package net.sf.jabref.collab;
import net.sf.jabref.Globals;
import net.sf.jabref.Util;
import java.util.HashMap;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
/**
* This thread monitors a set of files, each associated with a FileUpdateListener, for changes
* in the file's last modification time stamp. The
*/
public class FileUpdateMonitor extends Thread {
final int WAIT = 4000;
static int tmpNum = 0;
int no = 0;
HashMap<String, Entry> entries = new HashMap<String, Entry>();
boolean running;
public FileUpdateMonitor() {
setPriority(MIN_PRIORITY);
}
public void run() {
running = true;
// The running variable is used to make the thread stop when needed.
while (running) {
//System.out.println("Polling...");
Iterator<String> i = entries.keySet().iterator();
for (;i.hasNext();) {
Entry e = entries.get(i.next());
try {
if (e.hasBeenUpdated())
e.notifyListener();
//else
//System.out.println("File '"+e.file.getPath()+"' not modified.");
} catch (IOException ex) {
e.notifyFileRemoved();
}
}
// Sleep for a while before starting a new polling round.
try {
sleep(WAIT);
} catch (InterruptedException ex) {
}
}
}
/**
* Cause the thread to stop monitoring. It will finish the current round before stopping.
*/
public void stopMonitoring() {
running = false;
}
/**
* Add a new file to monitor. Returns a handle for accessing the entry.
* @param ul FileUpdateListener The listener to notify when the file changes.
* @param file File The file to monitor.
* @throws IOException if the file does not exist.
*/
public String addUpdateListener(FileUpdateListener ul, File file) throws IOException {
// System.out.println(file.getPath());
if (!file.exists())
throw new IOException("File not found");
no++;
String key = ""+no;
entries.put(key, new Entry(ul, file));
return key;
}
/**
* Forces a check on the file, and returns the result. Does not
* force a report to all listeners before the next routine check.
*/
public boolean hasBeenModified(String handle) throws IllegalArgumentException {
Object o = entries.get(handle);
if (o == null)
return false;
// throw new IllegalArgumentException("Entry not found");
try {
return ((Entry)o).hasBeenUpdated();
} catch (IOException ex) {
// Thrown if file has been removed. We return false.
return false;
}
}
/**
* Change the stored timestamp for the given file. If the timestamp equals
* the file's timestamp on disk, after this call the file will appear to
* have been modified. Used if a file has been modified, and the change
* scan fails, in order to ensure successive checks.
* @param handle the handle to the correct file.
*/
public void perturbTimestamp(String handle) {
Object o = entries.get(handle);
if (o == null)
return;
((Entry)o).timeStamp--;
}
/**
* Removes a listener from the monitor.
* @param handle String The handle for the listener to remove.
*/
public void removeUpdateListener(String handle) {
entries.remove(handle);
}
public void updateTimeStamp(String key) throws IllegalArgumentException {
Object o = entries.get(key);
if (o == null)
throw new IllegalArgumentException("Entry not found");
Entry entry = (Entry)o;
entry.updateTimeStamp();
}
public void changeFile(String key, File file) throws IOException, IllegalArgumentException {
if (!file.exists())
throw new IOException("File not found");
Object o = entries.get(key);
if (o == null)
throw new IllegalArgumentException("Entry not found");
((Entry)o).file = file;
}
/**
* Method for getting the temporary file used for this database. The tempfile
* is used for comparison with the changed on-disk version.
* @param key String The handle for this monitor.
* @throws IllegalArgumentException If the handle doesn't correspond to an entry.
* @return File The temporary file.
*/
public File getTempFile(String key) throws IllegalArgumentException {
Object o = entries.get(key);
if (o == null)
throw new IllegalArgumentException("Entry not found");
return ((Entry)o).tmpFile;
}
/**
* A class containing the File, the FileUpdateListener and the current time stamp for one file.
*/
class Entry {
FileUpdateListener listener;
File file;
File tmpFile;
long timeStamp, fileSize;
public Entry(FileUpdateListener ul, File f) {
listener = ul;
file = f;
timeStamp = file.lastModified();
fileSize = file.length();
tmpFile = getTempFile();
tmpFile.deleteOnExit();
copy();
}
/**
* Check if time stamp or the file size has changed.
* @throws IOException if the file does no longer exist.
* @return boolean true if the file has changed.
*/
public boolean hasBeenUpdated() throws IOException {
long modified = file.lastModified();
long fileSizeNow = file.length();
if (modified == 0L)
throw new IOException("File deleted");
return timeStamp != modified || fileSize != fileSizeNow;
}
public void updateTimeStamp() {
timeStamp = file.lastModified();
if (timeStamp == 0L)
notifyFileRemoved();
fileSize = file.length();
copy();
}
public boolean copy() {
//Util.pr("<copy file=\""+tmpFile.getPath()+"\">");
boolean res = false;
try {
res = Util.copyFile(file, tmpFile, true);
} catch (IOException ex) {
Globals.logger("Cannot copy to temporary file '"+tmpFile.getPath()+"'");
}
//Util.pr("</copy>");
return res;
//return true;
}
/**
* Call the listener method to signal that the file has changed.
*/
public void notifyListener() {
// Update time stamp.
timeStamp = file.lastModified();
fileSize = file.length();
listener.fileUpdated();
}
/**
* Call the listener method to signal that the file has been removed.
*/
public void notifyFileRemoved() {
listener.fileRemoved();
}
/*public void finalize() {
try {
tmpFile.delete();
} catch (Throwable e) {
Globals.logger("Cannot delete temporary file '"+tmpFile.getPath()+"'");
}
}*/
}
static synchronized File getTempFile() {
File f = null;
// Globals.prefs.get("tempDir")
//while ((f = File.createTempFile("jabref"+(tmpNum++), null)).exists());
try {
f = File.createTempFile("jabref", null);
f.deleteOnExit();
//System.out.println(f.getPath());
} catch (IOException ex) {
ex.printStackTrace();
}
return f;
}
}