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construct/include/ircd/m/vm.h

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/*
* charybdis: 21st Century IRC++d
*
* Copyright (C) 2016 Charybdis Development Team
* Copyright (C) 2016 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <ircd/cuckoo.h>
#pragma once
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#define HAVE_IRCD_M_VM_H
/// Matrix Virtual Machine
///
/// This is the processing unit for matrix events. The front-end interface to
/// m::vm consists of two parts: The query suite (observation) and the eval
/// (modification). The back-end interface consists of modules which supply
/// the features for the vm's logic. The m::vm operates primarily as a global
/// singleton and facilitates synchronization between multiple ircd::ctx's
/// using its interfaces.
///
/// The query suite tries to satisfy a query using the current state of the vm,
/// the database, and may even use the network. An idea of a basic pseudo-
/// query: was user X a member of room Y when event Z happened? Is X a member
/// of Y right now? etc.
///
/// The vm::eval is the primary input receptacle for events. The eval of an
/// event leads to its execution and will advance the global state of IRCd. That
/// advance may broadcast its effects to clients of IRCd, federation servers,
/// and alter the responses to future queries. Execution of an event is a
/// unique phenomenon: it only happens once. IRCd has thenceforth borne witness
/// to the event and will never execute it again unless it is forgotten by
/// erasing the db. Simulation options allow for evals without execution.
///
/// The back-end provides the business logic and features for the above user
/// interfaces.
///
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namespace ircd::m::vm
{
IRCD_M_EXCEPTION(m::error, VM_ERROR, http::INTERNAL_SERVER_ERROR);
IRCD_M_EXCEPTION(VM_ERROR, VM_FAULT, http::BAD_REQUEST);
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enum fault :uint;
struct frame;
struct capstan;
struct witness;
struct accumulator;
struct front;
struct eval;
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struct pipe;
struct port;
struct space;
struct opts;
using closure = std::function<void (const event &)>;
using closure_bool = std::function<bool (const event &)>;
extern struct log::log log;
extern uint64_t current_sequence;
extern ctx::view<const event> inserted;
extern struct fronts fronts;
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extern struct pipe pipe;
bool test(const query<> &, const closure_bool &);
bool test(const query<> &);
bool until(const query<> &, const closure_bool &);
bool until(const query<> &);
void for_each(const query<> &, const closure &);
void for_each(const closure &);
size_t count(const query<> &, const closure_bool &);
size_t count(const query<> &);
bool exists(const event::id &);
int test(eval &, const query<> &, const closure_bool &);
int test(eval &, const query<> &);
}
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/// Evaluation Options
struct ircd::m::vm::opts
{
/// Setting to false will disable the eval from exiting with a fault and
/// instead consider all faults as errors which throw exceptions. If
/// nothrow is also specified then the exception will be stored in the
/// exception_ptr and #gp will be set.
bool faults {true};
/// Setting to true will prevent any exception throwing from an eval and
/// instead only use the exception_ptr field. Note that eval does not make
/// a noexcept guarantee with or without this option and it may still throw
/// some rare or unexpected exception aborting the eval.
bool nothrow {false};
/// Setting to true will cause a successful eval to commit the result
/// which writes to the db and has global effects for the server.
/// False is the simulation mode to test evaluation without effects.
bool commit {false};
/// Setting to false will prevent the release sequence after a commit.
/// This is a really bad thing to do. testing/debug/devel use only.
bool release {true};
/// Setting to true will force the eval to be aware of an m.room.create
/// for a room for anything to succeed. There will be #ef's until found.
bool genesis {false};
/// Setting to true will cause #ef's until there is at least one unbroken
/// link of events down to an m.room.create.
bool cosmogonic {false};
/// Setting to true will cause #ef's until the entire reference cone is
/// known by the evaluation (if legit). i.e full history tree.
bool fullcone {false};
/// Setting to 1 forces evaluations to only proceed from oldest to newest
/// events; the capstan will only operate using forward mode and positive
/// accumulations. Because events only reference the past the machine won't
/// always #ef, it will just stop. More events can be input. Setting to
/// -1 is anti-causal: evaluations only proceed from newest to oldest and
/// only negative accumulations are used. 0 is automatic and may use both.
int causal {0};
/// Option to skip event signature verification when false.
bool verify_signature {true};
};
/// Individual evaluation state
///
/// Evaluation faults. These are reasons which evaluation has halted but may
/// continue after the user defaults the fault. They are basically types of
/// interrupts and traps, which are recoverable. Only the GENERAL protection
/// fault (#gp) is an abort and is not recoverable. An exception_ptr will be
/// set; aborts are otherwise just thrown as exceptions from eval. If any
/// fault isn't handled properly that is an abort.
///
enum ircd::m::vm::fault
:uint
{
ACCEPT, ///< No fault.
