--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/dancres/blitz/txn/OpCountingCheckpointTrigger.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,95 @@
+package org.dancres.blitz.txn;
+
+import java.io.IOException;
+
+import java.util.logging.Level;
+
+import org.dancres.blitz.ActiveObjectRegistry;
+
+/**
+   A checkpoint trigger that fires off a checkpoint every time a certain
+   number of operations have been logged.
+ */
+class OpCountingCheckpointTrigger implements CheckpointTrigger, Runnable {
+    private Checkpointer theCheckpointer;
+
+    private int theCommandThreshold;
+
+    private Thread theCheckpointThread;
+    private boolean stopCheckpointing = false;
+    private int theLogCount = 0;
+
+    OpCountingCheckpointTrigger(Checkpointer aCheckpointer,
+                                int aCommandThreshold) {
+        theCheckpointer = aCheckpointer;
+        theCommandThreshold = aCommandThreshold;
+
+        ActiveObjectRegistry.add(this);
+    }
+
+    public void loggedCommand() {
+        synchronized(this) {
+            ++theLogCount;
+            
+            if (theLogCount == theCommandThreshold) {
+                theLogCount = 0;
+                notify();
+            }
+        }
+    }
+
+    public void begin() {
+        theCheckpointThread = new Thread(this, "Checkpointer");
+        theCheckpointThread.start();
+    }
+
+    public void halt() {
+        synchronized(this) {
+            stopCheckpointing = true;
+            notify();
+        }
+
+        try {
+            theCheckpointThread.join();
+            theCheckpointThread = null;
+        } catch (InterruptedException anIE) {
+            TxnManager.theLogger.log(Level.SEVERE,
+                                     "Failed to wait for checkpointer",
+                                     anIE);
+        }
+    }
+
+    public void run() {
+        boolean timeToExit = false;
+
+        while(!timeToExit) {
+            synchronized(this) {
+                if (!stopCheckpointing) {
+                    try {
+                        wait();
+                    } catch (InterruptedException anIE) {
+                        TxnManager.theLogger.log(Level.INFO,
+                                                 "Checkpointer interrupted",
+                                                 anIE);
+                    }
+                }
+
+                timeToExit = stopCheckpointing;
+            }
+            
+            if (!timeToExit) {
+                try {
+                    theCheckpointer.sync();
+                } catch (IOException anIOE) {
+                    TxnManager.theLogger.log(Level.SEVERE,
+                                             "Checkpoint failed",
+                                             anIOE);
+                }
+            }
+        }
+    }
+
+    public boolean checkpointsDisabled() {
+        return false;
+    }
+}