Initial commit: RegionIO Minecraft server core (26.1.2/protocol 775)

Vanilla-faithful overworld generator (final_density + multi-noise biomes),
full connection lifecycle (status/login/configuration/play), chunk streaming,
creative block editing, and the protocol/nbt/registry infrastructure.

internal/world/bench_test.go

@@ -0,0 +1,79 @@
+package world
+
+import (
+	"bytes"
+	"compress/zlib"
+	"testing"
+)
+
+func BenchmarkGenerateFlat(b *testing.B) {
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = GenerateFlat(int32(i), 0)
+	}
+}
+
+func BenchmarkEncode(b *testing.B) {
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = GenerateFlat(int32(i), 0).Encode()
+	}
+}
+
+func BenchmarkEncodeAndCompress(b *testing.B) {
+	b.ReportAllocs()
+	var buf bytes.Buffer
+	for i := 0; i < b.N; i++ {
+		body := GenerateFlat(int32(i), 0).Encode()
+		buf.Reset()
+		zw := zlib.NewWriter(&buf)
+		zw.Write(body)
+		zw.Close()
+	}
+}
+
+// One join currently sends a (2*radius+1)^2 grid; benchmark that batch.
+func BenchmarkJoinChunkBatch(b *testing.B) {
+	const radius = 4
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		for cx := int32(-radius); cx <= radius; cx++ {
+			for cz := int32(-radius); cz <= radius; cz++ {
+				_ = GenerateFlat(cx, cz).Encode()
+			}
+		}
+	}
+}
+
+func BenchmarkCacheWarmJoin(b *testing.B) {
+	const radius = 4
+	c := NewCache(256, GenerateFlat)
+	// Warm the cache once (cold join).
+	for cx := int32(-radius); cx <= radius; cx++ {
+		for cz := int32(-radius); cz <= radius; cz++ {
+			c.Frame(cx, cz)
+		}
+	}
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		for cx := int32(-radius); cx <= radius; cx++ {
+			for cz := int32(-radius); cz <= radius; cz++ {
+				_ = c.Frame(cx, cz) // all hits
+			}
+		}
+	}
+}
+
+func BenchmarkCacheColdJoin(b *testing.B) {
+	const radius = 4
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		c := NewCache(256, GenerateFlat) // fresh cache each iter = all misses
+		for cx := int32(-radius); cx <= radius; cx++ {
+			for cz := int32(-radius); cz <= radius; cz++ {
+				_ = c.Frame(cx, cz)
+			}
+		}
+	}
+}