Add lazy wrappers around diagram generators to make server init more …

…robust

ditaa/src/main/java/org/asciidoctor/diagram/ditaa/Ditaa.java

@@ -16,18 +16,12 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 
-public class Ditaa implements DiagramGenerator
+public class Ditaa implements DiagramGeneratorFunction
 {
     public static final MimeType DEFAULT_OUTPUT_FORMAT = MimeType.PNG;
     public static final MimeType DEFAULT_CONTENT_TYPE = MimeType.TEXT_PLAIN_UTF8;
     public static final String DEFAULT_CHARSET = "UTF-8";
 
-    @Override
-    public String getName()
-    {
-        return "ditaa";
-    }
-
     @Override
     public ResponseData generate(Request request) throws IOException {
         MimeType format = request.headers.getValue(HTTPHeader.ACCEPT);

ditaa/src/main/java/org/asciidoctor/diagram/ditaa/DitaaDiagramGenerator.java

@@ -0,0 +1,15 @@
+package org.asciidoctor.diagram.ditaa;
+
+import org.asciidoctor.diagram.DiagramGeneratorFunction;
+import org.asciidoctor.diagram.LazyDiagramGenerator;
+
+public class DitaaDiagramGenerator extends LazyDiagramGenerator {
+    public DitaaDiagramGenerator() {
+        super("ditaa");
+    }
+
+    @Override
+    protected DiagramGeneratorFunction createGenerator() throws Exception {
+        return new Ditaa();
+    }
+}

ditaa/src/main/resources/META-INF/services/org.asciidoctor.diagram.DiagramGenerator

@@ -1 +1 @@
-org.asciidoctor.diagram.ditaa.Ditaa
+org.asciidoctor.diagram.ditaa.DitaaDiagramGenerator

plantuml/src/main/java/org/asciidoctor/diagram/plantuml/PlantUML.java

@@ -17,7 +17,7 @@
 import java.util.ArrayList;
 import java.util.List;
 
-public class PlantUML implements DiagramGenerator
+public class PlantUML implements DiagramGeneratorFunction
 {
     public static final String X_GRAPHVIZ = "X-Graphviz";
     public static final String X_PLANT_UML_CONFIG = "X-PlantUML-Config";
@@ -80,12 +80,6 @@ public class PlantUML implements DiagramGenerator
         }
     }
 
-    @Override
-    public String getName()
-    {
-        return "plantuml";
-    }
-
     @Override
     public ResponseData generate(Request request) throws IOException {
         File graphviz;

plantuml/src/main/java/org/asciidoctor/diagram/plantuml/PlantUMLDiagramGenerator.java

@@ -0,0 +1,15 @@
+package org.asciidoctor.diagram.plantuml;
+
+import org.asciidoctor.diagram.DiagramGeneratorFunction;
+import org.asciidoctor.diagram.LazyDiagramGenerator;
+
+public class PlantUMLDiagramGenerator extends LazyDiagramGenerator {
+    public PlantUMLDiagramGenerator() {
+        super("plantuml");
+    }
+
+    @Override
+    protected DiagramGeneratorFunction createGenerator() throws Exception {
+        return new PlantUML();
+    }
+}

plantuml/src/main/java/org/asciidoctor/diagram/plantuml/PlantUMLPreprocessor.java

@@ -17,16 +17,10 @@
 import java.util.List;
 import java.util.stream.Collectors;
 
-public class PlantUMLPreprocessor implements DiagramGenerator
+public class PlantUMLPreprocessor implements DiagramGeneratorFunction
 {
     private static final MimeType DEFAULT_OUTPUT_FORMAT = MimeType.TEXT_PLAIN_UTF8;
 
-    @Override
-    public String getName()
-    {
-        return "plantumlpreprocessor";
-    }
-
     @Override
     public ResponseData generate(Request request) throws IOException {
         MimeType format = request.headers.getValue(HTTPHeader.ACCEPT);

plantuml/src/main/java/org/asciidoctor/diagram/plantuml/PlantUMLPreprocessorDiagramGenerator.java

@@ -0,0 +1,15 @@
+package org.asciidoctor.diagram.plantuml;
+
+import org.asciidoctor.diagram.DiagramGeneratorFunction;
+import org.asciidoctor.diagram.LazyDiagramGenerator;
+
+public class PlantUMLPreprocessorDiagramGenerator extends LazyDiagramGenerator {
+    public PlantUMLPreprocessorDiagramGenerator() {
+        super("plantumlpreprocessor");
+    }
+
+    @Override
+    protected DiagramGeneratorFunction createGenerator() throws Exception {
+        return new PlantUMLPreprocessorDiagramGenerator();
+    }
+}

plantuml/src/main/resources/META-INF/services/org.asciidoctor.diagram.DiagramGenerator

@@ -1,2 +1,2 @@
-org.asciidoctor.diagram.plantuml.PlantUML
-org.asciidoctor.diagram.plantuml.PlantUMLPreprocessor
+org.asciidoctor.diagram.plantuml.PlantUMLDiagramGenerator
+org.asciidoctor.diagram.plantuml.PlantUMLPreprocessorDiagramGenerator

server/src/main/java/org/asciidoctor/diagram/DiagramGenerator.java

@@ -1,9 +1,5 @@
 package org.asciidoctor.diagram;
 
