Disabling ffd->svn_cache__t Re: svn commit: r1462413 - in /subversion/trunk/subversion: include/svn_fs.h libsvn_fs_fs/fs_fs.c

[Daniel Shahaf]

I have a function that looks like this:

    static svn_error_t *f(svn_fs_t *fs)
    {
      svn_fs_t *ft = svn_fs_open(fs);
      svn_fs_verify_root(ft, r42);
    }

I'd like the 'verify' call to bypass any information that is already
cached:  I don't mind if it the 'verify' process caches information for
itself and then reads it back, but I don't want it to read information
that is _right now_ in the cache (due to FS, or some other handle to the
same filesystem in another thread) in lieu of parsing it, for itself,
from the revision file.

What would be the best way to achieve this?  Do I set every cache in
ft->ffd->* to NULL or to a pointer to a newly-created, empty cache object?
Something else?

Thanks

Daniel

danie...@apache.org wrote on Fri, Mar 29, 2013 at 06:08:55 -0000:
> Author: danielsh
> Date: Fri Mar 29 06:08:55 2013
> New Revision: 1462413
> 
> URL: http://svn.apache.org/r1462413
> Log:
> In the FSFS "paranoid verify" code, disable caching.  See within for a 
> question.
> 
> * subversion/include/svn_fs.h
>   (SVN_FS_CONFIG_FSFS_CACHE_*): Add a note to maintainers who add such 
> symbols.
> 
> * subversion/libsvn_fs_fs/fs_fs.c
>   (verify_as_revision_before_current_plus_plus):
>     Disable caches the API allows to disable, and add a question.
> 
> Modified:
>     subversion/trunk/subversion/include/svn_fs.h
>     subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c
> 
> Modified: subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c
> URL: 
> http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c?rev=1462413&r1=1462412&r2=1462413&view=diff
> ==============================================================================
> --- subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c (original)
> +++ subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c Fri Mar 29 06:08:55 2013
> @@ -8278,11 +8278,20 @@ verify_as_revision_before_current_plus_p
>    svn_fs_t *ft; /* fs++ == ft */
>    svn_fs_root_t *root;
>    fs_fs_data_t *ft_ffd;
> +  apr_hash_t *fs_config;
>  
>    SVN_ERR_ASSERT(ffd->svn_fs_open_);
>  
> +  fs_config = apr_hash_make(pool);
> +  svn_hash_sets(fs_config, SVN_FS_CONFIG_FSFS_CACHE_DELTAS, "0");
> +  svn_hash_sets(fs_config, SVN_FS_CONFIG_FSFS_CACHE_FULLTEXTS, "0");
> +  svn_hash_sets(fs_config, SVN_FS_CONFIG_FSFS_CACHE_REVPROPS, "0");
> +  /* ### TODO: are there any other intra-process caches that FS populated
> +               and FT will read from?  Can we disable those (for FT at 
> least)?
> +   */
> +
>    SVN_ERR(ffd->svn_fs_open_(&ft, fs->path,
> -                            NULL /* ### TODO fs_config */,
> +                            fs_config,
>                              pool));
>    ft_ffd = ft->fsap_data;
>  
> 
>