package org.vamsas.client.simpleclient;
+
import org.vamsas.client.*;
import java.io.BufferedInputStream;
import java.util.Vector;
/**
- * @author jim
- * Handler for the clientsFile within a vamsas session.
+ * @author jim Handler for the clientsFile within a vamsas session.
*/
public class ClientsFile {
private File filelist;
+
/**
- * number of my client in list
- * (not known at start but used when known to make lock)
+ * number of my client in list (not known at start but used when known to make
+ * lock)
*/
- private int syncnum=1;
-
- ClientsFile(File filelist) {
- this.filelist=filelist;
+ private int syncnum = 1;
+
+ public ClientsFile(File filelist) throws IOException {
+ this.filelist = filelist;
+ if (!this.filelist.exists())
+ this.filelist.createNewFile();
}
- public ClientHandle[] retrieveClientList() {
- if (filelist!=null) {
+
+ private Lock listlock = null;
+
+ /**
+ * Get a lock for the ClientsFile
+ *
+ * @return true if lock was made
+ */
+ protected boolean lockList() {
+ if (listlock != null && listlock.isLocked())
+ return true;
+ listlock = null;
+ if (filelist != null) {
if (filelist.exists()) {
- Lock listlock;
- do {
- listlock = new Lock(filelist); // TODO: wait around if we can't get the lock.
- } while (!listlock.isLocked());
+ // TODO: see if we need to loop-wait for locks or they just block until
+ // lock is made...
+ // do {
+ // 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 boolean unlockList() {
+ if (listlock != null) {
+
+ if (listlock.isLocked()) {
try {
- ObjectInputStream is = new ObjectInputStream(new BufferedInputStream(new java.io.FileInputStream(filelist)));
- ClientHandle[] clients;
- clients = (ClientHandle[]) ((Vector) is.readObject()).toArray();
- return clients;
+ listlock.lock.release();
+ } catch (IOException e) {
+ // TODO Deal with unlock Lock.release exception!
+ e.printStackTrace(System.err);
}
- catch (FileNotFoundException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- } catch (Exception e) {
- e.printStackTrace();
+ }
+
+ listlock = null;
+ return true;
+ }
+ return false;
+ }
+
+ /**
+ * internal method for getting clientList - ensures a lock has been made but
+ * does not release it.
+ *
+ * @return list of clients
+ */
+ private ClientHandle[] retrieveClientHandles() {
+ if (lockList()) {
+ try {
+ ClientHandle[] clients=null;
+ if (this.listlock.rafile.length()>0) {
+ ObjectInputStream is = new ObjectInputStream(new BufferedInputStream(
+ new java.io.FileInputStream(filelist)));
+ Object o;
+ o=is.readObject();
+ if (o!=null) {
+ try {
+ clients = (ClientHandle[]) o;
+ }
+ catch (Exception e) {
+ System.err.println("Garbage in the clientHandle list "+this.filelist);
+ }
+ }
}
+ return clients;
+ } catch (FileNotFoundException e) {
+ // TODO Auto-generated catch block
+ e.printStackTrace(System.err);
+ } catch (Exception e) {
+ e.printStackTrace(System.err);
}
- // else return null.
- } else {
- throw new Error("Tried to retrieve a clientList without specifying client list filename");
}
return null;
-
}
- public boolean putClientList(ClientHandle[] clients) {
- if (filelist!=null) {
- if (filelist.exists()) {
- Lock listlock;
- do {
- listlock = new Lock(filelist); // TODO: wait around if we can't get the lock? should return and make client wait until write has finished so it can read new client info...
- } while (!listlock.isLocked());
+ /**
+ * get the clientList from the file. May return false if lock failed!
+ * @return clientList
+ */
+ public ClientHandle[] retrieveClientList() {
+ if (lockList()) {
+ ClientHandle[] clients = retrieveClientHandles();
+ if (unlockList())
+ return clients;
+ }
+ return null;
+ }
+
+ /**
+ * adds the ClientHandle to the list - if it is not unique, then the
+ * ClientHandle object is modified to make it unique in the list. returns the
+ * clientNumber for the client in the session.
+ *
+ * @param me
+ * @return
+ */
+
+ public int addClient(ClientHandle me) {
+ syncnum = addClient(me, true);
+ unlockList();
+ return syncnum;
+ }
+
+ /**
+ * removes 'me' from the session ClientList without complaint if 'me' isn't in the clientList already.
