Hi All,

in a project we needed to be able to flush a logfile regularly (besides using
buffered logger). I'm enclosing the patch to FileAppender. This introduces a new
parameter called BufferFlushTime. This specifies how often (in seconds) should
the logfile be flushed. If not specified, nothing happens. Use it freely if you
wish.

--- FileAppender.java.orig	2006-09-14 02:04:20.000000000 +0200
+++ FileAppender.java	2007-08-08 15:54:04.436673600 +0200
@@ -64,6 +64,37 @@
    */
   protected int bufferSize = 8*1024;
 
+  /**
+   * Sets the time in seconds to flush the logfile unconditionally.
+   */
+  private int bufferFlushTime = -1;
+
+  /**
+   * The instance that flushes the logfile periodically.
+   */
+  private LogFlusher logFlusher = null;
+
+  /**
+   * Inner class to periodically flush the logfile.
+   */
+  class LogFlusher extends Thread {
+    private boolean stop = false;
+
+    private void quit() {
+       stop = true;
+    }
+
+    public void run() {
+      while (!stop) {
+        try {
+          Thread.sleep(FileAppender.this.bufferFlushTime * 1000);
+        } catch (InterruptedException ie) {
+          // ignore
+        }
+        FileAppender.this.flush();
+      }
+    }
+  }
 
   /**
      The default constructor does not do anything.
@@ -84,12 +115,17 @@
     <p>If the <code>bufferedIO</code> parameter is <code>true</code>,
     then buffered IO will be used to write to the output file.
 
+    <p>If the <code>bufferFlushTime</code> parameter is set to a
+    non-negative value, then the file will be flushed every
+    <code>bufferFlushTime</code> seconds unconditionally.
+
   */
   public
   FileAppender(Layout layout, String filename, boolean append, boolean bufferedIO,
-	       int bufferSize) throws IOException {
+	       int bufferSize, final int bufferFlushTime) throws IOException {
     this.layout = layout;
     this.setFile(filename, append, bufferedIO, bufferSize);
+    setBufferFlushTime(bufferFlushTime);
   }
 
   /**
@@ -214,6 +250,18 @@
 
 
   /**
+     Get the value of the <b>BufferFlushTime</b> option.
+
+     <p>Setting BufferFlushTime will cause the log file to be periodally flushed.
+
+  */
+  public
+  int getBufferFlushTime() {
+    return this.bufferFlushTime;
+  }
+
+
+  /**
      The <b>Append</b> option takes a boolean value. It is set to
      <code>true</code> by default. If true, then <code>File</code>
      will be opened in append mode by {@link #setFile setFile} (see
@@ -256,6 +304,25 @@
   }
 
   /**
+     Set the value of the <b>BufferFlushTime</b> option.
+
+     <p>Setting BufferFlushTime will cause the log file to be periodally flushed.
+
+  */
+  public
+  void setBufferFlushTime(int bufferFlushTime) {
+    this.bufferFlushTime = bufferFlushTime;
+
+    if (logFlusher != null) {
+      logFlusher.quit();
+    }
+    logFlusher = new LogFlusher();
+    logFlusher.setDaemon(true);
+    logFlusher.start();
+  }
+
+
+  /**
     <p>Sets and <i>opens</i> the file where the log output will
     go. The specified file must be writable.
 
@@ -339,5 +406,12 @@
     this.fileName = null;
     super.reset();
   }
+
+  /**
+     Flush the logfile.  */
+  private
+  void flush() {
+    this.qw.flush();
+  }
 }