From df5fb1988c7eb6f6a328cf7da9134f005e88e03f Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <ziegler.patrick@hotmail.de>
Date: Sat, 1 Jun 2024 11:10:54 +0200
Subject: [PATCH] Calculate BOM representation for each IU only once

The BOM representation is currently calculated twice for each artifact.
Within a reactor build, such IUs should always produce the same BOM
representation and should therefore be cached.

Resolves https://github.com/eclipse-tycho/tycho/issues/3911
---
 .../TychoProjectDependenciesConverter.java    | 57 ++++++++++---------
 1 file changed, 31 insertions(+), 26 deletions(-)

diff --git a/tycho-sbom/src/main/java/org/eclipse/tycho/sbom/TychoProjectDependenciesConverter.java b/tycho-sbom/src/main/java/org/eclipse/tycho/sbom/TychoProjectDependenciesConverter.java
index 28cd2c73ca..5b30ae970d 100644
--- a/tycho-sbom/src/main/java/org/eclipse/tycho/sbom/TychoProjectDependenciesConverter.java
+++ b/tycho-sbom/src/main/java/org/eclipse/tycho/sbom/TychoProjectDependenciesConverter.java
@@ -15,6 +15,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
@@ -57,6 +58,8 @@ public class TychoProjectDependenciesConverter extends DefaultProjectDependencie
 	@Inject
 	private MavenProjectDependencyProcessor dependencyProcessor;
 
+	private final Map<IInstallableUnit, List<String>> bomRepresentations = new HashMap<>();
+
 	@Override
 	public void cleanupBomDependencies(Metadata metadata, Map<String, Component> components,
 			Map<String, Dependency> dependencies) {
@@ -117,35 +120,37 @@ private void convertToDependency(DependencyTreeNode node, Set<Dependency> depend
 	private List<String> getBomRepresentation(IInstallableUnit iu) {
 		final MavenSession mavenSession = legacySupport.getSession();
 		final List<MavenProject> reactorProjects = mavenSession.getAllProjects();
-		// mutable!
-		List<String> bomRefs = new ArrayList<>();
-		// (I) IU describes local reactor project
-		try {
-			ProjectDependencyClosure dependencyClosure = dependencyProcessor
-					.computeProjectDependencyClosure(reactorProjects, mavenSession);
-			MavenProject iuProject = dependencyClosure.getProject(iu).orElse(null);
-			if (iuProject != null) {
-				String bomRef = modelConverter.generatePackageUrl(iuProject.getArtifact());
-				if (bomRef == null) {
-					LOG.error("Unable to calculate BOM for: " + iuProject);
+		return bomRepresentations.computeIfAbsent(iu, ignore -> {
+			// mutable!
+			List<String> bomRefs = new ArrayList<>();
+			// (I) IU describes local reactor project
+			try {
+				ProjectDependencyClosure dependencyClosure = dependencyProcessor
+						.computeProjectDependencyClosure(reactorProjects, mavenSession);
+				MavenProject iuProject = dependencyClosure.getProject(iu).orElse(null);
+				if (iuProject != null) {
+					String bomRef = modelConverter.generatePackageUrl(iuProject.getArtifact());
+					if (bomRef == null) {
+						LOG.error("Unable to calculate BOM for: " + iuProject);
+						return bomRefs;
+					}
+					bomRefs.add(bomRef);
 					return bomRefs;
 				}
-				bomRefs.add(bomRef);
-				return bomRefs;
+			} catch (CoreException e) {
+				LOG.error(e.getMessage(), e);
+				return Collections.emptyList();
 			}
-		} catch (CoreException e) {
-			LOG.error(e.getMessage(), e);
-			return Collections.emptyList();
-		}
-		// (II) IU describes external artifact
-		for (IArtifactKey p2artifactKey : iu.getArtifacts()) {
-			String bomRef = modelConverter.generateP2PackageUrl(p2artifactKey, true, true, false);
-			if (bomRef == null) {
-				LOG.error("Unable to calculate BOM for: " + p2artifactKey);
-				continue;
+			// (II) IU describes external artifact
+			for (IArtifactKey p2artifactKey : iu.getArtifacts()) {
+				String bomRef = modelConverter.generateP2PackageUrl(p2artifactKey, true, true, false);
+				if (bomRef == null) {
+					LOG.error("Unable to calculate BOM for: " + p2artifactKey);
+					continue;
+				}
+				bomRefs.add(bomRef);
 			}
-			bomRefs.add(bomRef);
-		}
-		return bomRefs; // mutable!
+			return bomRefs; // mutable!
+		});
 	}
 }