/* Glazed Lists (c) 2003-2006 */
/* http://publicobject.com/glazedlists/ publicobject.com,*/
/* O'Dell Engineering Ltd.*/
package ca.odell.glazedlists.impl.pmap;
// NIO is used for CTP
import ca.odell.glazedlists.impl.io.Bufferlo;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.text.ParseException;
import java.util.logging.Logger;
/**
* Opens a file for reading and writing a persistent map.
*
* @author <a href="mailto:jesse@swank.ca">Jesse Wilson</a>
*/
class OpenFile implements Runnable {
/** logging */
private static Logger logger = Logger.getLogger(OpenFile.class.toString());
/** the host map */
private PersistentMap persistentMap = null;
/**
* Create a new OpenFile.
*/
public OpenFile(PersistentMap persistentMap) {
this.persistentMap = persistentMap;
}
/**
* Open the file, read any data if it exists, and prepare everything.
*/
public void run() {
FileChannel fileChannel = persistentMap.getFileChannel();
try {
// if the file doesn't already exist
if(fileChannel.size() == 0) {
createFile();
return;
}
// first read the header
readHeader();
// now read the data
while(true) {
Chunk chunk = Chunk.readChunk(persistentMap);
if(chunk == null) break;
persistentMap.loadedChunk(chunk);
if(chunk.isOn()) {
logger.info("Successfully loaded key \"" + chunk.getKey() + "\"");
}
}
} catch(IOException e) {
persistentMap.fail(e, "Failed to access file " + persistentMap.getFile().getPath());
}
}
/**
* Reads the file header, or creates a new file if the header is broken or
* doesn't exist.
*/
private void readHeader() throws IOException {
try {
// process the file header
Bufferlo fileHeader = new Bufferlo();
fileHeader.readFromChannel(persistentMap.getFileChannel(), 8);
fileHeader.consume("GLAZED\n\n");
} catch(ParseException e) {
// the file header is broken, bail
throw new IOException("The file cannot be read because it is not of the expected type");
}
logger.info("Successfully read file header");
}
/**
* Creates the PersistentMap file.
*/
private void createFile() throws IOException {
// write the file header
Bufferlo fileHeader = new Bufferlo();
fileHeader.write("GLAZED\n\n");
persistentMap.getFileChannel().position(0);
fileHeader.writeToChannel(persistentMap.getFileChannel());
logger.info("Successfully created file");
}
}