minor code cleanup

sample/Benchmark.java

@@ -21,8 +21,8 @@ public class Benchmark {
     public static void main(String[] args) throws IOException, InvalidDatabaseException {
         File file = new File(args.length > 0 ? args[0] : "GeoLite2-City.mmdb");
         System.out.println("No caching");
-        loop("Warming up", file, WARMUPS, new NoCache());
-        loop("Benchmarking", file, BENCHMARKS, new NoCache());
+        loop("Warming up", file, WARMUPS, NoCache.getInstance());
+        loop("Benchmarking", file, BENCHMARKS, NoCache.getInstance());
 
         System.out.println("With caching");
         loop("Warming up", file, WARMUPS, new CHMCache());

src/main/java/com/maxmind/db/NoCache.java

@@ -5,13 +5,22 @@
 import com.fasterxml.jackson.databind.JsonNode;
 
 /**
- * A no-op cache.
+ * A no-op cache singleton.
  */
 public class NoCache implements NodeCache {
 
+    private static final NoCache INSTANCE = new NoCache();
+
+    private NoCache() {
+    }
+
     @Override
     public JsonNode get(int key, Loader loader) throws IOException {
         return loader.load(key);
     }
 
+    public static NoCache getInstance() {
+        return INSTANCE;
+    }
+
 }

src/main/java/com/maxmind/db/Reader.java

@@ -20,8 +20,6 @@ public final class Reader implements Closeable {
             (byte) 0xCD, (byte) 0xEF, 'M', 'a', 'x', 'M', 'i', 'n', 'd', '.',
             'c', 'o', 'm'};
 
-    private static final NodeCache NO_CACHE = new NoCache();
-
     private final int ipV4Start;
     private final Metadata metadata;
     private final AtomicReference<BufferHolder> bufferHolderReference;
@@ -52,7 +50,7 @@ public enum FileMode {
      * @throws IOException if there is an error opening or reading from the file.
      */
     public Reader(File database) throws IOException {
-        this(database, NO_CACHE);
+        this(database, NoCache.getInstance());
     }
 
     /**
@@ -76,7 +74,7 @@ public Reader(File database, NodeCache cache) throws IOException {
      * @throws IOException if there is an error reading from the Stream.
      */
     public Reader(InputStream source) throws IOException {
-        this(source, NO_CACHE);
+        this(source, NoCache.getInstance());
     }
 
     /**
@@ -101,7 +99,7 @@ public Reader(InputStream source, NodeCache cache) throws IOException {
      * @throws IOException if there is an error opening or reading from the file.
      */
     public Reader(File database, FileMode fileMode) throws IOException {
-        this(database, fileMode, NO_CACHE);
+        this(database, fileMode, NoCache.getInstance());
     }
 
     /**

src/test/java/com/maxmind/db/PointerTest.java

@@ -17,7 +17,7 @@ public class PointerTest {
     public void testWithPointers() throws IOException {
         File file = ReaderTest.getFile("maps-with-pointers.raw");
         BufferHolder ptf = new BufferHolder(file, FileMode.MEMORY);
-        Decoder decoder = new Decoder(new NoCache(), ptf.get(), 0);
+        Decoder decoder = new Decoder(NoCache.getInstance(), ptf.get(), 0);
 
         ObjectMapper om = new ObjectMapper();