Non-buffered backend

[Martin Schut]

Hi all,



First an easy question: what is does the postpone filter do? I can't find  
it in the docs.

On the next questions:

My current understanding of the webserver to send the response goes along  
the following lines (I haven't spent much time reading the source yet):

1. nginx receives the stream to send from the back-end, be it a static  
file or one of the other back-end means and buffers this until this  
streamis closed
2. nginx routes the stream through all the need modules
3. nginx sends the stream to the client

I've a few questions regarding this:
a. Are 2 & 3 indeed seperate steps or will everything be sent as soon at  
is processed in chunks (as I actually expect).
b. Is it possible to not transfer control to next module (with  
ngx_http_next_*) but to request more chunks (maybe return with NGX_AGAIN?)
c. What I actually would like to try (in a few weeks) is to skip the  
buffering step between 1&2. I see 2 options for this: I. buffer a small  
amount then call the modules and wait until I receive a request back for  
more info. This has the disadvantage that the backend can not send it's  
response at the highest rate possible if the modules are not fast enough);  
II. Use 2 threads, the first to read from the backend and the second to  
immediatly start feeding the stream into the modules. Any opinions about  
these options and the possibility to implement this in nginx. Or maybe a  
third possibility?



Best regards,

Martin Schut