refactor into a service

src/main/java/com/commafeed/backend/service/FeedEntryFilteringService.java

@@ -0,0 +1,111 @@
+package com.commafeed.backend.service;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import org.apache.commons.jexl2.JexlContext;
+import org.apache.commons.jexl2.JexlEngine;
+import org.apache.commons.jexl2.JexlException;
+import org.apache.commons.jexl2.JexlInfo;
+import org.apache.commons.jexl2.MapContext;
+import org.apache.commons.jexl2.Script;
+import org.apache.commons.jexl2.introspection.JexlMethod;
+import org.apache.commons.jexl2.introspection.JexlPropertyGet;
+import org.apache.commons.jexl2.introspection.Uberspect;
+import org.apache.commons.jexl2.introspection.UberspectImpl;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.commons.logging.LogFactory;
+import org.jsoup.Jsoup;
+
+import com.commafeed.backend.model.FeedEntry;
+
+public class FeedEntryFilteringService {
+
+	private static final JexlEngine ENGINE = initEngine();
+
+	private static JexlEngine initEngine() {
+		// classloader that prevents object creation
+		ClassLoader cl = new ClassLoader() {
+			@Override
+			public Class<?> loadClass(String name) throws ClassNotFoundException {
+				return null;
+			}
+
+			@Override
+			protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
+				return null;
+			}
+		};
+
+		// uberspect that prevents access to .class and .getClass()
+		Uberspect uberspect = new UberspectImpl(LogFactory.getLog(JexlEngine.class)) {
+			@Override
+			public JexlPropertyGet getPropertyGet(Object obj, Object identifier, JexlInfo info) {
+				if ("class".equals(identifier)) {
+					return null;
+				}
+				return super.getPropertyGet(obj, identifier, info);
+			}
+
+			@Override
+			public JexlMethod getMethod(Object obj, String method, Object[] args, JexlInfo info) {
+				if ("getClass".equals(method)) {
+					return null;
+				}
+				return super.getMethod(obj, method, args, info);
+			}
+		};
+
+		JexlEngine engine = new JexlEngine(uberspect, null, null, null);
+		engine.setStrict(true);
+		engine.setClassLoader(cl);
+		return engine;
+	}
+
+	private ExecutorService executor = Executors.newCachedThreadPool();
+
+	public boolean filterMatchesEntry(String filter, FeedEntry entry) throws FeedEntryFilterException {
+		if (StringUtils.isBlank(filter)) {
+			return true;
+		}
+
+		Script script = null;
+		try {
+			script = ENGINE.createScript(filter);
+		} catch (JexlException e) {
+			throw new FeedEntryFilterException("Exception while parsing expression " + filter, e);
+		}
+
+		JexlContext context = new MapContext();
+		context.set("title", Jsoup.parse(entry.getContent().getTitle()).text().toLowerCase());
+		context.set("author", entry.getContent().getAuthor().toLowerCase());
+		context.set("content", Jsoup.parse(entry.getContent().getContent()).text().toLowerCase());
+		context.set("url", entry.getUrl().toLowerCase());
+
+		Callable<Object> callable = script.callable(context);
+		Future<Object> future = executor.submit(callable);
+		Object result = null;
+		try {
+			result = future.get(500, TimeUnit.MILLISECONDS);
+		} catch (InterruptedException e) {
+			throw new FeedEntryFilterException("interrupted while evaluating expression " + filter, e);
+		} catch (ExecutionException e) {
+			throw new FeedEntryFilterException("Exception while evaluating expression " + filter, e);
+		} catch (TimeoutException e) {
+			throw new FeedEntryFilterException("Took too long evaluating expression " + filter, e);
+		}
+		return (boolean) result;
+	}
+
+	@SuppressWarnings("serial")
+	public static class FeedEntryFilterException extends Exception {
+		public FeedEntryFilterException(String message, Throwable t) {
+			super(message, t);
+		}
+	}
+}

src/main/java/com/commafeed/backend/service/FeedUpdateService.java

@@ -13,13 +13,12 @@ import org.apache.commons.codec.digest.DigestUtils;
 
 import com.commafeed.backend.dao.FeedEntryDAO;
 import com.commafeed.backend.dao.FeedEntryStatusDAO;
-import com.commafeed.backend.feed.FeedEntryFilter;
-import com.commafeed.backend.feed.FeedEntryFilter.FeedEntryFilterException;
 import com.commafeed.backend.model.Feed;
 import com.commafeed.backend.model.FeedEntry;
 import com.commafeed.backend.model.FeedEntryContent;
 import com.commafeed.backend.model.FeedEntryStatus;
 import com.commafeed.backend.model.FeedSubscription;
+import com.commafeed.backend.service.FeedEntryFilteringService.FeedEntryFilterException;
 
 @Slf4j
 @RequiredArgsConstructor(onConstructor = @__({ @Inject }))
@@ -29,6 +28,7 @@ public class FeedUpdateService {
 	private final FeedEntryDAO feedEntryDAO;
 	private final FeedEntryStatusDAO feedEntryStatusDAO;
 	private final FeedEntryContentService feedEntryContentService;
+	private final FeedEntryFilteringService feedEntryFilteringService;
 
 	/**
 	 * this is NOT thread-safe
@@ -49,10 +49,9 @@ public class FeedUpdateService {
 
 		// if filter does not match the entry, mark it as read
 		for (FeedSubscription sub : subscriptions) {
-			FeedEntryFilter filter = new FeedEntryFilter(sub.getFilter());
 			boolean matches = true;
 			try {
-				matches = filter.matchesEntry(entry);
+				matches = feedEntryFilteringService.filterMatchesEntry(sub.getFilter(), entry);
 			} catch (FeedEntryFilterException e) {
 				log.error("could not evaluate filter {}", sub.getFilter(), e);
 			}