From 021b17897224feb353a72b8862768ded209417fc 2015-04-13 23:13:55
From: Lance Edgar <ledgar@sacfoodcoop.com>
Date: 2015-04-13 23:13:55
Subject: [PATCH] Add `files.locking_copy_test()` function.

The hope is that simplifying the lockout will help with certain network
issues that can plague a certain server I know...  If this test is
successful then the `locking_copy()` function will be silently replaced.

---

diff --git a/rattail/files.py b/rattail/files.py
index e212618c6d90f9549951dd0e104336e5b9d4aa6a..54d3b78b81bba29a5e66fe8c256c79245d2770ac 100644
--- a/rattail/files.py
+++ b/rattail/files.py
@@ -113,6 +113,37 @@ def locking_copy(src, dst, timeout=None):
         shutil.copy(src, dst)
 
 
+def locking_copy_test(src, dst):
+    """
+    Implements a "locking" version of the standard library's
+    :func:`python:shutil.copy()` function.
+
+    This exists to provide a more atomic method for copying a file into a
+    folder which is being watched by a file monitor.  The assumption is that
+    the monitor is configured to watch for file "locks" and therefore only
+    process files once they have had their locks removed.  See also
+    :ref:`filemon-profile-watchlocks`.
+
+    :param src: Path to the source file.
+    :type src: string
+
+    :param dst: Path to the destination file (or directory).
+    :type dst: string
+    """
+    if os.path.isdir(dst):
+        fn = os.path.basename(src)
+        dst = os.path.join(dst, fn)
+
+    lockdir = '{0}.lock'.format(dst)
+    try:
+        os.mkdir(lockdir)
+    except OSError as error:
+        if error.errno != 17:   # file exists
+            raise
+    shutil.copy(src, dst)
+    os.rmdir(lockdir)
+
+
 def overwriting_move(src, dst):
     """
     Convenience function which is equivalent to ``shutil.move()``, except it