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use crate::error::GgrsError;
use crate::frame_info::PlayerInput;
use crate::network::messages::ConnectionStatus;
use crate::network::network_stats::NetworkStats;
use crate::network::protocol::{UdpProtocol, MAX_CHECKSUM_HISTORY_SIZE};
use crate::sync_layer::SyncLayer;
use crate::DesyncDetection;
use crate::{
network::protocol::Event, Config, Frame, GgrsEvent, GgrsRequest, NonBlockingSocket,
PlayerHandle, PlayerType, SessionState, NULL_FRAME,
};
use std::collections::vec_deque::Drain;
use std::collections::HashMap;
use std::collections::VecDeque;
use std::convert::TryInto;
const RECOMMENDATION_INTERVAL: Frame = 60;
const MIN_RECOMMENDATION: u32 = 3;
const MAX_EVENT_QUEUE_SIZE: usize = 100;
pub(crate) struct PlayerRegistry<T>
where
T: Config,
{
pub(crate) handles: HashMap<PlayerHandle, PlayerType<T::Address>>,
pub(crate) remotes: HashMap<T::Address, UdpProtocol<T>>,
pub(crate) spectators: HashMap<T::Address, UdpProtocol<T>>,
}
impl<T> std::fmt::Debug for PlayerRegistry<T>
where
T: Config,
{
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("PlayerRegistry")
.field("handles", &self.handles)
.field("remotes", &self.remotes.keys())
.field("spectators", &self.spectators.keys())
.finish()
}
}
impl<T: Config> PlayerRegistry<T> {
pub(crate) fn new() -> Self {
Self {
handles: HashMap::new(),
remotes: HashMap::new(),
spectators: HashMap::new(),
}
}
pub(crate) fn local_player_handles(&self) -> Vec<PlayerHandle> {
self.handles
.iter()
.filter_map(|(k, v)| match v {
PlayerType::Local => Some(*k),
PlayerType::Remote(_) => None,
PlayerType::Spectator(_) => None,
})
.collect()
}
pub(crate) fn remote_player_handles(&self) -> Vec<PlayerHandle> {
self.handles
.iter()
.filter_map(|(k, v)| match v {
PlayerType::Local => None,
PlayerType::Remote(_) => Some(*k),
PlayerType::Spectator(_) => None,
})
.collect()
}
pub(crate) fn spectator_handles(&self) -> Vec<PlayerHandle> {
self.handles
.iter()
.filter_map(|(k, v)| match v {
PlayerType::Local => Some(*k),
PlayerType::Remote(_) => None,
PlayerType::Spectator(_) => Some(*k),
})
.collect()
}
pub(crate) fn num_players(&self) -> usize {
self.handles
.iter()
.filter(|(_, v)| matches!(v, PlayerType::Local | PlayerType::Remote(_)))
.count()
}
pub(crate) fn num_spectators(&self) -> usize {
self.handles
.iter()
.filter(|(_, v)| matches!(v, PlayerType::Spectator(_)))
.count()
}
pub fn handles_by_address(&self, addr: T::Address) -> Vec<PlayerHandle> {
let handles: Vec<PlayerHandle> = self
.handles
.iter()
.filter_map(|(h, player_type)| match player_type {
PlayerType::Local => None,
PlayerType::Remote(a) => Some((h, a)),
PlayerType::Spectator(a) => Some((h, a)),
})
.filter_map(|(h, a)| if addr == *a { Some(*h) } else { None })
.collect();
handles
}
}
/// A [`P2PSession`] provides all functionality to connect to remote clients in a peer-to-peer fashion, exchange inputs and handle the gamestate by saving, loading and advancing.
pub struct P2PSession<T>
where
T: Config,
{
/// The number of players of the session.
num_players: usize,
/// The maximum number of frames GGRS will roll back. Every gamestate older than this is guaranteed to be correct.
max_prediction: usize,
/// The sync layer handles player input queues and provides predictions.
sync_layer: SyncLayer<T>,
/// With sparse saving, the session will only request to save the minimum confirmed frame.
sparse_saving: bool,
/// If we receive a disconnect from another client, we have to rollback from that frame on in order to prevent wrong predictions
disconnect_frame: Frame,
/// Internal State of the Session.
state: SessionState,
/// The [`P2PSession`] uses this socket to send and receive all messages for remote players.
