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Tracerestrict: Allow nesting temporary slot states

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Use a temporary state stack instead of passing the state directly
in TraceRestrictProgramInput

No longer exit early from ExtendTrainReservation to handle slots, this
fixes reservation failures when starting from a signal with a slot acquire

More thorough fix for 9e8a4314
This commit is contained in:
Jonathan G Rennison
2024-01-29 22:16:29 +00:00
parent e148f7653b
commit 5e29901d02
4 changed files with 117 additions and 20 deletions
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41
src/train_cmd.cpp
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@@ -3822,9 +3822,10 @@ static Track DoTrainPathfind(const Train *v, TileIndex tile, DiagDirection enter
* @param origin The tile from which the reservation have to be extended
* @param new_tracks [out] Tracks to choose from when encountering a choice
* @param enterdir [out] The direction from which the choice tile is to be entered
* @param temporary_slot_state The temporary slot to use (will be activated/deactivated as necessary if it isn't already)
* @return INVALID_TILE indicates that the reservation failed.
*/
static PBSTileInfo ExtendTrainReservation(const Train *v, const PBSTileInfo &origin, TrackBits *new_tracks, DiagDirection *enterdir)
static PBSTileInfo ExtendTrainReservation(const Train *v, const PBSTileInfo &origin, TrackBits *new_tracks, DiagDirection *enterdir, TraceRestrictSlotTemporaryState &temporary_slot_state)
{
CFollowTrackRail ft(v);
@@ -3844,7 +3845,6 @@ static PBSTileInfo ExtendTrainReservation(const Train *v, const PBSTileInfo &ori
/* Station, depot or waypoint are a possible target. */
bool target_seen = ft.m_is_station || (IsTileType(ft.m_new_tile, MP_RAILWAY) && !IsPlainRail(ft.m_new_tile));
if (target_seen || KillFirstBit(ft.m_new_td_bits) != TRACKDIR_BIT_NONE) {
target_seen_path:
/* Choice found or possible target encountered.
* On finding a possible target, we need to stop and let the pathfinder handle the
* remaining path. This is because we don't know if this target is in one of our
@@ -3878,10 +3878,20 @@ static PBSTileInfo ExtendTrainReservation(const Train *v, const PBSTileInfo &ori
if (IsTileType(tile, MP_RAILWAY) && HasSignals(tile) && IsRestrictedSignal(tile) && HasSignalOnTrack(tile, TrackdirToTrack(cur_td))) {
const TraceRestrictProgram *prog = GetExistingTraceRestrictProgram(tile, TrackdirToTrack(cur_td));
if (prog != nullptr && prog->actions_used_flags & (TRPAUF_WAIT_AT_PBS | TRPAUF_SLOT_ACQUIRE)) {
/* The pathfinder must deal with this, because temporary slot states can't be nested.
* See target_seen path above.
*/
goto target_seen_path;
if (!temporary_slot_state.IsActive()) {
/* The temporary slot state needs to be be pushed because permission to use it is granted by TRPISP_ACQUIRE_TEMP_STATE */
temporary_slot_state.PushToChangeStack();
}
TraceRestrictProgramInput input(tile, cur_td, &VehiclePosTraceRestrictPreviousSignalCallback, nullptr);
input.permitted_slot_operations = TRPISP_ACQUIRE_TEMP_STATE;
TraceRestrictProgramResult out;
prog->Execute(v, input, out);
if (out.flags & TRPRF_WAIT_AT_PBS) {
/* Wait at PBS is set, take this as waiting at the start signal, handle as a reservation failure */
break;
}
}
}
@@ -3913,6 +3923,8 @@ static PBSTileInfo ExtendTrainReservation(const Train *v, const PBSTileInfo &ori
UnreserveRailTrackdir(tile, cur_td);
}
if (temporary_slot_state.IsActive()) temporary_slot_state.PopFromChangeStackRevertTemporaryChanges(v->index);
