Use btree_multimap for pending speed restrictions

Avoid unnecessary iteration when saving VESR chunk

src/saveload/vehicle_sl.cpp

@@ -22,6 +22,7 @@
 #include "../string_func.h"
 #include "../error.h"
 #include "../strings_func.h"
+#include "../3rdparty/cpp-btree/btree_map.h"
 
 #include "saveload.h"
 
@@ -29,6 +30,8 @@
 
 #include "../safeguards.h"
 
+extern btree::btree_multimap<VehicleID, PendingSpeedRestrictionChange> _pending_speed_restriction_change_map;
+
 /**
  * Link front and rear multiheaded engines to each other
  * This is done when loading a savegame
@@ -1134,15 +1137,10 @@ const SaveLoadTable GetVehicleSpeedRestrictionDescription()
 
 void Save_VESR()
 {
-	for (Train *t : Train::Iterate()) {
-		if (HasBit(t->flags, VRF_PENDING_SPEED_RESTRICTION)) {
-			auto range = pending_speed_restriction_change_map.equal_range(t->index);
-			for (auto it = range.first; it != range.second; ++it) {
-				SlSetArrayIndex(t->index);
-				PendingSpeedRestrictionChange *ptr = &(it->second);
-				SlObject(ptr, GetVehicleSpeedRestrictionDescription());
-			}
-		}
+	for (auto &it : _pending_speed_restriction_change_map) {
+		SlSetArrayIndex(it.first);
+		PendingSpeedRestrictionChange *ptr = &(it.second);
+		SlObject(ptr, GetVehicleSpeedRestrictionDescription());
 	}
 }
 
@@ -1150,7 +1148,7 @@ void Load_VESR()
 {
 	int index;
 	while ((index = SlIterateArray()) != -1) {
-		auto iter = pending_speed_restriction_change_map.insert({ static_cast<VehicleID>(index), {} });
+		auto iter = _pending_speed_restriction_change_map.insert({ static_cast<VehicleID>(index), {} });
 		PendingSpeedRestrictionChange *ptr = &(iter->second);
 		SlObject(ptr, GetVehicleSpeedRestrictionDescription());
 	}

src/train_cmd.cpp

@@ -46,12 +46,15 @@
 #include "debug_settings.h"
 #include "train_speed_adaptation.h"
 #include "event_logs.h"
+#include "3rdparty/cpp-btree/btree_map.h"
 
 #include "table/strings.h"
 #include "table/train_cmd.h"
 
 #include "safeguards.h"
 
+extern btree::btree_multimap<VehicleID, PendingSpeedRestrictionChange> _pending_speed_restriction_change_map;
+
 enum {
 	REALISTIC_BRAKING_MIN_SPEED = 5,
 };
@@ -2988,12 +2991,11 @@ void ReverseTrainDirection(Train *v)
 	if (crossing != INVALID_TILE) MaybeBarCrossingWithSound(crossing);
 
 	if (HasBit(v->flags, VRF_PENDING_SPEED_RESTRICTION)) {
-		auto range = pending_speed_restriction_change_map.equal_range(v->index);
-		for (auto it = range.first; it != range.second;) {
+		for (auto it = _pending_speed_restriction_change_map.lower_bound(v->index); it != _pending_speed_restriction_change_map.end() && it->first == v->index;) {
 			it->second.distance = (v->gcache.cached_total_length + (HasBit(it->second.flags, PSRCF_DIAGONAL) ? 8 : 4)) - it->second.distance;
 			if (it->second.distance == 0) {
 				v->speed_restriction = it->second.prev_speed;
-				it = pending_speed_restriction_change_map.erase(it);
+				it = _pending_speed_restriction_change_map.erase(it);
 			} else {
 				std::swap(it->second.prev_speed, it->second.new_speed);
 				++it;
@@ -5356,29 +5358,29 @@ int ReversingDistanceTargetSpeed(const Train *v)
 
 void DecrementPendingSpeedRestrictions(Train *v)
 {
-	auto range = pending_speed_restriction_change_map.equal_range(v->index);
-	if (range.first == range.second) ClrBit(v->flags, VRF_PENDING_SPEED_RESTRICTION);
-	for (auto it = range.first; it != range.second;) {
+	bool remaining = false;
+	for (auto it = _pending_speed_restriction_change_map.lower_bound(v->index); it != _pending_speed_restriction_change_map.end() && it->first == v->index;) {
 		if (--it->second.distance == 0) {
 			v->speed_restriction = it->second.new_speed;
-			it = pending_speed_restriction_change_map.erase(it);
+			it = _pending_speed_restriction_change_map.erase(it);
 		} else {
 			++it;
+			remaining = true;
 		}
 	}
+	if (!remaining) ClrBit(v->flags, VRF_PENDING_SPEED_RESTRICTION);
 }
 
