Paper/Spigot-Server-Patches/0390-Elide-lock-in-DataWatcher.patch
Spottedleaf 5c7081fecc Update upstream & fix some chunk related issues (#2177)
* Updated Upstream (Bukkit/CraftBukkit)

Upstream has released updates that appears to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing

Bukkit Changes:
45690fe9 SPIGOT-5047: Correct slot types for 1.14 inventories

CraftBukkit Changes:
4090d01f SPIGOT-5047: Correct slot types for 1.14 inventories
e8c08362 SPIGOT-5046: World#getLoadedChunks returning inaccessible cached chunks.
d445af3b SPIGOT-5067: Add item meta for 1.14 spawn eggs

* Bring Chunk load checks in-line with spigot

As of the last upstream merge spigot now checks ticket level status
when returning loaded chunks for a world from api. Now our checks
will respect that decision.

* Fix spawn ticket levels

Vanilla would keep the inner chunks of spawn available for ticking,
however my changes made all chunks non-ticking. Resolve by changing
ticket levels for spawn chunks inside the border to respect this
behavior.


* Make World#getChunkIfLoadedImmediately return only entity ticking chunks

Mojang appears to be using chunks with level > 33 (non-ticking chunks)
as cached chunks and not actually loaded chunks.

* Bring all loaded checks in line with spigot

Loaded chunks must be at least border  chunks, or level <= 33
2019-06-14 03:27:40 +01:00

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Diff

From 51fd7997bca218ef386063113130b7108f779682 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sat, 11 May 2019 08:19:27 -0700
Subject: [PATCH] Elide lock in 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).
diff --git a/src/main/java/net/minecraft/server/DataWatcher.java b/src/main/java/net/minecraft/server/DataWatcher.java
index f224043d8e..bbea8ef726 100644
--- a/src/main/java/net/minecraft/server/DataWatcher.java
+++ b/src/main/java/net/minecraft/server/DataWatcher.java
@@ -23,7 +23,7 @@ public class DataWatcher {
private static final Map<Class<? extends Entity>, Integer> b = Maps.newHashMap();
private final Entity c;
private final Int2ObjectOpenHashMap<DataWatcher.Item<?>> d = new Int2ObjectOpenHashMap<>(); // Paper
- private final ReadWriteLock e = new ReentrantReadWriteLock();
+ //private final ReadWriteLock e = new ReentrantReadWriteLock(); // Paper - not required
private boolean f = true;
private boolean g;
@@ -88,30 +88,14 @@ public class DataWatcher {
private <T> void registerObject(DataWatcherObject<T> datawatcherobject, T t0) {
DataWatcher.Item<T> datawatcher_item = new DataWatcher.Item<>(datawatcherobject, t0);
- this.e.writeLock().lock();
+ //this.e.writeLock().lock(); // Paper - not required
this.d.put(datawatcherobject.a(), datawatcher_item);
this.f = false;
- this.e.writeLock().unlock();
+ //this.e.writeLock().unlock(); // Paper - not required
}
private <T> DataWatcher.Item<T> b(DataWatcherObject<T> datawatcherobject) {
- this.e.readLock().lock();
-
- DataWatcher.Item datawatcher_item;
-
- try {
- datawatcher_item = (DataWatcher.Item) this.d.get(datawatcherobject.a());
- } catch (Throwable throwable) {
- CrashReport crashreport = CrashReport.a(throwable, "Getting synched entity data");
- CrashReportSystemDetails crashreportsystemdetails = crashreport.a("Synched entity data");
-
- crashreportsystemdetails.a("Data ID", (Object) datawatcherobject);
- throw new ReportedException(crashreport);
- } finally {
- this.e.readLock().unlock();
- }
-
- return datawatcher_item;
+ return (DataWatcher.Item<T>)this.d.get(datawatcherobject.a()); // Paper - avoid lock and try catch, get() does not fail
}
public <T> T get(DataWatcherObject<T> datawatcherobject) {
@@ -158,7 +142,7 @@ public class DataWatcher {
List<DataWatcher.Item<?>> list = null;
if (this.g) {
- this.e.readLock().lock();
+ //this.e.readLock().lock(); // Paper - not required
Iterator iterator = this.d.values().iterator();
while (iterator.hasNext()) {
@@ -174,7 +158,7 @@ public class DataWatcher {
}
}
- this.e.readLock().unlock();
+ //this.e.readLock().unlock(); // Paper - not required
}
this.g = false;
@@ -182,7 +166,7 @@ public class DataWatcher {
}
public void a(PacketDataSerializer packetdataserializer) throws IOException {
- this.e.readLock().lock();
+ //this.e.readLock().lock(); // Paper - not required
Iterator iterator = this.d.values().iterator();
while (iterator.hasNext()) {
@@ -191,7 +175,7 @@ public class DataWatcher {
a(packetdataserializer, datawatcher_item);
}
- this.e.readLock().unlock();
+ //this.e.readLock().unlock(); // Paper - not required
packetdataserializer.writeByte(255);
}
@@ -199,7 +183,7 @@ public class DataWatcher {
public List<DataWatcher.Item<?>> c() {
List<DataWatcher.Item<?>> list = null;
- this.e.readLock().lock();
+ //this.e.readLock().lock(); // Paper - not required
DataWatcher.Item datawatcher_item;
@@ -210,7 +194,7 @@ public class DataWatcher {
}
}
- this.e.readLock().unlock();
+ //this.e.readLock().unlock(); // Paper - not required
return list;
}
@@ -261,7 +245,7 @@ public class DataWatcher {
public void e() {
this.g = false;
- this.e.readLock().lock();
+ //this.e.readLock().lock(); // Paper - not required
Iterator iterator = this.d.values().iterator();
while (iterator.hasNext()) {
@@ -270,7 +254,7 @@ public class DataWatcher {
datawatcher_item.a(false);
}
- this.e.readLock().unlock();
+ //this.e.readLock().unlock(); // Paper - not required
}
public static class Item<T> {
--
2.21.0