[MNG-8396] Add a cache layer to the filtered dependency graph (#1944)

Author: gnodet

impl/maven-core/src/main/java/org/apache/maven/graph/FilteredProjectDependencyGraph.java

@@ -24,6 +24,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.maven.execution.ProjectDependencyGraph;
 import org.apache.maven.project.MavenProject;
@@ -40,6 +41,10 @@ class FilteredProjectDependencyGraph implements ProjectDependencyGraph {
 
     private final List<MavenProject> sortedProjects;
 
+    private final Map<Key, List<MavenProject>> cache = new ConcurrentHashMap<>();
+
+    private record Key(MavenProject project, boolean transitive, boolean upstream) {}
+
     /**
      * Creates a new project dependency graph from the specified graph.
      *
@@ -74,12 +79,28 @@ public List<MavenProject> getSortedProjects() {
 
     @Override
     public List<MavenProject> getDownstreamProjects(MavenProject project, boolean transitive) {
-        return applyFilter(projectDependencyGraph.getDownstreamProjects(project, transitive), transitive, false);
+        Key key = new Key(project, transitive, false);
+        // Do not use computeIfAbsent here, as the computation is recursive
+        // and this is not supported by computeIfAbsent.
+        List<MavenProject> list = cache.get(key);
+        if (list == null) {
+            list = applyFilter(projectDependencyGraph.getDownstreamProjects(project, transitive), transitive, false);
+            cache.put(key, list);
+        }
+        return list;
     }
 
     @Override
     public List<MavenProject> getUpstreamProjects(MavenProject project, boolean transitive) {
-        return applyFilter(projectDependencyGraph.getUpstreamProjects(project, transitive), transitive, true);
+        Key key = new Key(project, transitive, true);
+        // Do not use computeIfAbsent here, as the computation is recursive
+        // and this is not supported by computeIfAbsent.
+        List<MavenProject> list = cache.get(key);
+        if (list == null) {
+            list = applyFilter(projectDependencyGraph.getUpstreamProjects(project, transitive), transitive, true);
+            cache.put(key, list);
+        }
+        return list;
     }
 
     /**