From b2d1562595d5adc68d9cfad4e92387b448635816 Mon Sep 17 00:00:00 2001
From: sk89q <the.sk89q@gmail.com>
Date: Mon, 31 Mar 2014 18:43:47 -0700
Subject: [PATCH] Implemented last-access-caching for getLazyBlock().

---
 .../java/com/sk89q/worldedit/EditSession.java |  3 +-
 .../extent/LastAccessExtentCache.java         | 66 +++++++++++++++++++
 2 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/com/sk89q/worldedit/extent/LastAccessExtentCache.java

diff --git a/src/main/java/com/sk89q/worldedit/EditSession.java b/src/main/java/com/sk89q/worldedit/EditSession.java
index de74e7608..249d55d7c 100644
--- a/src/main/java/com/sk89q/worldedit/EditSession.java
+++ b/src/main/java/com/sk89q/worldedit/EditSession.java
@@ -129,7 +129,8 @@ public class EditSession implements Extent {
         // This extents are ALWAYS used
         fastModeExtent                          = new FastModeExtent(world, false);
         ChunkLoadingExtent chunkLoadingExtent   = new ChunkLoadingExtent(fastModeExtent, world);
-        BlockQuirkExtent quirkExtent            = new BlockQuirkExtent(chunkLoadingExtent, world);
+        LastAccessExtentCache cacheExtent       = new LastAccessExtentCache(chunkLoadingExtent);
+        BlockQuirkExtent quirkExtent            = new BlockQuirkExtent(cacheExtent, world);
         DataValidatorExtent validator           = new DataValidatorExtent(quirkExtent, world);
         blockBagExtent                          = new BlockBagExtent(validator, world, blockBag);
 
diff --git a/src/main/java/com/sk89q/worldedit/extent/LastAccessExtentCache.java b/src/main/java/com/sk89q/worldedit/extent/LastAccessExtentCache.java
new file mode 100644
index 000000000..d7277cb0d
--- /dev/null
+++ b/src/main/java/com/sk89q/worldedit/extent/LastAccessExtentCache.java
@@ -0,0 +1,66 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.extent;
+
+import com.sk89q.worldedit.BlockVector;
+import com.sk89q.worldedit.Vector;
+import com.sk89q.worldedit.blocks.BaseBlock;
+
+/**
+ * Returns the same cached {@link BaseBlock} for repeated calls to
+ * {@link #getLazyBlock(Vector)} with the same position.
+ */
+public class LastAccessExtentCache extends ExtentDelegate {
+
+    private CachedBlock lastBlock;
+
+    /**
+     * Create a new instance.
+     *
+     * @param extent the extent
+     */
+    public LastAccessExtentCache(Extent extent) {
+        super(extent);
+    }
+
+    @Override
+    public BaseBlock getLazyBlock(Vector position) {
+        BlockVector blockVector = position.toBlockVector();
+        CachedBlock lastBlock = this.lastBlock;
+        if (lastBlock != null && lastBlock.position.equals(blockVector)) {
+            return lastBlock.block;
+        } else {
+            BaseBlock block = super.getLazyBlock(position);
+            this.lastBlock = new CachedBlock(blockVector, block);
+            return block;
+        }
+    }
+
+    private static class CachedBlock {
+        private final BlockVector position;
+        private final BaseBlock block;
+
+        private CachedBlock(BlockVector position, BaseBlock block) {
+            this.position = position;
+            this.block = block;
+        }
+    }
+
+}