Michael Haggerty [off-list ref] writes:
quoted hunk
If safe_create_leading_directories() fails because a file along the
path unexpectedly vanished, try again (up to 3 times).
This can occur if another process is deleting directories at the same
time as we are trying to make them. For example, "git pack-refs
--all" tries to delete the loose refs and any empty directories that
are left behind. If a pack-refs process is running, then it might
delete a directory that we need to put a new loose reference in.
If safe_create_leading_directories() thinks this might have happened,
then take its advice and try again (maximum three attempts).
Signed-off-by: Michael Haggerty <redacted>
---
refs.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/refs.c b/refs.c
index 3926136..6eb8a02 100644
--- a/refs.c
+++ b/refs.c
@@ -2039,6 +2039,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
int type, lflags;
int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
int missing = 0;
+ int attempts = 3;
lock = xcalloc(1, sizeof(struct ref_lock));
lock->lock_fd = -1;
@@ -2093,7 +2094,15 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
lock->force_write = 1;
- if (safe_create_leading_directories(ref_file)) {
+ retry:
+ switch (safe_create_leading_directories(ref_file)) {
+ case SCLD_OK:
+ break; /* success */
+ case SCLD_VANISHED:
+ if (--attempts > 0)
+ goto retry;
+ /* fall through */
Hmph.
Having no backoff/sleep at all might be OK here as long as the other
side that removes does not retry (and I do not think the other side
would, even though I haven't read through the series to the end yet
;-)).
This may be just a style thing, but I find that the variable name
"attempts" that starts out as 3 quite misleading, as its value is
not "the number of attempts made" but "the remaining number of
attempts allowed." Starting it from 0 and then
if (attempts++ < MAX_ATTEMPTS)
goto retry;
would be one way to clarify it. Renaming it to remaining_attempts
would be another.
+ default:
last_errno = errno;
error("unable to create directory for %s", ref_file);
goto error_return;
On 01/06/2014 06:54 PM, Junio C Hamano wrote:
Michael Haggerty [off-list ref] writes:
quoted
If safe_create_leading_directories() fails because a file along the
path unexpectedly vanished, try again (up to 3 times).
This can occur if another process is deleting directories at the same
time as we are trying to make them. For example, "git pack-refs
--all" tries to delete the loose refs and any empty directories that
are left behind. If a pack-refs process is running, then it might
delete a directory that we need to put a new loose reference in.
If safe_create_leading_directories() thinks this might have happened,
then take its advice and try again (maximum three attempts).
Signed-off-by: Michael Haggerty <redacted>
---
refs.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/refs.c b/refs.c
index 3926136..6eb8a02 100644
--- a/refs.c
+++ b/refs.c
@@ -2039,6 +2039,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
int type, lflags;
int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
int missing = 0;
+ int attempts = 3;
lock = xcalloc(1, sizeof(struct ref_lock));
lock->lock_fd = -1;
@@ -2093,7 +2094,15 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
lock->force_write = 1;
- if (safe_create_leading_directories(ref_file)) {
+ retry:
+ switch (safe_create_leading_directories(ref_file)) {
+ case SCLD_OK:
+ break; /* success */
+ case SCLD_VANISHED:
+ if (--attempts > 0)
+ goto retry;
+ /* fall through */
Hmph.
Having no backoff/sleep at all might be OK here as long as the other
side that removes does not retry (and I do not think the other side
would, even though I haven't read through the series to the end yet
;-)).
remove_dir_recurse() only tries deleting directories once (I haven't
changed that). And from a broader perspective, it would be pretty silly
for any tidy-up-directories function to try deleting things more than
once. So I don't think it is a problem. But even in the worst case,
this function only tries three times before giving up, so it shouldn't
be a disaster.
This may be just a style thing, but I find that the variable name
"attempts" that starts out as 3 quite misleading, as its value is
not "the number of attempts made" but "the remaining number of
attempts allowed." Starting it from 0 and then
if (attempts++ < MAX_ATTEMPTS)
goto retry;
would be one way to clarify it. Renaming it to remaining_attempts
would be another.
I just renamed the variable to attempts_remaining. (I thought I was
following your suggestion, but now I see that I put the words in the
opposite order; oh well, I think it's fine either way.)
Thanks for your review! I will wait a day or so for any additional
comments, and then send a v3.
Michael
--
Michael Haggerty
mhagger@alum.mit.edu
http://softwareswirl.blogspot.com/