Re: [PATCH v4 17/22] read-cache: unlink old sharedindex files

[Junio C Hamano]

Christian Couder  writes:

> +static int can_delete_shared_index(const char *shared_index_path)
> +{
> + struct stat st;
> + unsigned long expiration;
> +
> + /* Check timestamp */
> + expiration = get_shared_index_expire_date();
> + if (!expiration)
> + return 0;
> + if (stat(shared_index_path, ))
> + return error_errno(_("could not stat '%s"), shared_index_path);
> + if (st.st_mtime > expiration)
> + return 0;
> +
> + return 1;
> +}
> +
> +static int clean_shared_index_files(const char *current_hex)
> +{
> + struct dirent *de;
> + DIR *dir = opendir(get_git_dir());
> +
> + if (!dir)
> + return error_errno(_("unable to open git dir: %s"), 
> get_git_dir());
> +
> + while ((de = readdir(dir)) != NULL) {
> + const char *sha1_hex;
> + const char *shared_index_path;
> + if (!skip_prefix(de->d_name, "sharedindex.", _hex))
> + continue;
> + if (!strcmp(sha1_hex, current_hex))
> + continue;
> + shared_index_path = git_path("%s", de->d_name);
> + if (can_delete_shared_index(shared_index_path) > 0 &&

Is this "can" or "should"?  This sounds like the latter.

> + unlink(shared_index_path))
> + error_errno(_("unable to unlink: %s"), 
> shared_index_path);

This does not make the entire operation to fail (and I think the
behaviour you have here is preferrable--we just want to report
without failing the main operation).

But should it be reported as "error: unable to unlink"?  It may be
better to give this message as a warning.

[PATCH v4 17/22] read-cache: unlink old sharedindex files

[Christian Couder]

Everytime split index is turned on, it creates a "sharedindex."
file in the git directory. This change makes sure that shared index
files that haven't been used for a long time are removed when a new
shared index file is created.

The new "splitIndex.sharedIndexExpire" config variable is created
to tell the delay after which an unused shared index file can be
deleted. It defaults to "2.weeks.ago".

A previous commit made sure that each time a split index file is
created the mtime of the shared index file it references is updated.
This makes sure that recently used shared index file will not be
deleted.

Signed-off-by: Christian Couder 
---
 read-cache.c | 64 +++-
 1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/read-cache.c b/read-cache.c
index 5f295af4c6..45fc831010 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -2199,6 +2199,65 @@ static int write_split_index(struct index_state *istate,
return ret;
 }
 
+static const char *shared_index_expire = "2.weeks.ago";
+
+static unsigned long get_shared_index_expire_date(void)
+{
+   static unsigned long shared_index_expire_date;
+   static int shared_index_expire_date_prepared;
+
+   if (!shared_index_expire_date_prepared) {
+   git_config_get_expiry("splitindex.sharedindexexpire",
+ _index_expire);
+   shared_index_expire_date = approxidate(shared_index_expire);
+   shared_index_expire_date_prepared = 1;
+   }
+
+   return shared_index_expire_date;
+}
+
+static int can_delete_shared_index(const char *shared_index_path)
+{
+   struct stat st;
+   unsigned long expiration;
+
+   /* Check timestamp */
+   expiration = get_shared_index_expire_date();
+   if (!expiration)
+   return 0;
+   if (stat(shared_index_path, ))
+   return error_errno(_("could not stat '%s"), shared_index_path);
+   if (st.st_mtime > expiration)
+   return 0;
+
+   return 1;
+}
+
+static int clean_shared_index_files(const char *current_hex)
+{
+   struct dirent *de;
+   DIR *dir = opendir(get_git_dir());
+
+   if (!dir)
+   return error_errno(_("unable to open git dir: %s"), 
get_git_dir());
+
+   while ((de = readdir(dir)) != NULL) {
+   const char *sha1_hex;
+   const char *shared_index_path;
+   if (!skip_prefix(de->d_name, "sharedindex.", _hex))
+   continue;
+   if (!strcmp(sha1_hex, current_hex))
+   continue;
+   shared_index_path = git_path("%s", de->d_name);
+   if (can_delete_shared_index(shared_index_path) > 0 &&
+   unlink(shared_index_path))
+   error_errno(_("unable to unlink: %s"), 
shared_index_path);
+   }
+   closedir(dir);
+
+   return 0;
+}
+
 static struct tempfile temporary_sharedindex;
 
 static int write_shared_index(struct index_state *istate,
@@ -2220,8 +2279,11 @@ static int write_shared_index(struct index_state *istate,
}
ret = rename_tempfile(_sharedindex,
  git_path("sharedindex.%s", 
sha1_to_hex(si->base->sha1)));
-   if (!ret)
+   if (!ret) {
hashcpy(si->base_sha1, si->base->sha1);
+   clean_shared_index_files(sha1_to_hex(si->base->sha1));
+   }
+
return ret;
 }
 
-- 
2.12.0.22.g0672473d40