On 1/8/21 3:51 PM, Daniel Stenberg via curl-library wrote:
Hi all,
Here's something that's been itching in me for a long time. Something
I've even (twice!) tried to fix. Both times my patch ended up so huge
and complicated for me that I had to give it and postpone the idea.
Put shortly: "conn->data considered bad". The association *from* a
connection object to a transfer object is bad, because it is fragile
and error-prone due to the fact that it can and will change very
frequently for multiplexed transfers.
A transfer can use one (or no) connection. A connection can have no,
one or very many transfers associated with it.
Conclusion: we should stop using 'conn->data' in libcurl
Status: there are 939 current uses of this pointer
Mission: reduce the use of this pointer, aiming to reach a point in
the future when we can remove it from the connection struct.
Happy new year to everyone!
Considering the large number of references, I would suggest starting to
fix this "bottom up" by smaller commits rather than having a big patch,
even if it increases the reference count at first while the work is not
complete.
I also noticed there are a lot of references to conn->data for logging
purposes only (infof, failf, debug) in connection-oriented procedures:
maybe we should discuss an alternate strategy for logging from those
procedures.
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