Re: svn commit: r16244 - in trunk: . subversion/clients/cmdline subversion/include subversion/libsvn_client subversion/libsvn_wc subversion/svnversion subversion/tests/clients/cmdline subversion/tests/clients/cmdline/svntest tools/examples

Philip Martin <philip@codematters.co.uk> writes:

> There's also a performance issue here. Any function that simply wants
> to read the adm directory name now has to go through a CAS. The
> default CAS implementation is the generic mutex based implementation
> in apr_atomic.c, so that means that every time a file in the .svn
> directory is accessed a mutex will need to locked and unlocked.
> That's a *lot* of mutex operations, could this be a bottleneck? Linux
> on x86 can use the asm versions, but that's not the default and
> doesn't help other platforms.

Perhaps we should simply drop the CAS stuff and require that
svn_wc_set_adm_dir is called when no other threads are doing any wc
operations. After all is multi-thread support sensible? If one
thread is successfully accessing a wc and another thread changes the
the adm directory name the first thread is going to get libsvn_wc
errors as the adm directory will no longer be found.

-- 
Philip Martin
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