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/*
 * Copyright (c) 2011-2017 Pivotal Software Inc, All Rights Reserved.
 *
 * 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 reactor.core.publisher;


import reactor.core.CoreSubscriber;
import reactor.core.Fuseable;
import reactor.core.publisher.FluxOnAssembly.AssemblySnapshotException;
import reactor.util.annotation.Nullable;

/**
 * Captures the current stacktrace when this publisher is created and makes it
 * available/visible for debugging purposes from the inner Subscriber.
 * 
 * Note that getting a stacktrace is a costly operation.
 * 

 * The operator sanitizes the stacktrace and removes noisy entries such as: 

 * java.lang.Thread entries
 method references with source line of 1 (bridge
 * methods)
 Tomcat worker thread entries
 JUnit setup
 
 *
 * @param  the value type passing through
 * @see https://github.com/reactor/reactive-streams-commons
 */
final class MonoOnAssembly extends MonoOperator implements Fuseable,
                                                                    AssemblyOp {

	final AssemblySnapshotException stacktrace;

	/**
	 * Create an assembly trace exposed as a {@link Mono}.
	 */
	MonoOnAssembly(Mono source) {
		super(source);
		this.stacktrace = new AssemblySnapshotException();
	}

	/**
	 * Create a potentially light assembly trace augmented with a description (that must
	 * be unique enough to identify the assembly site in case of light mode),
	 * wrapping a {@link ParallelFlux}.
	 */
	MonoOnAssembly(Mono source, @Nullable String description, boolean light) {
		super(source);
		if (light) {
			this.stacktrace = new FluxOnAssembly.AssemblyLightSnapshotException(description);
		}
		else {
			this.stacktrace = new AssemblySnapshotException(description);
		}
	}

	@Override
	public void subscribe(CoreSubscriber actual) {
		if (actual instanceof ConditionalSubscriber) {
			@SuppressWarnings("unchecked") ConditionalSubscriber cs =
					(ConditionalSubscriber) actual;
			source.subscribe(new FluxOnAssembly.OnAssemblyConditionalSubscriber<>(cs,
					stacktrace,
					source));
		}
		else {
			source.subscribe(new FluxOnAssembly.OnAssemblySubscriber<>(actual,
					stacktrace,
					source));
		}
	}

	@Override
	public String toString() {
		return stacktrace.stackFirst();
	}

}