Modified SessionManager to recognize session idle property updates

Reverted changes in apache#4780, which marked the properties as not mutable.
Passed the ServerContext to the sweep method instead of the property
values. The property values are resolved at sweep method execution
time.

Closes apache#4723

core/src/main/java/org/apache/accumulo/core/conf/Property.java

@@ -1898,8 +1898,7 @@ public static boolean isValidTablePropertyKey(String key) {
       COMPACTOR_MINTHREADS_TIMEOUT,
 
       // others
-      TSERV_NATIVEMAP_ENABLED, TSERV_SCAN_MAX_OPENFILES, MANAGER_RECOVERY_WAL_EXISTENCE_CACHE_TIME,
-      TSERV_SESSION_MAXIDLE, TSERV_UPDATE_SESSION_MAXIDLE);
+      TSERV_NATIVEMAP_ENABLED, TSERV_SCAN_MAX_OPENFILES, MANAGER_RECOVERY_WAL_EXISTENCE_CACHE_TIME);
 
   /**
    * Checks if the given property may be changed via Zookeeper, but not recognized until the restart

server/tserver/src/main/java/org/apache/accumulo/tserver/session/SessionManager.java

@@ -70,22 +70,15 @@ public class SessionManager {
 
   private static final SecureRandom random = new SecureRandom();
   private final ConcurrentMap<Long,Session> sessions = new ConcurrentHashMap<>();
-  private final long maxIdle;
-  private final long maxUpdateIdle;
   private final BlockingQueue<Session> deferredCleanupQueue = new ArrayBlockingQueue<>(5000);
   private final Long expiredSessionMarker = (long) -1;
-  private final AccumuloConfiguration aconf;
   private final ServerContext ctx;
   private volatile LongConsumer zombieCountConsumer = null;
 
   public SessionManager(ServerContext context) {
     this.ctx = context;
-    this.aconf = context.getConfiguration();
-    maxUpdateIdle = aconf.getTimeInMillis(Property.TSERV_UPDATE_SESSION_MAXIDLE);
-    maxIdle = aconf.getTimeInMillis(Property.TSERV_SESSION_MAXIDLE);
-
-    Runnable r = () -> sweep(maxIdle, maxUpdateIdle);
-
+    long maxIdle = ctx.getConfiguration().getTimeInMillis(Property.TSERV_SESSION_MAXIDLE);
+    Runnable r = () -> sweep(ctx);
     ThreadPools.watchCriticalScheduledTask(context.getScheduledExecutor().scheduleWithFixedDelay(r,
         0, Math.max(maxIdle / 2, 1000), TimeUnit.MILLISECONDS));
   }
@@ -107,7 +100,7 @@ public long createSession(Session session, boolean reserve) {
   }
 
   public long getMaxIdleTime() {
-    return maxIdle;
+    return ctx.getConfiguration().getTimeInMillis(Property.TSERV_SESSION_MAXIDLE);
   }
 
   /**
@@ -309,7 +302,10 @@ private void cleanup(Session session) {
     cleanup(deferredCleanupQueue, session);
   }
 
-  private void sweep(final long maxIdle, final long maxUpdateIdle) {
+  private void sweep(final ServerContext context) {
+    final AccumuloConfiguration conf = context.getConfiguration();
+    final long maxUpdateIdle = conf.getTimeInMillis(Property.TSERV_UPDATE_SESSION_MAXIDLE);
+    final long maxIdle = conf.getTimeInMillis(Property.TSERV_SESSION_MAXIDLE);
     List<Session> sessionsToCleanup = new LinkedList<>();
     Iterator<Session> iter = sessions.values().iterator();
     while (iter.hasNext()) {