socket: Box<dyn NonBlockingSocket<T::Address>>,
/// Handles players and their endpoints
player_reg: PlayerRegistry<T>,
/// This struct contains information about remote players, like connection status and the frame of last received input.
local_connect_status: Vec<ConnectionStatus>,
/// notes which inputs have already been sent to the spectators
next_spectator_frame: Frame,
/// The soonest frame on which the session can send a [`GgrsEvent::WaitRecommendation`] again.
next_recommended_sleep: Frame,
/// How many frames we estimate we are ahead of every remote client
frames_ahead: i32,
/// Contains all events to be forwarded to the user.
event_queue: VecDeque<GgrsEvent<T>>,
/// Contains all local inputs not yet sent into the system. This should have inputs for every local player before calling advance_frame
local_inputs: HashMap<PlayerHandle, PlayerInput<T::Input>>,
/// With desync detection, the session will compare checksums for all peers to detect discrepancies / desyncs between peers
desync_detection: DesyncDetection,
/// Desync detection over the network
local_checksum_history: HashMap<Frame, u128>,
/// The last frame we sent a checksum for
last_sent_checksum_frame: Frame,
}
impl<T: Config> P2PSession<T> {
/// Creates a new [`P2PSession`] for players who participate on the game input. After creating the session, add local and remote players,
/// set input delay for local players and then start the session. The session will use the provided socket.
pub(crate) fn new(
num_players: usize,
max_prediction: usize,
socket: Box<dyn NonBlockingSocket<T::Address>>,
players: PlayerRegistry<T>,
sparse_saving: bool,
desync_detection: DesyncDetection,
input_delay: usize,
) -> Self {
// local connection status
let mut local_connect_status = Vec::new();
for _ in 0..num_players {
local_connect_status.push(ConnectionStatus::default());
}
// sync layer & set input delay
let mut sync_layer = SyncLayer::new(num_players, max_prediction);
for (player_handle, player_type) in players.handles.iter() {
if let PlayerType::Local = player_type {
sync_layer.set_frame_delay(*player_handle, input_delay);
}
}
// initial session state - if there are no endpoints, we don't need a synchronization phase
let state = if players.remotes.len() + players.spectators.len() == 0 {
SessionState::Running
} else {
SessionState::Synchronizing
};
Self {
state,
num_players,
max_prediction,
sparse_saving,
socket,
local_connect_status,
next_recommended_sleep: 0,
next_spectator_frame: 0,
frames_ahead: 0,
sync_layer,
disconnect_frame: NULL_FRAME,
player_reg: players,
event_queue: VecDeque::new(),
local_inputs: HashMap::new(),
desync_detection,
local_checksum_history: HashMap::new(),
last_sent_checksum_frame: NULL_FRAME,
}
}
/// Registers local input for a player for the current frame. This should be successfully called for every local player before calling [`advance_frame()`].
/// If this is called multiple times for the same player before advancing the frame, older given inputs will be overwritten.
///
/// # Errors
/// - Returns [`InvalidRequest`] when the given handle does not refer to a local player.
///
/// [`advance_frame()`]: Self#method.advance_frame
/// [`InvalidRequest`]: GgrsError::InvalidRequest
pub fn add_local_input(
&mut self,
player_handle: PlayerHandle,
input: T::Input,
) -> Result<(), GgrsError> {
// make sure the input is for a registered local player
if !self
.player_reg
.local_player_handles()
.contains(&player_handle)
{
return Err(GgrsError::InvalidRequest {
info: "The player handle you provided is not referring to a local player."
.to_owned(),
});
}
let player_input = PlayerInput::<T::Input>::new(self.sync_layer.current_frame(), input);
self.local_inputs.insert(player_handle, player_input);
Ok(())
}
/// You should call this to notify GGRS that you are ready to advance your gamestate by a single frame.
/// Returns an order-sensitive [`Vec<GgrsRequest>`]. You should fulfill all requests in the exact order they are provided.
/// Failure to do so will cause panics later.
///
/// # Errors
/// - Returns [`InvalidRequest`] if the provided player handle refers to a remote player.
/// - Returns [`NotSynchronized`] if the session is not yet ready to accept input. In this case, you either need to start the session or wait for synchronization between clients.
