--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/dancres/blitz/txn/CheckpointTrigger.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,26 @@
+package org.dancres.blitz.txn;
+
+import org.dancres.blitz.ActiveObject;
+
+/**
+   <p>Checkpoints can be triggered as the result of a number of different
+   stimuli. Typically, these stimuli are the number of operations since the
+   last checkpoint or the time since the last checkpoint.</p>
+
+   <p>Instances of this class encapsulate a particular policy with respect to
+   when a checkpoint should be triggered.  When they determine that a
+   checkpoint is required, they invoke the <code>sync</code> of a
+   <code>Checkpointer</code> instance (typically passed in at construction
+   time).  This call should be made in an independent thread - i.e. it is
+   <em>not</em> appropriate for CheckpointTrigger methods to block.</p>
+
+   @see org.dancres.blitz.txn.Checkpointer
+ */
+public interface CheckpointTrigger extends ActiveObject {
+    public void loggedCommand();
+
+    /**
+       @return <code>true</code> if checkpointing is not allowed.
+     */
+    public boolean checkpointsDisabled();
+}