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

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Here is the source code for org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.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.concurrent.atomic.AtomicBoolean;

import brave.Span;
import brave.Tracer;
import brave.Tracing;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;
import reactor.util.context.Context;

/**
 * A trace representation of the {@link Subscriber} that always continues a span.
 *
 * @param - span subscription type
 * @author Marcin Grzejszczak
 * @since 2.0.0
 */
final class ScopePassingSpanSubscriber<T> extends AtomicBoolean implements SpanSubscription<T> {

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

    private final Span span;

    private final Subscriber<? super T> subscriber;

    private final Context context;

    private final Tracer tracer;

    private Subscription s;

    ScopePassingSpanSubscriber(Subscriber<? super T> subscriber, Context ctx, Tracing tracing) {
        this.subscriber = subscriber;
        this.tracer = tracing.tracer();
        Span root = ctx != null ? ctx.getOrDefault(Span.class, this.tracer.currentSpan()) : null;
        this.span = root;
        this.context = ctx != null && root != null ? ctx.put(Span.class, root)
                : ctx != null ? ctx : Context.empty();
        if (log.isTraceEnabled()) {
            log.trace("Root span [" + root + "], context [" + this.context + "]");
        }
    }

    @Override
    public void onSubscribe(Subscription subscription) {
        this.s = subscription;
        try (Tracer.SpanInScope inScope = this.tracer.withSpanInScope(this.span)) {
            this.subscriber.onSubscribe(this);
        }
    }

    @Override
    public void request(long n) {
        try (Tracer.SpanInScope inScope = this.tracer.withSpanInScope(this.span)) {
            this.s.request(n);
        }
    }

    @Override
    public void cancel() {
        try (Tracer.SpanInScope inScope = this.tracer.withSpanInScope(this.span)) {
            this.s.cancel();
        }
    }

    @Override
    public void onNext(T o) {
        try (Tracer.SpanInScope inScope = this.tracer.withSpanInScope(this.span)) {
            this.subscriber.onNext(o);
        }
    }

    @Override
    public void onError(Throwable throwable) {
        try (Tracer.SpanInScope inScope = this.tracer.withSpanInScope(this.span)) {
            this.subscriber.onError(throwable);
        }
    }

    @Override
    public void onComplete() {
        try (Tracer.SpanInScope inScope = this.tracer.withSpanInScope(this.span)) {
            this.subscriber.onComplete();
        }
    }

    @Override
    public Context currentContext() {
        return this.context;
    }

}