///
/// [`Vec<GgrsRequest>`]: GgrsRequest
/// [`InvalidRequest`]: GgrsError::InvalidRequest
/// [`NotSynchronized`]: GgrsError::NotSynchronized
pub fn advance_frame(&mut self) -> Result<Vec<GgrsRequest<T>>, GgrsError> {
// receive info from remote players, trigger events and send messages
self.poll_remote_clients();
// session is not running and synchronized
if self.state != SessionState::Running {
return Err(GgrsError::NotSynchronized);
}
// This list of requests will be returned to the user
let mut requests = Vec::new();
/*
* ROLLBACKS AND GAME STATE MANAGEMENT
*/
// if we are in the first frame, we have to save the state
if self.sync_layer.current_frame() == 0 {
requests.push(self.sync_layer.save_current_state());
}
// propagate disconnects to multiple players
self.update_player_disconnects();
// find the confirmed frame for which we received all inputs
let confirmed_frame = self.confirmed_frame();
// check game consistency and rollback, if necessary.
// The disconnect frame indicates if a rollback is necessary due to a previously disconnected player
let first_incorrect = self
.sync_layer
.check_simulation_consistency(self.disconnect_frame);
if first_incorrect != NULL_FRAME {
self.adjust_gamestate(first_incorrect, confirmed_frame, &mut requests);
self.disconnect_frame = NULL_FRAME;
}
let last_saved = self.sync_layer.last_saved_frame();
if self.sparse_saving {
self.check_last_saved_state(last_saved, confirmed_frame, &mut requests);
} else {
// without sparse saving, always save the current frame after correcting and rollbacking
requests.push(self.sync_layer.save_current_state());
}
/*
* SEND OFF AND THROW AWAY INPUTS BEFORE THE CONFIRMED FRAME
*/
// send confirmed inputs to spectators before throwing them away
self.send_confirmed_inputs_to_spectators(confirmed_frame);
// set the last confirmed frame and discard all saved inputs before that frame
self.sync_layer
.set_last_confirmed_frame(confirmed_frame, self.sparse_saving);
/*
* DESYNC DETECTION
*/
// collect, send, compare and check the last checksums against the other peers
if self.desync_detection != DesyncDetection::Off {
self.check_checksum_send_interval();
self.compare_local_checksums_against_peers();
}
/*
* WAIT RECOMMENDATION
*/
// check time sync between clients and send wait recommendation, if appropriate
self.check_wait_recommendation();
/*
* INPUTS
*/
// register local inputs in the system and send them
for handle in self.player_reg.local_player_handles() {
match self.local_inputs.get_mut(&handle) {
Some(player_input) => {
// send the input into the sync layer
let actual_frame = self.sync_layer.add_local_input(handle, *player_input)?;
assert!(actual_frame != NULL_FRAME);
// if not dropped, send the input to all other clients, but with the correct frame (influenced by input delay)
player_input.frame = actual_frame;
self.local_connect_status[handle].last_frame = actual_frame;
}
None => {
return Err(GgrsError::InvalidRequest {
info: "Missing local input while calling advance_frame().".to_owned(),
});
}
}
}
// send the inputs to all clients
for endpoint in self.player_reg.remotes.values_mut() {
// send the input directly
endpoint.send_input(&self.local_inputs, &self.local_connect_status);
endpoint.send_all_messages(&mut self.socket);
}
// clear the local inputs after sending them
self.local_inputs.clear();
/*
* ADVANCE THE STATE
*/
// get correct inputs for the current frame
let inputs = self
.sync_layer
.synchronized_inputs(&self.local_connect_status);
// advance the frame count
self.sync_layer.advance_frame();
requests.push(GgrsRequest::AdvanceFrame { inputs });
Ok(requests)
}
/// Should be called periodically by your application to give GGRS a chance to do internal work.
/// GGRS will receive packets, distribute them to corresponding endpoints, handle all occurring events and send all outgoing packets.
pub fn poll_remote_clients(&mut self) {
// Get all packets and distribute them to associated endpoints.
