note on occasional null pointer exceptions raised on JVM shutdown

[vamsas.git] / src / uk / ac / vamsas / client / simpleclient / FileLock.java

diff --git a/src/uk/ac/vamsas/client/simpleclient/FileLock.java b/src/uk/ac/vamsas/client/simpleclient/FileLock.java
index ef29f47..8a340c3 100644 (file)
--- a/src/uk/ac/vamsas/client/simpleclient/FileLock.java
+++ b/src/uk/ac/vamsas/client/simpleclient/FileLock.java
@@ -34,10 +34,13 @@ public class FileLock extends Lock {
     try { 
       advisory=new NativeLock(_lock, block);
     } catch (Exception e) {
-      log.fatal("Failed to create advisory lock file "+_lock,e);
-      throw new Error("Failed to create advisory lock file "+_lock);          
+      if (!_lock.exists()) {
+        // advisory cannot be created. this is serious.
+        log.fatal("Failed to create advisory lock file "+_lock,e);
+        throw new Error("Failed to create advisory lock file "+_lock);
+      }
     }
-    return advisory.isLocked();
+    return (advisory!=null) && advisory.isLocked();
   }
   /**
    * call to clear up a filelock file after its been made
@@ -45,9 +48,13 @@ public class FileLock extends Lock {
    */
   private void tidy() {
     if (_lock!=null) { 
-      if ( advisory!=null) 
+      if ( advisory!=null) {
+        // TODO: fix occasional exceptions raised here (usually on JVM shutdown)
+        if (advisory.target!=null) {
+           advisory.target.deleteOnExit(); // release will null the target
+        }
         advisory.release(true);
-      advisory.target.deleteOnExit();
+      }
       advisory=null;
       _lock=null;
     }
@@ -60,7 +67,7 @@ public class FileLock extends Lock {
     super(lockfile);
     // try and get a lock.
     try {
-      _lock = new File(lockfile.getParentFile(), lockfile.getName()+"."+_LockSuffix);
+      _lock = make_lockForTarget(lockfile);
       if (!ensureLockFile(block)) {
         log.debug("Couldn't get lock on "+_lock);
         tidy();
@@ -83,7 +90,14 @@ public class FileLock extends Lock {
           + lockfile.getAbsolutePath(),e);
     }
   }
-  
+  /**
+   * 
+   * @param lockfile target of lock
+   * @return file object that will be locked for lockfile
+   */
+  private File make_lockForTarget(File lockfile) {
+    return new File(lockfile.getParentFile(), lockfile.getName()+"."+_LockSuffix);
+  }
   private boolean openRaFile() throws IOException {
     if (target==null)
       return false;
@@ -204,4 +218,12 @@ public class FileLock extends Lock {
     log.debug("Failed to getRaChannel on target "+target);
     return null;
   }
+  public boolean isTargetLockFile(File afile) {
+    if (isLocked())
+    {
+      if (target.equals(afile) || make_lockForTarget(target).equals(afile))
+        return true;
+    }
+    return false;
+  }
 }