added file caching for DBs

osaca/utils.py

@@ -1,6 +1,8 @@
 #!/usr/bin/env python3
 import os.path
 
+CACHE_DIR = os.path.expanduser('~/.osaca/cache')
+
 
 def find_file(name):
     """Check for existence of name in user or package data folders and return path."""
@@ -10,4 +12,17 @@ def find_file(name):
         path = os.path.join(dir, name)
         if os.path.exists(path):
             return path
-    raise FileNotFoundError("Could not find {!r} in {!r}.".format(name, search_paths))
+    raise FileNotFoundError("Could not find {!r} in {!r}.".format(name, search_paths))
+
+
+def exists_cached_file(name):
+    """Check for existence of file in cache dir. Returns path if it exists and False otherwise."""
+    if not os.path.exists(CACHE_DIR):
+        os.makedirs(CACHE_DIR)
+        return False
+    search_paths = [CACHE_DIR]
+    for dir in search_paths:
+        path = os.path.join(dir, name)
+        if os.path.exists(path):
+            return path
+    return False