ch.squaredesk.nova.metrics.MetricsDumpToMapConverter Maven / Gradle / Ivy

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package ch.squaredesk.nova.metrics;

import ch.squaredesk.nova.tuples.Pair;
import ch.squaredesk.nova.tuples.Tuple3;
import com.codahale.metrics.Metric;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.HashMap;
import java.util.Map;

/**
 * This class takes a dump, generated by Nova's Metrics instance and converts them into a map
 * that can easily be serialized and deserialized.
 *
 * The resulting map contains one entry per metric in the dump, each can be looked up by the Metric name. Additionally,
 * we add the following
 *   - timestamp
 *   - hostName
 *   - hostAddress
 *
 * Every Metric itself is again represented as a Map, one MapEntry per attribute. Additionally, we add
 *   - type
 *
 */
public class MetricsDumpToMapConverter {
    private static final ObjectMapper objectMapper = new ObjectMapper();

    private MetricsDumpToMapConverter() {
    }

    public static Map convert(MetricsDump dump) {
        return convert(dump,null);
    }

    public static Map convert(MetricsDump dump, Map additionalAttributes) {
        HashMap returnValue = new HashMap<>();

        dump.metrics.entrySet().stream()
                // for each metric, create a tuple containing the type, the name and the metric itself
                .map(entry -> new Tuple3<>(
                        entry.getValue().getClass().getSimpleName(),
                        entry.getKey(),
                        entry.getValue()))
                // convert each metric to a Map and enrich with our default values, as well as the
                // (eventually) passed additionalAttributes
                .map(tupleTypeAndNameAndMetric -> {
                    Map map = toMap(tupleTypeAndNameAndMetric._3);
                    map.put("type", tupleTypeAndNameAndMetric._1);
                    if (additionalAttributes != null) {
                        map.putAll(additionalAttributes);
                    }
                    return new Pair<>(tupleTypeAndNameAndMetric._2, map);
                })
                // and add it to the return value
                .forEach(metricNameMapPair -> returnValue.put(metricNameMapPair._1, metricNameMapPair._2));

        returnValue.put("timestamp", dump.timestamp);
        returnValue.put("hostName", dump.hostName);
        returnValue.put("hostAddress", dump.hostAddress);

        return returnValue;
    }

    private static Map toMap(Metric metric) {
        if (metric instanceof CompoundMetric) {
            return ((CompoundMetric) metric).getValues();
        } else {
            return objectMapper.convertValue(metric, Map.class);
        }
    }

}