working on timezone problems

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

Dockerfile

@@ -1,7 +1,7 @@
 FROM alpine:3.22 AS svelte_build
 RUN apk add npm
 RUN adduser -Dh /home/svelte svelte
-ADD . /home/svelte/Umbrella
+ADD frontend /home/svelte/Umbrella/frontend
 RUN chown -R svelte /home/svelte/Umbrella
 USER svelte
 WORKDIR /home/svelte/Umbrella/frontend
@@ -17,14 +17,18 @@ RUN gradle --no-daemon build
 
 
 FROM alpine
-RUN apk add bash fontconfig font-opensans graphviz openjdk21-jre weasyprint
-RUN adduser -D umbrella
-COPY --from=java_build /Umbrella/backend/build/libs/backend.jar /home/umbrella/jar/
-RUN chown -R umbrella /home/umbrella
-ADD https://github.com/plantuml/plantuml/releases/download/v1.2025.10/plantuml-1.2025.10.jar /home/umbrella/plantuml.jar
+RUN apk --no-cache add bash fontconfig font-opensans graphviz openjdk21-jre weasyprint \
+ && adduser -D umbrella
 WORKDIR /home/umbrella
-RUN chmod a+rx plantuml.jar
-USER umbrella
-RUN mkdir .config && ln -s /host/config.json .config/Umbrella.json
+
 EXPOSE 80
 CMD java -jar jar/backend.jar
+
+ADD https://github.com/plantuml/plantuml/releases/download/v1.2025.10/plantuml-1.2025.10.jar /home/umbrella/plantuml.jar
+COPY --from=java_build /Umbrella/backend/build/libs/backend.jar /home/umbrella/jar/
+RUN mkdir .config \
+ && ln -s /host/config.json .config/Umbrella.json \
+ && chmod a+rx plantuml.jar \
+ && chown -R umbrella . \
+ && ln -s /usr/share/zoneinfo/Europe/Berlin /etc/localtime
+USER umbrella

core/src/main/java/de/srsoftware/umbrella/core/Util.java

@@ -40,6 +40,7 @@ public class Util {
 	private static final JParsedown MARKDOWN = new JParsedown();
 	public static final String SHA1 = "SHA-1";
 	private static final MessageDigest SHA1_DIGEST;
+	private static final Map<Integer,String> umlCache = new HashMap<>();
 
 	static {
 		try {
@@ -84,6 +85,17 @@ public class Util {
 					var start = matcher.start(0);
 					var end = matcher.end(0);
 
+					var umlHash = uml.hashCode();
+					LOG.log(DEBUG,"Hash of Plantuml code: {0}",umlHash);
+					var svg = umlCache.get(umlHash);
+					if (svg != null){
+						LOG.log(DEBUG,"Serving Plantuml generated SVG from cache…");
+						source = source.substring(0, start) + svg + source.substring(end);
+						matcher = UML_PATTERN.matcher(source);
+						continue;
+					}
+
+					LOG.log(DEBUG,"Cache miss. Generating SVG from plantuml code…");
 					ProcessBuilder processBuilder = new ProcessBuilder("java", "-jar", plantumlJar.getAbsolutePath(), "-tsvg", "-pipe");
 					var ignored = processBuilder.redirectErrorStream();
 					var process = processBuilder.start();
@@ -94,7 +106,9 @@ public class Util {
 
 					try (InputStream is = process.getInputStream()) {
 						byte[] out = is.readAllBytes();
-						var svg = new String(out, UTF_8);
+						LOG.log(DEBUG,"Generated SVG. Pushing to cache…");
+						svg = new String(out, UTF_8);
+						umlCache.put(umlHash,svg);
 						source = source.substring(0, start) + svg + source.substring(end);
 						matcher = UML_PATTERN.matcher(source);
 					}