Defer per-node speed calculation until end of tick

src/main/java/com/simibubi/create/content/contraptions/solver/KineticNetwork.java

@@ -2,8 +2,6 @@ package com.simibubi.create.content.contraptions.solver;
 
 import com.simibubi.create.foundation.utility.Pair;
 
-import net.minecraft.util.Mth;
-
 import javax.annotation.Nullable;
 
 import java.util.HashSet;
@@ -17,32 +15,37 @@ public class KineticNetwork {
 	private final Set<KineticNode> generators = new HashSet<>();
 	private final Set<Pair<KineticNode, KineticNode>> conflictingCycles = new HashSet<>();
 	private float rootSpeed;
+	private @Nullable KineticNode mainGenerator;
+	private boolean speedDirty;
 
 	public KineticNetwork(KineticNode root) {
 		addMember(root);
-		rootSpeed = root.getGeneratedSpeed();
 	}
 
 	public void addMember(KineticNode node) {
 		members.add(node);
-		if (node.isGenerator()) {
+		if (node.isGenerator() && !generators.contains(node)) {
 			generators.add(node);
+			speedDirty = true;
 		}
 	}
 
 	public void updateMember(KineticNode node) {
 		if (!members.contains(node)) throw new IllegalArgumentException();
+
 		if (node.isGenerator()) {
 			generators.add(node);
 		} else {
 			generators.remove(node);
 		}
+		speedDirty = true;
 	}
 
 	public void removeMember(KineticNode node) {
 		members.remove(node);
-		if (node.isGenerator()) {
+		if (node.isGenerator() && generators.contains(node)) {
 			generators.remove(node);
+			speedDirty = true;
 		}
 		conflictingCycles.removeIf(p -> p.getFirst() == node || p.getSecond() == node);
 	}
@@ -56,70 +59,88 @@ public class KineticNetwork {
 		return rootSpeed;
 	}
 
+	public boolean isStopped() { return generators.isEmpty(); }
+
 	/**
-	 * Recalculates the speed at the root of this network, and if it has changed, recalculates the speed of all
-	 * KineticNodes in the network and pops any nodes whose speed has increased above the speed limit.
-	 * @param checkRoot Node to start performing a breadth-first from in order to find and pop speeding nodes. If null,
-	 *                  speeding nodes are ignored.
-	 * @param forced	If true, will check for speeding nodes from checkRoot even if the root speed has not changed.
-	 * @return			CONTRADICTION if the network currently has a cycle with conflicting speed ratios or
-	 * 					has generators turning against each other, and OK otherwise.
+	 * Recalculates the speed at the root node of this network.
+	 * @return	CONTRADICTION if the network has generators turning against each other, and OK otherwise
 	 */
-	public SolveResult recalculateSpeed(@Nullable KineticNode checkRoot, boolean forced) {
-		if (!conflictingCycles.isEmpty() && !generators.isEmpty()) {
-			// cycle with conflicting speed ratios is present
-			return SolveResult.CONTRADICTION;
-		}
+	public SolveResult recalculateSpeed() {
+		if (!speedDirty) return SolveResult.OK;
+
+		float newSpeed = 0;
+		KineticNode newGenerator = null;
+		float sign = 0;
 
 		// search over all generators to maximize the root speed
-		float newSpeed = 0;
-		float sign = 0;
 		for (KineticNode generator : generators) {
 			float speedAtRoot = generator.getGeneratedSpeedAtRoot();
+
 			if (newSpeed == 0) {
 				sign = Math.signum(speedAtRoot);
-			} else if (Math.signum(speedAtRoot) != sign) {
+			}
+
+			if (Math.signum(speedAtRoot) != sign) {
 				// generators are turning against each other
 				return SolveResult.CONTRADICTION;
 			}
-			newSpeed = Math.max(newSpeed, sign * speedAtRoot);
-		}
-		newSpeed *= sign;
 
-		if (!Mth.equal(rootSpeed, newSpeed)) {
-			rootSpeed = newSpeed;
-
-			if (checkRoot == null) {
-				members.forEach(KineticNode::tryUpdateSpeed);
-			} else {
-				updateNodeSpeeds(checkRoot, false);
+			if (newSpeed < speedAtRoot * sign) {
+				newSpeed = speedAtRoot * sign;
+				newGenerator = generator;
 			}
-		} else if (forced) {
-			updateNodeSpeeds(checkRoot, true);
 		}
-
+		rootSpeed = newSpeed * sign;
+		mainGenerator = newGenerator;
+		speedDirty = false;
 		return SolveResult.OK;
 	}
 
