mirror of
https://github.com/matrix-construct/construct
synced 2024-08-22 01:24:53 +02:00
190 lines
6.5 KiB
C++
190 lines
6.5 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_M_ROOM_EVENTS_H
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// The "viewport" is comprised of events starting from the tophead (most recent
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// in room timeline) and covering about ~20 events leading up to that. Note
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// that this is a completely ad hoc and configurable server value. Events in
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// the viewport must be eval'ed and synced to clients in the order they will
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// be displayed. Events not in the viewport are not /synced to clients and any
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// client request provides event ordering: thus older events (backfills, etc)
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// can be eval'ed without this constraint.
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//
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// The "sounding" is the depth of the first gap. In any attempt to trace
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// the room timeline from the tophead to the m.room.create event: the sounding
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// is the [highest number] depth preventing that.
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//
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// The "twain" marks the depth at the end of the first gap; the server is in
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// possession of one or more events again at the twain.
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//
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// The "hazard" is the depth of the first gap starting from the m.room.create
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// event toward the tophead. In any attempt to trace the room timeline with
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// an increasing depth, the hazard is the next gap to frontfill.
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namespace ircd::m
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{
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std::pair<int64_t, event::idx> viewport(const room &);
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std::pair<int64_t, event::idx> sounding(const room &); // Last missing (one)
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std::pair<int64_t, event::idx> twain(const room &);
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std::pair<int64_t, event::idx> hazard(const room &); // First missing (one)
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}
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/// Interface to room events
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///
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/// This interface has the form of an STL-style iterator over room events
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/// which are state and non-state events from all integrated timelines.
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/// Moving the iterator is cheap, but the dereference operators fetch a
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/// full event. One can iterate just event_idx's by using event_idx() instead
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/// of the dereference operators.
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///
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struct ircd::m::room::events
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{
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struct sounding;
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struct horizon;
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struct missing;
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static conf::item<ssize_t> viewport_size;
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m::room room;
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db::domain::const_iterator it;
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event::fetch _event;
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public:
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explicit operator bool() const { return bool(it); }
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bool operator!() const { return !it; }
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// Observers from the current valid iterator
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uint64_t depth() const;
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event::idx event_idx() const;
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explicit operator event::idx() const;
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// Perform a new lookup / iterator
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bool seek_idx(const event::idx &);
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bool seek(const uint64_t &depth = -1);
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bool seek(const event::id &);
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// Prefetch a new iterator lookup (async)
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bool preseek(const uint64_t &depth = -1);
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// Move the iterator
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auto &operator++() { return --it; }
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auto &operator--() { return ++it; }
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// Fetch the actual event data at the iterator's position
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const m::event &operator*();
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const m::event *operator->() { return &operator*(); }
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const m::event &fetch(std::nothrow_t);
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const m::event &fetch();
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// Prefetch the actual event data at the iterator's position (async)
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bool prefetch(const string_view &event_prop);
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bool prefetch(); // uses supplied fetch::opts.
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events(const m::room &,
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const uint64_t &depth,
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const event::fetch::opts *const & = nullptr);
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events(const m::room &,
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const event::id &,
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const event::fetch::opts *const & = nullptr);
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events(const m::room &,
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const event::fetch::opts *const & = nullptr);
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events() = default;
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events(const events &) = delete;
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events &operator=(const events &) = delete;
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// Prefetch a new iterator (without any construction)
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static bool preseek(const m::room &, const uint64_t &depth = -1);
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// Prefetch the actual room event data for a range; or most recent.
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using depth_range = std::pair<uint64_t, uint64_t>;
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static size_t prefetch(const m::room &, const depth_range &);
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static size_t prefetch_viewport(const m::room &);
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// Note the range here is unusual: The start index is exclusive, the ending
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// index is inclusive. The start index must be valid and in the room.
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static size_t count(const m::room &, const event::idx_range &);
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static size_t count(const event::idx_range &);
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};
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/// Find missing room events. This is a breadth-first iteration of missing
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/// references from the tophead (or at the event provided in the room arg)
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///
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/// The closure is invoked with the first argument being the event_id unknown
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/// to the server, followed by the depth and event::idx of the event making the
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/// reference.
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///
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struct ircd::m::room::events::missing
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{
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using closure = std::function<bool (const event::id &, const uint64_t &, const event::idx &)>;
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m::room room;
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public:
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bool for_each(const int64_t &min_depth, const closure &) const;
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bool for_each(const closure &) const;
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size_t count() const;
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missing() = default;
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missing(const m::room &room)
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:room{room}
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{}
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};
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/// Find gaps in the room's events. A gap is where this server has no events
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/// at a certain depth. This is a path-finding diagnostic interface, useful to
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/// understand what areas of the timeline have not been acquired by the server
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/// to calculate backfill requests, etc. This interface is depth-first oriented,
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/// rather than the breadth-first room::events::missing interface.
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///
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struct ircd::m::room::events::sounding
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{
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using range = std::pair<int64_t, int64_t>;
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using closure = std::function<bool (const range &, const event::idx &)>;
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m::room room;
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public:
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bool for_each(const closure &) const;
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bool rfor_each(const closure &) const;
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sounding() = default;
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sounding(const m::room &room)
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:room{room}
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{}
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};
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/// Find missing room events. This is an interface to the event-horizon for
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/// this room. The event horizon is keyed by event_id and the value is the
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/// event::idx of the event referencing it. There can be multiple entries for
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/// an event_id. The closure is also invoked with the depth of the referencer.
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///
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struct ircd::m::room::events::horizon
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{
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using closure = std::function<bool (const event::id &, const uint64_t &, const event::idx &)>;
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m::room room;
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public:
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bool for_each(const closure &) const;
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size_t count() const;
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size_t rebuild();
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horizon() = default;
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horizon(const m::room &room)
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:room{room}
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{}
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};
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