mirror of
https://github.com/matrix-construct/construct
synced 2024-10-05 15:18:52 +02:00
163 lines
6.4 KiB
C++
163 lines
6.4 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) 2016-2018 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_STATE_H
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namespace ircd::m::state
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{
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struct node;
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using id_closure = std::function<void (const string_view &)>;
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using node_closure = std::function<void (const json::object &)>;
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using key_closure = std::function<void (const json::array &)>;
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constexpr size_t ID_MAX_SZ { 64 };
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constexpr size_t KEY_MAX_SZ { 256 + 256 + 16 };
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constexpr size_t VAL_MAX_SZ { 256 + 16 };
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constexpr size_t NODE_MAX_SZ { 4_KiB };
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constexpr size_t NODE_MAX_KEY { 2 }; // tmp for now
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constexpr size_t NODE_MAX_VAL { NODE_MAX_KEY };
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constexpr size_t NODE_MAX_DEG { NODE_MAX_KEY + 1 }; // tmp for now
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constexpr int8_t MAX_HEIGHT { 16 }; // good for few mil at any degree :)
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int keycmp(const json::array &a, const json::array &b);
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json::array make_key(const mutable_buffer &out, const string_view &type, const string_view &state_key);
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string_view set_node(db::txn &txn, const mutable_buffer &id, const json::object &node);
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void get_node(db::column &, const string_view &id, const node_closure &);
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void get_node(const string_view &id, const node_closure &);
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string_view get_head(db::column &, const mutable_buffer &out, const id::room &);
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string_view get_head(const mutable_buffer &out, const id::room &);
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void set_head(db::txn &txn, const id::room &, const string_view &head);
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void get_value(db::column &, const string_view &head, const json::array &key, const id_closure &);
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void get_value(const string_view &head, const json::array &key, const id_closure &);
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void get_value(const string_view &head, const string_view &type, const string_view &state_key, const id_closure &);
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void get_value__room(const id::room &, const string_view &type, const string_view &state_key, const id_closure &);
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void insert(db::txn &txn, const id::room &, const json::array &key, const id::event &);
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void insert(db::txn &txn, const id::room &, const string_view &type, const string_view &state_key, const id::event &);
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void append_nodes(db::txn &, const event &);
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}
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namespace ircd::m::state::name
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{
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constexpr const char *const k {"k"};
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constexpr const char *const v {"v"};
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constexpr const char *const c {"c"};
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}
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wsubobject-linkage"
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/// Format for node: Node is plaintext and not binary at this time. In fact,
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/// *evil chuckle*, node might as well be JSON and can easily become content
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/// of another event sent to other rooms over network *snorts*. (important:
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/// database is well compressed).
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///
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/// { ;
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/// "k": ; Key array
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/// [ ;
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/// ["m.room.member", "@ar4an:matrix.org"], ; Left key
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/// ["m.room.member", "@jzk:matrix.org"] ; Right key
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/// ], ;
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/// "v": ; Value array
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/// [ ;
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/// "$14961836116kXQRA:matrix.org", ; Left accept
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/// "$15018692261xPQDB:matrix.org", ; Right accept
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/// ] ;
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/// "c": ; Child array
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/// [ ;
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/// "nPKN9twTF9a8k5dD7AApFcaraHTX", ; Left child
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/// "PcxAAACvkvyUMz19AZcCfrC3S84s", ; Center child
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/// "2jVYKIMKErJ6w6BLMhfVjsXearhB", ; Right child
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/// ] ;
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/// } ;
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///
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/// Elements are ordered based on type+state_key lexical sort. The type
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/// and the state_key strings are literally concatenated to this effect.
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/// They're not hashed. We can have some more control over data locality
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/// this way. Any number of values may be in a key array, not just type+
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/// state_key. The concatenation involves the string with its surrounding
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/// quotes as to not allow the user to mess about conflicting values.
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/// ```
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/// "m.room.member""@jzk" > "m.room.create"""
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/// ```
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/// Unlike traditional trees of such variety, the number of elements is not
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/// really well defined and not even fixed. There just has to be one more
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/// value in the "child" list than there are keys in the "key" list. To make
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/// this structure efficient we have to figure out a good number of
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/// children per node, and that might even be a contextual decision. The
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/// more children, the less depth to the query, but at the cost of a larger
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/// node size. A larger node in this system isn't just relevant to
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/// retrieval, but consider nodes are also immutable. Changes to the tree
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/// create new nodes for each changed path so the old nodes can still
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/// represent the old state.
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struct ircd::m::state::node
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:json::tuple
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<
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json::property<name::k, json::array>,
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json::property<name::v, json::array>,
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json::property<name::c, json::array>
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>
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{
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struct rep;
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size_t keys() const;
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size_t vals() const;
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size_t childs() const;
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json::array key(const size_t &) const;
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string_view val(const size_t &) const;
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string_view child(const size_t &) const;
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size_t keys(json::array *const &out, const size_t &max) const;
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size_t vals(string_view *const &out, const size_t &max) const;
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size_t childs(string_view *const &out, const size_t &max) const;
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size_t find(const json::array &key) const;
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bool has_key(const json::array &key) const;
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bool has_child(const size_t &) const;
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using super_type::tuple;
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using super_type::operator=;
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};
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#pragma GCC diagnostic pop
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struct ircd::m::state::node::rep
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{
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std::array<json::array, NODE_MAX_KEY + 1> keys;
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std::array<string_view, NODE_MAX_VAL + 1> vals;
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std::array<string_view, NODE_MAX_DEG + 1> chld;
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size_t kn {0};
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size_t vn {0};
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size_t cn {0};
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bool full() const;
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bool overfull() const;
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size_t find(const json::array &key) const;
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void shr(const size_t &pos);
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json::object write(const mutable_buffer &out);
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string_view write(db::txn &, const mutable_buffer &id);
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rep(const node &node);
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rep() = default;
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};
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static_assert
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(
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ircd::m::state::NODE_MAX_KEY == ircd::m::state::NODE_MAX_VAL
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);
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