HBASE-29726 Allow updating time limit on ScannerContext

Author: stoty

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/ScannerContext.java

@@ -321,6 +321,18 @@ void setSizeLimitScope(LimitScope scope) {
     limits.setSizeScope(scope);
   }
 
+  /**
+   * Update the time limit.
+   * If the new limit would be later than the current one or would be in the past then do nothing.
+   * 
+   * @param timeLimit The new time limit in milliseconds.
+   */
+  void setTimeLimit(long newLimit) {
+    if (newLimit < limits.getTime() && newLimit > EnvironmentEdgeManager.currentTime()) {
+      limits.setTime(newLimit);
+    }
+  }
+
   /**
    * @param scope The scope in which the time limit will be enforced
    */