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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.Scannable;
import reactor.core.publisher.FluxOnAssembly.AssemblyLightSnapshotException;
import reactor.core.publisher.FluxOnAssembly.AssemblySnapshotException;
import reactor.util.annotation.Nullable;

/**
 * Captures the current stacktrace when this connectable 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 ParallelFluxOnAssembly extends ParallelFlux
		implements Fuseable, AssemblyOp, Scannable {

	final ParallelFlux           source;
	final AssemblySnapshotException stacktrace;

	/**
	 * Create an assembly trace wrapping a {@link ParallelFlux}.
	 */
	ParallelFluxOnAssembly(ParallelFlux source) {
		this.source = source;
		this.stacktrace = new AssemblySnapshotException();
	}

	/**
	 * Create an assembly trace augmented with a custom description (eg. a name for a
	 * ParallelFlux or a wider correlation ID), wrapping a {@link ParallelFlux}.
	 */
	ParallelFluxOnAssembly(ParallelFlux source, @Nullable String description) {
		this.source = source;
		this.stacktrace = new AssemblySnapshotException(description);
	}

	/**
	 * 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}.
	 */
	ParallelFluxOnAssembly(ParallelFlux source, String description, boolean light) {
		this.source = source;
		if (light) {
			 this.stacktrace = new AssemblyLightSnapshotException(description);
		}
		else {
			this.stacktrace = new AssemblySnapshotException(description);
		}
	}

	@Override
	public int getPrefetch() {
		return source.getPrefetch();
	}

	@Override
	public int parallelism() {
		return source.parallelism();
	}

	@Override
	@SuppressWarnings("unchecked")
	public void subscribe(CoreSubscriber[] subscribers) {
		if (!validate(subscribers)) {
			return;
		}

		int n = subscribers.length;
		@SuppressWarnings("unchecked") CoreSubscriber[] parents =
				new CoreSubscriber[n];
		CoreSubscriber s;
		for (int i = 0; i < n; i++) {
			s = subscribers[i];
			if (s instanceof ConditionalSubscriber) {
				ConditionalSubscriber cs = (ConditionalSubscriber) s;
				s = new FluxOnAssembly.OnAssemblyConditionalSubscriber<>(cs,
						stacktrace,
						source);
			}
			else {
				s = new FluxOnAssembly.OnAssemblySubscriber<>(s, stacktrace, source);
			}
			parents[i] = s;
		}

		source.subscribe(parents);
	}

	@Override
	@Nullable
	public Object scanUnsafe(Attr key) {
		if (key == Attr.PARENT) return source;
		if (key == Attr.PREFETCH) return getPrefetch();

		return null;
	}

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