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Re: [PATCH] issue #4134 (partial): sort deleted nodes before dumping them

From: Stefan Sperling <stsp_at_elego.de>
Date: Tue, 29 May 2012 22:10:55 +0200

On Tue, May 29, 2012 at 03:09:08PM -0400, Dustin Lang wrote:
>
> Hi,
>
> This is my first time working on the subversion code, so be gentle :)
>
> I believe the attached patch solves one component of #4134
> ("svnadmin dump files are not reproducible, due to APR 1.4.6 hash
> order changes"), namely that deleted nodes are stored in a hash and
> dumped out in (now-arbitrary) hash iteration order. This patch
> simply uses "svn_sort_hash" to get a sorted view of the keys before
> dumping them.
>
> I have verified that it runs valgrind-clean when "svnadmin dump"ing
> >700 revs of the astrometry.net repo (and now my repo and its
> svnsync'd mirror produce exactly equal dumps, hoorah), but I don't
> really know if I've used the apr infrastructure appropriately.
>
> I don't know whether this completely solves #4134; it works for me,
> but my repo is simple.
>
> cheers,
> dustin
>

This patch looks correct to me overall but I have some nits.

> http://subversion.tigris.org/issues/show_bug.cgi?id=4134

> Index: subversion/libsvn_repos/dump.c
> ===================================================================
> --- subversion/libsvn_repos/dump.c (revision 1343881)
> +++ subversion/libsvn_repos/dump.c (working copy)
> @@ -34,6 +34,7 @@
> #include "svn_time.h"
> #include "svn_checksum.h"
> #include "svn_props.h"
> +#include "svn_sorts.h"
>
> #include "private/svn_mergeinfo_private.h"
> #include "private/svn_fs_private.h"
> @@ -736,12 +737,14 @@
> struct edit_baton *eb = db->edit_baton;
> apr_hash_index_t *hi;
> apr_pool_t *subpool = svn_pool_create(pool);
> + unsigned int Npaths = apr_hash_count(db->deleted_entries);

No CamelCase please. You don't need this variable at all (see below).

> + unsigned int i;
> + apr_array_header_t* sorted;

Maybe call the array 'sorted_deleted_entries', or 'sorted_entries', instead?

>
> - for (hi = apr_hash_first(pool, db->deleted_entries);
> - hi;
> - hi = apr_hash_next(hi))
> + sorted = svn_sort__hash(db->deleted_entries, svn_sort_compare_items_as_paths, pool);

Please try to wrap lines at 78 columns.

You can use svn_sort_compare_items_lexically because entries are single
path components that do not contain slashes. In which case
svn_sort_compare_items_as_paths produces the same result but is less efficient.

> + for (i = 0; i < Npaths; i++)

Here, you can use the idiom:

  for (i = 0; i < sorted->nelts; i++)

which means you don't need 'Npaths'.

> {
> - const char *path = svn__apr_hash_index_key(hi);
> + const char* path = APR_ARRAY_IDX(sorted, i, svn_sort__item_t).key;

Please put the asterisk next to the variable name for consistency with code
formatting elsewhere. Same applies to the declaration of 'sorted' above.

>
> svn_pool_clear(subpool);
>
> @@ -753,6 +756,8 @@
> FALSE, NULL, SVN_INVALID_REVNUM, subpool));
> }
>
> + apr_array_clear(sorted);

No need to do this. This doesn't actually free any memory, it just marks
array slots for reuse. Array memory will be freed when the caller clears
or destroys 'pool'. It's up to the caller to do this, so just delete that line.

> +
> svn_pool_destroy(subpool);
> return SVN_NO_ERROR;
> }
Received on 2012-05-29 22:11:37 CEST

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