Summary:
Check if hash is empty before computing the hash key and look inside the
hash to find data.
Note: could have called the eina_hash_population() api but didn't
because of extra function call.
Reviewers: Hermet
Reviewed By: Hermet
Subscribers: cedric, #reviewers, #committers
Tags: #efl
Differential Revision: https://phab.enlightenment.org/D9531
Summary:
this simplifies the process of manipulating lists inside hashes with a
non-copied key
@feature
Depends on D9205
Reviewers: cedric
Reviewed By: cedric
Subscribers: #reviewers, #committers
Tags: #efl
Differential Revision: https://phab.enlightenment.org/D9206
Before this patch, the key would always be zero and the hash would solely
rely on the rbtree to be efficient. This improve the situation by using the pointer
as the key during hash computation.
this fixes T3638
@fix
a note... thanks so much to aerodynamik for spotting this. i'm rather
surprised coverity didn't spot this... unless someone said to "shut up
coverity you're wrong" and they should not have.
i also might have expected compilers to spot this too... and add a
warning.
anyway ... this was a seriously subtle bug that could have caused all
kinds of havoc in efl. keys that are different may be compared to be
the same. it could get ordering wrong and sorting thus maybe insert
keys that cannot be found anymore and oh so much more besides.
This is the correct implementation of the idea developped in Lucas De Marchi's blog :
http://www.politreco.com/2013/09/optimizing-hash-table-with-kmod-as-testbed/
This give an interesting +15% for all Eina_Hash user whatever hash function they use. The inlined
djb2 is still the fastest one and all other give very close result. It does increase memory foot
print, but as much as the previous way of doing it.
This give an interesting +15% for all Eina_Hash user whatever hash function they use. The inlined
djb2 is still the fastest one and all other give very close result.
This idea was given by Lucas De Marchi's blog :
http://www.politreco.com/2013/09/optimizing-hash-table-with-kmod-as-testbed/
I do believe that rolling a crc32 implementation as a hash function should give interesting result
in our test.
We did use this 'begin' boolean to make eina_hash always allocate only
once per item it push in the hash. This boolean was alone at the end of
a structure. It would have costed us 4bytes on 32bits system and 8bytes
on 64bits. Removing it make elemines consume 100KB less on 32bits system.
We may have a speed impact on hash insertion here, but I don't think we
do use eina_hash_add and friends in any hot path, at the moment. If that
was the case there would be some way to mitigate this, just not worth it
at the moment.
Thanks goes to Thiago Macieira for sharing the issue. This
is the result of the cross-desktop talk at fosdem. A lot more
comming in the futur !
SVN revision: 83578
subhransu mohanty
Mike Blumenkrantz
Vincent Torri
Cedric BAIL
Carsten Haitzler
Cedric Bail
Cedric Bail
Lucas De Marchi