Hi all, I have attached a patch that attempts to support async write completion for the full connection filter stack, not just the core output filter. In turn, this should bring async write completion to mod_ssl, and can be backported to v2.4.
The idea behind the patch is to change the brigade used during write completion from a NULL brigade passed to the core output filter to an empty brigade, and pass this empty brigade to all connection filters. The obvious problem is existing filters that don’t pass empty brigades down the stack - the patch compensates for this by detecting these not-pass-brigade cases and then by passing the empty brigade to the next filter in the chain manually, ensuring that every filter gets a turn to attempt to flush any buffers. The test suite passes with this patch, I need some more eyeballs to verify I didn’t miss anything. The next obvious problem to solve is to look at how to run request filters through write completion. There are a number of ways to approach this. One is to replace c->output_filters with r->output_filters and reinstate c->output_filters on cleanup of r->pool, or have a formal c->request_output_filters that would override c->output_filters if present (there would need to be some magic to ensure that it is possible to remove the first filter in the chain, separate problem). The problem of the output filter stack trying to process the entire response in one go could potentially be solved by a request filter that attempts to pass “bite sized chunks” down the filter stack while setting aside the rest, mirroring what the core output filter does now, but for the whole stack. Ideas to explore. Regards, Graham —
httpd-async-fullstack.patch
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