Paper/patches/server/0385-Thread-Safe-Vanilla-Command-permission-checking.patch
Bjarne Koll c5a10665b8
Remove wall-time / unused skip tick protection (#11412)
Spigot still maintains some partial implementation of "tick skipping", a
practice in which the MinecraftServer.currentTick field is updated not
by an increment of one per actual tick, but instead set to
System.currentTimeMillis() / 50. This behaviour means that the tracked
tick may "skip" a tick value in case a previous tick took more than the
expected 50ms.

To compensate for this in important paths, spigot/craftbukkit
implements "wall-time". Instead of incrementing/decrementing ticks on
block entities/entities by one for each call to their tick() method,
they instead increment/decrement important values, like
an ItemEntity's age or pickupDelay, by the difference of
`currentTick - lastTick`, where `lastTick` is the value of
`currentTick` during the last tick() call.

These "fixes" however do not play nicely with minecraft's simulation
distance as entities/block entities implementing the above behaviour
would "catch up" their values when moving from a non-ticking chunk to a
ticking one as their `lastTick` value remains stuck on the last tick in
a ticking chunk and hence lead to a large "catch up" once ticked again.

Paper completely removes the "tick skipping" behaviour (See patch
"Further-improve-server-tick-loop"), making the above precautions
completely unnecessary, which also rids paper of the previous described
incompatibility with non-ticking chunks.
2024-09-19 16:36:07 +02:00

54 lines
3.3 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 11 Jul 2020 03:54:28 -0400
Subject: [PATCH] Thread Safe Vanilla Command permission checking
Datapacks check this on load and are built concurrently. This was breaking them badly due
to race conditions.
Plus, .canUse we want to be safe for async anyways.
diff --git a/src/main/java/com/mojang/brigadier/tree/CommandNode.java b/src/main/java/com/mojang/brigadier/tree/CommandNode.java
index 14ccd0c8f721e9be7dca8a5dcb8ef95b5cd82731..1f4963bf4681a771130abc1da179819626ecfc1f 100644
--- a/src/main/java/com/mojang/brigadier/tree/CommandNode.java
+++ b/src/main/java/com/mojang/brigadier/tree/CommandNode.java
@@ -75,10 +75,10 @@ public abstract class CommandNode<S> implements Comparable<CommandNode<S>> {
public synchronized boolean canUse(final S source) {
if (source instanceof CommandSourceStack) {
try {
- ((CommandSourceStack) source).currentCommand = this;
+ ((CommandSourceStack) source).currentCommand.put(Thread.currentThread(), this); // Paper - Thread Safe Vanilla Command permission checking
return this.requirement.test(source);
} finally {
- ((CommandSourceStack) source).currentCommand = null;
+ ((CommandSourceStack) source).currentCommand.remove(Thread.currentThread()); // Paper - Thread Safe Vanilla Command permission checking
}
}
// CraftBukkit end
diff --git a/src/main/java/net/minecraft/commands/CommandSourceStack.java b/src/main/java/net/minecraft/commands/CommandSourceStack.java
index 2a22827f44dd0d524c22264447959a6979e9f0de..f3c83bb20a73b489f1fb6bacb69388902b1b6fe7 100644
--- a/src/main/java/net/minecraft/commands/CommandSourceStack.java
+++ b/src/main/java/net/minecraft/commands/CommandSourceStack.java
@@ -64,7 +64,7 @@ public class CommandSourceStack implements ExecutionCommandSource<CommandSourceS
private final Vec2 rotation;
private final CommandSigningContext signingContext;
private final TaskChainer chatMessageChainer;
- public volatile CommandNode currentCommand; // CraftBukkit
+ public java.util.Map<Thread, CommandNode> currentCommand = new java.util.concurrent.ConcurrentHashMap<>(); // CraftBukkit // Paper - Thread Safe Vanilla Command permission checking
public boolean bypassSelectorPermissions = false; // Paper - add bypass for selector permissions
public CommandSourceStack(CommandSource output, Vec3 pos, Vec2 rot, ServerLevel world, int level, String name, Component displayName, MinecraftServer server, @Nullable Entity entity) {
@@ -193,9 +193,11 @@ public class CommandSourceStack implements ExecutionCommandSource<CommandSourceS
@Override
public boolean hasPermission(int level) {
// CraftBukkit start
- CommandNode currentCommand = this.currentCommand;
+ // Paper start - Thread Safe Vanilla Command permission checking
+ CommandNode currentCommand = this.currentCommand.get(Thread.currentThread());
if (currentCommand != null) {
return this.hasPermission(level, org.bukkit.craftbukkit.command.VanillaCommandWrapper.getPermission(currentCommand));
+ // Paper end - Thread Safe Vanilla Command permission checking
}
// CraftBukkit end