-	private void updateNodeSpeeds(KineticNode root, boolean followSources) {
+	/**
+	 * @return	a List of new networks created during this function call
+	 */
+	public List<KineticNetwork> tick() {
+		List<KineticNetwork> newNetworks = updateMemberSpeeds();
+		members.forEach(KineticNode::flushChangedSpeed);
+		return newNetworks;
+	}
+
+	private List<KineticNetwork> updateMemberSpeeds() {
+		SolveResult recalculateSpeedResult = recalculateSpeed();
+		// generators should not be turning against each other by now
+		assert(recalculateSpeedResult.isOk());
+
+		// if we're stopped then all members' speeds will be 0, so no need to check for speeding nodes
+		if (isStopped()) {
+			members.forEach(KineticNode::tryUpdateSpeed);
+			return List.of();
+		}
+
+		// there should be no cycles with conflicting speed ratios by now
+		assert(conflictingCycles.isEmpty());
+
+		// update node speeds in a breadth-first order, checking for speeding nodes along the way
+		List<KineticNetwork> newNetworks = new LinkedList<>();
 		Set<KineticNode> visited = new HashSet<>();
 		List<KineticNode> frontier = new LinkedList<>();
-		frontier.add(root);
+		frontier.add(mainGenerator);
 
-		// update node speeds in a breadth-first order, starting at root
 		while (!frontier.isEmpty()) {
 			KineticNode cur = frontier.remove(0);
 			visited.add(cur);
 			if (cur.tryUpdateSpeed().isOk()) {
-				for (KineticNode next : cur.getActiveConnections().keySet()) {
-					if (!(visited.contains(next) || (followSources && !cur.isSourceOf(next))))
-						frontier.add(next);
-				}
+				cur.getActiveConnections()
+						.map(Pair::getFirst)
+						.filter(n -> !visited.contains(n))
+						.forEach(frontier::add);
 			} else {
 				// stop searching on this branch once a speeding node is found
 				cur.onPopBlock();
+				newNetworks.add(cur.getNetwork());
 			}
 		}
+
+		return newNetworks;
 	}
 
 }

src/main/java/com/simibubi/create/content/contraptions/solver/KineticNode.java

@@ -11,10 +11,10 @@ import javax.annotation.Nullable;
 
 import java.util.LinkedList;
 import java.util.List;
-import java.util.Map;
 import java.util.Optional;
 import java.util.function.Function;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 public class KineticNode {
 
@@ -46,18 +46,25 @@ public class KineticNode {
 		return connections;
 	}
 
+	public KineticNetwork getNetwork() {
+		return network;
+	}
+
 	/**
-	 * @return a map where the keys are every node with a compatible connection to this node, and the values are the
-	 * speed ratios of those connections
+	 * @return 	a Stream containing a pair for each compatible connection with this node, where the first value is
+	 * 			the connecting node and the second value is the speed ratio of the connection
 	 */
-	public Map<KineticNode, Float> getActiveConnections() {
+	public Stream<Pair<KineticNode, Float>> getActiveConnections() {
 		return connections.getDirections().stream()
 				.map(d -> nodeAccessor.apply(entity.getBlockPos().offset(d))
 						.map(n -> connections.checkConnection(n.connections, d)
 								.map(r -> Pair.of(n, r))))
 				.flatMap(Optional::stream)
-				.flatMap(Optional::stream)
-				.collect(Collectors.toMap(Pair::getFirst, Pair::getSecond));
+				.flatMap(Optional::stream);
+	}
+
+	public Iterable<Pair<KineticNode, Float>> getActiveConnectionsList() {
+		return getActiveConnections().collect(Collectors.toList());
 	}
 
 	public float getGeneratedSpeed() {
@@ -73,87 +80,92 @@ public class KineticNode {
 	}
 
 	public void setGeneratedSpeed(float newSpeed) {
-		if (Mth.equal(generatedSpeed, newSpeed)) return;
+		if (generatedSpeed == newSpeed) return;
 		generatedSpeed = newSpeed;
 		network.updateMember(this);
-		if (network.recalculateSpeed(this, false).isContradiction())
+		if (network.recalculateSpeed().isContradiction()) {
 			onPopBlock();
+		}
 	}
 
-	private void setNetwork(KineticNetwork network) {
+	private SolveResult setNetwork(KineticNetwork network) {
 		this.network.removeMember(this);
 		this.network = network;
 		network.addMember(this);
+		return network.recalculateSpeed();
 	}
 
-	private void setSource(KineticNode from, float ratio) {
+	private SolveResult setSource(KineticNode from, float ratio) {
 		source = from;
 		speedRatio = from.speedRatio * ratio;
-		setNetwork(from.network);
+		return setNetwork(from.network);
 	}
 
 	public void onAdded() {
 		getActiveConnections()
-				.keySet()
-				.stream()
 				.findAny()
-				.ifPresent(n -> {
-					if (n.propagateSource(this).isContradiction())
+				.ifPresent(e -> {
+					if (setSource(e.getFirst(), 1/e.getSecond()).isOk()) {
+						propagateSource();
+					} else {
 						onPopBlock();
+					}
 				});
 	}
 
