For both servers and proxies, use one connection queue per thread-group,
instead of only one. Having only one can lead to severe performance
issues on NUMA machines, it is actually trivial to get the watchdog to
trigger on an AMD machine, having a server with a maxconn of 96, and an
injector that uses 160 concurrent connections.
We now have one queue per thread-group, however when dequeueing, we're
dequeuing MAX_SELF_USE_QUEUE (currently 9) pendconns from our own queue,
before dequeueing one from another thread group, if available, to make
sure everybody is still running.
Add a per-thread group queue and associated fields in per-thread group
field in struct server, as well as a new field, queues length.
This is currently unused, so should change nothing.
This patch is a direct follow-up to the previous one. Thanks to watcher
type, it is not safe to assume that servers manipulated via stats dump
were not targetted by a "delete server" CLI command. As such,
prev_deleted list server member is now unneeded. This patch thus removes
any reference to it.
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
Each server is inserted in a global list named servers_list on
new_server(). This list is then only used to finalize servers
initialization after parsing.
On dynamic server creation, there is no issue as new_server() is under
thread isolation. However, when a server is deleted after its refcount
reached zero, srv_drop() removes it from servers_list without lock
protection. In the longterm, this can cause list corruption and crashes,
especially if multiple adjacent servers are removed in parallel.
To fix this, convert servers_list to a mt_list. This should not impact
performance as servers_list is not used during runtime outside of server
creation/deletion.
This should fix github issue #2733. Thanks to Chris Staite who first
found the issue here.
This must be backported up to 2.6.
Pierre Bonnat reported that SRV-based server-template recently stopped
to work properly.
After reviewing the changes, it was found that the regression was caused
by a4d04c6 ("BUG/MINOR: server: make sure the HMAINT state is part of MAINT")
Indeed, HMAINT is not a regular maintenance flag. It was implemented in
b418c122 a4d04c6 ("BUG/MINOR: server: make sure the HMAINT state is part
of MAINT"). This flag is only set (and never removed) when the server FQDN
is changed from its initial config-time value. This can happen with "set
server fqdn" command as well as SRV records updates from the DNS. This
flag should ideally belong to server flags.. but it was stored under
srv_admin enum because cur_admin is properly exported/imported via server
state-file while regular server's flags are not.
Due to a4d04c6, when a server FQDN changes, the server is considered in
maintenance, and since the HMAINT flag is never removed, the server is
stuck in maintenance.
To fix the issue, we partially revert a4d04c6. But this latter commit is
right on one point: HMAINT flag was way too confusing and mixed-up between
regular MAINT flags, thus there's nothing to blame about a4d04c6 as it was
error-prone anyway.. To prevent such kind of bugs from happening again,
let's rename HMAINT to something more explicit (SRV_ADMF_FQDN_CHANGED) and
make it stand out under srv_admin enum so we're not tempted to mix it with
regular maintenance flags anymore.
Since a4d04c6 was set to be backported in all versions, this patch must
be backported there as well.
In 1.8 when adding "set server fqdn" with commit b418c1228c ("MINOR:
server: cli: Add server FQDNs to server-state file and stats socket."),
the HMAINT flag was not made part of the MAINT ones, so technically
speaking when changing the FQDN, the server is not completely considered
as in maintenance mode.
In its defense, the code location around that was completely messy, with
the aggregator flag being hidden between other values and purposely but
discretely ignoring one of the flags, so the comments were updated to
make the intent clearer (particularly regarding CMAINT which looked like
it was also forgotten while it was on purpose).
This can be backported anywhere.
As unveiled in GH issue #2711, commit 5541d4995d ("BUG/MEDIUM: queue:
deal with a rare TOCTOU in assign_server_and_queue()") does have some
side effects in that it can occasionally cause an endless loop.
As Christopher analysed it, the problem is that process_srv_queue(),
which uses a trylock in order to leave only one thread in charge of
the dequeueing process, can lose the lock race against pendconn_add().
If this happens on the last served request, then there's no more thread
to deal with the dequeuing, and assign_server_and_queue() will loop
forever on a condition that was initially exepected to be extremely
rare (and still is, except that now it can become sticky). Previously
what was happening is that such queued requests would just time out
and since that was very rare, nobody would notice.
The root of the problem really is that trylock. It was added so that
only one thread dequeues at a time but it doesn't offer only that
guarantee since it also prevents a thread from dequeuing if another
one is in the process of queuing. We need a different criterion.
What we're doing now is to set a flag "dequeuing" in the server, which
indicates that one thread is currently in the process of dequeuing
requests. This one is atomically tested, and only if no thread is in
this process, then the thread grabs the queue's lock and dequeues.
This way it will be serialized with pendconn_add() and no request
addition will be missed.
It is not certain whether the original race covered by the fix above
can still happen with this change, so better keep that fix for now.
Thanks to @Yenya (Jan Kasprzak) for the precise and complete report
allowing to spot the problem.
This patch should be backported wherever the patch above was backported.
