1 package org.vamsas.client.simpleclient;
3 import org.vamsas.client.*;
5 import java.io.BufferedInputStream;
6 import java.io.BufferedOutputStream;
8 import java.io.FileInputStream;
9 import java.io.FileNotFoundException;
10 import java.io.FileOutputStream;
11 import java.io.IOException;
12 import java.io.InputStreamReader;
13 import java.io.ObjectInputStream;
14 import java.io.ObjectOutput;
15 import java.io.ObjectOutputStream;
16 import java.io.OutputStream;
17 import java.util.Vector;
20 * @author jim Handler for the clientsFile within a vamsas session.
22 public class ClientsFile {
23 private File filelist;
26 * number of my client in list (not known at start but used when known to make
29 private int syncnum = 1;
31 public ClientsFile(File filelist) throws IOException {
32 this.filelist = filelist;
33 if (!this.filelist.exists())
34 this.filelist.createNewFile();
37 private Lock listlock = null;
40 * Get a lock for the ClientsFile
42 * @return true if lock was made
44 protected boolean lockList() {
45 if (listlock != null && listlock.isLocked())
48 if (filelist != null) {
49 if (filelist.exists()) {
50 // TODO: see if we need to loop-wait for locks or they just block until
53 listlock = new Lock(filelist); // TODO: wait around if we can't get the lock.
54 } while (!listlock.isLocked());
55 // listlock = new Lock(filelist);
56 return listlock.isLocked();
60 "org.vamsas.client.simpleclient.ClientsFile.lockList called for non-initialised ClientsFile!");
67 * Explicitly release the ClientsFile lock.
69 * @return true if lock was released.
71 protected boolean unlockList() {
72 if (listlock != null) {
74 if (listlock.isLocked()) {
76 listlock.lock.release();
77 } catch (IOException e) {
78 // TODO Deal with unlock Lock.release exception!
79 e.printStackTrace(System.err);
90 * internal method for getting clientList - ensures a lock has been made but
91 * does not release it.
93 * @return list of clients
95 private ClientHandle[] retrieveClientHandles() {
98 ClientHandle[] clients=null;
99 if (this.listlock.rafile.length()>0) {
100 ObjectInputStream is = new ObjectInputStream(new BufferedInputStream(
101 new java.io.FileInputStream(filelist)));
106 clients = (ClientHandle[]) o;
108 catch (Exception e) {
109 System.err.println("Garbage in the clientHandle list "+this.filelist);
114 } catch (FileNotFoundException e) {
115 // TODO Auto-generated catch block
116 e.printStackTrace(System.err);
117 } catch (Exception e) {
118 e.printStackTrace(System.err);
124 * get the clientList from the file. May return false if lock failed!
127 public ClientHandle[] retrieveClientList() {
129 ClientHandle[] clients = retrieveClientHandles();
137 * adds the ClientHandle to the list - if it is not unique, then the
138 * ClientHandle object is modified to make it unique in the list. returns the
139 * clientNumber for the client in the session.
145 public int addClient(ClientHandle me) {
146 syncnum = addClient(me, true);
152 * removes 'me' from the session ClientList without complaint if 'me' isn't in the clientList already.
155 public void removeClient(ClientHandle me) {
158 ClientHandle[] clients = retrieveClientHandles();
159 if (clients != null) {
160 if (clients[syncnum-1]!=me) {
161 for (int i = 0, j = clients.length; i < j; i++)
162 if (clients[i].equals(me)) {
170 ClientHandle[] newlist = new ClientHandle[clients.length - 1];
171 for (int k=0,i = 0, j = clients.length; i < j; i++)
173 newlist[k++] = clients[i];
174 if (!putClientList(newlist))
175 throw new Error("Failed to write new clientList!"); // failed to put the clientList to disk.
180 throw new Error("Couldn't get lock for "+((filelist==null) ? "Unitialised filelist in ClientsFile" : filelist.getAbsolutePath()));
184 * Adds a ClientHandle to the ClientList file - optionally disambiguating
185 * the ClientHandle (modifes the URN).
186 * Note: Caller is left to release the lock on the ClientList.
188 * @param disambiguate -
189 * flag indicating if the URN for me should be disambiguated to
190 * differentiate between sessions.
191 * @return index of clientHandle in new list, or -1-position of existing
192 * clientHandle (if disambiguate is true)
194 protected int addClient(ClientHandle me, boolean disambiguate) {
197 ClientHandle[] clients = retrieveClientHandles();
198 if (me.getClientUrn()==null) {
199 // TODO: move this into ClientUrn as a standard form method.
200 me.setClientUrn("vamsas://"+me.getClientName()+":"+me.getVersion()+"/");
202 if (clients == null) {
203 clients = new ClientHandle[1];
208 for (int i = 0, j = clients.length; i < j; i++) {
209 if (clients[i].equals(me)) {
211 while (clients[i].equals(me)) {
212 me.setClientUrn(me.getClientUrn() + k++); // TODO: make a better
217 // will not write the ambiguous clientHandle to disk, just return
224 ClientHandle[] newlist = new ClientHandle[clients.length + 1];
225 for (i = 0, j = clients.length; i < j; i++)
226 newlist[i] = clients[i];
231 if (!putClientList(clients))
232 return 0; // failed to put the clientList to disk.
238 * safely writes clients array to the file referred to by filelist.
241 * @return true if successful write. Throws Errors otherwise.
243 protected boolean putClientList(ClientHandle[] clients) {
245 File templist = null;
247 templist = File.createTempFile(filelist.getName(),".old", filelist.getParentFile());
248 FileOutputStream tos = new FileOutputStream(templist);
249 tos.getChannel().transferFrom(listlock.rafile.getChannel(), 0,
250 listlock.rafile.length());
252 } catch (FileNotFoundException e1) {
253 System.err.println("Can't create temp file for clientlist");
254 e1.printStackTrace(System.err);
255 } catch (IOException e1) {
257 .println("Error when copying content to temp file for clientlist");
258 e1.printStackTrace(System.err);
260 if (templist != null) {
262 listlock.rafile.setLength(0);
263 ObjectOutputStream os = new ObjectOutputStream(
264 new BufferedOutputStream(new FileOutputStream(this.filelist)));
265 os.writeObject(clients);
267 // All done - remove the backup.
270 } catch (Exception e) {
271 if (templist != null) {
273 .println("Serious - problems writing to filelist. Backup in "
274 + templist.getAbsolutePath());
275 e.printStackTrace(System.err);
280 "Couldn't create backup of the clientList before writing to it!");
283 throw new Error("Could not lock the clientList: "
284 + ((filelist == null) ? "Unitialized ClientsFile"
285 : " failed to get lock on " + filelist.getAbsolutePath()));