Add construct() methods to specify the milliseconds being used for time-based UUID generation (#84)

Author: BranchPredictor

src/main/java/com/fasterxml/uuid/impl/TimeBasedEpochGenerator.java

@@ -97,13 +97,22 @@ public TimeBasedEpochGenerator(Random rnd, UUIDClock clock)
     /* UUID generation
     /**********************************************************************
      */
-    
+
     @Override
     public UUID generate()
+    {
+        return construct(_clock.currentTimeMillis());
+    }
+
+    /**
+     * @since 4.3
+     * @param rawTimestamp unix epoch millis
+     * @return unix epoch time based UUID
+     */
+    public UUID construct(long rawTimestamp)
     {
         lock.lock();
         try { 
-            long rawTimestamp = _clock.currentTimeMillis();
             if (rawTimestamp == _lastTimestamp) {
                 boolean c = true;
                 for (int i = ENTROPY_BYTE_LENGTH - 1; i >= 0; i--) {

src/main/java/com/fasterxml/uuid/impl/TimeBasedGenerator.java

@@ -90,6 +90,16 @@ public TimeBasedGenerator(EthernetAddress ethAddr, UUIDTimer timer)
     public UUID generate()
     {
         final long rawTimestamp = _timer.getTimestamp();
+        return construct(rawTimestamp);
+    }
+
+    /**
+     * @since 4.3
+     * @param rawTimestamp unix epoch millis
+     * @return unix epoch time based UUID
+     */
+    public UUID construct(long rawTimestamp)
+    {
         // Time field components are kind of shuffled, need to slice:
         int clockHi = (int) (rawTimestamp >>> 32);
         int clockLo = (int) rawTimestamp;

src/main/java/com/fasterxml/uuid/impl/TimeBasedReorderedGenerator.java

@@ -96,7 +96,16 @@ public UUID generate()
     {
         // Ok, get 60-bit timestamp (4 MSB are ignored)
         final long rawTimestamp = _timer.getTimestamp();
+        return construct(rawTimestamp);
+    }
 
+    /**
+     * @since 4.3
+     * @param rawTimestamp unix epoch millis
+     * @return unix epoch time based UUID
+     */
+    public UUID construct(long rawTimestamp)
+    {
         // First: discard 4 MSB, next 32 bits (top of 60-bit timestamp) form the
         // highest 32-bit segments
         final long timestampHigh = (rawTimestamp >>> 28) << 32;