From 8caf3de634984cbc5c7ac5e25f368877321a334e Mon Sep 17 00:00:00 2001
From: Kenneth Endfinger <kaendfinger@gmail.com>
Date: Sat, 8 Jan 2022 15:04:16 -0500
Subject: [PATCH] Gjallarhorn: Implement block state global cache.

This reduces memory usage by reusing block state objects.
---
 .../foundation/gjallarhorn/state/BlockChangelog.kt    |  4 ++--
 .../foundation/gjallarhorn/state/BlockState.kt        | 11 +++++++----
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/tool-gjallarhorn/src/main/kotlin/cloud/kubelet/foundation/gjallarhorn/state/BlockChangelog.kt b/tool-gjallarhorn/src/main/kotlin/cloud/kubelet/foundation/gjallarhorn/state/BlockChangelog.kt
index d076991..3f9d259 100644
--- a/tool-gjallarhorn/src/main/kotlin/cloud/kubelet/foundation/gjallarhorn/state/BlockChangelog.kt
+++ b/tool-gjallarhorn/src/main/kotlin/cloud/kubelet/foundation/gjallarhorn/state/BlockChangelog.kt
@@ -29,7 +29,7 @@ class BlockChangelog(
         val location = BlockCoordinate(x.toLong(), y.toLong(), z.toLong())
 
         val fromBlock = if (changeIsBreak) {
-          BlockState(block)
+          BlockState.cached(block)
         } else {
           BlockState.AirBlock
         }
@@ -37,7 +37,7 @@ class BlockChangelog(
         val toBlock = if (changeIsBreak) {
           BlockState.AirBlock
         } else {
-          BlockState(block)
+          BlockState.cached(block)
         }
 
         BlockChange(
diff --git a/tool-gjallarhorn/src/main/kotlin/cloud/kubelet/foundation/gjallarhorn/state/BlockState.kt b/tool-gjallarhorn/src/main/kotlin/cloud/kubelet/foundation/gjallarhorn/state/BlockState.kt
index 48ff7b2..78a20e0 100644
--- a/tool-gjallarhorn/src/main/kotlin/cloud/kubelet/foundation/gjallarhorn/state/BlockState.kt
+++ b/tool-gjallarhorn/src/main/kotlin/cloud/kubelet/foundation/gjallarhorn/state/BlockState.kt
@@ -1,10 +1,13 @@
 package cloud.kubelet.foundation.gjallarhorn.state
 
-import kotlinx.serialization.Serializable
+import java.util.concurrent.ConcurrentHashMap
 
-@Serializable
-data class BlockState(val type: String) {
+class BlockState(val type: String) {
   companion object {
-    val AirBlock = BlockState("minecraft:air")
+    private val cache = ConcurrentHashMap<String, BlockState>()
+
+    val AirBlock: BlockState = cached("minecraft:air")
+
+    fun cached(type: String): BlockState = cache.computeIfAbsent(type) { BlockState(type) }
   }
 }