--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/dancres/blitz/StatsDumper.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,123 @@
+package org.dancres.blitz;
+
+import java.net.*;
+
+import java.util.logging.Level;
+
+import org.dancres.blitz.disk.Disk;
+
+import org.dancres.blitz.stats.StatsBoard;
+import org.dancres.blitz.stats.Stat;
+
+/**
+   <p>This class implements a remote access feature which allows a programmer
+   to trigger dumping of useful debug information.  It is triggered by
+   <code>telnet</code>'ing to the debug port. StatsDumper detects the connection,
+   closes it and dumps relevant output to console.</p>
+
+   <p>For example, if Blitz were suffering from a deadlock, one could arrange
+   for a connection on the debug port, to dump lock information, the default
+   implementation (note that it requires a tweak to Db for it to provide the
+   right information, contact dan@dancres.org, for information).</p>
+
+   <p>If the port number is non-zero, the StatsDumper is enabled otherwise it's
+   disabled.  See <code>debugPort</code> in the configuration file.</p>
+
+   @todo Find a nice way to handle the stack tracing stuff - only works on
+   JDK 1.5
+ */
+class StatsDumper implements Runnable, ActiveObject {
+
+    private static StatsDumper theStatsDumper;
+
+    private Thread theDebugThread;
+    private boolean stopDebugging;
+    private long theCycleTime;
+    
+    static void start(long aPause) {
+        try {
+            if (aPause == 0)
+                return;
+
+            System.err.println("Starting Stats Dumper: " + aPause);
+
+            theStatsDumper = new StatsDumper(aPause);
+        } catch (Exception anE) {
+            System.err.println("StatsDumper didn't start!");
+            anE.printStackTrace(System.err);
+        }
+    }
+
+    private StatsDumper(long aPause) throws Exception {
+        theCycleTime = aPause;
+        ActiveObjectRegistry.add(this);
+    }
+
+    public void begin() {
+        theDebugThread = new Thread(this, "StatsDumper");
+        theDebugThread.start();
+    }
+
+    public void halt() {
+        synchronized(this) {
+            stopDebugging = true;
+        }
+
+        theDebugThread.interrupt();
+
+        try {
+            theDebugThread.join();
+            theDebugThread = null;
+        } catch (InterruptedException anIE) {
+            SpaceImpl.theLogger.log(Level.SEVERE,
+                                    "Failed to wait for StatsDumper",
+                                    anIE);
+        }
+    }
+
+    public void run() {
+        synchronized(this) {            
+            while(!stopDebugging) {
+                try {
+                    
+                    wait(theCycleTime);
+                    
+                    if (stopDebugging) {
+                        continue;
+                    }
+                    
+                    Stat[] myStats = StatsBoard.get().getStats();
+                    for (int i = 0; i < myStats.length; i++) {
+                        System.err.println(myStats[i]);
+                    }
+                    
+                /*
+                   Only works on JDK 1.5!!!!!!!!
+                 
+                 
+                Map myTraces = Thread.getAllStackTraces();
+                 
+                Iterator myThreads = myTraces.keySet().iterator();
+                while (myThreads.hasNext()) {
+                    Thread myThread = (Thread) myThreads.next();
+                    StackTraceElement[] myTrace =
+                        (StackTraceElement[]) myTraces.get(myThread);
+                 
+                    System.err.println();
+                    System.err.println(myThread);
+                    System.err.println();
+                    for (int i = 0; i < myTrace.length; i++) {
+                        System.err.println("       " + myTrace[i]);
+                    }
+                }
+                 
+                 */
+                } catch (InterruptedException anIE) {
+                    SpaceImpl.theLogger.log(Level.SEVERE, "StatsDumper interrupted");
+                } catch (Exception anE) {
+                    System.err.println("Whoops couldn't do dump stats");
+                }
+            }
+        }
+    }
+}