PaperMC/Spigot-Server-Patches/0079-Use-Optimized-Collections.patch
Spottedleaf 05d074d557 Optimize DataWatcher
The lock in DataWatcher is used to prevent concurrent modifications
to the 'd' field (entries in MCP). However any modifications to
this map only occur on initialization of an Entity in its
constructor. This modification is write-locked.

Every other access is through a readlock, which allows
the threads to pass if there is no thread holding the
writelock.

Since the writelock is only obtained in the constructor
of the Entity, the further readlocks are actually
useless (which get obtained on set, get, etc calls).

The entries field ('d' currently) has also been declared as
Int2ObjectOpenHashMap to avoid autoboxing on put(), get(), etc
calls.
2019-05-13 20:37:18 -07:00

38 lines
1.8 KiB
Diff

From b82a8f1e62534de6c4f4bfceeda56a580ca0eaa6 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 30 Mar 2016 02:13:24 -0400
Subject: [PATCH] Use Optimized Collections
Swap out CraftBukkit LongObjectHashMap with Long2ObjectOpenHashMap
Swap out Integer key HashMap for a Int2ObjectOpenHashMap For ChunkProviderServer
Amaranth, the creator of LongObjectHashMap, tested it vs fastutil and determined fastutil to be 3x faster
and could not create anything faster than fastutil.
These collections are super fast as seen
http://java-performance.info/hashmap-overview-jdk-fastutil-goldman-sachs-hppc-koloboke-trove-january-2015/
diff --git a/src/main/java/net/minecraft/server/DataWatcher.java b/src/main/java/net/minecraft/server/DataWatcher.java
index 79a240cd1d..f224043d8e 100644
--- a/src/main/java/net/minecraft/server/DataWatcher.java
+++ b/src/main/java/net/minecraft/server/DataWatcher.java
@@ -12,6 +12,7 @@ import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import javax.annotation.Nullable;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap; // Paper
import org.apache.commons.lang3.ObjectUtils;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
@@ -21,7 +22,7 @@ public class DataWatcher {
private static final Logger LOGGER = LogManager.getLogger();
private static final Map<Class<? extends Entity>, Integer> b = Maps.newHashMap();
private final Entity c;
- private final Map<Integer, DataWatcher.Item<?>> d = Maps.newHashMap();
+ private final Int2ObjectOpenHashMap<DataWatcher.Item<?>> d = new Int2ObjectOpenHashMap<>(); // Paper
private final ReadWriteLock e = new ReentrantReadWriteLock();
private boolean f = true;
private boolean g;
--
2.21.0