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
55 listlock = new Lock(filelist); // TODO: wait around if we can't get the lock.
56 } while (!listlock.isLocked());
57 // listlock = new Lock(filelist);
58 return listlock.isLocked();
62 "org.vamsas.client.simpleclient.ClientsFile.lockList called for non-initialised ClientsFile!");
69 * Explicitly release the ClientsFile lock.
71 * @return true if lock was released.
73 protected void unlockList() {
74 if (listlock != null) {
76 if (listlock.isLocked()) {
85 * internal method for getting clientList - ensures a lock has been made but
86 * does not release it.
88 * @return list of clients
90 private ClientHandle[] retrieveClientHandles() {
93 ClientHandle[] clients=null;
94 if (this.listlock.rafile.length()>0) {
95 ObjectInputStream is = new ObjectInputStream(new BufferedInputStream(
96 new java.io.FileInputStream(filelist)));
101 clients = (ClientHandle[]) o;
103 catch (Exception e) {
104 System.err.println("Garbage in the clientHandle list "+this.filelist);
109 } catch (FileNotFoundException e) {
110 // TODO Auto-generated catch block
111 e.printStackTrace(System.err);
112 } catch (Exception e) {
113 e.printStackTrace(System.err);
119 * get the clientList from the file. May return false if lock failed!
122 public ClientHandle[] retrieveClientList() {
124 ClientHandle[] clients = retrieveClientHandles();
132 * adds the ClientHandle to the list - if it is not unique, then the
133 * ClientHandle object is modified to make it unique in the list. returns the
134 * clientNumber for the client in the session.
140 public int addClient(ClientHandle me) {
141 syncnum = addClient(me, true);
147 * removes 'me' from the session ClientList without complaint if 'me' isn't in the clientList already.
150 public void removeClient(ClientHandle me) {
153 ClientHandle[] clients = retrieveClientHandles();
154 if (clients != null) {
155 if (clients[syncnum-1]!=me) {
156 for (int i = 0, j = clients.length; i < j; i++)
157 if (clients[i].equals(me)) {
165 ClientHandle[] newlist = new ClientHandle[clients.length - 1];
166 for (int k=0,i = 0, j = clients.length; i < j; i++)
168 newlist[k++] = clients[i];
169 if (!putClientList(newlist))
170 throw new Error("Failed to write new clientList!"); // failed to put the clientList to disk.
175 throw new Error("Couldn't get lock for "+((filelist==null) ? "Unitialised filelist in ClientsFile" : filelist.getAbsolutePath()));
179 * Adds a ClientHandle to the ClientList file - optionally disambiguating
180 * the ClientHandle (modifes the URN).
181 * Note: Caller is left to release the lock on the ClientList.
183 * @param disambiguate -
184 * flag indicating if the URN for me should be disambiguated to
185 * differentiate between sessions.
186 * @return index of clientHandle in new list, or -1-position of existing
187 * clientHandle (if disambiguate is true)
189 protected int addClient(ClientHandle me, boolean disambiguate) {
192 ClientHandle[] clients = retrieveClientHandles();
193 if (me.getClientUrn()==null) {
194 // TODO: move this into ClientUrn as a standard form method.
195 me.setClientUrn("vamsas://"+me.getClientName()+":"+me.getVersion()+"/");
197 if (clients == null) {
198 clients = new ClientHandle[1];
203 for (int i = 0, j = clients.length; i < j; i++) {
204 if (clients[i].equals(me)) {
206 while (clients[i].equals(me)) {
207 me.setClientUrn(me.getClientUrn() + k++); // TODO: make a better
212 // will not write the ambiguous clientHandle to disk, just return
219 ClientHandle[] newlist = new ClientHandle[clients.length + 1];
220 for (i = 0, j = clients.length; i < j; i++)
221 newlist[i] = clients[i];
226 if (!putClientList(clients))
227 return 0; // failed to put the clientList to disk.
233 * safely writes clients array to the file referred to by filelist.
236 * @return true if successful write. Throws Errors otherwise.
238 protected boolean putClientList(ClientHandle[] clients) {
240 File templist = null;
242 templist = File.createTempFile(filelist.getName(),".old", filelist.getParentFile());
243 FileOutputStream tos = new FileOutputStream(templist);
244 tos.getChannel().transferFrom(listlock.rafile.getChannel(), 0,
245 listlock.rafile.length());
247 } catch (FileNotFoundException e1) {
248 System.err.println("Can't create temp file for clientlist");
249 e1.printStackTrace(System.err);
250 } catch (IOException e1) {
252 .println("Error when copying content to temp file for clientlist");
253 e1.printStackTrace(System.err);
255 if (templist != null) {
257 listlock.rafile.setLength(0);
258 ObjectOutputStream os = new ObjectOutputStream(
259 new BufferedOutputStream(new FileOutputStream(this.filelist)));
260 os.writeObject(clients);
262 // All done - remove the backup.
265 } catch (Exception e) {
266 if (templist != null) {
268 .println("Serious - problems writing to filelist. Backup in "
269 + templist.getAbsolutePath());
270 e.printStackTrace(System.err);
275 "Couldn't create backup of the clientList before writing to it!");
278 throw new Error("Could not lock the clientList: "
279 + ((filelist == null) ? "Unitialized ClientsFile"
280 : " failed to get lock on " + filelist.getAbsolutePath()));