in api/src/main/java/com/spotify/metrics/core/MetricIdCache.java [134:154]
public MetricId get(MetricId metricId, T key) {
final MetricId candidate = cache.get(key);
if (candidate != null) {
return candidate;
}
final MetricId addition = loader.load(metricId, key);
if (addition == null) {
throw new IllegalStateException("loader returned null value");
}
final MetricId put;
if ((put = cache.putIfAbsent(key, addition)) != null) {
return put;
}
return addition;
}