+ * @param me
+ */
+ public void removeClient(ClientHandle me) {
+ int mynum=-1;
+ if (lockList()) {
+ ClientHandle[] clients = retrieveClientHandles();
+ if (clients != null) {
+ if (clients[syncnum-1]!=me) {
+ for (int i = 0, j = clients.length; i < j; i++)
+ if (clients[i].equals(me)) {
+ mynum=i;
+ break;
+ }
+ } else {
+ mynum=syncnum-1;
+ }
+ if (mynum>-1) {
+ ClientHandle[] newlist = new ClientHandle[clients.length - 1];
+ for (int k=0,i = 0, j = clients.length; i < j; i++)
+ if (i!=mynum)
+ newlist[k++] = clients[i];
+ if (!putClientList(clients))
+ throw new Error("Failed to write new clientList!"); // failed to put the clientList to disk.
+ }
+ }
+ unlockList();
+ } else {
+ throw new Error("Couldn't get lock for "+((filelist==null) ? "Unitialised filelist in ClientsFile" : filelist.getAbsolutePath()));
+ }
+ }
+ /**
+ * Adds a ClientHandle to the ClientList file - optionally disambiguating
+ * the ClientHandle (modifes the URN).
+ * Note: Caller is left to release the lock on the ClientList.
+ * @param me
+ * @param disambiguate -
+ * flag indicating if the URN for me should be disambiguate to
+ * differentiate between sessions.
+ * @return index of clientHandle in new list, or -1-position of existing
+ * clientHandle (if disambiguate is true)
+ */
+ protected int addClient(ClientHandle me, boolean disambiguate) {
+ int newclient = 0;
+ if (lockList()) {
+ ClientHandle[] clients = retrieveClientHandles();
+ if (me.getClientUrn()==null) {
+ // TODO: move this into ClientUrn as a standard form method.
+ me.setClientUrn("vamsas://"+me.getClientName()+":"+me.getVersion()+"/");
+ }
+ if (clients == null) {
+ clients = new ClientHandle[1];
+ clients[0] = me;
+ newclient = 1;
+ } else {
+ int k = 0;
+ for (int i = 0, j = clients.length; i < j; i++) {
+ if (clients[i].equals(me)) {
+ if (disambiguate) {
+ while (clients[i].equals(me)) {
+ me.setClientUrn(me.getClientUrn() + k++); // TODO: make a better
+ // disambiguation of
+ // urn.
+ }
+ } else {
+ // will not write the ambiguous clientHandle to disk, just return
+ // its index.
+ return -1 - i;
+ }
+ }
+ }
+ int i, j;
+ ClientHandle[] newlist = new ClientHandle[clients.length + 1];
+ for (i = 0, j = clients.length; i < j; i++)
+ newlist[i] = clients[i];
+ newlist[j] = me;
+ clients = newlist;
+ newclient = j+1;
+ }
+ if (!putClientList(clients))
+ return 0; // failed to put the clientList to disk.
+ }
+ return newclient;
+ }
+
+ /**
+ * safely writes clients array to the file referred to by filelist.
+ *
+ * @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 (templist != null) {
try {
- File templist=File.createTempFile(filelist.getName(),".temp",filelist);
- ObjectOutputStream os = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(templist)));
+ listlock.rafile.setLength(0);
+ ObjectOutputStream os = new ObjectOutputStream(
+ new BufferedOutputStream(new FileOutputStream(this.filelist)));
os.writeObject(clients);
os.close();
- }
- catch (FileNotFoundException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
+ // All done - remove the backup.
+ templist.delete();
+ templist = null;
} catch (Exception e) {
- e.printStackTrace();
+ if (templist != null) {
+ System.err
+ .println("Serious - problems writing to filelist. Backup in "
+ + templist.getAbsolutePath());
+ e.printStackTrace(System.err);
+ }
}
+ } else {
+ throw new Error(
+ "Couldn't create backup of the clientList before writing to it!");
}
- // else return null.
} else {
- throw new Error("Tried to retrieve a clientList without specifying client list filename");
+ throw new Error("Could not lock the clientList: "
+ + ((filelist == null) ? "Unitialized ClientsFile"
+ : " failed to get lock on " + filelist.getAbsolutePath()));
}
- return false;
+ // successful!
+ return true;
}
}
git://source.jalview.org / vamsas.git / blobdiff