// The endpoints will handle their packets, which will trigger both events and UPD replies.
for (from_addr, msg) in &self.socket.receive_all_messages() {
if let Some(endpoint) = self.player_reg.remotes.get_mut(from_addr) {
endpoint.handle_message(msg);
}
if let Some(endpoint) = self.player_reg.spectators.get_mut(from_addr) {
endpoint.handle_message(msg);
}
}
// update frame information between remote players
for remote_endpoint in self.player_reg.remotes.values_mut() {
if remote_endpoint.is_running() {
remote_endpoint.update_local_frame_advantage(self.sync_layer.current_frame());
}
}
// run endpoint poll and get events from players and spectators. This will trigger additional packets to be sent.
let mut events = VecDeque::new();
for endpoint in self.player_reg.remotes.values_mut() {
let handles = endpoint.handles().clone();
let addr = endpoint.peer_addr();
for event in endpoint.poll(&self.local_connect_status) {
events.push_back((event, handles.clone(), addr.clone()))
}
}
for endpoint in self.player_reg.spectators.values_mut() {
let handles = endpoint.handles().clone();
let addr = endpoint.peer_addr();
for event in endpoint.poll(&self.local_connect_status) {
events.push_back((event, handles.clone(), addr.clone()))
}
}
// handle all events locally
for (event, handles, addr) in events.drain(..) {
self.handle_event(event, handles, addr);
}
// send all queued packets
for endpoint in self.player_reg.remotes.values_mut() {
endpoint.send_all_messages(&mut self.socket);
}
for endpoint in self.player_reg.spectators.values_mut() {
endpoint.send_all_messages(&mut self.socket);
}
}
/// Disconnects a remote player and all other remote players with the same address from the session.
/// # Errors
/// - Returns [`InvalidRequest`] if you try to disconnect a local player or the provided handle is invalid.
///
/// [`InvalidRequest`]: GgrsError::InvalidRequest
pub fn disconnect_player(&mut self, player_handle: PlayerHandle) -> Result<(), GgrsError> {
match self.player_reg.handles.get(&player_handle) {
// the local player cannot be disconnected
None => Err(GgrsError::InvalidRequest {
info: "Invalid Player Handle.".to_owned(),
}),
Some(PlayerType::Local) => Err(GgrsError::InvalidRequest {
info: "Local Player cannot be disconnected.".to_owned(),
}),
// a remote player can only be disconnected if not already disconnected, since there is some additional logic attached
Some(PlayerType::Remote(_)) => {
if !self.local_connect_status[player_handle].disconnected {
let last_frame = self.local_connect_status[player_handle].last_frame;
self.disconnect_player_at_frame(player_handle, last_frame);
return Ok(());
}
Err(GgrsError::InvalidRequest {
info: "Player already disconnected.".to_owned(),
})
}
// disconnecting spectators is simpler
Some(PlayerType::Spectator(_)) => {
self.disconnect_player_at_frame(player_handle, NULL_FRAME);
Ok(())
}
}
}
/// Returns a [`NetworkStats`] struct that gives information about the quality of the network connection.
/// # Errors
/// - Returns [`InvalidRequest`] if the handle not referring to a remote player or spectator.
/// - Returns [`NotSynchronized`] if the session is not connected to other clients yet.
///
/// [`InvalidRequest`]: GgrsError::InvalidRequest
/// [`NotSynchronized`]: GgrsError::NotSynchronized
pub fn network_stats(&self, player_handle: PlayerHandle) -> Result<NetworkStats, GgrsError> {
match self.player_reg.handles.get(&player_handle) {
Some(PlayerType::Remote(addr)) => self
.player_reg
.remotes
.get(addr)
.expect("Endpoint should exist for any registered player")
.network_stats(),
Some(PlayerType::Spectator(addr)) => self
.player_reg
.remotes
.get(addr)
.expect("Endpoint should exist for any registered player")
.network_stats(),
_ => Err(GgrsError::InvalidRequest {
info: "Given player handle not referring to a remote player or spectator"
.to_owned(),
}),
}
}
/// Returns the highest confirmed frame. We have received all input for this frame and it is thus correct.
pub fn confirmed_frame(&self) -> Frame {
let mut confirmed_frame = i32::MAX;
for con_stat in &self.local_connect_status {
if !con_stat.disconnected {
confirmed_frame = std::cmp::min(confirmed_frame, con_stat.last_frame);
}
}
assert!(confirmed_frame < i32::MAX);
confirmed_frame
}
/// Returns the current frame of a session.
pub fn current_frame(&self) -> Frame {
self.sync_layer.current_frame()
}
/// Returns the maximum prediction window of a session.
pub fn max_prediction(&self) -> usize {
self.max_prediction
}
/// Returns the current [`SessionState`] of a session.
pub fn current_state(&self) -> SessionState {
self.state
}
/// Returns all events that happened since last queried for events. If the number of stored events exceeds `MAX_EVENT_QUEUE_SIZE`, the oldest events will be discarded.
pub fn events(&mut self) -> Drain<GgrsEvent<T>> {
self.event_queue.drain(..)
