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 void unlockList() {
72 if (listlock != null) {
74 if (listlock.isLocked()) {
83 * internal method for getting clientList - ensures a lock has been made but
84 * does not release it.
86 * @return list of clients
88 private ClientHandle[] retrieveClientHandles() {
91 ClientHandle[] clients=null;
92 if (this.listlock.rafile.length()>0) {
93 ObjectInputStream is = new ObjectInputStream(new BufferedInputStream(
94 new java.io.FileInputStream(filelist)));
99 clients = (ClientHandle[]) o;
101 catch (Exception e) {
102 System.err.println("Garbage in the clientHandle list "+this.filelist);
107 } catch (FileNotFoundException e) {
108 // TODO Auto-generated catch block
109 e.printStackTrace(System.err);
110 } catch (Exception e) {
111 e.printStackTrace(System.err);
117 * get the clientList from the file. May return false if lock failed!
120 public ClientHandle[] retrieveClientList() {
122 ClientHandle[] clients = retrieveClientHandles();
130 * adds the ClientHandle to the list - if it is not unique, then the
131 * ClientHandle object is modified to make it unique in the list. returns the
132 * clientNumber for the client in the session.
138 public int addClient(ClientHandle me) {
139 syncnum = addClient(me, true);
145 * removes 'me' from the session ClientList without complaint if 'me' isn't in the clientList already.
148 public void removeClient(ClientHandle me) {
151 ClientHandle[] clients = retrieveClientHandles();
152 if (clients != null) {
153 if (clients[syncnum-1]!=me) {
154 for (int i = 0, j = clients.length; i < j; i++)
155 if (clients[i].equals(me)) {
163 ClientHandle[] newlist = new ClientHandle[clients.length - 1];
164 for (int k=0,i = 0, j = clients.length; i < j; i++)
166 newlist[k++] = clients[i];
167 if (!putClientList(newlist))
168 throw new Error("Failed to write new clientList!"); // failed to put the clientList to disk.
173 throw new Error("Couldn't get lock for "+((filelist==null) ? "Unitialised filelist in ClientsFile" : filelist.getAbsolutePath()));
177 * Adds a ClientHandle to the ClientList file - optionally disambiguating
178 * the ClientHandle (modifes the URN).
179 * Note: Caller is left to release the lock on the ClientList.
181 * @param disambiguate -
182 * flag indicating if the URN for me should be disambiguated to
183 * differentiate between sessions.
184 * @return index of clientHandle in new list, or -1-position of existing
185 * clientHandle (if disambiguate is true)
187 protected int addClient(ClientHandle me, boolean disambiguate) {
190 ClientHandle[] clients = retrieveClientHandles();
191 if (me.getClientUrn()==null) {
192 // TODO: move this into ClientUrn as a standard form method.
193 me.setClientUrn("vamsas://"+me.getClientName()+":"+me.getVersion()+"/");
195 if (clients == null) {
196 clients = new ClientHandle[1];
201 for (int i = 0, j = clients.length; i < j; i++) {
202 if (clients[i].equals(me)) {
204 while (clients[i].equals(me)) {
205 me.setClientUrn(me.getClientUrn() + k++); // TODO: make a better
210 // will not write the ambiguous clientHandle to disk, just return
217 ClientHandle[] newlist = new ClientHandle[clients.length + 1];
218 for (i = 0, j = clients.length; i < j; i++)
219 newlist[i] = clients[i];
224 if (!putClientList(clients))
225 return 0; // failed to put the clientList to disk.
231 * safely writes clients array to the file referred to by filelist.
234 * @return true if successful write. Throws Errors otherwise.
236 protected boolean putClientList(ClientHandle[] clients) {
238 File templist = null;
240 templist = File.createTempFile(filelist.getName(),".old", filelist.getParentFile());
241 FileOutputStream tos = new FileOutputStream(templist);
242 tos.getChannel().transferFrom(listlock.rafile.getChannel(), 0,
243 listlock.rafile.length());
245 } catch (FileNotFoundException e1) {
246 System.err.println("Can't create temp file for clientlist");
247 e1.printStackTrace(System.err);
248 } catch (IOException e1) {
250 .println("Error when copying content to temp file for clientlist");
251 e1.printStackTrace(System.err);
253 if (templist != null) {
255 listlock.rafile.setLength(0);
256 ObjectOutputStream os = new ObjectOutputStream(
257 new BufferedOutputStream(new FileOutputStream(this.filelist)));
258 os.writeObject(clients);
260 // All done - remove the backup.
263 } catch (Exception e) {
264 if (templist != null) {
266 .println("Serious - problems writing to filelist. Backup in "
267 + templist.getAbsolutePath());
268 e.printStackTrace(System.err);
273 "Couldn't create backup of the clientList before writing to it!");
276 throw new Error("Could not lock the clientList: "
277 + ((filelist == null) ? "Unitialized ClientsFile"
278 : " failed to get lock on " + filelist.getAbsolutePath()));