// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.

#pragma once
#define HAVE_IRCD_DB_COMPACTOR_H

namespace ircd::db
{
	struct compactor;
}

/// Compaction callback
///
/// return db::op::GET (0) from callback for no-op
/// return db::op::DELETE from callback to delete this kv.
/// return db::op::SET from callback if replacement modified.
/// return db::op::DELETE_RANGE from callback if skip_until modified.
///
struct ircd::db::compactor
{
	using prototype = db::op (const int &level,
	                          const string_view &key,
	                          const string_view &val,
	                          std::string *const replace,
	                          std::string *const skip_until);

	std::function<prototype> value;
	std::function<prototype> merge;
};