On Fri, Jun 21, 2013 at 12:36 AM, Ivan Zhakov <i...@visualsvn.com> wrote:
> On Fri, Jun 21, 2013 at 2:11 AM, <stef...@apache.org> wrote: > > Author: stefan2 > > Date: Thu Jun 20 22:11:31 2013 > > New Revision: 1495209 > > > > URL: http://svn.apache.org/r1495209 > > Log: > > Make the hash function used by the FSFS DAG node cache > > platform-independent. That should help us reproducing issues > > detected on "exotic" platforms. > > > > * subversion/libsvn_fs_fs/tree.c > > (cache_lookup): normalize chunked calculation to big endian > > > > Patch by: stsp > > > > Modified: > > subversion/trunk/subversion/libsvn_fs_fs/tree.c > > > > Modified: subversion/trunk/subversion/libsvn_fs_fs/tree.c > > URL: > http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_fs_fs/tree.c?rev=1495209&r1=1495208&r2=1495209&view=diff > > > ============================================================================== > > --- subversion/trunk/subversion/libsvn_fs_fs/tree.c (original) > > +++ subversion/trunk/subversion/libsvn_fs_fs/tree.c Thu Jun 20 22:11:31 > 2013 > > @@ -355,14 +355,15 @@ cache_lookup( fs_fs_dag_cache_t *cache > > (HASH_VALUE has been initialized to REVISION). */ > > for (i = 0; i + 4 <= path_len; i += 4) > > #if SVN_UNALIGNED_ACCESS_IS_OK > > - hash_value = hash_value * 0xd1f3da69 + *(const apr_uint32_t*)(path > + i); > > + hash_value = hash_value * 0xd1f3da69 > > + + ntohl(*(const apr_uint32_t*)(path + i)); > ntohl() is real function, not inline function or macro on Windows [1]. > So most likely your change make hash calculation significantly slower > on Windows due function call for each four bytes. > > [1] > http://msdn.microsoft.com/en-us/library/windows/desktop/ms740069%28v=vs.85%29.aspx > > The offending revisions have been removed from STATUS. After some discussion on IRC, we realized that going for a platform-independent hash function is simply not worth the hassle. So, the /trunk code already looks different. Not sure how much of this should be backported (tons of back-and-forth changes). -- Stefan^2.
