1 files changed, 53 insertions, 0 deletions
diff --git a/patches/server/0683-Optimize-indirect-passenger-iteration.patch b/patches/server/0683-Optimize-indirect-passenger-iteration.patch
new file mode 100644
index 0000000000..24b6d99483
--- /dev/null
+++ b/patches/server/0683-Optimize-indirect-passenger-iteration.patch
@@ -0,0 +1,53 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Andrew Steinborn <[email protected]>
+Date: Mon, 9 Aug 2021 00:38:37 -0400
+Subject: [PATCH] Optimize indirect passenger iteration
+
+
+diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
+index dafe29f3e2b4e7a51d4232c60fd27645e5f20335..517ee85a7425d89e4197887eb6b385bc64ecedd3 100644
+--- a/src/main/java/net/minecraft/world/entity/Entity.java
++++ b/src/main/java/net/minecraft/world/entity/Entity.java
+@@ -3661,20 +3661,34 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
+     }
+ 
+     private Stream<Entity> getIndirectPassengersStream() {
++        if (this.passengers.isEmpty()) { return Stream.of(); } // Paper
+         return this.passengers.stream().flatMap(Entity::getSelfAndPassengers);
+     }
+ 
+     @Override
+     public Stream<Entity> getSelfAndPassengers() {
++        if (this.passengers.isEmpty()) { return Stream.of(this); } // Paper
+         return Stream.concat(Stream.of(this), this.getIndirectPassengersStream());
+     }
+ 
+     @Override
+     public Stream<Entity> getPassengersAndSelf() {
++        if (this.passengers.isEmpty()) { return Stream.of(this); } // Paper
+         return Stream.concat(this.passengers.stream().flatMap(Entity::getPassengersAndSelf), Stream.of(this));
+     }
+ 
+     public Iterable<Entity> getIndirectPassengers() {
++        // Paper start - rewrite this method
++        if (this.passengers.isEmpty()) { return ImmutableList.of(); }
++        ImmutableList.Builder<Entity> indirectPassengers = ImmutableList.builder();
++        for (Entity passenger : this.passengers) {
++            indirectPassengers.add(passenger);
++            indirectPassengers.addAll(passenger.getIndirectPassengers());
++        }
++        return indirectPassengers.build();
++    }
++    private Iterable<Entity> getIndirectPassengers_old() {
++        // Paper end
+         return () -> {
+             return this.getIndirectPassengersStream().iterator();
+         };
+@@ -3691,6 +3705,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
+     // Paper end - rewrite chunk system
+ 
+     public boolean hasExactlyOnePlayerPassenger() {
++        if (this.passengers.isEmpty()) { return false; } // Paper
+         return this.getIndirectPassengersStream().filter((entity) -> {
+             return entity instanceof Player;
+         }).count() == 1L;