construct/matrix/dbs_event_horizon.cc

// The Construct
//
// Copyright (C) The Construct Developers, Authors & Contributors
// Copyright (C) 2016-2020 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.

decltype(ircd::m::dbs::event_horizon)
ircd::m::dbs::event_horizon;

decltype(ircd::m::dbs::desc::event_horizon__block__size)
ircd::m::dbs::desc::event_horizon__block__size
{
	{ "name",     "ircd.m.dbs._event_horizon.block.size" },
	{ "default",  512L                                   },
};

decltype(ircd::m::dbs::desc::event_horizon__meta_block__size)
ircd::m::dbs::desc::event_horizon__meta_block__size
{
	{ "name",     "ircd.m.dbs._event_horizon.meta_block.size" },
	{ "default",  1024L                                       },
};

decltype(ircd::m::dbs::desc::event_horizon__cache__size)
ircd::m::dbs::desc::event_horizon__cache__size
{
	{
		{ "name",     "ircd.m.dbs._event_horizon.cache.size" },
		{ "default",  long(16_MiB)                           },
	}, []
	{
		const size_t &value{event_horizon__cache__size};
		db::capacity(db::cache(dbs::event_horizon), value);
	}
};

decltype(ircd::m::dbs::desc::event_horizon__cache_comp__size)
ircd::m::dbs::desc::event_horizon__cache_comp__size
{
	{
		{ "name",     "ircd.m.dbs._event_horizon.cache_comp.size" },
		{ "default",  long(0_MiB)                                 },
	}, []
	{
		const size_t &value{event_horizon__cache_comp__size};
		db::capacity(db::cache_compressed(dbs::event_horizon), value);
	}
};

const ircd::db::prefix_transform
ircd::m::dbs::desc::event_horizon__pfx
{
	"_event_horizon",

	[](const string_view &key)
	{
		return has(key, '\0');
	},

	[](const string_view &key)
	{
		assert(size(key) >= sizeof(event::idx));
		return split(key, '\0').first;
	}
};

const ircd::db::descriptor
ircd::m::dbs::desc::event_horizon
{
	// name
	"_event_horizon",

	// explanation
	R"(Unresolved references in the reverse reference graph of events.

	event_id | event_idx => --

	The first part of the key is an event_id which the server does not have.
	The suffix of the key is the index number of an event which the server
	does have and it contains a reference to event_id.

	We use the information in this column to find all of the events which
	have an unresolved reference to this event and complete the holes in the
	event_refs graph which could not be completed without this event.

	When a new event is written to the database the event_horizon column is
	queried seeking the event's ID. Each entry in event_horizon is the index
	of an event which we previously wrote to the database without knowing the
	index of the event currently being written (an out-of-order write).

	)",

	// typing (key, value)
	{
		typeid(string_view), typeid(string_view)
	},

	// options
	{},

	// comparator
	{},

	// prefix transform
	event_horizon__pfx,

	// drop column
	false,

	// cache size
	bool(cache_enable)? -1 : 0, //uses conf item

	// cache size for compressed assets
	bool(cache_comp_enable)? -1 : 0,

	// bloom filter bits
	0,

	// expect queries hit
	false,

	// block size
	size_t(event_horizon__block__size),

	// meta_block size
	size_t(event_horizon__meta_block__size),

	// compression
	"kLZ4Compression;kSnappyCompression"s,

	// compactor
	{},

	// compaction priority algorithm
	"kOldestSmallestSeqFirst"s,
};

//
// indexer
//

// NOTE: QUERY
void
ircd::m::dbs::_index_event_horizon_resolve(db::txn &txn,
                                           const event &event,
                                           const write_opts &opts)
{
	char buf[EVENT_HORIZON_KEY_MAX_SIZE];
	assert(opts.appendix.test(appendix::EVENT_HORIZON_RESOLVE));
	assert(opts.event_idx != 0);
	assert(event.event_id);
	const string_view &key
	{
		event_horizon_key(buf, event.event_id)
	};

	auto it
	{
		dbs::event_horizon.begin(key)
	};

	for(; it; ++it)
	{
		const auto parts
		{
			event_horizon_key(it->first)
		};

		const auto &event_idx
		{
			std::get<0>(parts)
		};

		assert(event_idx != 0);
		assert(event_idx != opts.event_idx);
		const event::fetch _event
		{
			std::nothrow, event_idx
		};

		if(!_event.valid)
		{
			log::dwarning
			{
				log, "Horizon resolve for %s @%lu not possible @%lu",
				string_view{event.event_id},
				opts.event_idx,
				event_idx,
			};

			continue;
		}

		log::debug
		{
			log, "Horizon resolve for %s @%lu; remisé %s @%lu",
			string_view{event.event_id},
			opts.event_idx,
			string_view{_event.event_id},
			event_idx,
		};

		// Make the references on behalf of the future event
		write_opts _opts;
		_opts.op = opts.op;
		_opts.event_idx = event_idx;
		_opts.appendix.reset();
		_opts.appendix.set(appendix::EVENT_REFS);
		_opts.appendix.set(appendix::ROOM_REDACT);
		_opts.appendix.set(appendix::ROOM_HEAD_RESOLVE);
		_opts.event_refs = opts.horizon_resolve;
		_opts.interpose = &txn;
		write(txn, _event, _opts);

		// Delete the event_horizon entry after resolving.
		thread_local char buf[EVENT_HORIZON_KEY_MAX_SIZE];
		const string_view &key
		{
			event_horizon_key(buf, event.event_id, event_idx)
		};

		db::txn::append
		{
			txn, dbs::event_horizon,
			{
				opts.op == db::op::SET?
					db::op::DELETE:
					db::op::SET,
				key
			}
		};
	}
}

void
ircd::m::dbs::_index_event_horizon(db::txn &txn,
                                   const event &event,
                                   const write_opts &opts,
                                   const m::event::id &unresolved_id)
{
	thread_local char buf[EVENT_HORIZON_KEY_MAX_SIZE];
	assert(opts.appendix.test(appendix::EVENT_HORIZON));
	assert(opts.event_idx != 0 && unresolved_id);
	const string_view &key
	{
		event_horizon_key(buf, unresolved_id, opts.event_idx)
	};

	db::txn::append
	{
		txn, dbs::event_horizon,
		{
			opts.op, key
		}
	};
}

//
// key
//

std::tuple<ircd::m::event::idx>
ircd::m::dbs::event_horizon_key(const string_view &amalgam)
{
	assert(size(amalgam) == 1 + sizeof(event::idx));
	assert(amalgam[0] == '\0');

	const byte_view<event::idx> &event_idx
	{
		amalgam.substr(1)
	};

	return
	{
		static_cast<event::idx>(event_idx)
	};
}

ircd::string_view
ircd::m::dbs::event_horizon_key(const mutable_buffer &out,
                                const event::id &event_id)
{
	return event_horizon_key(out, event_id, 0UL);
}

ircd::string_view
ircd::m::dbs::event_horizon_key(const mutable_buffer &out,
                                const event::id &event_id,
                                const event::idx &event_idx)
{
	mutable_buffer buf(out);
	consume(buf, copy(buf, event_id));

	if(event_idx)
	{
		consume(buf, copy(buf, '\0'));
		consume(buf, copy(buf, byte_view<string_view>(event_idx)));
	}

	const string_view ret
	{
		data(out), data(buf)
	};

	assert(size(ret) == size(event_id) || size(ret) == size(event_id) + sizeof(event::idx) + 1);
	return ret;
}