com.expedia.www.haystack.client.metrics.Gauge Maven / Gradle / Ivy

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Metrics api consumed by the haystack client library to generate performance metrics for the client integration code

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/*
 * Copyright 2018 Expedia, 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.expedia.www.haystack.client.metrics;

import java.util.ArrayList;
import java.util.Collection;
import java.util.function.ToDoubleFunction;

public interface Gauge {
    static  Builder builder(String name, T obj, ToDoubleFunction f) {
        return new Builder<>(name, obj, f);
    }

    double value();

    class Builder {
        private final String name;
        private final ToDoubleFunction f;
        private final Collection tags = new ArrayList<>();

        private final T obj;

        private Builder(String name, T obj, ToDoubleFunction f) {
            this.name = name;
            this.obj = obj;
            this.f = f;
        }

        public Builder tags(Collection tags) {
            this.tags.addAll(tags);
            return this;
        }

        public Builder tag(Tag tag) {
            tags.add(tag);
            return this;
        }

        public Gauge register(MetricsRegistry registry) {
            return registry.gauge(name, tags, obj, f);
        }
    }
}