It seems obvious. On a classical workflow, the request headers analysis is
finished when these applets are woken up for the first time. So they don't
take care to really have the request to start to process it and to send the
response. But with a filter, it is possible to stop the request analysis
after the applet creation.
If this happens for the stats applet, this leads to a crash because we
retrieve the request start-line without checking if it is available. For the
cache applet, the response is just immediatly sent. And here it is a problem
if the compression is enabled. In that case too, this may lead to a crash
because the compression may be enabled but not initialized.
For a true server, there is no issue because the connection cannot be
established. The server is chosen only after the request analysis. The issue
with applets is that once created, an applet is quickly switched to the
established state. So it is probably a point that must be carefully reviewed
and probably reworked.
In the mean time, as a fix, in the cache and the stats applet, we just take
care to have the request before sending the response. This will do the
trick.
The patch must be backported as far as 2.6. On 2.6, the patch must be adapted.
Now SPOP connections can be reused, it could be pretty useful to know the
reuse rate. The corresponding backend and server counters are already
incremented, but not displayed on the stats HTML page. Thanks to this patch,
it is now possible to get it, just like for HTTP proxies.
The related issue is #2502.
Start-line flags for 303-See-Other response returned by the stats applet are
not properly set. Indeed, the reponse has a "content-length" header but both
HTX_SL_F_CHNK and HTX_SL_F_CLEN flags are set. Because of this bug, the
reponse is considered as chunked. So, let's remove HTX_SL_F_CHNK flag.
And also add HTX_SL_F_BODYLESS flag because there is no payload
("content-length" header is always set to 0).
This patch must be backported to all stable versions. On the 2.8 and lower
versions, the commit d0b04920d1 ("BUG/MINOR: htpp-ana/stats: Specify that
HTX redirect messages have a C-L header") must be backported first.
Instead of having each caller of appctx_get_buf() think about setting
the blocking flag, better have the function do it, since it's already
handling the queue anyway. This way we're sure that both are consistent.
Some flags are defined during statistics generation and output. They use
the prefix STAT_* which is also used for other purposes. Rename them
with the new prefix STAT_F_* to differentiate them from the other
usages.
This commit is the first one of a serie which adjust naming convention
for stats module. The objective is to remove ambiguity and better
reflect how stats are implemented, especially since the introduction of
stats module.
This patch renames elements related to proxies statistics. One of the
main change is to rename ST_F_* statistics indexes prefix with the new
name ST_I_PX_*. This remove the reference to field which represents
another concept in the stats module. In the same vein, global
stat_fields variable is renamed metrics_px.
Extract functions related to HTML stats webpage from stats.c into a new
module named stats-html. This allows to reduce stats.c to roughly half
of its original size.
