Paul Burba wrote:
> On Wed, Nov 28, 2012 at 2:25 PM, Julian Foad wrote:
>>> +/* Remove all prop name value pairs from PROP_HASH where the property
>>> + name is not PROPNAME. */
>>> +static void
>>> +filter_unwanted_props(apr_hash_t *prop_hash,
>>> + const char * propname,
>>> + apr_pool_t *scratch_pool)
>>> +{
>>> + apr_hash_index_t *hi;
>>> +
>>> + for (hi = apr_hash_first(scratch_pool, prop_hash);
>>> + hi;
>>> + hi = apr_hash_next(hi))
>>> + {
>>> + const char *ipropname = svn__apr_hash_index_key(hi);
>>> +
>>> + if (strcmp(ipropname, propname) != 0)
>>> + apr_hash_set(prop_hash, ipropname, APR_HASH_KEY_STRING, NULL);
>>> + }
>>
>> I suppose a much quicker way to select just the wanted key-value pair from
>> the hash is:
>>
>> propval = hash_get(propname)
>> hash_clear()
>
> (Julian - sorry for the tardy reply, I was cleaning out old TODOs
> today and found this)
>
> apr_hash_clear clears the hash by iterating over it just like we do above:
[...]
> I did a quick test: Set 10,000 properties on the root of a WC then
> ran 'svn pg some-prop some-subtree-path --show-inherited-props'.
> Average execution time over 5 runs was .052s for the existing code and
> .056s for your suggested change
IIRC I was thinking how many seconds quicker I could read the code as well as
how many nanoseconds quicker I assumed hash_clear would be at run time. That
using the latter adds a microsecond [1] surprises me -- and I'm sure
apr_hash_clear could be optimized if you care about such things -- but either
way you'll have to run "svn pg" an awful lot of times now for it to add up to
the hour I've spent looking at this.
> ...so I'll leave the code as is.
OK.
- Julian
[1] Linear extrapolation, assuming << 10 props on a typical directory.
