_artifactcache.py: Fixing concurrent artifact extractions

Catch both EEXIST and not ENOTEMPTY from os.rename().

Seems that low level rename() calls (see `man 2 rename`) document
this call to report either EEXIST _or_ ENOTEMPTY (at the OS/libc's
discretion) in the case that the destination directory exists and
is not empty.

1 files changed, 6 insertions, 4 deletions

diff --git a/buildstream/_artifactcache.py b/buildstream/_artifactcache.py
index 191d821e8..7e89f6c86 100644
--- a/buildstream/_artifactcache.py
+++ b/buildstream/_artifactcache.py
@@ -111,13 +111,15 @@ class ArtifactCache():
             try:
                 os.rename(checkoutdir, dest)
             except OSError as e:
-                if e.errno != os.errno.ENOTEMPTY:
+                # With rename, it's possible to get either ENOTEMPTY or EEXIST
+                # in the case that the destination path is a not empty directory.
+                #
+                # If rename fails with these errors, another process beat
+                # us to it so just ignore.
+                if e.errno not in [os.errno.ENOTEMPTY, os.errno.EEXIST]:
                     raise ArtifactError("Failed to extract artifact for ref '{}': {}"
                                         .format(ref, e)) from e
 
-                # If rename fails with ENOTEMPTY, another process beat
-                # us to it. This is no issue.
-
         return dest
 
     # commit():