Implement metadata caching for S3 backend.

[cumulus.git] / python / cumulus / store / __init__.py

diff --git a/python/cumulus/store/__init__.py b/python/cumulus/store/__init__.py
index 5ebf0d7..35de0ee 100644 (file)
--- a/python/cumulus/store/__init__.py
+++ b/python/cumulus/store/__init__.py
@@ -1,4 +1,4 @@
-import re
+import exceptions, re, urlparse
 
 type_patterns = {
     'checksums': re.compile(r"^snapshot-(.*)\.(\w+)sums$"),
@@ -6,6 +6,11 @@ type_patterns = {
     'snapshots': re.compile(r"^snapshot-(.*)\.lbs$")
 }
 
+class NotFoundError(exceptions.KeyError):
+    """Exception thrown when a file is not found in a repository."""
+
+    pass
+
 class Store:
     """Base class for all cumulus storage backends."""
 
@@ -20,3 +25,29 @@ class Store:
 
     def delete(self, type, name):
         raise NotImplementedException
+
+    def stat(self, type, name):
+        raise NotImplementedException
+
+    def scan(self):
+        """Cache file information stored in this backend.
+
+        This might make subsequent list or stat calls more efficient, but this
+        function is intended purely as a performance optimization."""
+
+        pass
+
+def open(url):
+    (scheme, netloc, path, params, query, fragment) \
+        = urlparse.urlparse(url)
+
+    if scheme == "file":
+        import cumulus.store.file
+        return cumulus.store.file.FileStore(path)
+    elif scheme == "s3":
+        import cumulus.store.s3
+        while path.startswith("/"): path = path[1:]
+        (bucket, path) = path.split("/", 1)
+        return cumulus.store.s3.S3Store(bucket, path)
+    else:
+        raise NotImplementedException