 void HandleTraceRestrictSpeedRestrictionAction(const TraceRestrictProgramResult &out, Train *v, Trackdir signal_td)
 {
 	if (out.flags & TRPRF_SPEED_RESTRICTION_SET) {
 		SetBit(v->flags, VRF_PENDING_SPEED_RESTRICTION);
-		auto range = pending_speed_restriction_change_map.equal_range(v->index);
-		for (auto it = range.first; it != range.second; ++it) {
+		for (auto it = _pending_speed_restriction_change_map.lower_bound(v->index); it != _pending_speed_restriction_change_map.end() && it->first == v->index; ++it) {
 			if ((uint16) (out.speed_restriction + 0xFFFF) < (uint16) (it->second.new_speed + 0xFFFF)) it->second.new_speed = out.speed_restriction;
 		}
 		uint16 flags = 0;
 		if (IsDiagonalTrack(TrackdirToTrack(signal_td))) SetBit(flags, PSRCF_DIAGONAL);
-		pending_speed_restriction_change_map.insert({ v->index, { (uint16) (v->gcache.cached_total_length + (HasBit(flags, PSRCF_DIAGONAL) ? 8 : 4)), out.speed_restriction, v->speed_restriction, flags } });
+		_pending_speed_restriction_change_map.insert({ v->index, { (uint16) (v->gcache.cached_total_length + (HasBit(flags, PSRCF_DIAGONAL) ? 8 : 4)), out.speed_restriction, v->speed_restriction, flags } });
 		if ((uint16) (out.speed_restriction + 0xFFFF) < (uint16) (v->speed_restriction + 0xFFFF)) v->speed_restriction = out.speed_restriction;
 	}
 	if (out.flags & TRPRF_SPEED_ADAPT_EXEMPT && !HasBit(v->flags, VRF_SPEED_ADAPTATION_EXEMPT)) {

src/vehicle.cpp

@@ -60,6 +60,7 @@
 #include "scope_info.h"
 #include "debug_settings.h"
 #include "3rdparty/cpp-btree/btree_set.h"
+#include "3rdparty/cpp-btree/btree_map.h"
 
 #include "table/strings.h"
 
@@ -105,7 +106,7 @@ INSTANTIATE_POOL_METHODS(Vehicle)
 static btree::btree_set<VehicleID> _vehicles_to_pay_repair;
 static btree::btree_set<VehicleID> _vehicles_to_sell;
 
-std::unordered_multimap<VehicleID, PendingSpeedRestrictionChange> pending_speed_restriction_change_map;
+btree::btree_multimap<VehicleID, PendingSpeedRestrictionChange> _pending_speed_restriction_change_map;
 
 /**
  * Determine shared bounds of all sprites.
@@ -1168,7 +1169,7 @@ void Vehicle::PreDestructor()
 		ClrBit(this->vehicle_flags, VF_HAVE_SLOT);
 	}
 	if (this->type == VEH_TRAIN && HasBit(Train::From(this)->flags, VRF_PENDING_SPEED_RESTRICTION)) {
-		pending_speed_restriction_change_map.erase(this->index);
+		_pending_speed_restriction_change_map.erase(this->index);
 		ClrBit(Train::From(this)->flags, VRF_PENDING_SPEED_RESTRICTION);
 	}
 
@@ -1240,7 +1241,7 @@ Vehicle::~Vehicle()
  */
 void Vehicle::PreCleanPool()
 {
-	pending_speed_restriction_change_map.clear();
+	_pending_speed_restriction_change_map.clear();
 }
 
 /**

src/vehicle_base.h

@@ -28,7 +28,6 @@
 #include "saveload/saveload_common.h"
 #include <list>
 #include <map>
-#include <unordered_map>
 
 CommandCost CmdRefitVehicle(TileIndex, DoCommandFlag, uint32, uint32, const char*);
 
@@ -224,7 +223,6 @@ struct PendingSpeedRestrictionChange {
 	uint16 prev_speed;
 	uint16 flags;
 };
-extern std::unordered_multimap<VehicleID, PendingSpeedRestrictionChange> pending_speed_restriction_change_map;
 
 /** A vehicle pool for a little over 1 million vehicles. */
 typedef Pool<Vehicle, VehicleID, 512, 0xFF000> VehiclePool;