org.springframework.cloud.sleuth.instrument.reactor.SpanSubscriptionProvider.java Source code

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Here is the source code for org.springframework.cloud.sleuth.instrument.reactor.SpanSubscriptionProvider.java

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/*
 * Copyright 2013-2018 the original author or authors.
 *
 * 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 org.springframework.cloud.sleuth.instrument.reactor;

import java.util.function.Supplier;

import brave.Tracing;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.reactivestreams.Subscriber;
import org.springframework.beans.factory.BeanFactory;
import reactor.util.context.Context;

/**
 * Supplier to lazily start a {@link SpanSubscription}.
 *
 * @param <T> type of returned subscription
 * @author Marcin Grzejszczak
 */
class SpanSubscriptionProvider<T> implements Supplier<SpanSubscription<T>> {

    private static final Log log = LogFactory.getLog(SpanSubscriptionProvider.class);

    final BeanFactory beanFactory;

    final Subscriber<? super T> subscriber;

    final Context context;

    final String name;

    private volatile Tracing tracing;

    SpanSubscriptionProvider(BeanFactory beanFactory, Subscriber<? super T> subscriber, Context context,
            String name) {
        this.beanFactory = beanFactory;
        this.subscriber = subscriber;
        this.context = context;
        this.name = name;
        if (log.isTraceEnabled()) {
            log.trace("Context [" + context + "], name [" + name + "]");
        }
    }

    @Override
    public SpanSubscription<T> get() {
        return newCoreSubscriber(tracing());
    }

    SpanSubscription<T> newCoreSubscriber(Tracing tracing) {
        return new SpanSubscriber<>(this.subscriber, this.context, tracing, this.name);
    }

    private Tracing tracing() {
        if (this.tracing == null) {
            this.tracing = this.beanFactory.getBean(Tracing.class);
        }
        return this.tracing;
    }

}