}
/// Returns the number of players added to this session
pub fn num_players(&self) -> usize {
self.player_reg.num_players()
}
/// Return the number of spectators currently registered
pub fn num_spectators(&self) -> usize {
self.player_reg.num_spectators()
}
/// Returns the handles of local players that have been added
pub fn local_player_handles(&self) -> Vec<PlayerHandle> {
self.player_reg.local_player_handles()
}
/// Returns the handles of remote players that have been added
pub fn remote_player_handles(&self) -> Vec<PlayerHandle> {
self.player_reg.remote_player_handles()
}
/// Returns the handles of spectators that have been added
pub fn spectator_handles(&self) -> Vec<PlayerHandle> {
self.player_reg.spectator_handles()
}
/// Returns all handles associated to a certain address
pub fn handles_by_address(&self, addr: T::Address) -> Vec<PlayerHandle> {
self.player_reg.handles_by_address(addr)
}
/// Returns the number of frames this session is estimated to be ahead of other sessions
pub fn frames_ahead(&self) -> i32 {
self.frames_ahead
}
fn disconnect_player_at_frame(&mut self, player_handle: PlayerHandle, last_frame: Frame) {
// disconnect the remote player
match self
.player_reg
.handles
.get(&player_handle)
.expect("Invalid player handle")
{
PlayerType::Remote(addr) => {
let endpoint = self
.player_reg
.remotes
.get_mut(addr)
.expect("There should be no address without registered endpoint");
// mark the affected players as disconnected
for &handle in endpoint.handles() {
self.local_connect_status[handle].disconnected = true;
}
endpoint.disconnect();
if self.sync_layer.current_frame() > last_frame {
// remember to adjust simulation to account for the fact that the player disconnected a few frames ago,
// resimulating with correct disconnect flags (to account for user having some AI kick in).
self.disconnect_frame = last_frame + 1;
}
}
PlayerType::Spectator(addr) => {
let endpoint = self
.player_reg
.spectators
.get_mut(addr)
.expect("There should be no address without registered endpoint");
endpoint.disconnect();
}
PlayerType::Local => (),
}
// check if all remotes are synchronized now
self.check_initial_sync();
}
/// Change the session state to [`SessionState::Running`] if all UDP endpoints are synchronized.
fn check_initial_sync(&mut self) {
// if we are not synchronizing, we don't need to do anything
if self.state != SessionState::Synchronizing {
return;
}
// if any endpoint is not synchronized, we continue synchronizing
for endpoint in self.player_reg.remotes.values_mut() {
if !endpoint.is_synchronized() {
return;
}
}
for endpoint in self.player_reg.spectators.values_mut() {
if !endpoint.is_synchronized() {
return;
}
}
// everyone is synchronized, so we can change state and accept input
self.state = SessionState::Running;
}
/// Roll back to `min_confirmed` frame and resimulate the game with most up-to-date input data.
fn adjust_gamestate(
&mut self,
first_incorrect: Frame,
min_confirmed: Frame,
requests: &mut Vec<GgrsRequest<T>>,
) {
let current_frame = self.sync_layer.current_frame();
// determine the frame to load
let frame_to_load = if self.sparse_saving {
// if sparse saving is turned on, we will rollback to the last saved state
self.sync_layer.last_saved_frame()
} else {
// otherwise, we will rollback to first_incorrect
first_incorrect
};
// we should always load a frame that is before or exactly the first incorrect frame
assert!(frame_to_load <= first_incorrect);
let count = current_frame - frame_to_load;
// request to load that frame
requests.push(self.sync_layer.load_frame(frame_to_load));
// we are now at the desired frame
assert_eq!(self.sync_layer.current_frame(), frame_to_load);
self.sync_layer.reset_prediction();
// step forward to the previous current state, but with updated inputs
for i in 0..count {
let inputs = self
.sync_layer
.synchronized_inputs(&self.local_connect_status);
// decide whether to request a state save
if self.sparse_saving {
// with sparse saving, we only save exactly the min_confirmed frame
if self.sync_layer.current_frame() == min_confirmed {
requests.push(self.sync_layer.save_current_state());
}
} else {
// without sparse saving, we save every state except the very first (just loaded that))
if i > 0 {
requests.push(self.sync_layer.save_current_state());
}
}
// advance the frame
self.sync_layer.advance_frame();
requests.push(GgrsRequest::AdvanceFrame { inputs });
}
// after all this, we should have arrived at the same frame where we started
assert_eq!(self.sync_layer.current_frame(), current_frame);
}
/// For each spectator, send all confirmed input up until the minimum confirmed frame.
