package com.atlassian.vcache.internal.core.metrics;
   
   import com.atlassian.marshalling.api.MarshallingException;
   import com.atlassian.marshalling.api.Unmarshaller;
   
   import static com.atlassian.vcache.internal.MetricLabel.NUMBER_OF_BYTES_UNMARSHALLED;
   import static com.atlassian.vcache.internal.MetricLabel.NUMBER_OF_FAILED_UNMARSHALL;
   import static com.atlassian.vcache.internal.MetricLabel.TIMED_UNMARSHALL_CALL;
   import static com.atlassian.vcache.internal.core.metrics.CacheType.EXTERNAL;
  import static java.util.Objects.requireNonNull;
  
  /**
   * Wrapper for a {@link Unmarshaller} that records metrics.
   *
   * @param <T> the value type
   * @since 1.0.0
   */
  class TimedUnmarshaller<T> implements Unmarshaller<T> {
      private final Unmarshaller<T> delegate;
      private final MetricsRecorder metricsRecorder;
      private final String cacheName;
  
      TimedUnmarshaller(Unmarshaller<T> delegate, MetricsRecorder metricsRecorder, String cacheName) {
          this.delegate = requireNonNull(delegate);
          this.metricsRecorder = requireNonNull(metricsRecorder);
          this.cacheName = requireNonNull(cacheName);
      }
  
      @Override
      public T unmarshallFrom(byte[] raw) throws MarshallingException {
          metricsRecorder.record(cacheName, EXTERNAL, NUMBER_OF_BYTES_UNMARSHALLED, raw.length);
          try (ElapsedTimer ignored = new ElapsedTimer(
                  t -> metricsRecorder.record(cacheName, EXTERNAL, TIMED_UNMARSHALL_CALL, t))) {
              return delegate.unmarshallFrom(raw);
          } catch (MarshallingException me) {
              metricsRecorder.record(cacheName, EXTERNAL, NUMBER_OF_FAILED_UNMARSHALL, 1);
              throw me;
          }
      }
  }