Once a player joins, rollback runs from tick 0 to current tick #260
Description
I'm currently focused on other PRs but this is a performance bug which I have to at least bring up.
The following function is inside the class rollback-synchronizer.gd
The below logger I added, reports that a new player joining, runs the below function from tick 0 to whatever tick you joined.
func _get_history(buffer: Dictionary, tick: int) -> Dictionary:
if buffer.has(tick):
return buffer[tick]
if buffer.is_empty():
return {}
var earliest = buffer.keys().min()
var latest = buffer.keys().max()
if tick < earliest:
_logger.warning("Tried to load tick %s which is earlier than the earliest we have recorded (%s)
Try increasing the history limit." % [tick, earliest])
return buffer[earliest]
#For inputs, this is extrapolation aka prediction
#For example, if you move to the right (at latest)
#at tick, you will still be moving to the right ;)
if tick > latest:
return buffer[latest]
var before: int = buffer.keys() \
.filter(func (key): return key < tick) \
.max()
return buffer[before]The full stack trace is this:
rollback-synchronizer -> func _prepare_tick(tick: int)
network-rollback -> on_prepare_tick.emit(tick)
network-rollback -> func _rollback()
Below class is network-rollback.gd
func _ready():
NetworkTime.after_tick_loop.connect(_rollback)
func _rollback():
if not enabled:
return
_is_rollback = true
# Ask all rewindables to submit their earliest inputs
_resim_from = NetworkTime.tick
before_loop.emit()
# from = Earliest input amongst all rewindables
var from: int = _resim_from
# to = Current tick
var to: int = NetworkTime.tick
# for tick in from .. to:
for tick in range(from, to): #FORLOOP FROM 0 TO player_joined_at_tick
_tick = tick
_simulated_nodes.clear()
# Prepare state
# Done individually by Rewindables ( usually Rollback Synchronizers )
# Restore input and state for tick
on_prepare_tick.emit(tick) #IT ENTERS HEREIt shouldn't run these loops (imagine if a player joins tick 100000 lol), as at each one, it returns buffer[earliest]
Anyway, needs more investigation, I only stumbled into it while implementing input delay, its not serious even for full games, since normally lobby games start everyone at tick 0 instead of joining at whatever tick