fn send_confirmed_inputs_to_spectators(&mut self, confirmed_frame: Frame) {
if self.num_spectators() == 0 {
return;
}
while self.next_spectator_frame <= confirmed_frame {
let mut inputs = self
.sync_layer
.confirmed_inputs(self.next_spectator_frame, &self.local_connect_status);
assert_eq!(inputs.len(), self.num_players);
let mut input_map = HashMap::new();
for (handle, input) in inputs.iter_mut().enumerate() {
assert!(input.frame == NULL_FRAME || input.frame == self.next_spectator_frame);
input_map.insert(handle, *input);
}
// send it to all spectators
for endpoint in self.player_reg.spectators.values_mut() {
if endpoint.is_running() {
endpoint.send_input(&input_map, &self.local_connect_status);
}
}
// onto the next frame
self.next_spectator_frame += 1;
}
}
/// Check if players are registered as disconnected for earlier frames on other remote players in comparison to our local assumption.
/// Disconnect players that are disconnected for other players and update the frame they disconnected
fn update_player_disconnects(&mut self) {
for handle in 0..self.num_players {
let mut queue_connected = true;
let mut queue_min_confirmed = i32::MAX;
// check all player connection status for every remote player
for endpoint in self.player_reg.remotes.values() {
if !endpoint.is_running() {
continue;
}
let con_status = endpoint.peer_connect_status(handle);
let connected = !con_status.disconnected;
let min_confirmed = con_status.last_frame;
queue_connected = queue_connected && connected;
queue_min_confirmed = std::cmp::min(queue_min_confirmed, min_confirmed);
}
// check our local info for that player
let local_connected = !self.local_connect_status[handle].disconnected;
let local_min_confirmed = self.local_connect_status[handle].last_frame;
if local_connected {
queue_min_confirmed = std::cmp::min(queue_min_confirmed, local_min_confirmed);
}
if !queue_connected {
// check to see if the remote disconnect is further back than we have disconnected that player.
// If so, we need to re-adjust. This can happen when we e.g. detect our own disconnect at frame n
// and later receive a disconnect notification for frame n-1.
if local_connected || local_min_confirmed > queue_min_confirmed {
self.disconnect_player_at_frame(handle as PlayerHandle, queue_min_confirmed);
}
}
}
}
/// Gather average frame advantage from each remote player endpoint and return the maximum.
fn max_frame_advantage(&self) -> i32 {
let mut interval = i32::MIN;
for endpoint in self.player_reg.remotes.values() {
for &handle in endpoint.handles() {
if !self.local_connect_status[handle].disconnected {
interval = std::cmp::max(interval, endpoint.average_frame_advantage());
}
}
}
// if no remote player is connected
if interval == i32::MIN {
interval = 0;
}
interval
}
fn check_wait_recommendation(&mut self) {
self.frames_ahead = self.max_frame_advantage();
if self.sync_layer.current_frame() > self.next_recommended_sleep
&& self.frames_ahead >= MIN_RECOMMENDATION as i32
{
self.next_recommended_sleep = self.sync_layer.current_frame() + RECOMMENDATION_INTERVAL;
self.event_queue.push_back(GgrsEvent::WaitRecommendation {
skip_frames: self
.frames_ahead
.try_into()
.expect("frames ahead is negative despite being positive."),
});
}
}
fn check_last_saved_state(
&mut self,
last_saved: Frame,
confirmed_frame: Frame,
requests: &mut Vec<GgrsRequest<T>>,
) {
// in sparse saving mode, we need to make sure not to lose the last saved frame
if self.sync_layer.current_frame() - last_saved >= self.max_prediction as i32 {
// check if the current frame is confirmed, otherwise we need to roll back
if confirmed_frame >= self.sync_layer.current_frame() {
// the current frame is confirmed, save it
requests.push(self.sync_layer.save_current_state());
} else {
// roll back to the last saved state, resimulate and save on the way
self.adjust_gamestate(last_saved, confirmed_frame, requests);
}
// after all this, we should have saved the confirmed state
assert!(
confirmed_frame == NULL_FRAME
|| self.sync_layer.last_saved_frame()
== std::cmp::min(confirmed_frame, self.sync_layer.current_frame())
);
}
}
/// Handle events received from the UDP endpoints. Most events are being forwarded to the user for notification, but some require action.
