This commit similar to the following one :
65ae241dcfe710e1cdd3ec4e7a9bde38d2e4c116
MEDIUM: server: close idle conn before server deletion
This patch implements a similar logic, this time to close private idle
connections stored in sessions. The principle is identical to the above
commit : conn_release() is used on idle connections after a takeover to
ensure thread safety.
An extra change was required to be able to execute takeover on such
connections. Their original thread ID was unknown, contrary to non
private connections which are stored in sharded lists. As such, a new
tid member has been added under sess_priv_conns chaining element.
A server can only be deleted if there is no elements which reference it.
This is taken care via srv_check_for_deletion(), most notably for active
and idle connections.
A special case occurs for connections directly managed by a session.
This is for so-called private connections, when using http-reuse never
or H2 + http-reuse safe for example. In this case. server does not
account these connections into its idle lists. This caused a bug as the
server is deleted despite the session still being able to access it.
To properly fix this, add a new referencing element into the server for
these session connections. A mt_list has been chosen for this. On
default http-reuse, private connections are typically not used so it
won't make any difference. If using H2 servers, or more generally when
dealing with private connections, insert/delete should typically occur
only once per session lifetime so impact on performance should be
minimal.
This should be backported up to 2.4. Note that srv_check_for_deletion()
was introduced in 3.0 dev tree. On backport, the extra condition in it
should be placed in cli_parse_delete_server() instead.
By default, backend connections are attached to a server instance. This
allows to implement connection reuse. However, in some particular cases,
connection cannot be shared accross several clients. These connections
are considered and private and are attached to the session instance
instead.
These private connections are also indexed by the target server to not
mix them. All of this is implemented via a dedicated structure
previously named struct sess_srv_list.
Rename it to better reflect its usage to struct sess_priv_conns. Also
rename its internal members and all of the associated functions.
This commit is only a renaming, thus no functional impact is expected.
Let's get rid of timeval in storage of internal timestamps so that they
are no longer mistaken for wall clock time. These were exclusively used
subtracted from each other or to/from "now" after being converted to ns,
so this patch removes the tv_to_ns() conversion to use them natively. Two
occurrences of tv_isge() were turned to a regular wrapping subtract.
The number of stick-counter entries usable by track-sc rules is currently
set at build time. There is no good value for this since the vast majority
of users don't need any, most need only a few and rare users need more.
Adding more counters for everyone increases memory and CPU usages for no
reason.
This patch moves the per-session and per-stream arrays to a pool of a size
defined at boot time. This way it becomes possible to set the number of
entries at boot time via a new global setting "tune.stick-counters" that
sets the limit for the whole process. When not set, the MAX_SESS_STR_CTR
value still applies, or 3 if not set, as before.
It is also possible to lower the value to 0 to save a bit of memory if
not used at all.
Note that a few low-level sample-fetch functions had to be protected due
to the ability to use sample-fetches in the global section to set some
variables.
That's similar to what was done for conn_streams and connections. The
flags were only set exactly when the relevant pointers were allocated,
so better test the pointer than the flag and stop setting the flag.
For now, these addresses are never set. But the idea is to be able to set
client source and destination addresses at the session level without
updating the connection ones.
Functions to fill these addresses have been added: sess_get_src() and
sess_get_dst(). If not already set, these functions relies on
conn_get_src() and conn_get_dst() to fill session addresses.
And just like for conncetions, sess_src() and sess_dst() may be used to get
source and destination addresses. However, if not set, the corresponding
address from the underlying client connection is returned. When this
happens, the addresses is filled in the connection object.
The idle duration between two streams is added to the session structure. It
is not necessarily pertinent on all protocols. In fact, it is only defined
for H1 connections. It is the duration between two H1 transactions. But the
.get_cs_info() callback function on the multiplexers only exists because
this duration is missing at the session level. So it is a simplification
opportunity for a really low cost.
To reduce the cost, a hole in the session structure is filled by moving
.srv_list field at the end of the structure.
There are list definitions everywhere in the code, let's drop the need
for including list-t.h to declare them. The rest of the list manipulation
is huge however and not needed everywhere so using the list walking macros
still requires to include list.h.
