* Handler for the clientsFile within a vamsas session thread.
* @author jim
*/
-public class ClientsFile {
- private File filelist;
-
+public class ClientsFile extends SessionFile {
/**
- * number of my client in list (not known at start but used when known to make
- * lock)
+ * number of my client in list - passed back when a client
+ * is added to list, and used (if valid) for quickly
+ * looking up presence of client handle in the list.
*/
private int syncnum = 1;
public ClientsFile(File filelist) throws IOException {
- this.filelist = filelist;
- if (!this.filelist.exists())
- this.filelist.createNewFile();
- }
-
- private Lock listlock = null;
-
- protected boolean lockList(Lock extantlock) {
- if (listlock!=null && !listlock.isLocked()) {
- listlock.release();// tidy up invalid lock
- }
- listlock=extantlock;
- return lockList();
- }
- /**
- * Get a lock for the ClientsFile
- *
- * @return true if lock was made
- */
- protected boolean lockList() {
- if (listlock != null)
- if (listlock.isLocked())
- return true;
- else
- // lock failed for some reason.
- listlock.release();
- listlock = null;
- if (filelist != null) {
- if (filelist.exists()) {
- // TODO: see if we need to loop-wait for locks or they just block until
- // lock is made...
- do {
- if (listlock!=null)
- listlock.release();
- listlock = new Lock(filelist); // TODO: wait around if we can't get the lock.
- } while (!listlock.isLocked());
- // listlock = new Lock(filelist);
- return listlock.isLocked();
- }
- } else
- throw new Error(
- "org.vamsas.client.simpleclient.ClientsFile.lockList called for non-initialised ClientsFile!");
-
- // no lock possible
- return false;
- }
-
- /**
- * Explicitly release the ClientsFile lock.
- *
- * @return true if lock was released.
- */
- protected void unlockList() {
- if (listlock != null) {
- listlock.release();
- listlock = null;
- }
+ this.sessionFile = filelist;
+ if (!this.sessionFile.exists())
+ this.sessionFile.createNewFile();
}
/**
* @return list of clients
*/
private ClientHandle[] retrieveClientHandles() {
- if (lockList()) {
+ if (lockFile()) {
try {
ClientHandle[] clients=null;
- if (this.listlock.rafile.length()>0) {
+ if (this.fileLock.rafile.length()>0) {
ObjectInputStream is = new ObjectInputStream(new BufferedInputStream(
- new java.io.FileInputStream(filelist)));
+ new java.io.FileInputStream(sessionFile)));
Object o;
o=is.readObject();
if (o!=null) {
clients = (ClientHandle[]) o;
}
catch (Exception e) {
- System.err.println("Garbage in the clientHandle list "+this.filelist);
+ System.err.println("Garbage in the clientHandle list "+this.sessionFile);
}
}
}
* @return clientList
*/
public ClientHandle[] retrieveClientList() {
- if (lockList()) {
+ if (lockFile()) {
ClientHandle[] clients = retrieveClientHandles();
- unlockList();
+ unlockFile();
return clients;
}
return null;
* @return clientList or null if lock failed (or file was empty)
*/
public ClientHandle[] retrieveClientList(Lock extantlock) {
- if (lockList(extantlock)) {
+ if (lockFile(extantlock)) {
ClientHandle[] clients = retrieveClientHandles();
- unlockList();
+ unlockFile();
return clients;
}
return null;
*/
public int addClient(ClientHandle me, boolean disambig, Lock extantLock) {
- if (lockList(extantLock)) {
+ if (lockFile(extantLock)) {
syncnum = addClient(me, disambig);
- unlockList();
+ unlockFile();
return syncnum;
}
return 0;
public int addClient(ClientHandle me) {
syncnum = addClient(me, true);
- unlockList();
+ unlockFile();
return syncnum;
}
*/
public void removeClient(ClientHandle me, Lock clientlock) {
int mynum=-1;
- if (lockList(clientlock)) {
+ if (lockFile(clientlock)) {
ClientHandle[] clients = retrieveClientHandles();
if (clients != null) {
if ((syncnum<=0 || syncnum>clients.length) || clients[syncnum-1]!=me) {
throw new Error("Failed to write new clientList!"); // failed to put the clientList to disk.
}
}
- unlockList();
+ unlockFile();
} else {
- throw new Error("Couldn't get lock for "+((filelist==null) ? "Unitialised filelist in ClientsFile" : filelist.getAbsolutePath()));
+ throw new Error("Couldn't get lock for "+((sessionFile==null) ? "Unitialised sessionFile in ClientsFile" : sessionFile.getAbsolutePath()));
}
}
/**
*/
protected int addClient(ClientHandle me, boolean disambiguate) {
int newclient = 0;
- if (lockList()) {
+ if (lockFile()) {
ClientHandle[] clients = retrieveClientHandles();
if (me.getClientUrn()==null) {
// TODO: move this into ClientUrn as a standard form method.
}
return newclient;
}
-
+
/**
- * safely writes clients array to the file referred to by filelist.