fn handle_event(
&mut self,
event: Event<T>,
player_handles: Vec<PlayerHandle>,
addr: T::Address,
) {
match event {
// forward to user
Event::Synchronizing { total, count } => {
self.event_queue
.push_back(GgrsEvent::Synchronizing { addr, total, count });
}
// forward to user
Event::NetworkInterrupted { disconnect_timeout } => {
self.event_queue.push_back(GgrsEvent::NetworkInterrupted {
addr,
disconnect_timeout,
});
}
// forward to user
Event::NetworkResumed => {
self.event_queue
.push_back(GgrsEvent::NetworkResumed { addr });
}
// check if all remotes are synced, then forward to user
Event::Synchronized => {
self.check_initial_sync();
self.event_queue.push_back(GgrsEvent::Synchronized { addr });
}
// disconnect the player, then forward to user
Event::Disconnected => {
for handle in player_handles {
let last_frame = if handle < self.num_players as PlayerHandle {
self.local_connect_status[handle].last_frame
} else {
NULL_FRAME // spectator
};
self.disconnect_player_at_frame(handle, last_frame);
}
self.event_queue.push_back(GgrsEvent::Disconnected { addr });
}
// add the input and all associated information
Event::Input { input, player } => {
// input only comes from remote players, not spectators
assert!(player < self.num_players as PlayerHandle);
if !self.local_connect_status[player].disconnected {
// check if the input comes in the correct sequence
let current_remote_frame = self.local_connect_status[player].last_frame;
assert!(
current_remote_frame == NULL_FRAME
|| current_remote_frame + 1 == input.frame
);
// update our info
self.local_connect_status[player].last_frame = input.frame;
// add the remote input
self.sync_layer.add_remote_input(player, input);
}
}
}
// check event queue size and discard oldest events if too big
while self.event_queue.len() > MAX_EVENT_QUEUE_SIZE {
self.event_queue.pop_front();
}
}
fn compare_local_checksums_against_peers(&mut self) {
match self.desync_detection {
DesyncDetection::On { .. } => {
for remote in self.player_reg.remotes.values_mut() {
let mut checked_frames = Vec::new();
for (&remote_frame, &remote_checksum) in &remote.pending_checksums {
if remote_frame >= self.sync_layer.last_confirmed_frame() {
// we're still waiting for inputs for this frame
continue;
}
if let Some(&local_checksum) =
self.local_checksum_history.get(&remote_frame)
{
if local_checksum != remote_checksum {
self.event_queue.push_back(GgrsEvent::DesyncDetected {
frame: remote_frame,
local_checksum,
remote_checksum,
addr: remote.peer_addr(),
});
}
checked_frames.push(remote_frame);
}
}
for frame in checked_frames {
remote.pending_checksums.remove_entry(&frame);
}
}
}
DesyncDetection::Off => (),
}
}
fn check_checksum_send_interval(&mut self) {
match self.desync_detection {
DesyncDetection::On { interval } => {
let frame_to_send = if self.last_sent_checksum_frame == NULL_FRAME {
interval as i32
} else {
self.last_sent_checksum_frame + interval as i32
};
if frame_to_send <= self.sync_layer.last_confirmed_frame()
&& frame_to_send < self.sync_layer.last_saved_frame()
{
let cell = self
.sync_layer
.saved_state_by_frame(frame_to_send)
.unwrap_or_else(|| panic!("cell not found!: frame {frame_to_send}"));
if let Some(checksum) = cell.checksum() {
for remote in self.player_reg.remotes.values_mut() {
remote.send_checksum_report(frame_to_send, checksum);
}
self.last_sent_checksum_frame = frame_to_send;
// collect locally for later comparison
self.local_checksum_history.insert(frame_to_send, checksum);
}
if self.local_checksum_history.len() > MAX_CHECKSUM_HISTORY_SIZE {
let oldest_frame_to_keep = frame_to_send
- (MAX_CHECKSUM_HISTORY_SIZE as i32 - 1) * interval as i32;
self.local_checksum_history
.retain(|&frame, _| frame >= oldest_frame_to_keep);
}
}
}
DesyncDetection::Off => (),
}
}
}