From 6e49834ea2f19d8731df052ac9de3f2a04b8abe9 Mon Sep 17 00:00:00 2001 From: egg82 Date: Tue, 7 Aug 2018 01:24:23 -0600 Subject: [PATCH] Use ConcurrentHashMap in JsonList This is specifically aimed at fixing #471 Using a ConcurrentHashMap because thread safety The performance benefit of Map over ConcurrentMap is negligabe at best in this scenaio, as most operations will be get and not add or remove Even without considering the use-case the benefits are still negligable Original ideas for the system included an expiration policy and/or handler The simpler solution was to use a computeIfPresent in the get method This will simultaneously have an O(1) lookup time and automatically expire any values Since the get method (nor other similar methods) don't seem to have a critical need to flush the map to disk at any of these points further processing is simply wasteful Meaning the original function expired values unrelated to the current value without actually having any explicit need to The h method was heavily modified to be much more efficient in its processing Also instead of being called on every get, it's now called just before a save This will eliminate stale values being flushed to disk Modified isEmpty to use the isEmpty() method instead of the slightly confusing size() < 1 The point of this is readability, but does have a side-benefit of a small microptimization Finally, added a couple obfhelpers for the modified code diff --git a/src/main/java/net/minecraft/server/JsonList.java b/src/main/java/net/minecraft/server/JsonList.java index 026ef7939..b7cde4d41 100644 --- a/src/main/java/net/minecraft/server/JsonList.java +++ b/src/main/java/net/minecraft/server/JsonList.java @@ -35,7 +35,8 @@ public class JsonList> { protected static final Logger a = LogManager.getLogger(); protected final Gson b; private final File c; - private final Map d = Maps.newHashMap(); + // Paper - replace HashMap is ConcurrentHashMap + private final Map d = Maps.newConcurrentMap(); private final Map getBackingMap() { return this.d; } // Paper - OBFHELPER private boolean e = true; private static final ParameterizedType f = new ParameterizedType() { public Type[] getActualTypeArguments() { @@ -84,8 +85,13 @@ public class JsonList> { @Nullable public V get(K k0) { - this.h(); - return (V) this.d.get(this.a(k0)); // CraftBukkit - fix decompile error + // Paper start + // this.h(); + // return (V) this.d.get(this.a(k0)); // CraftBukkit - fix decompile error + return (V) this.getBackingMap().computeIfPresent(this.getMappingKey(k0), (k, v) -> { + return v.hasExpired() ? null : v; + }); + // Paper end } public void remove(K k0) { @@ -114,9 +120,11 @@ public class JsonList> { // CraftBukkit end public boolean isEmpty() { - return this.d.size() < 1; + // return this.d.size() < 1; // Paper + return this.getBackingMap().isEmpty(); // Paper - readability is the goal. As an aside, isEmpty() uses only sumCount() and a comparison. size() uses sumCount(), casts, and boolean logic } + protected final String getMappingKey(K k0) { return a(k0); } // Paper - OBFHELPER protected String a(K k0) { return k0.toString(); } @@ -125,8 +133,9 @@ public class JsonList> { return this.d.containsKey(this.a(k0)); } + private void removeStaleEntries() { h(); } // Paper - OBFHELPER private void h() { - List list = Lists.newArrayList(); + /*List list = Lists.newArrayList(); Iterator iterator = this.d.values().iterator(); while (iterator.hasNext()) { @@ -143,8 +152,10 @@ public class JsonList> { K k0 = (K) iterator.next(); // CraftBukkit - decompile error this.d.remove(this.a(k0)); - } + }*/ + this.getBackingMap().values().removeIf(JsonListEntry::hasExpired); + // Paper end } protected JsonListEntry a(JsonObject jsonobject) { @@ -156,6 +167,7 @@ public class JsonList> { } public void save() throws IOException { + this.removeStaleEntries(); // Paper - remove expired values before saving Collection collection = this.d.values(); String s = this.b.toJson(collection); BufferedWriter bufferedwriter = null; -- 2.20.1