 	/**
 	 * Propagates this node's source and network to any connected nodes that aren't yet part of the same network, then
 	 * repeats this recursively with the connected nodes in a breadth-first order.
-	 * @param checkRoot Node to start searching from when looking for nodes that started speeding because of this call
-	 * @return			whether or not this propagation caused a contradiction in the kinetic network
 	 */
-	private SolveResult propagateSource(KineticNode checkRoot) {
+	private void propagateSource() {
 		List<KineticNode> frontier = new LinkedList<>();
 		frontier.add(this);
 
 		while (!frontier.isEmpty()) {
 			KineticNode cur = frontier.remove(0);
-			for (Map.Entry<KineticNode, Float> entry : cur.getActiveConnections().entrySet()) {
-				KineticNode next = entry.getKey();
-				float ratio = entry.getValue();
+			for (Pair<KineticNode, Float> pair : cur.getActiveConnectionsList()) {
+				KineticNode next = pair.getFirst();
+				float ratio = pair.getSecond();
 
 				if (next == cur.source) continue;
+
 				if (next.network == network) {
 					if (!Mth.equal(next.speedRatio, cur.speedRatio * ratio)) {
-						// we found a cycle with conflicting speed ratios
-						network.markConflictingCycle(cur, next);
+						// this node will cause a cycle with conflicting speed ratios
+						if (network.isStopped()) {
+							network.markConflictingCycle(cur, next);
+						} else {
+							onPopBlock();
+							return;
+						}
 					}
 					continue;
 				}
 
-				next.setSource(cur, ratio);
-				frontier.add(next);
+				if (next.setSource(cur, ratio).isOk()) {
+					frontier.add(next);
+				} else {
+					// this node will run against the network
+					onPopBlock();
+					return;
+				}
 			}
 		}
-
-		return network.recalculateSpeed(checkRoot, true);
 	}
 
 	public void onRemoved() {
 		network.removeMember(this);
-		for (KineticNode neighbor : getActiveConnections().keySet()) {
-			if (neighbor.source != this) continue;
-			neighbor.rerootHere();
-		}
-		network.recalculateSpeed(null, false);
+		getActiveConnections()
+				.map(Pair::getFirst)
+				.filter(n -> n.source == this)
+				.forEach(KineticNode::rerootHere);
 	}
 
 	private void rerootHere() {
 		source = null;
 		speedRatio = 1;
 		setNetwork(new KineticNetwork(this));
-		if (tryUpdateSpeed().isOk()) {
-			propagateSource(this);
-		} else {
-			onPopBlock();
-		}
+		propagateSource();
 	}
 
 	/**
@@ -182,5 +194,4 @@ public class KineticNode {
 	public boolean isSourceOf(KineticNode other) {
 		return other.source == this;
 	}
-
 }

src/main/java/com/simibubi/create/content/contraptions/solver/KineticSolver.java

@@ -1,8 +1,13 @@
 package com.simibubi.create.content.contraptions.solver;
 
 import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 import com.simibubi.create.content.contraptions.base.KineticTileEntity;
 import com.simibubi.create.foundation.utility.WorldAttached;
@@ -24,11 +29,7 @@ public class KineticSolver {
 		removeNode(entity);
 		KineticNode node = new KineticNode(entity, this::getNode);
 		nodes.put(entity.getBlockPos(), node);
-		if (node.tryUpdateSpeed().isOk()) {
-			node.onAdded();
-		} else {
-			node.onPopBlock();
-		}
+		node.onAdded();
 	}
 
 	public void updateNode(KineticTileEntity entity) {
@@ -54,7 +55,20 @@ public class KineticSolver {
 		if (node != null) node.onRemoved();
 	}
 
-	public void flushChangedSpeeds() {
-		nodes.values().forEach(KineticNode::flushChangedSpeed);
+	public void tick() {
+		Set<KineticNetwork> visited = new HashSet<>();
+		List<KineticNetwork> frontier = new LinkedList<>();
+
+		Set<KineticNetwork> networks = nodes.values().stream().map(KineticNode::getNetwork).collect(Collectors.toSet());
+		for (KineticNetwork network : networks) {
+			frontier.add(network);
+			while (!frontier.isEmpty()) {
+				KineticNetwork cur = frontier.remove(0);
+				if (visited.contains(cur)) continue;
+				visited.add(cur);
+				frontier.addAll(cur.tick());
+			}
+		}
 	}
+
 }

src/main/java/com/simibubi/create/events/CommonEvents.java

@@ -112,7 +112,7 @@ public class CommonEvents {
 		CouplingPhysics.tick(world);
 		LinkedControllerServerHandler.tick(world);
 
-		KineticSolver.getSolver(world).flushChangedSpeeds();
+		KineticSolver.getSolver(world).tick();
 	}
 
 	@SubscribeEvent