+ * safely writes clients array to the file referred to by sessionFile.
*
* @param clients
* @return true if successful write. Throws Errors otherwise.
*/
protected boolean putClientList(ClientHandle[] clients) {
- if (lockList()) {
- File templist = null;
- try {
- templist = File.createTempFile(filelist.getName(),".old", filelist.getParentFile());
- FileOutputStream tos = new FileOutputStream(templist);
- tos.getChannel().transferFrom(listlock.rafile.getChannel(), 0,
- listlock.rafile.length());
- tos.close();
- } catch (FileNotFoundException e1) {
- System.err.println("Can't create temp file for clientlist");
- e1.printStackTrace(System.err);
- } catch (IOException e1) {
- System.err
- .println("Error when copying content to temp file for clientlist");
- e1.printStackTrace(System.err);
- }
+ if (lockFile()) {
+ File templist = backupSessionFile();
if (templist != null) {
try {
- listlock.rafile.setLength(0);
+ fileLock.rafile.setLength(0);
ObjectOutputStream os = new ObjectOutputStream(
- new BufferedOutputStream(new FileOutputStream(this.filelist)));
+ new BufferedOutputStream(new FileOutputStream(this.sessionFile)));
os.writeObject(clients);
os.close();
// All done - remove the backup.
} catch (Exception e) {
if (templist != null) {
System.err
- .println("Serious - problems writing to filelist. Backup in "
+ .println("Serious - problems writing to sessionFile. Backup in "
+ templist.getAbsolutePath());
e.printStackTrace(System.err);
}
}
} else {
throw new Error("Could not lock the clientList: "
- + ((filelist == null) ? "Unitialized ClientsFile"
- : " failed to get lock on " + filelist.getAbsolutePath()));
+ + ((sessionFile == null) ? "Unitialized ClientsFile"
+ : " failed to get lock on " + sessionFile.getAbsolutePath()));
}
// successful!
return true;
--- /dev/null
+package org.vamsas.client.simpleclient;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+/**
+ * Basic methods for classes handling locked IO on files
+ * monitored by all (simpleclient) clients in a vamsas session.
+ * @author jimp
+ *
+ */
+public class SessionFile {
+
+ protected File sessionFile;
+ protected Lock fileLock = null;
+
+ protected boolean lockFile(Lock extantlock) {
+ if (fileLock!=null && !fileLock.isLocked()) {
+ fileLock.release();// tidy up invalid lock
+ }
+ fileLock=extantlock;
+ return lockFile();
+ }
+
+ /**
+ * Get a lock for the SessionFile
+ *
+ * @return true if lock was made
+ */
+ protected boolean lockFile() {
+ if (fileLock != null)
+ if (fileLock.isLocked())
+ return true;
+ else
+ // lock failed for some reason.
+ fileLock.release();
+ fileLock = null;
+ if (sessionFile != null) {
+ if (sessionFile.exists()) {
+ // TODO: see if we need to loop-wait for locks or they just block until
+ // lock is made...
+ do {
+ if (fileLock!=null)
+ fileLock.release();
+ fileLock = new Lock(sessionFile); // TODO: wait around if we can't get the lock.
+ } while (!fileLock.isLocked());
+ // fileLock = new Lock(sessionFile);
+ return fileLock.isLocked();
+ }
+ } else
+ throw new Error(
+ "org.vamsas.client.simpleclient.ClientsFile.lockList called for non-initialised ClientsFile!");
+
+ // no lock possible
+ return false;
+ }
+
+ /**
+ * Explicitly release the SessionFile's lock.
+ *
+ * @return true if lock was released.
+ */
+ protected void unlockFile() {
+ if (fileLock != null) {
+ fileLock.release();
+ fileLock = null;
+ }
+ }
+
+ /**
+ * Makes a backup of the sessionFile.
+ * @return Backed up SessionFile or null if failed to make backup.
+ */
+ protected File backupSessionFile() {
+ return backupSessionFile(null, sessionFile.getName(),".old", sessionFile.getParentFile());
+ }
+
+ protected File backupSessionFile(Lock extantLock, String backupPrefix, String backupSuffix, File backupDir) {
+ File tempfile=null;
+ if (lockFile(extantLock)) {
+ try {
+ tempfile = File.createTempFile(backupPrefix, backupSuffix, backupDir);
+ FileOutputStream tos = new FileOutputStream(tempfile);
+ tos.getChannel().transferFrom(fileLock.rafile.getChannel(), 0,
+ fileLock.rafile.length());
+ tos.close();
+ } catch (FileNotFoundException e1) {
+ System.err.println("Can't create temp file for "+sessionFile.getName());
+ e1.printStackTrace(System.err);
+ tempfile=null;
+ } catch (IOException e1) {
+ System.err
+ .println("Error when copying content to temp file for "+sessionFile.getName());
+ e1.printStackTrace(System.err);
+ tempfile=null;
+ }
+ }
+ return tempfile;
+ }
+
+}
git://source.jalview.org / vamsas.git / commitdiff