Metrics.java

/**
 * Copyright 2016 Yahoo 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.yahoo.pulsar.common.stats;

import java.util.Collections;
import java.util.Map;

import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.google.common.base.Objects;
import com.google.common.collect.Maps;

/**
 * WARNING : do not add any getters as the Jackson parser will output that getter.
 *
 * You may want to use the ignore annotation provided by jackson parser if you need some getters.
 *
 * Dimensions map should be unmodifiable and immutable
 *
 *
 */
public class Metrics {

    final Map<String, Object> metrics;

    @JsonSerialize(include = JsonSerialize.Inclusion.NON_EMPTY)
    final Map<String, String> dimensions;

    // hide constructor
    protected Metrics(Map<String, String> unmodifiableDimensionMap) {
        this.metrics = Maps.newTreeMap();
        this.dimensions = unmodifiableDimensionMap;
    }

    /**
     * Creates a metrics object with the dimensions map immutable
     *
     * @param application
     * @param timestamp
     * @param dimensionsMap
     * @return
     */
    public static Metrics create(Map<String, String> dimensionMap) {
        // make the dimensions map unmodifiable and immutable;
        Map<String, String> map = Maps.newTreeMap();
        map.putAll(dimensionMap);
        return new Metrics(Collections.unmodifiableMap(map));
    }

    public void put(String metricsName, Object value) {
        metrics.put(metricsName, value);
    }

    public Map<String, Object> getMetrics() {
        return Collections.unmodifiableMap(this.metrics);
    }

    public void putAll(Map<String, Object> metrics) {
        this.metrics.putAll(metrics);
    }

    public Map<String, String> getDimensions() {
        // already unmodifiable
        return this.dimensions;
    }

    public String getDimension(String dimensionName) {
        return dimensions.get(dimensionName);
    }

    @Override
    public int hashCode() {
        // the business key will be my metrics dimension [ immutable ]
        return Objects.hashCode(dimensions);
    }

    @Override
    public boolean equals(Object obj) {
        // the business key will be my metrics dimension [ immutable ]
        return (obj instanceof Metrics) && Objects.equal(this.dimensions, ((Metrics) obj).dimensions);
    }

    @Override
    public String toString() {
        return String.format("dimensions=[%s], metrics=[%s]", dimensions, metrics);
    }
}