/**
 * Copyright 2013 Netflix, Inc.
 *
 * Licensed 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 com.netflix.servo.publish;

import com.google.common.base.Function;
import com.google.common.collect.Lists;
import com.netflix.servo.Metric;

import java.util.List;

/**
 * An observer that will transform the list of metrics using a given function.
 */
public class MetricTransformObserver implements MetricObserver {
    private final Function<Metric, Metric> transformer;
    private final MetricObserver observer;

    /**
     * Create a new MetricTransformObserver using the given transfomer function
     * @param transformer The function used to transform metrics.
     * @param observer    The MetricObserver that will receive the transfomed metrics.
     */
    public MetricTransformObserver(Function<Metric, Metric> transformer, MetricObserver observer) {
        this.transformer = transformer;
        this.observer = observer;
    }

    @Override
    public void update(List<Metric> metrics) {
        final List<Metric> newMetrics = Lists.newArrayListWithCapacity(metrics.size());
        for (Metric m : metrics) {
            newMetrics.add(transformer.apply(m));
        }
        observer.update(newMetrics);
    }

    @Override
    public String getName() {
        return "MetricTransformObserver";
    }
}

/**
 * Copyright 2013 Netflix, Inc.
 *
 * Licensed 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 com.netflix.servo.publish;

import com.google.common.base.Function;
import com.google.common.collect.Lists;
import com.netflix.servo.Metric;

import java.util.List;

/**
 * An observer that will transform the list of metrics using a given function.
 */
public class MetricTransformObserver implements MetricObserver {
    private final Function<Metric, Metric> transformer;
    private final MetricObserver observer;

    /**
     * Create a new MetricTransformObserver using the given transfomer function
     *
     * @param transformer The function used to transform metrics.
     * @param observer    The MetricObserver that will receive the transfomed metrics.
     */
    public MetricTransformObserver(Function<Metric, Metric> transformer, MetricObserver observer) {
        this.transformer = transformer;
        this.observer = observer;
    }

    @Override
    public void update(List<Metric> metrics) {
        observer.update(Lists.transform(metrics, transformer));
    }

    @Override
    public String getName() {
        return "MetricTransformObserver";
    }
}

Use Lists.transform