/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.beam.runners.core.metrics;

import java.io.Serializable;
import org.apache.beam.sdk.metrics.MetricQueryResults;

/**
 * Abstract base class for all metric sinks it can use different serializers.
 */

public abstract class MetricsSink<OutputT> implements Serializable{

  private MetricsSerializer<OutputT> metricsSerializer = provideSerializer();

  void writeMetrics(MetricQueryResults metricQueryResults) throws Exception {
    if (metricsSerializer != null) {
      OutputT serializedMetrics = metricsSerializer.serializeMetrics(metricQueryResults);
      writeSerializedMetrics(serializedMetrics);
    }
  }
  protected abstract MetricsSerializer<OutputT> provideSerializer();
  protected abstract void writeSerializedMetrics(OutputT metrics) throws Exception;
}


/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.beam.runners.core.metrics;

import java.io.Serializable;
import org.apache.beam.sdk.metrics.MetricQueryResults;

/** Abstract base class for all metric sinks it can use different serializers. */
public abstract class MetricsSink<OutputT> implements Serializable {

  private MetricsSerializer<OutputT> metricsSerializer = provideSerializer();

  void writeMetrics(MetricQueryResults metricQueryResults) throws Exception {
    OutputT serializedMetrics = metricsSerializer.serializeMetrics(metricQueryResults);
    writeSerializedMetrics(serializedMetrics);
  }

  protected abstract MetricsSerializer<OutputT> provideSerializer();

  protected abstract void writeSerializedMetrics(OutputT metrics) throws Exception;
}

Remove unneeded null check, format