Improve scaling of memory use with large numbers of tiles, prep for suspend/resume support

src/main/java/org/dynmap/utils/TileFlags.java

@@ -0,0 +1,66 @@
+package org.dynmap.utils;
+
+import java.util.HashMap;
+/**
+ * scalable flags primitive - used for keeping track of potentially huge number of tiles
+ * 
+ * Represents a flag for each tile, with 2D coordinates based on 0,0 origin.  Flags are grouped
+ * 64 x 64, represented by an array of 64 longs.  Each set is stored in a hashmap, keyed by a long
+ * computed by ((x/64)<<32)+(y/64).
+ * 
+ */
+public class TileFlags {
+	private HashMap<Long, long[]> chunkmap = new HashMap<Long, long[]>(); 
+	private long last_key = Long.MIN_VALUE;
+	private long[] last_row;
+	
+	public TileFlags() {
+	}
+	
+	public boolean getFlag(int x, int y) {
+		long k = (((long)(x >> 6)) << 32) | (0xFFFFFFFFL & (long)(y >> 6));
+		long[] row;
+		if(k == last_key) {
+			row = last_row;
+		}
+		else {
+			row = chunkmap.get(k);
+			last_key = k;
+			last_row = row;
+		}
+		if(row == null)
+			return false;
+		else
+			return (row[y & 0x3F] & (1L << (x & 0x3F))) != 0;
+	}
+	
+	public void setFlag(int x, int y, boolean f) {
+		long k = (((long)(x >> 6)) << 32) | (0xFFFFFFFFL & (long)(y >> 6));
+		long[] row;
+		if(k == last_key) {
+			row = last_row;
+		}
+		else {
+			row = chunkmap.get(k);
+			last_key = k;
+			last_row = row;
+		}
+		if(f) {
+			if(row == null) {
+				row = new long[64];
+				chunkmap.put(k, row);
+				last_row = row;
+			}
+			row[y & 0x3F] |= (1L << (x & 0x3F));
+		}
+		else {
+			if(row != null)
+				row[y & 0x3F] &= ~(1L << (x & 0x3F));
+		}
+	}
+	public void clear() {
+		chunkmap.clear();
+		last_row = null;
+		last_key = Long.MIN_VALUE;
+	}
+}