private Metric.Context getChainMetricContext(String chainName) {
        Metric.Context context = chainContexts.get(chainName);
        if (context == null) {
            Map<String, String> dimensions = new HashMap<>();
            dimensions.put("chain", chainName);
            context = this.metric.createContext(dimensions);
            chainContexts.put(chainName, context);
        }
        return context;
    }
<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