genode/repos/base/include/base/sync_allocator.h

/*
 * \brief  Lock-guarded allocator interface
 * \author Norman Feske
 * \date   2008-08-05
 */

/*
 * Copyright (C) 2008-2013 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__SYNC_ALLOCATOR_H_
#define _INCLUDE__BASE__SYNC_ALLOCATOR_H_

#include <base/allocator.h>
#include <base/lock.h>

namespace Genode {
	
	template <typename> class Synchronized_allocator;
	template <typename> class Synchronized_range_allocator;
}


/**
 * Lock-guarded allocator
 *
 * This class wraps the complete 'Allocator' interface while
 * preventing concurrent calls to the wrapped allocator implementation.
 *
 * \param ALLOCATOR_IMPL  class implementing the 'Allocator'
 *                        interface
 */
template <typename ALLOCATOR_IMPL>
class Genode::Synchronized_allocator : public Allocator
{
	private:

		Lock            _default_lock;
		Lock           *_lock;
		ALLOCATOR_IMPL _alloc;

	public:

		/**
		 * Constructor
		 *
		 * This constructor uses an embedded lock for synchronizing the
		 * access to the allocator.
		 */
		Synchronized_allocator()
		: _lock(&_default_lock) { }

		/**
		 * Constructor
		 *
		 * This constructor uses an embedded lock for synchronizing the
		 * access to the allocator.
		 */
		explicit Synchronized_allocator(Allocator *metadata_alloc)
		: _lock(&_default_lock), _alloc(metadata_alloc) { }

		/**
		 * Return reference to wrapped (non-thread-safe) allocator
		 *
		 * This is needed, for example, if the wrapped allocator implements
		 * methods in addition to the Range_allocator interface.
		 */
		ALLOCATOR_IMPL *raw() { return &_alloc; }

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

		bool alloc(size_t size, void **out_addr) override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.alloc(size, out_addr);
		}

		void free(void *addr, size_t size) override
		{
			Lock::Guard lock_guard(*_lock);
			_alloc.free(addr, size);
		}

		size_t consumed() const override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.consumed();
		}

		size_t overhead(size_t size) const override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.overhead(size);
		}

		bool need_size_for_free() const override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.need_size_for_free();
		}
};


/**
 * Lock-guarded range allocator
 *
 * This class wraps the complete 'Range_allocator' interface while
 * preventing concurrent calls to the wrapped allocator implementation.
 *
 * \param ALLOCATOR_IMPL  class implementing the 'Range_allocator'
 *                        interface
 */
template <typename ALLOCATOR_IMPL>
class Genode::Synchronized_range_allocator : public Range_allocator
{
	private:

		Lock           _default_lock;
		Lock          *_lock;
		ALLOCATOR_IMPL _alloc;

	public:

		/**
		 * Constructor
		 *
		 * This constructor uses an embedded lock for synchronizing the
		 * access to the allocator.
		 */
		Synchronized_range_allocator()
		: _lock(&_default_lock) { }

		/**
		 * Constructor
		 *
		 * This constructor uses an embedded lock for synchronizing the
		 * access to the allocator.
		 */
		explicit Synchronized_range_allocator(Allocator *metadata_alloc)
		: _lock(&_default_lock), _alloc(metadata_alloc) { }

		/**
		 * Constructor
		 *
		 * \param lock  use specified lock rather then an embedded lock for
		 *              synchronization
		 *
		 * This constructor is useful if multiple allocators must be
		 * synchronized with each other. In such as case, the shared
		 * lock can be passed to each 'Synchronized_range_allocator'
		 * instance.
		 */
		Synchronized_range_allocator(Lock *lock, Allocator *metadata_alloc)
		: _lock(lock), _alloc(metadata_alloc) { }

		/**
		 * Return reference to wrapped (non-thread-safe) allocator
		 *
		 * This is needed, for example, if the wrapped allocator implements
		 * methods in addition to the Range_allocator interface.
		 *
		 * NOTE: Synchronize accesses to the raw allocator by facilitating
		 * the lock() method.
		 */
		ALLOCATOR_IMPL *raw() { return &_alloc; }

		/**
		 * Return reference to synchronization lock
		 */
		Lock *lock() { return _lock; }


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

		bool alloc(size_t size, void **out_addr) override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.alloc(size, out_addr);
		}

		void free(void *addr, size_t size) override
		{
			Lock::Guard lock_guard(*_lock);
			_alloc.free(addr, size);
		}

		size_t consumed() const override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.consumed();
		}

		size_t overhead(size_t size) const override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.overhead(size);
		}

		bool need_size_for_free() const override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.need_size_for_free();
		}


		/*******************************
		 ** Range-allocator interface **
		 *******************************/

		int add_range(addr_t base, size_t size) override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.add_range(base, size);
		}

		int remove_range(addr_t base, size_t size) override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.remove_range(base, size);
		}

		Alloc_return alloc_aligned(size_t size, void **out_addr, int align = 0,
		                           addr_t from = 0, addr_t to = ~0UL) override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.alloc_aligned(size, out_addr, align, from, to);
		}

		Alloc_return alloc_addr(size_t size, addr_t addr) override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.alloc_addr(size, addr);
		}

		void free(void *addr) override
		{
			Lock::Guard lock_guard(*_lock);
			_alloc.free(addr);
		}

		size_t avail() const override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.avail();
		}

		bool valid_addr(addr_t addr) const override
		{
			Lock::Guard lock_guard(*_lock);
			return _alloc.valid_addr(addr);
		}
};

#endif /* _INCLUDE__BASE__SYNC_ALLOCATOR_H_ */