X-Git-Url: http://source.jalview.org/gitweb/?a=blobdiff_plain;f=src%2Forg%2Fvamsas%2Fclient%2Fsimpleclient%2FClientsFile.java;h=c624100a2e11c32f5b3b99ca934bdd688660b6a6;hb=88059ea1fef3519af2ba4d038b97523e596d062c;hp=132280e504cc0a36e8c4f83a62594216da7e87da;hpb=de5c431d734c37ef35afb58a849a321010df1a99;p=vamsas.git

diff --git a/src/org/vamsas/client/simpleclient/ClientsFile.java b/src/org/vamsas/client/simpleclient/ClientsFile.java
index 132280e..c624100 100644
--- a/src/org/vamsas/client/simpleclient/ClientsFile.java
+++ b/src/org/vamsas/client/simpleclient/ClientsFile.java
@@ -1,4 +1,5 @@
 package org.vamsas.client.simpleclient;
+
 import org.vamsas.client.*;
 
 import java.io.BufferedInputStream;
@@ -16,71 +17,269 @@ import java.io.OutputStream;
 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;
+        // 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.
+          if (listlock!=null)
+            listlock.release();
+          listlock = new Lock(filelist); // TODO: wait around if we can't get the lock.
         } while (!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 = 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) {
+
+      if (listlock.isLocked()) {
+        listlock.release();
+      }
+
+      listlock = null;
+    }
+  }
+
+  /**
+   * 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);
+            }
+          }
         }
-        catch (FileNotFoundException e) {
-          // TODO Auto-generated catch block
-          e.printStackTrace();
-        } catch (Exception e) {
-          e.printStackTrace();
+        return clients;
+      } catch (FileNotFoundException e) {
+        // TODO Auto-generated catch block
+        e.printStackTrace(System.err);
+      } catch (Exception e) {
+        e.printStackTrace(System.err);
+      }
+    }
+    return null;
+  }
+  /**
+   * get the clientList from the file. May return false if lock failed!
+   * @return clientList
+   */
+  public ClientHandle[] retrieveClientList() {
+    if (lockList()) {
+      ClientHandle[] clients = retrieveClientHandles();
+      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(newlist))
+            throw new Error("Failed to write new clientList!"); // failed to put the clientList to disk.
         }
       }
-      // else return null.
+      unlockList();
     } else {
-      throw new Error("Tried to retrieve a clientList without specifying client list filename");
+      throw new Error("Couldn't get lock for "+((filelist==null) ? "Unitialised filelist in ClientsFile" : filelist.getAbsolutePath()));
     }
-    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());
+  /**
+   * 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 disambiguated 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;
   }
 }