Restored interface that was mitakenly deleted in r2552.

git-svn-id: https://hyracks.googlecode.com/svn/branches/hyracks_lsm_tree@2561 123451ca-8445-de46-9d55-352943316053
diff --git a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIOOperationCallbackFactory.java b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIOOperationCallbackFactory.java
new file mode 100644
index 0000000..52361ee
--- /dev/null
+++ b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIOOperationCallbackFactory.java
@@ -0,0 +1,7 @@
+package edu.uci.ics.hyracks.storage.am.lsm.common.api;
+
+import java.io.Serializable;
+
+public interface ILSMIOOperationCallbackFactory extends Serializable {
+    public ILSMIOOperationCallback createIOOperationCallback(Object syncObj);
+}