Fixing master

akka-actor/src/main/java/se/scalablesolutions/akka/util/UUID.java

@@ -0,0 +1,59 @@
+/**
+ * Copyright (C) 2009-2010 Scalable Solutions AB <http://scalablesolutions.se>
+ */
+package se.scalablesolutions.akka.util;
+
+/**
+ * NOTE:
+ * <p/>
+ * This code is based on code from the [Plasmid Replication Engine] project.
+ * <br/>
+ * Licensed under [Mozilla Public License 1.0 (MPL)].
+ * <p/>
+ * Original JavaDoc:
+ * <p/>
+ * Our distributed objects are generally named most efficiently (and cleanly)
+ * by their UUID's. This class provides some static helpers for using UUID's.
+ * If it was efficient to do in Java, I would make the uuid an normal class
+ * and use instances of it. However, in current JVM's, we would end up using an
+ * Object to represent a long, which is pretty expensive. Maybe someday. ###
+ * <p/>
+ * UUID format: currently using currentTimeMillis() for the low bits. This uses
+ * about 40 bits for the next 1000 years, leaving 24 bits for debugging
+ * and consistency data. I'm using 8 of those for a magic asci 'U' byte.
+ * <p/>
+ * Future: use one instance of Uuid per type of object for better performance
+ * and more detailed info (instance could be matched to its uuid's via a map or
+ * array). This all static version bites.###
+ */
+public final class UUID {
+
+    public static final long UUID_NONE = 0;
+    public static final long UUID_WILD = -1;
+    public static final long UUID_MAGICMASK = 0xff << 56;
+    public static final long UUID_MAGIC = 'U' << 56;
+
+    protected static long lastTime;
+
+    /**
+     * Generate and return a new Universally Unique ID.
+     * Happens to be monotonically increasing.
+     */
+    public synchronized static long newUuid() {
+        long time = System.currentTimeMillis();
+
+        if (time <= lastTime) {
+            time = lastTime + 1;
+        }
+        lastTime = time;
+        return UUID_MAGIC | time;
+    }
+
+    /**
+     * Returns true if uuid could have been generated by Uuid.
+     */
+    public static boolean isValid(final long uuid) {
+        return (uuid & UUID_MAGICMASK) == UUID_MAGIC
+               && (uuid & ~UUID_MAGICMASK) != 0;
+    }
+}