Implemented FileState serialization/deserialization.

src/main/java/info/fetter/logstashforwarder/FileState.java

@@ -61,7 +61,7 @@ public class FileState {
 	}
 	
 	private void setFileFromDirectoryAndName() {
-		this.file = new File(directory + File.pathSeparator + fileName);
+		this.file = new File(directory + File.separator + fileName);
 	}
 
 	public File getFile() {

src/main/java/info/fetter/logstashforwarder/FileWatcher.java

@@ -40,8 +40,17 @@ public class FileWatcher {
 	public static final int ONE_DAY = 24 * 3600 * 1000;
 	private Map<File,FileState> watchMap = new HashMap<File,FileState>();
 	private Map<File,FileState> changedWatchMap = new HashMap<File,FileState>();
+	private FileState[] savedStates;
 	private static int MAX_SIGNATURE_LENGTH = 1024;
 
+	public FileWatcher() {
+		try {
+			savedStates = Registrar.readStateFromJson();
+		} catch(Exception e) {
+			logger.warn("Could not load saved states : " + e.getMessage());
+		}
+	}
+
 	public void addFilesToWatch(String fileToWatch, Event fields, int deadTime) {
 		try {
 			if(fileToWatch.equals("-")) {
@@ -65,11 +74,13 @@ public class FileWatcher {
 		processModifications();
 		printWatchMap();
 	}
-	
+
 	public int readFiles(FileReader reader) throws IOException {
 		logger.debug("Reading files");
 		logger.trace("==============");
-		return reader.readFiles(watchMap.values());
+		int numberOfLinesRead = reader.readFiles(watchMap.values());
+		Registrar.writeStateToJson(watchMap.values());
+		return numberOfLinesRead;
 	}
 
 	private void processModifications() throws IOException {
@@ -204,7 +215,46 @@ public class FileWatcher {
 		observerList.add(observer);
 		observer.initialize();
 		for(File file : FileUtils.listFiles(directory, fileFilter, null)) {
-			addFileToWatchMap(watchMap, file, fields);
+			FileState savedState = null;
+			if(savedStates != null) {
+				for(FileState state : savedStates) {
+					logger.trace("Comparing file : " + file + " with saved file : " + state.getFile());
+					if(file.equals(state.getFile())) {
+						savedState = state;
+						logger.debug("Match found with saved file " + state.getFile());
+					}
+				}
+			}
+			if(savedState == null) {
+				addFileToWatchMap(watchMap, file, fields);
+			} else {
+				addSavedFileToWatchMap(savedState, fields);
+			}
+		}
+	}
+
+	private void addSavedFileToWatchMap(FileState savedFileState, Event fields) {
+		try {
+			File file = savedFileState.getFile();
+			FileState state = new FileState(file);
+			state.setFields(fields);
+			int savedSignatureLength = savedFileState.getSignatureLength();
+			state.setSignatureLength(savedSignatureLength);
+			long savedSignature = savedFileState.getSignature();
+			int signatureLength = (int) (state.getSize() > MAX_SIGNATURE_LENGTH ? MAX_SIGNATURE_LENGTH : state.getSize());
+			long signature = FileSigner.computeSignature(state.getRandomAccessFile(), signatureLength);
+			if(signature == savedSignature) { 
+				state.setPointer(savedFileState.getPointer());
+				logger.debug("Restoring signature of size : " + savedSignatureLength + " on file : " + file + " : " + savedSignature);
+			} else {
+				logger.debug("File " + file + " signature has changed");
+				logger.trace("Setting signature of size : " + signatureLength + " on file : " + file + " : " + signature);
+			}
+			state.setSignatureLength(signatureLength);
+			state.setSignature(signature);
+			watchMap.put(file, state);
+		} catch (IOException e) {
+			logger.error("Caught IOException : " + e.getMessage());
 		}
 	}
 

src/main/java/info/fetter/logstashforwarder/Forwarder.java

@@ -42,7 +42,7 @@ public class Forwarder {
 	private static int idleTimeout = 5000;
 	private static String config;
 	private static ConfigurationManager configManager;
-	private static FileWatcher watcher = new FileWatcher();
+	private static FileWatcher watcher;
 	private static FileReader reader;
 	private static Level logLevel = INFO;
 	private static ProtocolAdapter adapter;
@@ -55,6 +55,7 @@ public class Forwarder {
 //			Logger.getLogger(FileReader.class).addAppender((Appender)RootLogger.getRootLogger().getAllAppenders().nextElement());
 //			Logger.getLogger(FileReader.class).setLevel(TRACE);
 //			Logger.getLogger(FileReader.class).setAdditivity(false);
+			watcher = new FileWatcher();
 			configManager = new ConfigurationManager(config);
 			configManager.readConfiguration();
 			for(FilesSection files : configManager.getConfig().getFiles()) {

