public void setContext(Metric.Context metricContext) {
            if (this.metricContext == null) {
                synchronized(this) {
                    this.metricContext = metricContext;
                }
            }
        }
<p>A searcher to gather statistics such as queries completed and query latency.  There
may be more than 1 StatisticsSearcher in the Searcher chain, each identified by a
Searcher ID.  The statistics accumulated by all StatisticsSearchers are stored
in the singleton StatisticsManager object. </p>
<p>
TODO: Fix events to handle more than one of these searchers properly.

@author Gene Meyers
@author Steinar Knutsen
@author bergum
container-search/src/main/java/com/yahoo/prelude/statistics/StatisticsSearcher.java