[MRESOLVER-262] Provide contextual data in trace during collect

maven-resolver-api/src/main/java/org/eclipse/aether/collection/CollectStepData.java

@@ -0,0 +1,50 @@
+package org.eclipse.aether.collection;
+
+/*
+ * 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.util.List;
+
+import org.eclipse.aether.graph.Dependency;
+import org.eclipse.aether.graph.DependencyNode;
+
+/**
+ * A trace data object revealing collect step (while executing {@link CollectRequest}.
+ *
+ * @see org.eclipse.aether.RequestTrace
+ * @since 1.8.1
+ */
+public interface CollectStepData
+{
+    /**
+     * Returns the context of collection. Never {@code null}.
+     */
+    String getContext();
+
+    /**
+     * Returns the path of dependency nodes that led collector to current node returned by {@link #getNode()}.
+     * Never {@code null}.
+     */
+    List<DependencyNode> getPath();
+
+    /**
+     * Returns the current node being collected. Never {@code null}.
+     */
+    Dependency getNode();
+}

maven-resolver-demos/maven-resolver-demo-snippets/src/main/java/org/apache/maven/resolver/examples/AllResolverDemos.java

@@ -39,6 +39,7 @@ public static void main( String[] args )
         GetDependencyHierarchy.main( args );
         ResolveArtifact.main( args );
         ResolveTransitiveDependencies.main( args );
+        ReverseDependencyTree.main( args );
         InstallArtifacts.main( args );
         DeployArtifacts.main( args );
     }

maven-resolver-demos/maven-resolver-demo-snippets/src/main/java/org/apache/maven/resolver/examples/ReverseDependencyTree.java

@@ -0,0 +1,83 @@
+package org.apache.maven.resolver.examples;
+
+/*
+ * 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 org.apache.maven.resolver.examples.util.Booter;
+import org.apache.maven.resolver.examples.util.ReverseTreeRepositoryListener;
+import org.eclipse.aether.DefaultRepositorySystemSession;
+import org.eclipse.aether.RepositorySystem;
+import org.eclipse.aether.artifact.Artifact;
+import org.eclipse.aether.artifact.DefaultArtifact;
+import org.eclipse.aether.collection.CollectRequest;
+import org.eclipse.aether.resolution.ArtifactDescriptorRequest;
+import org.eclipse.aether.resolution.ArtifactDescriptorResult;
+import org.eclipse.aether.util.graph.manager.DependencyManagerUtils;
+import org.eclipse.aether.util.graph.transformer.ConflictResolver;
+import org.eclipse.aether.util.listener.ChainedRepositoryListener;
+
+/**
+ * Example of building reverse dependency tree using custom {@link ReverseTreeRepositoryListener}.
+ */
+public class ReverseDependencyTree
+{
+
+    /**
+     * Main.
+     * @param args
+     * @throws Exception
+     */
+    public static void main( String[] args )
+        throws Exception
+    {
+        System.out.println( "------------------------------------------------------------" );
+        System.out.println( ReverseDependencyTree.class.getSimpleName() );
+
+        RepositorySystem system = Booter.newRepositorySystem( Booter.selectFactory( args ) );
+
+        DefaultRepositorySystemSession session = Booter.newRepositorySystemSession( system );
+
+        // install the listener into session
+        session.setRepositoryListener( new ChainedRepositoryListener( session.getRepositoryListener(),
+                new ReverseTreeRepositoryListener() ) );
+
+        session.setConfigProperty( ConflictResolver.CONFIG_PROP_VERBOSE, true );
+        session.setConfigProperty( DependencyManagerUtils.CONFIG_PROP_VERBOSE, true );
+
+        Artifact artifact = new DefaultArtifact( "org.apache.maven:maven-resolver-provider:3.6.1" );
+
+        ArtifactDescriptorRequest descriptorRequest = new ArtifactDescriptorRequest();
+        descriptorRequest.setArtifact( artifact );
+        descriptorRequest.setRepositories( Booter.newRepositories( system, session ) );
+        ArtifactDescriptorResult descriptorResult = system.readArtifactDescriptor( session, descriptorRequest );
+
+        CollectRequest collectRequest = new CollectRequest();
+        collectRequest.setRequestContext( "demo" );
+        collectRequest.setRootArtifact( descriptorResult.getArtifact() );
+        collectRequest.setDependencies( descriptorResult.getDependencies() );
+        collectRequest.setManagedDependencies( descriptorResult.getManagedDependencies() );
+        collectRequest.setRepositories( descriptorRequest.getRepositories() );
+
+        system.collectDependencies( session, collectRequest );
+
+        // in this demo we are not interested in collect result,
+        // as all the "demo work" is done by installed ReverseTreeRepositoryListener
+    }
+
+}

maven-resolver-demos/maven-resolver-demo-snippets/src/main/java/org/apache/maven/resolver/examples/util/ReverseTreeRepositoryListener.java

