On Fri, Apr 10, 2020 at 2:36 PM Christopher Schultz <ch...@christopherschultz.net> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > All, > > First-time httpd hacker, here. I'm looking at: > https://bz.apache.org/bugzilla/show_bug.cgi?id=64338 > > I've found that around line 637 of mod_proxy_balancer.c it looks like > I just need to poke a value into the r->subprocess_env like this: > > apt_table_setn(r->subprocess_env, > "BALANCER_WORKER_STATUS", XXX); > > The question is what "XXX" should be. I need to convert > (*worker)->s->status (an unsigned int) into a char*. > > I can manually malloc a char*, stick it in there, and deallocate it > each time back through, but that will leak memory when the pool is > recycled and I don't get a chance to free my char*. > > I can use apt_table_set instead of apt_table_setn but that will make > performance suck even more than a single allocation each time > mod_proxy handles a request. > > I can also use something like apr_itoa/apr_ltoa which will allocate > from the pool which presumably will be cleaned-up at some point, > but... when? I don't know anything about how APR/httpd handle memory > management and I'm afraid I'll much it all up if I don't ask this > question. > > So ... what's the right way to do this? > > A performance optimization is likely to be that most workers (a) have > all the same "everything is fine" status and (b) the status doesn't > change very often. So maybe having a table of predefined status > strings sitting around wouldn't be the worth possible thing in the > world; that would avoid many needless memory (re)allocations.
Hi Chris. You have access to a request_rec then you can allocate from r->pool. Allocations from there are automatically returned at the end of the request. You could also just test the value in that status field and "setn" the variable to a constant character or string. Note: If you move to r->notes (also a table) you can use apr_table_setn to pass a casted pointer and retrieve the pointer on the other side. But this is probably a last resort.
