refactored from org.vamsas to uk.ac.vamsas

[vamsas.git] / src / org / vamsas / client / simpleclient / FileWatcher.java

diff --git a/src/org/vamsas/client/simpleclient/FileWatcher.java b/src/org/vamsas/client/simpleclient/FileWatcher.java
deleted file mode 100644 (file)
index fe72381..0000000
--- a/src/org/vamsas/client/simpleclient/FileWatcher.java
+++ /dev/null
@@ -1,168 +0,0 @@
-/**
- * 
- */
-package org.vamsas.client.simpleclient;
-
-import java.io.File;
-
-
-/**
- * Watches a particular file for its creation, deletion, or
- * modification. The watcher is thread safe and different 
- * instances watching the state of a particular file carry
- * their own state record for the file.
- */
-public class FileWatcher {
-
-  private File subject = null;
-
-  private long lastStat[];
-  boolean waslocked=false;
-  boolean exists = false;
-  /**
-   * transient lock on subject - can be passed back to calling class
-   * to preserve new state of file for immediate reading.
-   */
-  private Lock subjectLock = null;
-  /**
-   * clear local locks on subject.
-   *
-   */
-  private void clearLock() {
-    if (subjectLock!=null)
-      subjectLock.release();
-    subjectLock=null;
-  }
-  /**
-   *  
-   * @return true if subject exists and is locked by another process.
-   */
-  private boolean checkLock() {
-    if (subject!=null && subject.exists()) {
-      if (subjectLock!=null) {
-        subjectLock.release();
-      }
-      subjectLock = LockFactory.tryLock(subject);
-      if (subjectLock.isLocked()) {
-        return false;
-      }
-      clearLock();
-      return true;
-    }
-    return false;
-  }
-  
-  private long[] getStat(File subject) {
-    return new long[] { subject.lastModified(), subject.length() };
-  }
-  private boolean compStat(long[] stat, long[] newstat) {
-    if (stat[0]!=newstat[0] || stat[1]!=newstat[1])
-      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. Leaves lock in subjectLock (ready to be passed to caller)
-   */
-  private boolean check() {
-    if (subject != null) {
-      if (!subject.exists()) {
-        if (exists) {
-          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 (!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;
-        }
-      }
-    }
-    return false;
-  }
-  /**
-   * updates internal record of file state when caller has intentionally
-   * modified subject. (ignores locked-state of subject)
-   */
-  public void setState() {
-    if (subject!=null) {
-      if (exists = subject.exists()) {
-        lastStat = getStat(subject);
-        waslocked = 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) 
-   * For locked files, the removal of a lock constitutes a change of 
-   * state if the file was modified.
-   * 
-   * @param subject
-   */
-  
-  public FileWatcher(File subject) {
-    this.subject = subject;
-    setState();
-  }
-  /**
-   * Test for change in file state. Only indicates a change 
-   * after any lock on a file has been released.
-   * @return true if file has been modified.
-   */
-  public boolean hasChanged() {
-    boolean res = check();
-    clearLock();
-    return res;
-  }
-  /**
-   * passes lock back to caller if hasChanged returned true.
-   * @return
-   */
-  public Lock getChangedState() {
-    boolean res = check();
-    if (res)
-      return subjectLock;
-    else {
-      clearLock();
-      return null;
-    }
-  }
-  /**
-   * safely? getting current state of the watched file
-   * @return
-   */
-  public long[] getCurrentState() {
-    return getStat(subject);
-  }
-  /**
-   * safely compare an externally recorded state with the current state
-   * for significant modifications.
-   * @param a
-   * @param b
-   * @return
-   */
-  public boolean diffState(long[] a, long[] b) {
-    return compStat(a,b);
-  }
-}