Add a new stats column in proxy stats to display server counter for
private idle connections. This counter has been introduced recently.
The value is displayed on CSV output on the last column before modules.
It is also displayed on HTLM page alongside other idle server counters.
Multiplexers already explicitly announce their HTX support. Now it is
possible to set flags on applet, it could be handy to do the same. So, now,
HTX aware applets must set the APPLET_FL_HTX flag.
A new field was added in the applet structure to be able to set flags on the
applets The first one is related to the new API. APPLET_FL_NEW_API is set
for applets based on the new API. It was set on all HAProxy's applets.
If a server A is deleted while a stats dump is currently on it, deletion
is delayed thanks to reference counting. Server A is nonetheless removed
from the proxy list. However, this list is a single linked list. If the
next server B is deleted and freed immediately, server A would still
point to it. This problem has been solved by the prev_deleted list in
servers.
This model seems correct, but it is difficult to ensure completely its
validity. In particular, it implies when stats dump is resumed, server A
elements will be accessed despite the server being in a half-deleted
state.
Thus, it has been decided to completely ditch the refcount mechanism for
stats dump. Instead, use the watcher element to register every stats
dump currently tracking a server instance. Each time a server is deleted
on the CLI, each stats dump element which may points to it are updated
to access the next server instance, or NULL if this is the last server.
This ensures that a server which was deleted via CLI but not completely
freed is never accessed on stats dump resumption.
Currently, no race condition related to dynamic servers and stats dump
is known. However, as described above, the previous model is deemed too
fragile, as such this patch is labelled as bug-fix. It should be
backported up to 2.6, after a reasonable period of observation. It
relies on the following patch :
MINOR: list: define a watcher type
During the zero-copy data forwarding, the caller specify the maximum amount
of data the producer may push. However, the HTML stats applet does not use
it and can fill all the free space in the buffer. It is especially an issue
when the consumer is limited by a flow control, like the H2. Because we may
emit too large DATA frame in this case. It is especially visible with big
buffer (for instance 32k).
In the early age or zero-copy data forwarding, the caller was responsible to
pass a properly resized buffer. And during the different refactoring steps,
this has changed but the HTML stats applet was not updated accordingly.
To fix the bug, the buffer used to dump the HTML page is resized to be sure
not too much data are dumped.
This patch should solve the issue #2757. It must be backported to 3.0.
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.
