#508 better caching of templates, disable caching in jar file connections to avoid suddenly closed InputStreams

processor/src/main/java/org/mapstruct/ap/writer/ModelWriter.java

@@ -19,14 +19,25 @@
 package org.mapstruct.ap.writer;
 
 import java.io.BufferedWriter;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.net.URL;
+import java.net.URLConnection;
+import java.nio.charset.Charset;
 import java.util.HashMap;
 import java.util.Map;
+
 import javax.tools.JavaFileObject;
 
+import org.mapstruct.ap.writer.Writable.Context;
+
+import freemarker.cache.StrongCacheStorage;
+import freemarker.cache.TemplateLoader;
 import freemarker.log.Logger;
 import freemarker.template.Configuration;
 import freemarker.template.DefaultObjectWrapper;
-import org.mapstruct.ap.writer.Writable.Context;
 
 /**
  * Writes Java source files based on given mapper models, using a FreeMarker
@@ -50,13 +61,17 @@ public class ModelWriter {
             throw new RuntimeException( e );
         }
 
-        CONFIGURATION = new Configuration();
+        CONFIGURATION = new Configuration( Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS );
-        CONFIGURATION.setClassForTemplateLoading( ModelWriter.class, "/" );
+        CONFIGURATION.setTemplateLoader( new SimpleClasspathLoader() );
-        CONFIGURATION.setObjectWrapper( new DefaultObjectWrapper() );
+        CONFIGURATION.setObjectWrapper( new DefaultObjectWrapper( Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS ) );
         CONFIGURATION.setSharedVariable(
             "includeModel",
             new ModelIncludeDirective( CONFIGURATION )
         );
+        // do not refresh/gc the cached templates, as we never change them at runtime
+        CONFIGURATION.setCacheStorage( new StrongCacheStorage() );
+        CONFIGURATION.setTemplateUpdateDelay( Integer.MAX_VALUE );
+        CONFIGURATION.setLocalizedLookup( false );
     }
 
     public void writeModel(JavaFileObject sourceFile, Writable model) {
@@ -65,6 +80,7 @@ public class ModelWriter {
 
             Map<Class<?>, Object> values = new HashMap<Class<?>, Object>();
             values.put( Configuration.class, CONFIGURATION );
+
             model.write( new DefaultModelElementWriterContext( values ), writer );
 
             writer.flush();
@@ -79,8 +95,42 @@ public class ModelWriter {
     }
 
     /**
-     * {@link Context} implementation which provides access to the current
+     * Simplified template loader that avoids reading modification timestamps and disables the jar-file caching.
-     * FreeMarker {@link Configuration}.
+     *
+     * @author Andreas Gudian
+     */
+    private static final class SimpleClasspathLoader implements TemplateLoader {
+        @Override
+        public Reader getReader(Object name, String encoding) throws IOException {
+            URL url = getClass().getClassLoader().getResource( String.valueOf( name ) );
+
+            URLConnection connection = url.openConnection();
+
+            // don't use jar-file caching, as it caused occasionally closed input streams [at least under JDK 1.8.0_25]
+            connection.setUseCaches( false );
+
+            InputStream is = connection.getInputStream();
+
+            return new InputStreamReader( is, Charset.forName( "UTF-8" ) );
+        }
+
+        @Override
+        public long getLastModified(Object templateSource) {
+            return 0;
+        }
+
+        @Override
+        public Object findTemplateSource(String name) throws IOException {
+            return name;
+        }
+
+        @Override
+        public void closeTemplateSource(Object templateSource) throws IOException {
+        }
+    }
+
+    /**
+     * {@link Context} implementation which provides access to the current FreeMarker {@link Configuration}.
      *
      * @author Gunnar Morling
      */