Performance optimizations

Refactor jar lifecycle listener invocation to reduce redundant plugin lookups:

- Fetch listeners once and pass them to beforeJarWrite/afterJarWrite instead of looking them up multiple times
- Create context map only when listeners exist (lazy initialization)
- Reuse DiffPluginImpl instance field instead of creating new instances
- Move timestamp fetch earlier in RebuildTriggerPolicy to simplify file existence check

Signed-off-by: Christoph Rueger <chrisrueger@gmail.com>

Author: chrisrueger

biz.aQute.bndlib/src/aQute/bnd/build/Project.java

@@ -2105,14 +2105,20 @@ private File saveBuildWithoutClose(Jar jar) throws Exception {
 		File outputFile = getOutputFile(jar.getName(), jar.getVersion());
 
 		// Notify BEFORE listeners
-		Map<String, Object> context = new HashMap<String, Object>();
-		beforeJarWrite(jar, outputFile, context);
+		List<JarLifecycleListener> listeners = getPlugins(JarLifecycleListener.class);
+		Map<String, Object> context = null;
+		if (!listeners.isEmpty()) {
+			context = new HashMap<String, Object>();
+			beforeJarWrite(jar, outputFile, context, listeners);
+		}
 
 		reportNewer(outputFile.lastModified(), jar);
 		File logicalFile = write(jar::write, outputFile);
 
 		// Notify AFTER listeners
-		afterJarWrite(this, outputFile, jar, context);
+		if (!listeners.isEmpty()) {
+			afterJarWrite(this, outputFile, jar, context, listeners);
+		}
 
 		logger.debug("{} ({}) {}", jar.getName(), outputFile.getName(), jar.getResources()
 			.size());
@@ -2143,8 +2149,8 @@ private File saveBuildWithoutClose(Jar jar) throws Exception {
 		return logicalFile;
 	}
 
-	private void beforeJarWrite(Jar jar, File outputFile, Map<String, Object> context) throws Exception {
-		List<JarLifecycleListener> listeners = getPlugins(JarLifecycleListener.class);
+	private void beforeJarWrite(Jar jar, File outputFile, Map<String, Object> context,
+		List<JarLifecycleListener> listeners) throws Exception {
 
 		for (JarLifecycleListener listener : listeners) {
 			try {
@@ -2155,9 +2161,10 @@ private void beforeJarWrite(Jar jar, File outputFile, Map<String, Object> contex
 		}
 	}
 
-	private void afterJarWrite(Project project, File outputFile, Jar jar, Map<String, Object> context)
+	private void afterJarWrite(Project project, File outputFile, Jar jar, Map<String, Object> context,
+		List<JarLifecycleListener> listeners)
 		throws Exception {
-		List<JarLifecycleListener> listeners = getPlugins(JarLifecycleListener.class);
+
 		for (JarLifecycleListener listener : listeners) {
 			try {
 				listener.afterWrite(project, outputFile, jar, context);

bndtools.core/src/bndtools/central/RebuildTriggerPolicy.java

@@ -84,6 +84,7 @@ public class RebuildTriggerPolicy {
 
 	private static final ILogger	logger	= Logger.getLogger(RebuildTriggerPolicy.class);
 	private final String			rebuildTriggerPolicyKey;
+	private final DiffPluginImpl	differ						= new DiffPluginImpl();
 
 	/**
 	 * Result of evaluating the build change policy.
@@ -167,11 +168,13 @@ RebuildTriggerPolicyResult doRebuildTriggerPolicy(Jar jar, File outputFile) {
 		String newContentDigestHex = calcContentDigest(jar);
 
 		// Fast path: no existing output means nothing to preserve.
-		if (!outputFile.isFile()) {
+		long existingTimestamp = outputFile.lastModified();
+
+		if (existingTimestamp == 0) {
+			// existingTimestamp==0 means file does not exist
 			return new RebuildTriggerPolicyResult(0, contentDigestFile, newContentDigestHex, null, null);
 		}
 
-		long existingTimestamp = outputFile.lastModified();
 
 		// Check 1: byte-identical content -> preserve immediately.
 		if (digestMatches(contentDigestFile, newContentDigestHex, outputFile, "stored content digest")) {
@@ -241,7 +244,7 @@ private String calcApiDigest(Jar jar) {
 			if (exportPackage == null || exportPackage.isEmpty()) {
 				return null;
 			}
-			Tree tree = new DiffPluginImpl().tree(jar);
+			Tree tree = differ.tree(jar);
 			Tree apiTree = tree.get("<api>");
 			if (apiTree == null) {
 				return null;