaces as backing store
	 *
	 * The heap class provides an allocator that uses a list of dataspaces of a ram
	 * session as backing store. One dataspace may be used for holding multiple blocks.
	 */
	class Heap : public Allocator
	{
		private:

			enum {
				MIN_CHUNK_SIZE =   4*1024,  /* in machine words */
				MAX_CHUNK_SIZE = 256*1024,
				/*
				 * Meta data includes the Dataspace structure and meta data of
				 * the AVL allocator.
				 */
				META_DATA_SIZE = 1024,      /* in bytes */
				/*
				 * Allocation sizes >= this value are considered as big
				 * allocations, which get their own dataspace. In contrast
				 * to smaller allocations, this memory is released to
				 * the RAM session when 'free()' is called.
				 */
				BIG_ALLOCATION_THRESHOLD = 64*1024 /* in bytes */
			};

			class Dataspace : public List<Dataspace>::Element
			{
				public:

					Ram_dataspace_capability cap;
					void  *local_addr;
					size_t size;

					Dataspace(Ram_dataspace_capability c, void *local_addr, size_t size)
					: cap(c), local_addr(local_addr), size(size) { }

					inline void * operator new(Genode::size_t, void* addr) {
						return addr; }
					inline void operator delete(void*) { }
			};

			/*
			 * This structure exists only to make sure that the dataspaces are
			 * destroyed after the AVL allocator.
			 */
			struct Dataspace_pool : public List<Dataspace>
			{
				Ram_session *ram_session; /* ram session for backing store */
				Rm_session  *rm_session;  /* region manager */

				Dataspace_pool(Ram_session *ram_session, Rm_session *rm_session)
				: ram_session(ram_session), rm_session(rm_session) { }

				/**
				 * Destructor
				 */
				~Dataspace_pool();

				void reassign_resources(Ram_session *ram, Rm_session *rm) {
					ram_session = ram, rm_session = rm; }
			};

			/*
			 * NOTE: The order of the member variables is important for
			 *       the calling order of the destructors!
			 */

			Lock           _lock;
			Dataspace_pool _ds_pool;      /* list of dataspaces */
			Allocator_avl  _alloc;        /* local allocator    */
			size_t         _quota_limit;
			size_t         _quota_used;
			size_t         _chunk_size;

			/**
			 * Allocate a new dataspace of the specified size
			 *
			 * \param size                       number of bytes to allocate
			 * \param enforce_separate_metadata  if true, the new dataspace
			 *                                   will not contain any meta data
			 * \throw                            Rm_session::Invalid_dataspace,
			 *                                   Rm_session::Region_conflict
			 * \return                           0 on success or negative error code
			 */
			Heap::Dataspace *_allocate_dataspace(size_t size, bool enforce_separate_metadata);

			/**
			 * Try to allocate block at our local allocator
			 *
			 * \return true on success
			 *
			 * This function is a utility used by '_unsynchronized_alloc' to
			 * avoid code duplication.
			 */
			bool _try_local_alloc(size_t size, void **out_addr);

			/**
			 * Unsynchronized implementation of 'alloc'
			 */
			bool _unsynchronized_alloc(size_t size, void **out_addr);

		public:

			enum { UNLIMITED = ~0 };

			Heap(Ram_session *ram_session,
			     Rm_session  *rm_session,
			     size_t       quota_limit = UNLIMITED,
			     void        *static_addr = 0,
			     size_t       static_size = 0)
			:
				_ds_pool(ram_session, rm_session),
				_alloc(0),
				_quota_limit(quota_limit), _quota_used(0),
				_chunk_size(MIN_CHUNK_SIZE)
			{
				if (static_addr)
					_alloc.add_range((addr_t)static_addr, static_size);
			}

			/**
			 * Reconfigure quota limit
			 *
			 * \return  negative error code if new quota limit is higher than
			 *          currently used quota.
			 */
			int quota_limit(size_t new_quota_limit);

			/**
			 * Re-assign RAM and RM sessions
			 */
			void reassign_resources(Ram_session *ram, Rm_session *rm) {
				_ds_pool.reassign_resources(ram, rm); }


			/*************************
			 ** Allocator interface **
			 *************************/

			bool   alloc(size_t, void **);
			void   free(void *, size_t);
			size_t consumed() { return _quota_used; }
			size_t overhead(size_t size) { return _alloc.overhead(size); }
			bool   need_size_for_free() const override { return false; }
	};


	/**
	 * Heap that allocates each block at a separate dataspace
	 */
	class Sliced_heap : public Allocator
	{
		private:

			class Block;

			Ram_session    *_ram_session;  /* ram session for backing store */
			Rm_session     *_rm_session;   /* region manager                */
			size_t          _consumed;     /* number of allocated bytes     */
			List<Block>     _block_list;   /* list of allocated blocks      */
			Lock            _lock;         /* serialize allocations         */

		public:

			/**
			 * Constructor
			 */
			Sliced_heap(Ram_session *ram_session, Rm_session *rm_session);

			/**
			 * Destructor
			 */
			~Sliced_heap();


			/*************************
			 ** Allocator interface **
			 *************************/

			bool   alloc(size_t, void **);
			void   free(void *, size_t);
			size_t consumed() { return _consumed; }
			size_t overhead(size_t size);
			bool   need_size_for_free() const override { return false; }
	};
}

#endif /* _INCLUDE__BASE__HEAP_H_ */