Allow the user to set the "initial state" of a server.
Context:
Servers are always set in an UP status by default. In
some cases, further checks are required to determine if the server is
ready to receive client traffic.
This introduces the "init-state {up|down}" configuration parameter to
the server.
- when set to 'fully-up', the server is considered immediately available
and can turn to the DOWN sate when ALL health checks fail.
- when set to 'up' (the default), the server is considered immediately
available and will initiate a health check that can turn it to the DOWN
state immediately if it fails.
- when set to 'down', the server initially is considered unavailable and
will initiate a health check that can turn it to the UP state immediately
if it succeeds.
- when set to 'fully-down', the server is initially considered unavailable
and can turn to the UP state when ALL health checks succeed.
The server's init-state is considered when the HAProxy instance
is (re)started, a new server is detected (for example via service
discovery / DNS resolution), a server exits maintenance, etc.
Link: https://github.com/haproxy/haproxy/issues/51
Add a new field alt_proto to the server structures that
specify if an alternate protocol should be used for this server.
This field can be transparently passed to protocol_lookup to get
an appropriate protocol structure.
This change allows thus to create servers with different protocols,
and not only TCP anymore.
Define a new server keyword pool-conn-name. The purpose of this keyword
will be to identify connections inside the idle connections pool,
replacing SNI in case SSL is not wanted.
This keyword uses a sample expression argument. It thus can reuse
existing function parse_srv_expr() for parsing. In the future, it may be
necessary to define a keyword variant which uses a logformat for
extensability.
This patch only implement parsing. Argument is stored inside new server
field <pool_conn_name> and expression is generated in
_srv_parse_finalize() into <pool_conn_name_expr>.
If pool-conn-name is not set but SNI is, the latter is reused
automatically as pool-conn-name via _srv_parse_finalize(). This ensures
current reuse behavior remains compatible and idle connection reuse will
not mix connections with different SNIs by mistake.
Main usage will be for rhttp when SSL is not wanted between the two
haproxy instances. Previously, it was possible to use "sni" keyword even
without SSL on a server line which have a similar effect. However,
having a dedicated "pool-conn-name" keyword is deemed clearer. Besides,
it would allow for more complex configuration where pool-conn-name and
SNI are use in parallel with different values.
last_change was a member present in both proxy and server struct. It is
used as an age statistics to report the last update of the object.
Move last_change into fe_counters/be_counters. This is necessary to be
able to manipulate it through generic stat column and report it into
stats-file.
Note that there is a change for proxy structure with now 2 different
last_change values, on frontend and backend side. Special care was taken
to ensure that the value is initialized only on the proxy side. The
other value is set to 0 unless a listen proxy is instantiated. For the
moment, only backend counter is reported in stats. However, with now two
distinct values, stats could be extended to report it on both side.
Move freq-ctr defined in proxy or server structures into their dedicated
fe_counters/be_counters struct.
Functionnaly no change here. This commit will allow to convert rate
stats column to generic one, which is mandatory to manipulate them in
the stats-file.
This commit is similar to previous one, except that it implements GUID
support for server instances. A guid_node field is inserted into server
structure. A new "guid" server keyword is defined.
log format expressions are broadly used within the code: once they are
parsed from input string, they are converted to a linked list of
logformat nodes.
We're starting to face some limitations because we're simply storing the
converted expression as a generic logformat_node list.
The first issue we're facing is that storing logformat expressions that
way doesn't allow us to add metadata alongside the list, which is part
of the prerequites for implementing log-profiles.
Another issue with storing logformat expressions as generic lists of
logformat_node elements is that it's starting to become really hard to
tell when we rely on logformat expressions or not in the code given that
there isn't always a comment near the list declaration or manipulation
to indicate that it's relying on logformat expressions under the hood,
so this adds some complexity for code maintenance.
This patch looks quite impressive due to changes in a lot of header and
source files (since logformat expressions are broadly used), but it does
a simple thing: it defines the lf_expr structure which itself holds a
generic list of logformat nodes, and then declares some helpers to
manipulate lf_expr elements and fixes the code so that we now exclusively
manipulate logformat_node lists as lf_expr elements outside of log.c.
For now, lf_expr struct only contains the list of logformat nodes (no
additional metadata), but now that we have dedicated type and helpers,
doing so in the future won't be problematic at all and won't require
extensive code changes.
Motivation: When services are discovered through DNS resolution, the order in
which DNS records get resolved and assigned to servers is arbitrary. Therefore,
even though two HAProxy instances using chash balancing might agree that a
particular request should go to server3, it is likely the case that they have
assigned different IPs and ports to the server in that slot.
This patch adds a server option, "hash-key <key>" which can be set to "id" (the
existing behaviour, default), "addr", or "addr-port". By deriving the keys for
the chash tree nodes from a server's address and port we ensure that independent
HAProxy instances will agree on routing decisions. If an address is not known
then the key is derived from the server's puid as it was previously.