DEBUGSTEP, ///< Debug step. (#db)
BREAKPOINT, ///< Debug breakpoint. (#bp)
GENERAL, ///< General protection fault. (#gp)
EVENT, ///< Eval requires addl events in the ef register (#ef)
STATE, ///< Required state is missing (#st)
};
struct ircd::m::vm::capstan
{
int64_t dc{0};
std::vector<std::unique_ptr<vm::accumulator>> acc;
ssize_t count(const query<> &) const;
int test(const query<> &) const;
void fwd(const event &);
void rev(const event &);
capstan();
~capstan() noexcept;
};
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struct ircd::m::vm::port
{
const m::event *event {nullptr};
std::exception_ptr error;
fault code;
bool h {false};
bool w {false};
};
struct ircd::m::vm::space
{
struct capstan capstan;
};
struct ircd::m::vm::pipe
{
std::unordered_map<string_view, space> s;
std::deque<port> p;
};
/// Event Evaluation Device
///
/// This object conducts the evaluation of an event or a tape of multiple
/// events. An event is evaluated in an attempt to execute it. Events which
/// fail during evaluation won't be executed; such is the case for events which
/// have already been executed, or events which are invalid or lead to invalid
/// transitions or actions of the machine etc.
///
/// Basic usage of the eval is simply calling the ctor like a function with an
/// event; with the default options this evaluates and executes the event
/// throwing all errors. Advanced usage of eval takes the form of an instance
/// constructed with options; the user then drives the eval in a loop,
/// responding to its needs for more data or other issues, and then continuing
/// the loop until satisfied.
///
/// The back-end interface consists of a set of modules which register with the
/// vm::eval class and provide their piece of eval functionality to instances.
///
struct ircd::m::vm::eval
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{
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static const struct opts default_opts;
const struct opts *opts;
struct capstan capstan;
db::iov txn{*event::events};
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std::set<event::id> ef;
uint64_t cs {0};
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fault operator()();
fault operator()(const event &);
fault operator()(const vector_view<const event> &);
fault operator()(const json::vector &);
fault operator()(const json::array &);
template<class events> eval(const struct opts &, events&&);
template<class events> eval(const events &);
eval(const struct opts &);
eval();
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friend string_view reflect(const fault &);
};
/// Convenience construction passes events through to operator().
template<class events>
ircd::m::vm::eval::eval(const events &event)
:eval(default_opts)
{
operator()(event);
}
/// Convenience construction passes events through to operator().
template<class events>
ircd::m::vm::eval::eval(const struct opts &opts,
events&& event)
:eval(opts)
{
operator()(std::forward<events>(event));
}
// state accumulators:
//
// - (bool) event_id: Adds all event_ids to accumulator. On eval, capstan
// checks if event_id is not in set: accepts; Otherwise event_id duplicate in
// set: rejects.
//
// - (bool) membership: Capstan has a accumulator for each membership state.
// Adds accumulator[membership] = state_key. On eval, capstan knows about user not
// having membership of claimed type. Negative for all accumulators indicates no
// membership in the set.
//
// - (count) types: Counts all type names encountered to respond to
// queries about that type maybe or definitely not being in the poset.
//
// - (count) state types: Counts all type names encountered when there is
// a state_key defined.
//
// - (count) sender: Counts all sender strings. Responds to queries about
// whether a sender may have or definitely did not take part in the poset.
//
// - (count) origin: Counts all origin strings.
//
struct ircd::m::vm::witness
:ircd::instance_list<witness>
{
std::string name;
virtual ssize_t count(const accumulator *const &, const query<> &)
{
return -1;
}
virtual int test(const accumulator *const &, const query<> &)
{
return -1;
}
virtual int add(accumulator *const &, const event &)
{
return -1;
}
virtual int del(accumulator *const &, const event &)
{
return -1;
}
virtual std::unique_ptr<accumulator> init()
{
return {};
}
witness(std::string name);
virtual ~witness() noexcept;
};
struct ircd::m::vm::accumulator
{
virtual ~accumulator() noexcept;
};
/// The "event front" for a graph. This holds all of the childless events
/// for a room. Each childless event may exist at a different depth, but
/// we track the highest depth to increment it for issuing the next event.
/// The contents of the front will then be used as the prev references for
/// that new event. The front is then replaced by the new event. This is
/// managed by the vm core.
///
struct ircd::m::vm::front
{
int64_t top {0};
std::map<std::string, uint64_t, std::less<std::string_view>> map;
vm::capstan capstan;
};
/// Singleton iface to all "event fronts" - the top depth in an active graph
///
/// This extern singleton is a fundamental structure which holds the highest
/// depth events in a graph which have no children. The fronts collection
/// itself is a map of rooms by ID, and one 'front' is held in RAM for each
/// room. Each front is a collection of those events, which ideally, will
/// become the prev references for the next event this server issues in the
/// room.
///
/// This is managed by the vm core. The fronts interface is the root of the
/// RAM footprint for a room known to IRCd. In other words, all room data is
/// stored in the database except what is reachable through here.
///
struct ircd::m::vm::fronts
{
std::map<std::string, front, std::less<std::string_view>> map;
friend front &fetch(const room::id &, front &, const event &);
public:
front &get(const room::id &, const event &);
front &get(const room::id &);
};
namespace ircd::m::vm
{
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// Synchronous fetch and eval
size_t acquire(const vector_view<const id::event> &, const vector_view<const mutable_buffer> &);
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json::object acquire(const id::event &, const mutable_buffer &);
void statefill(const room::id &, const event::id &);
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void backfill(const room::id &, const event::id &v, const size_t &limit);
using tracer = std::function<bool (const event &, event::id::buf &)>;
void trace(const id::event &, const tracer &);
event::id::buf commit(json::iov &event);
event::id::buf join(const room::id &, json::iov &iov);
}