/* Path invalid. */
return PBSTileInfo();
}
@@ -4415,11 +4427,19 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
ClearLookAheadIfInvalid(v);
}
/* The temporary slot state only needs to be pushed to the stack (i.e. activated) on first use */
TraceRestrictSlotTemporaryState temporary_slot_state;
/* All exit paths except success should revert the temporary slot state if required */
auto slot_state_guard = scope_guard([&]() {
if (temporary_slot_state.IsActive()) temporary_slot_state.PopFromChangeStackRevertTemporaryChanges(v->index);
});
PBSTileInfo origin = FollowTrainReservation(v, nullptr, FTRF_OKAY_UNUSED);
PBSTileInfo res_dest(tile, INVALID_TRACKDIR, false);
DiagDirection dest_enterdir = enterdir;
if (do_track_reservation) {
res_dest = ExtendTrainReservation(v, origin, &tracks, &dest_enterdir);
res_dest = ExtendTrainReservation(v, origin, &tracks, &dest_enterdir, temporary_slot_state);
if (res_dest.tile == INVALID_TILE) {
/* Reservation failed? */
if (mark_stuck) MarkTrainAsStuck(v);
@@ -4427,6 +4447,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
return FindFirstTrack(tracks);
}
if (res_dest.okay) {
if (temporary_slot_state.IsActive()) temporary_slot_state.PopFromChangeStackApplyTemporaryChanges(v);
bool long_reserve = (CheckLongReservePbsTunnelBridgeOnTrackdir(v, res_dest.tile, res_dest.trackdir) != INVALID_TILE);
if (!long_reserve) {
CFollowTrackRail ft(v);
@@ -4444,8 +4465,6 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
if (_settings_game.vehicle.train_braking_model == TBM_REALISTIC) FillTrainReservationLookAhead(v);
return best_track;
}
} else if (res_dest.tile == tile) {
if (changed_signal != INVALID_TRACKDIR) SetSignalStateByTrackdir(tile, changed_signal, SIGNAL_STATE_RED);
}
/* Check if the train needs service here, so it has a chance to always find a depot.
@@ -4493,6 +4512,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
/* Try to find any safe destination. */
PBSTileInfo path_end = FollowTrainReservation(v, nullptr, FTRF_OKAY_UNUSED);
if (TryReserveSafeTrack(v, path_end.tile, path_end.trackdir, false)) {
if (temporary_slot_state.IsActive()) temporary_slot_state.PopFromChangeStackApplyTemporaryChanges(v);
TrackBits res = GetReservedTrackbits(tile) & DiagdirReachesTracks(enterdir);
best_track = FindFirstTrack(res);
if (!HasBit(lookahead_state.flags, CTTLASF_NO_RES_VEH_TILE)) TryReserveRailTrack(v->tile, TrackdirToTrack(v->GetVehicleTrackdir()));
@@ -4550,6 +4570,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
if (mark_stuck) MarkTrainAsStuck(v);
got_reservation = false;
changed_signal = INVALID_TRACKDIR;
if (temporary_slot_state.IsActive()) temporary_slot_state.PopFromChangeStackRevertTemporaryChanges(v->index);
break;
}
}
@@ -4559,11 +4580,13 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
if (mark_stuck) MarkTrainAsStuck(v);
got_reservation = false;
changed_signal = INVALID_TRACKDIR;
if (temporary_slot_state.IsActive()) temporary_slot_state.PopFromChangeStackRevertTemporaryChanges(v->index);
}
break;
}
if (got_reservation) {
if (temporary_slot_state.IsActive()) temporary_slot_state.PopFromChangeStackApplyTemporaryChanges(v);
if (v->current_order.IsBaseStationOrder() && HasStationTileRail(res_dest.tile) && v->current_order.GetDestination() == GetStationIndex(res_dest.tile)) {
if (v->current_order.ShouldStopAtStation(v, v->current_order.GetDestination(), v->current_order.IsType(OT_GOTO_WAYPOINT))) {
v->last_station_visited = v->current_order.GetDestination();