maven-core/src/test/java/org/apache/maven/lifecycle/internal/builder/multithreaded/ThreadOutputMuxerTest.java

package org.apache.maven.lifecycle.internal.builder.multithreaded;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional information regarding
 * copyright ownership. The ASF licenses this file to you 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.
 */

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import org.apache.maven.execution.MavenSession;
import org.apache.maven.lifecycle.LifecycleNotFoundException;
import org.apache.maven.lifecycle.LifecyclePhaseNotFoundException;
import org.apache.maven.lifecycle.internal.ProjectBuildList;
import org.apache.maven.lifecycle.internal.ProjectSegment;
import org.apache.maven.lifecycle.internal.stub.ProjectDependencyGraphStub;
import org.apache.maven.plugin.InvalidPluginDescriptorException;
import org.apache.maven.plugin.MojoNotFoundException;
import org.apache.maven.plugin.PluginDescriptorParsingException;
import org.apache.maven.plugin.PluginNotFoundException;
import org.apache.maven.plugin.PluginResolutionException;
import org.apache.maven.plugin.prefix.NoPluginFoundForPrefixException;
import org.apache.maven.plugin.version.PluginVersionResolutionException;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;

/**
 * @author Kristian Rosenvold
 */
public class ThreadOutputMuxerTest
{

    final String paid = "Paid";

    final String in = "In";

    final String full = "Full";

    @Test
    public void testSingleThreaded()
        throws Exception
    {
        ProjectBuildList src = getProjectBuildList();
        ProjectBuildList projectBuildList =
            new ProjectBuildList( Arrays.asList( src.get( 0 ), src.get( 1 ), src.get( 2 ) ) );

        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        PrintStream systemOut = new PrintStream( byteArrayOutputStream );
        ThreadOutputMuxer threadOutputMuxer = new ThreadOutputMuxer( projectBuildList, systemOut );

        threadOutputMuxer.associateThreadWithProjectSegment( projectBuildList.get( 0 ) );
        System.out.print( paid );  // No, this does not print to system.out. It's part of the test
        assertEquals( paid.length(), byteArrayOutputStream.size() );
        threadOutputMuxer.associateThreadWithProjectSegment( projectBuildList.get( 1 ) );
        System.out.print( in );  // No, this does not print to system.out. It's part of the test
        assertEquals( paid.length(), byteArrayOutputStream.size() );
        threadOutputMuxer.associateThreadWithProjectSegment( projectBuildList.get( 2 ) );
        System.out.print( full ); // No, this does not print to system.out. It's part of the test
        assertEquals( paid.length(), byteArrayOutputStream.size() );

        threadOutputMuxer.setThisModuleComplete( projectBuildList.get( 0 ) );
        threadOutputMuxer.setThisModuleComplete( projectBuildList.get( 1 ) );
        threadOutputMuxer.setThisModuleComplete( projectBuildList.get( 2 ) );
        threadOutputMuxer.close();
        assertEquals( ( paid + in + full ).length(), byteArrayOutputStream.size() );
    }

    @Test
    public void testMultiThreaded()
        throws Exception
    {
        ProjectBuildList projectBuildList = getProjectBuildList();

        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        PrintStream systemOut = new PrintStream( byteArrayOutputStream );
        final ThreadOutputMuxer threadOutputMuxer = new ThreadOutputMuxer( projectBuildList, systemOut );

        final List<String> stringList =
            Arrays.asList( "Thinkin", "of", "a", "master", "plan", "Cuz", "ain’t", "nuthin", "but", "sweat", "inside",
                           "my", "hand" );
        Iterator<String> lyrics = stringList.iterator();

        ExecutorService executor = Executors.newFixedThreadPool( 10 );
        CompletionService<ProjectSegment> service = new ExecutorCompletionService<>( executor );

        List<Future<ProjectSegment>> futures = new ArrayList<>();
        for ( ProjectSegment projectBuild : projectBuildList )
        {
            final Future<ProjectSegment> buildFuture =
                service.submit( new Outputter( threadOutputMuxer, projectBuild, lyrics.next() ) );
            futures.add( buildFuture );
        }

        for ( Future<ProjectSegment> future : futures )
        {
            future.get();
        }
        int expectedLength = 0;
        for ( int i = 0; i < projectBuildList.size(); i++ )
        {
            expectedLength += stringList.get( i ).length();
        }

        threadOutputMuxer.close();
        final byte[] bytes = byteArrayOutputStream.toByteArray();
        String result = new String( bytes );
        assertEquals( expectedLength, bytes.length, result );


    }

    class Outputter
        implements Callable<ProjectSegment>
    {
        private final ThreadOutputMuxer threadOutputMuxer;

        private final ProjectSegment item;

        private final String response;

        Outputter( ThreadOutputMuxer threadOutputMuxer, ProjectSegment item, String response )
        {
            this.threadOutputMuxer = threadOutputMuxer;
            this.item = item;
            this.response = response;
        }

        public ProjectSegment call()
            throws Exception
        {
            threadOutputMuxer.associateThreadWithProjectSegment( item );
            System.out.print( response );
            threadOutputMuxer.setThisModuleComplete( item );
            return item;
        }
    }


    private ProjectBuildList getProjectBuildList()
        throws InvalidPluginDescriptorException, PluginVersionResolutionException, PluginDescriptorParsingException,
        NoPluginFoundForPrefixException, MojoNotFoundException, PluginNotFoundException, PluginResolutionException,
        LifecyclePhaseNotFoundException, LifecycleNotFoundException
    {
        final MavenSession session = ProjectDependencyGraphStub.getMavenSession();
        return ProjectDependencyGraphStub.getProjectBuildList( session );
    }
}