Optionally add original exception to NodeMissing

2 files changed, 10 insertions, 5 deletions

diff --git a/larch/nodestore.py b/larch/nodestore.py
index 82bcfbc..fb0abe0 100644
--- a/larch/nodestore.py
+++ b/larch/nodestore.py
@@ -21,9 +21,14 @@ class NodeMissing(larch.Error):
 
     '''A node cannot be found from a NodeStore.'''
     
-    def __init__(self, node_store, node_id):
-        self.msg = ('Node %d cannot be found in the node store %s' % 
-                    (node_id, node_store))
+    def __init__(self, node_store, node_id, error=None):
+        if error is None:
+            error_msg = ''
+        else:
+            error_msg = (': %s: %s: %s' % 
+                         (error.errno, error.strerror, error.filename))
+        self.msg = ('Node %d cannot be found in the node store %s%s' % 
+                    (node_id, node_store, error_msg))
 
 
 class NodeTooBig(larch.Error):
diff --git a/larch/nodestore_disk.py b/larch/nodestore_disk.py
index 65c5f93..197a411 100644
--- a/larch/nodestore_disk.py
+++ b/larch/nodestore_disk.py
@@ -233,10 +233,10 @@ class NodeStoreDisk(larch.NodeStore):
         try:
             encoded = self.journal.cat(name)
         except (IOError, OSError), e:
-            logging.error('Error reading node: %s: %s: %s' % 
+            logging.debug('Error reading node: %s: %s: %s' % 
                             (e.errno, e.strerror, e.filename or name))
             logging.debug(traceback.format_exc())
-            raise larch.NodeMissing(self.dirname, node_id)
+            raise larch.NodeMissing(self.dirname, node_id, error=e)
         else:
             node = self.codec.decode(encoded)
             node.frozen = True