public void addTriggers(final List<Trigger> triggers) {
    if (triggers != null) {
      this.appliedTriggers.addAll(triggers);
      // reset and add counters. This can happen during start of query or a session being moved to another pool with its
      // own set of triggers
      Set<String> counters = new HashSet<>();
      for (Trigger trigger : triggers) {
        counters.add(trigger.getExpression().getCounterLimit().getName());
      }
      addSubscribedCounters(counters);
    }
  }
Some context information that are required for rule evaluation.
ql/src/java/org/apache/hadoop/hive/ql/wm/WmContext.java