[PATCH] Allow GUID buf-> struct GUID to avoid talloc

[Andrew Bartlett]

While looking into performance issues, I noticed that we call talloc()
a lot while parsing GUIDs, particularly in LDB.  We parse a lot of
GUIDs in LDB, and in general call talloc() way too much.

This patch keeps the PIDL generated parser, but instead uses stack
variables and never calls talloc().

I realise the new ndr_pull_struct_blob_all_noalloc() could be mis-used, 
but I figure setting mem_ctx to (void*)-1 should catch that pretty
fast.

Found with perf and FlameGraph visualisation.

Thoughts?

Thanks,

Andrew Bartlett
-- 
Andrew Bartlett
https://samba.org/~abartlet/
Authentication Developer, Samba Team         https://samba.org
Samba Development and Support, Catalyst IT   
https://catalyst.net.nz/services/samba





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