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construct/include/ircd/m/gossip.h

94 lines
2.6 KiB
C++

// 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.
#pragma once
#define HAVE_IRCD_M_GOSSIP_H
namespace ircd::m
{
struct gossip;
}
/// Matrix Gossip is a mechanism that proactively resolves the head (forward-
/// extremities) of a room on remote servers by sending the events they are
/// missing if we have them. Gossip may be performed multiple times, checking
/// for changes in the remote head and repeating based on options or until
/// completion.
struct ircd::m::gossip
:instance_list<ircd::m::gossip>
{
struct opts;
struct result;
static log::log log;
const struct opts &opts;
std::list<result> requests;
std::set<uint128_t> attempts;
private:
bool full() const noexcept;
bool started(const event::id &, const string_view &) const;
bool handle(result &);
bool handle();
bool start(const event::id &, const string_view &);
bool submit(const event::id &, const string_view &);
bool handle_head(const m::event &);
bool gossip_head();
public:
gossip(const struct opts &);
gossip(const gossip &) = delete;
gossip &operator=(const gossip &) = delete;
~gossip() noexcept;
};
struct ircd::m::gossip::opts
{
/// Room apropos; when room.event_id is true, only that event will be
/// the subject of gossip and that is only if the remote's head requires
/// it. room.event_id should not be given in most cases.
m::room room;
/// When hint_only=true this string is used to conduct gossip with the
/// single remote given.
string_view hint;
/// Forces remote operations to the remote given in the hint only.
bool hint_only {false};
/// Depthwise window of gossip: no gossip for events outside of a given
/// depth window. Ignored if !depth.second.
pair<int64_t> depth {0, 0};
/// Indexwise window of gossip: no gossip for events with a value outside
/// of the window.
pair<event::idx> ref {0, -1UL};
/// The number of rounds the algorithm runs for.
size_t rounds {-1UL};
/// Total event limit over all operations.
size_t max {-1UL};
/// Limit the number of gossips in flight at any given time.
size_t width {128};
};
struct ircd::m::gossip::result
{
unique_mutable_buffer buf;
string_view txn;
string_view txnid;
string_view remote;
event::id event_id;
m::fed::send request;
};