From f1f7e1f9ce8cadb3372c8b423d03b5cd1000991f Mon Sep 17 00:00:00 2001
From: jprocter <jprocter@compbio.dundee.ac.uk>
Date: Sat, 22 Oct 2005 21:58:11 +0000
Subject: [PATCH] debugged fileWatcher logic and Lock release function.

git-svn-id: https://svn.lifesci.dundee.ac.uk/svn/repository/trunk@72 be28352e-c001-0410-b1a7-c7978e42abec
---
 .../vamsas/client/simpleclient/FileWatcher.java    |   50 +++++++++++++++-----
 src/org/vamsas/client/simpleclient/Lock.java       |   23 +++++----
 2 files changed, 51 insertions(+), 22 deletions(-)

diff --git a/src/org/vamsas/client/simpleclient/FileWatcher.java b/src/org/vamsas/client/simpleclient/FileWatcher.java
index 84a5e0a..bc9f705 100644
--- a/src/org/vamsas/client/simpleclient/FileWatcher.java
+++ b/src/org/vamsas/client/simpleclient/FileWatcher.java
@@ -16,7 +16,7 @@ public class FileWatcher {
   private File subject = null;
 
   private long lastStat[];
-
+  boolean waslocked=false;
   boolean exists = false;
 
   /**
@@ -33,12 +33,13 @@ public class FileWatcher {
       if (tl.isLocked()) {
         tl.release();
         return false;
-      } else {
-        return true;
       }
+      tl.release();
+      return true;
     }
     return false;
   }
+  
   private long[] getStat(File subject) {
     return new long[] { subject.lastModified(), subject.length() };
   }
@@ -47,32 +48,57 @@ public class FileWatcher {
       return false;
     return true;
   }
+  /**
+   * Detect changes in file state and release of any
+   * lock in place during change.
+   * @return true if file state has changed
+   */
   private boolean check() {
     if (subject != null) {
       if (!subject.exists()) {
         if (exists) {
-          exists = false;
-          return true;
+          if (!waslocked) {
+            // !checkLock()) {
+          
+            exists = false;
+            // waslocked=false;
+            return true;
+          }
         }
+        // locked - state change registered after lock is released
         return false;
       } else {
-        
         long[] newStat = getStat(subject); // subject.lastModified();
-        if (exists && ((compStat(lastStat, newStat) || checkLock()))) {
+        if (!checkLock()) {
+          // file is free to access, return state change
+          if (!exists || !compStat(lastStat, newStat)) {
+            waslocked=false;
+            exists=true;
+            lastStat=newStat;
+            return true;
+          }
+          // no change
+          return false;
+        } else {
+          waslocked=true;
           return false;
         }
-        lastStat = newStat;
-        exists = true;
-        return true;
       }
     }
     return false;
   }
-
+  public void setState() {
+    if (subject!=null) {
+      lastStat = getStat(subject);
+      exists = subject.exists();
+      waslocked = checkLock();
+    }
+  }
+  
   public FileWatcher(File subject) {
     // TODO Auto-generated constructor stub
     this.subject = subject;
-    check();
+    setState();
   }
 
   public boolean hasChanged() {
diff --git a/src/org/vamsas/client/simpleclient/Lock.java b/src/org/vamsas/client/simpleclient/Lock.java
index a185233..ab159ba 100644
--- a/src/org/vamsas/client/simpleclient/Lock.java
+++ b/src/org/vamsas/client/simpleclient/Lock.java
@@ -16,7 +16,7 @@ import java.nio.channels.FileLock;
 
 public class Lock {
   FileLock lock = null;
-  RandomAccessFile rafile;
+  RandomAccessFile rafile=null;
   /**
    * creates a valid Lock (test with <method>isLocked</method>)
    * if a lock could be obtained for <param>lockfile</param>
@@ -25,7 +25,7 @@ public class Lock {
   public Lock(java.io.File lockfile) {
     // try and get a lock.
     lock = null;
-
+    
     try {
       if (!lockfile.exists())
         if (!lockfile.createNewFile()) {
@@ -43,7 +43,7 @@ public class Lock {
       e.printStackTrace();
     }
   }
-
+  
   boolean isLocked() {
     if (lock != null && lock.isValid()) {
       return true;
@@ -51,16 +51,19 @@ public class Lock {
     return false;
   }
   public void release() {
-    if (lock!=null) {
-      try {
-        rafile.close();
+    try {
+      if (lock!=null && lock.isValid())
         lock.release();
-      } catch (IOException e) {
-        // TODO Auto-generated catch block
-        e.printStackTrace(System.err);
-      }
+      if (rafile!=null && rafile.getChannel().isOpen())
+        rafile.getChannel().close();
+    } catch (IOException e) {
+      // TODO Auto-generated catch block
+      e.printStackTrace(System.err);
     }
+    lock=null;
+    rafile=null;
   }
+  
   /* Explicitly release lock (probably don't need to do this!)
    * @see java.lang.Object#finalize()
    */
-- 
1.7.10.2