@@ -0,0 +1,115 @@
+package org.apache.maven.resolver.examples.util;
+
+/*
+ * 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.IOException;
+import java.io.UncheckedIOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ListIterator;
+import java.util.Objects;
+
+import org.eclipse.aether.AbstractRepositoryListener;
+import org.eclipse.aether.RepositoryEvent;
+import org.eclipse.aether.RequestTrace;
+import org.eclipse.aether.artifact.Artifact;
+import org.eclipse.aether.collection.CollectStepData;
+import org.eclipse.aether.graph.Dependency;
+import org.eclipse.aether.graph.DependencyNode;
+
+import static java.util.Objects.requireNonNull;
+
+/**
+ * A demo class building reverse tree using {@link CollectStepData} trace data provided in {@link RepositoryEvent}
+ * events fired during collection.
+ */
+public class ReverseTreeRepositoryListener
+        extends AbstractRepositoryListener
+{
+    private static final String EOL = System.lineSeparator();
+
+    @Override
+    public void artifactResolved( RepositoryEvent event )
+    {
+        requireNonNull( event, "event cannot be null" );
+
+        RequestTrace trace = event.getTrace();
+        CollectStepData collectStepTrace = null;
+        while ( trace != null )
+        {
+            if ( trace.getData() instanceof CollectStepData )
+            {
+                collectStepTrace = (CollectStepData) trace.getData();
+                break;
+            }
+            trace = trace.getParent();
+        }
+
+        if ( collectStepTrace == null )
+        {
+            return;
+        }
+
+        Artifact resolvedArtifact = event.getArtifact();
+        Artifact nodeArtifact = collectStepTrace.getNode().getArtifact();
+
+        if ( isInScope( resolvedArtifact, nodeArtifact ) )
+        {
+            Dependency node = collectStepTrace.getNode();
+            String trackingData = node + " (" + collectStepTrace.getContext() + ")" + EOL;
+            String indent = "";
+            ListIterator<DependencyNode> iter = collectStepTrace.getPath()
+                    .listIterator( collectStepTrace.getPath().size() );
+            while ( iter.hasPrevious() )
+            {
+                DependencyNode curr = iter.previous();
+                indent += "  ";
+                trackingData += indent + curr + " (" + collectStepTrace.getContext() + ")" + EOL;
+            }
+            try
+            {
+                Path trackingDir = resolvedArtifact.getFile().getParentFile().toPath().resolve( ".tracking" );
+                Files.createDirectories( trackingDir );
+                Path trackingFile = trackingDir.resolve( collectStepTrace.getPath().get( 0 )
+                        .getArtifact().toString().replace( ":", "_" ) );
+                Files.write( trackingFile, trackingData.getBytes( StandardCharsets.UTF_8 ) );
+                System.out.println( trackingData );
+            }
+            catch ( IOException e )
+            {
+                throw new UncheckedIOException( e );
+            }
+        }
+    }
+
+    /**
+     * The event "artifact resolved" if fired WHENEVER an artifact is resolved, BUT it happens also when an artifact
+     * descriptor (model, the POM) is being built, and parent (and parent of parent...) is being asked for. Hence, this
+     * method "filters" out in WHICH artifact are we interested in, but it intentionally neglects extension as
+     * ArtifactDescriptorReader modifies extension to "pom" during collect. So all we have to rely on is GAV only.
+     */
+    private boolean isInScope( Artifact artifact, Artifact nodeArtifact )
+    {
+        return Objects.equals( artifact.getGroupId(), nodeArtifact.getGroupId() )
+                && Objects.equals( artifact.getArtifactId(), nodeArtifact.getArtifactId() )
+                && Objects.equals( artifact.getVersion(), nodeArtifact.getVersion() );
+    }
+}

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/CollectStepDataImpl.java

@@ -0,0 +1,67 @@
+package org.eclipse.aether.internal.impl.collect;
+
+/*
+ * 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.util.List;
+
+import org.eclipse.aether.collection.CollectStepData;
+import org.eclipse.aether.graph.Dependency;
+import org.eclipse.aether.graph.DependencyNode;
+
+import static java.util.Objects.requireNonNull;
+
+/**
+ * Trace objects for dependency collection.
+ *
+ * @since 1.8.1
+ */
+public final class CollectStepDataImpl implements CollectStepData
+{
+    private final String context;
+
+    private final List<DependencyNode> path;
+
+    private final Dependency node;
+
+    public CollectStepDataImpl( final String context, final List<DependencyNode> path, final Dependency node )
+    {
+        this.context = requireNonNull( context );
+        this.path = requireNonNull( path );
+        this.node = requireNonNull( node );
+    }
+
+    @Override
+    public String getContext()
+    {
+        return context;
+    }
+
+    @Override
+    public List<DependencyNode> getPath()
+    {
+        return path;
+    }
+
+    @Override
+    public Dependency getNode()
+    {
+        return node;
+    }
+}

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/DependencyCollectorDelegate.java

@@ -290,6 +290,33 @@ public final CollectResult collectDependencies( RepositorySystemSession session,
         return result;
     }
 
+    /**
+     * Creates child {@link RequestTrace} instance from passed in {@link RequestTrace} and parameters by creating
+     * {@link CollectStepDataImpl} instance out of passed in data. Caller must ensure that passed in parameters are
+     * NOT affected by threading (or that there is no multi threading involved). In other words, the passed in values
+     * should be immutable.
+     *
+     * @param trace   The current trace instance.
+     * @param context The context from {@link CollectRequest#getRequestContext()}, never {@code null}.
+     * @param path    List representing the path of dependency nodes, never {@code null}. Caller must ensure, that this
+     *                list does not change during the lifetime of the requested {@link RequestTrace} instance. If it may
+     *                change, simplest is to pass here a copy of used list.
+     * @param node    Currently collected node, that collector came by following the passed in path.
+     * @return A child request trance instance, never {@code null}.
+     */
+    protected RequestTrace collectStepTrace( RequestTrace trace, String context, List<DependencyNode> path,
+                                             Dependency node )
+    {
+        return RequestTrace.newChild(
+                trace,
+                new CollectStepDataImpl(
+                        context,
+                        path,
+                        node
+                )
+        );
+    }
+
     @SuppressWarnings( "checkstyle:parameternumber" )
     protected abstract void doCollectDependencies( RepositorySystemSession session, RequestTrace trace, DataPool pool,
                                                    DefaultDependencyCollectionContext context,