thin-provisioning-tools/persistent-data/transaction_manager.h

// Copyright (C) 2011 Red Hat, Inc. All rights reserved.
//
// This file is part of the thin-provisioning-tools source.
//
// thin-provisioning-tools is free software: you can redistribute it
// and/or modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation, either version 3 of
// the License, or (at your option) any later version.
//
// thin-provisioning-tools is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with thin-provisioning-tools.  If not, see
// <http://www.gnu.org/licenses/>.

#ifndef TRANSACTION_MANAGER_H
#define TRANSACTION_MANAGER_H

#include "block.h"
#include "space_map.h"

#include <set>

//----------------------------------------------------------------

namespace persistent_data {
	class transaction_manager : boost::noncopyable {
	public:
		typedef std::shared_ptr<transaction_manager> ptr;
		typedef block_manager::read_ref read_ref;
		typedef block_manager::write_ref write_ref;
		typedef bcache::validator::ptr validator;

		// If the space map is persistent, then the caller should
		// hold onto a reference and remember to call sm_->commit()
		// and update the superblock before dropping the superblock
		// reference.
		transaction_manager(block_manager::ptr bm,
				    space_map::ptr sm);
		~transaction_manager();

		// Drop the superblock reference to commit
		write_ref begin(block_address superblock, validator v);
		write_ref new_block(validator v);

		// shadowing returns a new write_ref, and a boolean which
		// indicates whether the children should be incremented.
		std::pair<write_ref, bool> shadow(block_address orig, validator v);

		read_ref read_lock(block_address b);
		read_ref read_lock(block_address b, validator v);

		space_map::ptr get_sm() {
			return sm_;
		}

		void set_sm(space_map::ptr sm) {
			sm_ = sm;
		}

		block_manager::ptr get_bm() {
			return bm_;
		}

		void prefetch(block_address b) {
			bm_->prefetch(b);
		}

		// mark a block as shadowed,
		// for the purpose of in-place modification
		void mark_shadowed(block_address b) {
			add_shadow(b);
		}

	private:
		void add_shadow(block_address b);
		void remove_shadow(block_address b);
	        bool is_shadow(block_address b) const;
		void wipe_shadow_table();

		block_manager::ptr bm_;
		space_map::ptr sm_;

		std::set<block_address> shadows_;
	};
}

//----------------------------------------------------------------

#endif