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Small optimization to prevent blocking netty threads on UUID.randomUUID() #1781

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Small optimization to prevent blocking netty threads on UUID.randomUUID() #1781

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2ff73b5
Small optimization to prevent blocking netty threads on UUID.randomUU…
Beaness Apr 24, 2026
c94104b
Change FastRandomUuid to be a valid uuid v4
Beaness Apr 24, 2026
4542043
Update javadoc for spotless
Beaness Apr 24, 2026
794b52e
Migrate method to VelocityTabListLegacy and add notice that it is ins…
Beaness Apr 24, 2026
c04928c
Bring back deleted override
Beaness May 24, 2026
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16 changes: 15 additions & 1 deletion proxy/src/main/java/com/velocitypowered/proxy/tablist/VelocityTabListLegacy.java
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
import java.util.Optional;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ThreadLocalRandom;
import net.kyori.adventure.text.Component;
import org.checkerframework.checker.nullness.qual.Nullable;

Expand Down Expand Up @@ -95,7 +96,7 @@ public void processLegacy(LegacyPlayerListItemPacket packet) {
entry.setLatencyInternal(item.getLatency());
}
} else {
UUID uuid = UUID.randomUUID(); // Use a fake uuid to preserve function of custom entries
UUID uuid = generateInsecureRandomUuid(); // Use a fake uuid to preserve function of custom entries
nameMapping.put(item.getName(), uuid);
entries.put(uuid, (KeyedVelocityTabListEntry) TabListEntry.builder()
.tabList(this)
Expand Down Expand Up @@ -153,4 +154,17 @@ public TabListEntry buildEntry(GameProfile profile, @Nullable Component displayN
int gameMode, @Nullable ChatSession chatSession, boolean listed, int listOrder, boolean showHat) {
return new VelocityTabListEntryLegacy(this, profile, displayName, latency, gameMode);
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}

/**
* Generates a random UUID v4 using {@link ThreadLocalRandom}. The result is a structurally valid
* UUID v4 but is not cryptographically secure
*
* @return a new random {@link UUID}
*/
private static UUID generateInsecureRandomUuid() {
ThreadLocalRandom random = ThreadLocalRandom.current();
long msb = (random.nextLong() & 0xffffffffffff0fffL) | 0x0000000000004000L; // version 4
long lsb = (random.nextLong() & 0x3fffffffffffffffL) | 0x8000000000000000L; // IETF variant
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return new UUID(msb, lsb);
}
}