pool: use mover's UUID to track xroot client reconnects

Motivation:
there are no reasons to prefer the string form of UUID over the plain
object.

Modification:
Update reconnectTimers map to use UUID as a key.

Result:
simplification.

Acked-by: Lea Morschel
Target: master
Require-book: no
Require-notes: no

modules/dcache-xrootd/src/main/java/org/dcache/xrootd/pool/XrootdTransferService.java

@@ -160,7 +160,7 @@ public String call() throws Exception {
     private ServerProtocolFlags serverProtocolFlags;
     private long tpcServerResponseTimeout;
     private TimeUnit tpcServerResponseTimeoutUnit;
-    private Map<String, Timer> reconnectTimers;
+    private Map<UUID, Timer> reconnectTimers;
     private long readReconnectTimeout;
     private TimeUnit readReconnectTimeoutUnit;
     private int tpcClientChunkSize;
@@ -207,7 +207,7 @@ public void setAccessLogPlugins(List<ChannelHandlerFactory> plugins) {
      * @param uuid of the mover (channel)
      */
     public synchronized void cancelReconnectTimeoutForMover(UUID uuid) {
-        Timer timer = reconnectTimers.remove(uuid.toString());
+        Timer timer = reconnectTimers.remove(uuid);
         if (timer != null) {
             timer.cancel();
             LOGGER.debug("cancelReconnectTimeoutForMover, timer cancelled for {}.", uuid);
@@ -240,7 +240,7 @@ public void run() {
                           key);
                 }
             };
-            reconnectTimers.put(key.toString(), timer);
+            reconnectTimers.put(key, timer);
             timer.schedule(task, readReconnectTimeoutUnit.toMillis(readReconnectTimeout));
         } else {
             LOGGER.debug("setReconnectTimeoutForMover for {}; " +
@@ -506,6 +506,6 @@ private void handleUploadDone(NettyMover<XrootdProtocolInfo> mover) throws Cache
     }
 
     private synchronized void removeReadReconnectTimer(UUID key) {
-        reconnectTimers.remove(key.toString());
+        reconnectTimers.remove(key);
     }
 }