src/main/java/info/fetter/logstashforwarder/Registrar.java

@@ -0,0 +1,58 @@
+package info.fetter.logstashforwarder;
+
+/*
+ * Copyright 2015 Didier Fetter
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Collection;
+
+import com.fasterxml.jackson.core.JsonGenerationException;
+import com.fasterxml.jackson.core.JsonParseException;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class Registrar {
+	private static final String SINCEDB = ".logstash-forwarder-java";
+	
+	private static ObjectMapper mapper = new ObjectMapper();
+	
+	public static FileState[] readStateFromJson(File file) throws JsonParseException, JsonMappingException, IOException {
+		FileState[] stateArray = mapper.readValue(file, FileState[].class);
+		return stateArray;
+	}
+	
+	public static FileState[] readStateFromJson(String file) throws JsonParseException, JsonMappingException, IOException {
+		return readStateFromJson(new File(file));
+	}
+	
+	public static FileState[] readStateFromJson() throws JsonParseException, JsonMappingException, IOException {
+		return readStateFromJson(SINCEDB);
+	}
+	
+	public static void writeStateToJson(File file, Collection<FileState> stateList) throws JsonGenerationException, JsonMappingException, IOException {
+		mapper.writeValue(file, stateList);
+	}
+	
+	public static void writeStateToJson(String file, Collection<FileState> stateList) throws JsonGenerationException, JsonMappingException, IOException {
+		writeStateToJson(new File(file), stateList);
+	}
+	
+	public static void writeStateToJson(Collection<FileState> stateList) throws JsonGenerationException, JsonMappingException, IOException {
+		writeStateToJson(SINCEDB, stateList);
+	}
+}

src/test/java/info/fetter/logstashforwarder/RegistrarTest.java

@@ -0,0 +1,81 @@
+package info.fetter.logstashforwarder;
+
+/*
+ * Copyright 2015 Didier Fetter
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import static org.apache.log4j.Level.DEBUG;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.log4j.BasicConfigurator;
+import org.apache.log4j.Logger;
+import org.apache.log4j.spi.RootLogger;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import com.fasterxml.jackson.core.JsonGenerationException;
+import com.fasterxml.jackson.core.JsonParseException;
+import com.fasterxml.jackson.databind.JsonMappingException;
+
+public class RegistrarTest {
+	Logger logger = Logger.getLogger(RegistrarTest.class);
+
+	@BeforeClass
+	public static void setUpBeforeClass() throws Exception {
+		BasicConfigurator.configure();
+		RootLogger.getRootLogger().setLevel(DEBUG);
+	}
+
+	@AfterClass
+	public static void tearDownAfterClass() throws Exception {
+		BasicConfigurator.resetConfiguration();
+	}
+	
+	@Test
+	public void testReadState1() throws JsonParseException, JsonMappingException, IOException {
+		FileState[] states = Registrar.readStateFromJson(new File(RegistrarTest.class.getClassLoader().getResource("state1.json").getFile()));
+		for(FileState state : states) {
+			logger.debug("Loaded state : " + state);
+		}
+	}
+	
+	@Test
+	public void testWriteState2() throws JsonGenerationException, JsonMappingException, IOException {
+		FileState state1 = new FileState();
+		state1.setDirectory("/directory1");
+		state1.setFileName("file1");
+		state1.setPointer(1234);
+		state1.setSignature(123456);
+		state1.setSignatureLength(135);
+		FileState state2 = new FileState();
+		state2.setDirectory("/directory2");
+		state2.setFileName("file2");
+		state2.setPointer(4321);
+		state2.setSignature(654321);
+		state2.setSignatureLength(531);
+		List<FileState> stateList = new ArrayList<FileState>(2);
+		stateList.add(state1);
+		stateList.add(state2);
+		File file = new File("state2.json");
+		logger.debug("Writing to file : " + file.getCanonicalPath());
+		Registrar.writeStateToJson(file, stateList);
+	}
+}