+ /*
+ * This looks ugly and unusual and there is a reason for that, as the locking involved is in multiple places.
+ *
+ * We need to make sure that a new proxy is not created while we are reconnecting, which is partially satisfied
+ * by client.getConnection() throwing InversibleLockException by the time this method is invoked. That does
+ * not cover the case when createHistoryProxy() has already acquired the connection, but has not yet populated
+ * the history map.
+ *
+ * Hence we need to make sure no potential computation is happening concurrently with us looking at the history
+ * map. Once we have performed that lookup, though, we can release the lock immediately, as all creation
+ * requests are established to happen either before or after the reconnect attempt.
+ */
+ final ProxyHistory oldProxy;
+ final long stamp = lock.writeLock();
+ try {
+ oldProxy = histories.get(newConn.cookie());
+ } finally {
+ lock.unlockWrite(stamp);
+ }
+