modified FileWatcher to only register file change after a lock release (incurs a...

tested multi-process watching.

git-svn-id: https://svn.lifesci.dundee.ac.uk/svn/repository/trunk@62 be28352e-c001-0410-b1a7-c7978e42abec

diff --git a/src/org/vamsas/client/simpleclient/ClientsFile.java b/src/org/vamsas/client/simpleclient/ClientsFile.java
index 4d34039..aa62482 100644 (file)
--- a/src/org/vamsas/client/simpleclient/ClientsFile.java
+++ b/src/org/vamsas/client/simpleclient/ClientsFile.java
@@ -49,11 +49,10 @@ public class ClientsFile {
       if (filelist.exists()) {
         // 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);
+        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

diff --git a/src/org/vamsas/client/simpleclient/FileWatcher.java b/src/org/vamsas/client/simpleclient/FileWatcher.java
index f486360..ce218ee 100644 (file)
--- a/src/org/vamsas/client/simpleclient/FileWatcher.java
+++ b/src/org/vamsas/client/simpleclient/FileWatcher.java
@@ -5,47 +5,68 @@ package org.vamsas.client.simpleclient;
 
 import java.io.File;
 
+import org.vamsas.client.SimpleClient;
+
 /**
- * @author jim
- * Watches a particular file for its creation, deletion, or modification.
+ * @author jim Watches a particular file for its creation, deletion, or
+ *         modification.
  */
 public class FileWatcher {
-  private File subject=null;
+
+  private File subject = null;
+
   private long lastStat;
-  boolean exists=false;
+
+  boolean exists = false;
+
   /**
-   * Make a watcher for a particular file.
-   * If the file doesn't exist, the watcher will watch
-   * for its creation (and indicate a change of state)
+   * Make a watcher for a particular file. If the file doesn't exist, the
+   * watcher will watch for its creation (and indicate a change of state) 
+   * For locked files, the removal of a lock constitutes a change of 
+   * state if the file was modified.
+   * 
    * @param subject
    */
-  private boolean check() {
+  private boolean checkLock() {
     if (subject!=null) {
+      Lock tl = new Lock(subject);
+      if (tl.isLocked()) {
+        tl.release();
+        return false;
+      } else {
+        return true;
+      }
+    }
+    return false;
+  }
+  private boolean check() {
+    if (subject != null) {
       if (!subject.exists()) {
         if (exists) {
-        exists=false;
-        return true;
-      } 
-      return false;
-    } else {
-      long newStat=subject.lastModified();
-      if (exists && lastStat==newStat) {
+          exists = false;
+          return true;
+        }
         return false;
+      } else {
+        
+        long newStat = subject.lastModified();
+        if (exists && ((lastStat == newStat) || checkLock())) {
+          return false;
+        }
+        lastStat = newStat;
+        exists = true;
+        return true;
       }
-      lastStat=newStat;
-      exists=true;
-      return true;
     }
-  }
     return false;
   }
-  
-  
+
   public FileWatcher(File subject) {
     // TODO Auto-generated constructor stub
     this.subject = subject;
     check();
   }
+
   public boolean hasChanged() {
     return check();
   }

diff --git a/src/org/vamsas/client/simpleclient/Lock.java b/src/org/vamsas/client/simpleclient/Lock.java
index d7239e6..a185233 100644 (file)
--- a/src/org/vamsas/client/simpleclient/Lock.java
+++ b/src/org/vamsas/client/simpleclient/Lock.java
@@ -31,7 +31,7 @@ public class Lock {
         if (!lockfile.createNewFile()) {
           return;
         }
-
+      
       lock = (rafile=new RandomAccessFile(lockfile,"rw")).getChannel().tryLock();
     } catch (FileNotFoundException e) {
       System.err.println("Error! Couldn't create a lockfile at "
@@ -50,13 +50,22 @@ public class Lock {
     }
     return false;
   }
-
+  public void release() {
+    if (lock!=null) {
+      try {
+        rafile.close();
+        lock.release();
+      } catch (IOException e) {
+        // TODO Auto-generated catch block
+        e.printStackTrace(System.err);
+      }
+    }
+  }
   /* Explicitly release lock (probably don't need to do this!)
    * @see java.lang.Object#finalize()
    */
   protected void finalize() throws Throwable {
-    if (lock!=null)
-      lock.release();
+    release();
     super.finalize();
   }
   

diff --git a/src/org/vamsas/test/simpleclient/ClientsFileTest.java b/src/org/vamsas/test/simpleclient/ClientsFileTest.java
index 9339600..f484a63 100644 (file)
--- a/src/org/vamsas/test/simpleclient/ClientsFileTest.java
+++ b/src/org/vamsas/test/simpleclient/ClientsFileTest.java
@@ -1,10 +1,12 @@
 package org.vamsas.test.simpleclient;
 
+import java.io.File;
 import java.util.Iterator;
 import java.util.Vector;
 
 import org.vamsas.client.ClientHandle;
 import org.vamsas.client.simpleclient.ClientsFile;
+import org.vamsas.client.simpleclient.FileWatcher;
 
 public class ClientsFileTest {
   private static Vector commands;
@@ -14,6 +16,7 @@ public class ClientsFileTest {
     ClientsFileTest.commands.add(new String("remove"));
     ClientsFileTest.commands.add(new String("list"));    
     ClientsFileTest.commands.add(new String("clear"));
+    ClientsFileTest.commands.add(new String("watch"));    
   }
   private static void complainArgs(int argl, int argpos, String cmd, int argneed, String msg) {
     if (argl-argpos<argneed)
@@ -84,6 +87,26 @@ public class ClientsFileTest {
               e.printStackTrace(System.err);
             }
             break;
+          case 4:
+            // watch
+            FileWatcher w=new FileWatcher(cf);
+            while (cf.exists()) {
+              if (w.hasChanged()) {
+                System.out.println("-- Watching "+cf.getName());
+                //while (w.hasChanged())
+                //  ;
+                ClientHandle[] cl = cfhand.retrieveClientList();
+                if (cl!=null) {
+                  for (int chi=0,che=cl.length; chi<che; chi++) {
+                    System.out.println("Client "+chi+" ("+cl[chi].getClientName()+" "+cl[chi].getVersion()+" "+cl[chi].getClientUrn()+")");
+                  }
+                } else {
+                  System.out.println("Client list is empty.");
+                }
+              }
+              
+            }
+            
           }
           coms = null;
         }