-import java.io.IOException;
-
-public interface DiagramGenerator {
+public interface DiagramGenerator extends DiagramGeneratorFunction {
     String getName();
-
-    ResponseData generate(Request request) throws IOException;
 }

server/src/main/java/org/asciidoctor/diagram/DiagramGeneratorFunction.java

@@ -0,0 +1,7 @@
+package org.asciidoctor.diagram;
+
+import java.io.IOException;
+
+public interface DiagramGeneratorFunction {
+    ResponseData generate(Request request) throws IOException;
+}

server/src/main/java/org/asciidoctor/diagram/LazyDiagramGenerator.java

@@ -0,0 +1,41 @@
+package org.asciidoctor.diagram;
+
+import java.io.IOException;
+
+public abstract class LazyDiagramGenerator implements DiagramGenerator {
+    private final String name;
+    private DiagramGeneratorFunction diagramGeneratorFunction;
+    private IOException loadError;
+
+    public LazyDiagramGenerator(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    protected abstract DiagramGeneratorFunction createGenerator() throws Exception;
+
+    public ResponseData generate(Request request) throws IOException {
+        if (loadError != null) {
+            throw loadError;
+        }
+
+        if (diagramGeneratorFunction == null) {
+            try {
+                diagramGeneratorFunction = createGenerator();
+            } catch (Throwable e) {
+                String message = getName() + " could not be initialised due to " + e.getClass().getSimpleName();
+                if (e.getMessage() != null) {
+                    message += ": " + e.getMessage();
+                }
+                loadError = new IOException(message);
+                loadError.setStackTrace(e.getStackTrace());
+                throw loadError;
+            }
+        }
+
+        return diagramGeneratorFunction.generate(request);
+    }
+}

structurizr/src/main/java/org/asciidoctor/diagram/structurizr/Structurizr.java

@@ -24,7 +24,7 @@
 import java.util.List;
 import java.util.stream.Stream;
 
-public class Structurizr implements DiagramGenerator {
+public class Structurizr implements DiagramGeneratorFunction {
     @FunctionalInterface
     interface ParseDsl {
         void parse(StructurizrDslParser parser, String dsl, File file) throws StructurizrDslParserException;
@@ -93,12 +93,6 @@ static ParseDsl createParseDsl() {
 
     private static final MimeType DEFAULT_OUTPUT_FORMAT = PLANTUML;
 
-    @Override
-    public String getName() {
-        return "structurizr";
-    }
-
-    @Override
     public ResponseData generate(Request request) throws IOException {
         MimeType format = request.headers.getValue(HTTPHeader.ACCEPT);
 

structurizr/src/main/java/org/asciidoctor/diagram/structurizr/StructurizrDiagramGenerator.java

@@ -0,0 +1,15 @@
+package org.asciidoctor.diagram.structurizr;
+
+import org.asciidoctor.diagram.DiagramGeneratorFunction;
+import org.asciidoctor.diagram.LazyDiagramGenerator;
+
+public class StructurizrDiagramGenerator extends LazyDiagramGenerator {
+    public StructurizrDiagramGenerator() {
+        super("structurizr");
+    }
+
+    @Override
+    protected DiagramGeneratorFunction createGenerator() throws Exception {
+        return new Structurizr();
+    }
+}

structurizr/src/main/resources/META-INF/services/org.asciidoctor.diagram.DiagramGenerator

@@ -1 +1 @@
-org.asciidoctor.diagram.structurizr.Structurizr
+org.asciidoctor.diagram.structurizr.StructurizrDiagramGenerator

syntrax/src/main/java/org/asciidoctor/diagram/syntrax/Syntrax.java

@@ -13,14 +13,9 @@
 import static org.atpfivt.jsyntrax.Main.generateSVG;
 import static org.atpfivt.jsyntrax.Main.getStyleConfig;
 
-public class Syntrax implements DiagramGenerator {
+public class Syntrax implements DiagramGeneratorFunction {
     public static final MimeType DEFAULT_OUTPUT_FORMAT = MimeType.SVG;
 
-    @Override
-    public String getName() {
-        return "syntrax";
-    }
-
     @Override
     public ResponseData generate(Request request) throws IOException {
         MimeType format = request.headers.getValue(HTTPHeader.ACCEPT);

syntrax/src/main/java/org/asciidoctor/diagram/syntrax/SyntraxDiagramGenerator.java

@@ -0,0 +1,15 @@
+package org.asciidoctor.diagram.syntrax;
+
+import org.asciidoctor.diagram.DiagramGeneratorFunction;
+import org.asciidoctor.diagram.LazyDiagramGenerator;
+
+public class SyntraxDiagramGenerator extends LazyDiagramGenerator {
+    public SyntraxDiagramGenerator() {
+        super("syntrax");
+    }
+
+    @Override
+    protected DiagramGeneratorFunction createGenerator() throws Exception {
+        return new Syntrax();
+    }
+}

syntrax/src/main/resources/META-INF/services/org.asciidoctor.diagram.DiagramGenerator

@@ -1 +1 @@
-org.asciidoctor.diagram.syntrax.Syntrax
+org.asciidoctor.diagram.syntrax.SyntraxDiagramGenerator

syntrax/src/test/java/org/asciidoctor/diagram/syntrax/SyntraxTest.java

@@ -34,7 +34,7 @@ public static void setUP() {
 
     @Test
     public void testTestGetName() {
-        org.junit.Assert.assertEquals("syntrax", new Syntrax().getName());
+        org.junit.Assert.assertEquals("syntrax", new SyntraxDiagramGenerator().getName());
     }
 
     @Test