Usage of the shadow field in ngx_buf_t?
agentzh at gmail.com
Fri Dec 4 10:05:05 MSK 2009
On Fri, Dec 4, 2009 at 1:32 PM, Dave Bailey <dave at daveb.net> wrote:
> On Thu, Dec 3, 2009 at 6:29 PM, Brian Pane <brianp at brianp.net> wrote:
>> After an afternoon with gdb, I think I've found one dependency: before
>> throwing away the buffers, the body filter needs to set buf->pos=buf->last
>> for each one.
> I think that's right. I've written an nginx body filter that uses
> ngx_chain_update_chains, and the input buffers need to be marked as
> fully consumed (buf->pos = buf->last) in order for
> ngx_chain_update_chains to recycle them properly.
I see. Thanks a lot for the correction and explanation :)
> In many cases, this
> permits the same one or two buffers to get recycled over and over
> again as the entire request body is passed through the filter. I
> think it's one of the reasons nginx body filters are so incredibly
> high performance.
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