When adjusting a server's weight, we now check whether the server's hash has
changed. If it has, we have to remove all its nodes first, since the node keys
will also have to change.
Willy reported that since 3ac79b504 ("MEDIUM: server:
make server_set_inetaddr() updater serializable"), haproxy fails to
compile on some older compilers such as gcc-4.4 with this kind of error:
src/server.c: In function 'snr_resolution_cb':
src/server.c:4471: error: unknown field 'dns_resolver' specified in initializer
compilation terminated due to -Wfatal-errors.
make: *** [Makefile:1006: src/server.o] Error 1
This is due to referencing a member inside anonymous union from a compound
literal assignment. Apparently such use of anonymous union wasn't properly
supported back then on older compilers. To fix the issue, we give "u" name
to the parent union use this name to explicitly refer to the union where
relevant in the code (only a few changes fortunately).
The fix itself was verified to restore build compatibility with gcc 4.4
(and even 4.2).
As 3ac79b504 is used as a prerequisite for 64c9c8ef3 ("BUG/MINOR:
server/dns: use server_set_inetaddr() to unset srv addr from DNS"), please
consider backporting this patch too if 64c9c8ef3 happens to be backported
in 2.9.
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.
Remove some QUIC definitions of members from server structure as the haproxy QUIC
stack does not support at all the server part (QUIC client) as this time.
Remove the statements in relation with their initializations.
This patch should be backported as far as 2.6 to save memory.
server_set_inetaddr() updater argument is a simple char * string
containing infos about the caller responsible for the update.
In this patch, we try to make this argument serializable, that is, make
it so that we can easily export it without having to keep the original
pointer passed by the caller or having to work with strings of variable
lengths.
This was a prerequisite for exposing more updater information through
SERVER_INETADDR event (upcoming patch).
Static strings were simply mapped to a fixed ID that can be converted back
to a string when needed using server_inetaddr_updater_by_to_str(). One
special case one made for the SERVER_INETADDR_UPDATER_DNS_RESOLVER updater
since in this case the updater hint has to be generated from the
corresponding resolver id / nameserver id combination. This was achieved
by saving the nameserver id within the updater struct. Knowing that the
resolver id can be guessed from the server struct directly, it was not
exposed through the updater struct.
This patch depends on:
- "MINOR: resolvers: add unique numeric id to nameservers"
No functional change should be expected.
server addr:svc_port updates during runtime might set or clear the
SRV_F_MAPPORTS flag. Unfortunately, the flag update is still directly
performed by srv_update_addr_port() function while the addr:svc_port
update is being scheduled for atomic update. Given that existing readers
don't take server's lock to read addr:svc_port, they also check the
SRV_F_MAPPORTS flag right after without the lock.
So we could cause the readers to incorrectly interpret the svc_port from
the server struct because the mapport information is not published
atomically, resulting in inconsistencies between svc_port / mapport flag.
(MAPPORTS flag causes svc_port to be used differently by the reader)
To fix this, we publish the mapport information within the INETADDR server
event and we let the task responsible for updating server's addr and port
position or clear the flag depending on the mapport hint.
This patch depends on:
- MINOR: server/event_hdl: add server_inetaddr struct to facilitate event data usage
- MINOR: server/event_hdl: update _srv_event_hdl_prepare_inetaddr prototype
This should be backported in 2.9 with 683b2ae01 ("MINOR: server/event_hdl:
add SERVER_INETADDR event")
event_hdl_cb_data_server_inetaddr struct had some anonymous structs
defined in it, making it impossible to pass as a function argument and
harder to maintain since changes must be performed at multiple places
at once. So instead we define a storage struct named server_inetaddr
that helps to save addr:port server information in INET context.
It is possible that a server's addr family is temporarily set to AF_UNSPEC
even if we're certain to be in INET context (ipv4, ipv6).
Indeed, as soon as IP address resolving is involved, srv->addr family will
be set to AF_UNSPEC when the resolution fails (could happen at anytime).
However, _srv_event_hdl_prepare_inetaddr() wrongly assumed that it would
only be called with AF_INET or AF_INET6 families. Because of that, the
function will handle AF_UNSPEC address as an IPV6 address: not only
we could risk reading from an unititialized area, but we would then
propagate false information when publishing the event.
In this patch we make sure to properly handle the AF_UNSPEC family in
both the "prev" and the "next" part for SERVER_INETADDR event and that
every members are explicitly initialized.
This bug was introduced by 6fde37e046 ("MINOR: server/event_hdl: add
SERVER_INETADDR event"), no backport needed.
In this patch we add the support for a new SERVER event in the
event_hdl API.
SERVER_INETADDR is implemented as an advanced server event.
It is published each time the server's ip address or port is
about to change. (ie: from the cli, dns, lua...)
SERVER_INETADDR data is an event_hdl_cb_data_server_inetaddr struct
that provides additional info related to the server inet addr change,
but can be casted as a regular event_hdl_cb_data_server struct if
additional info is not needed.
Previous commit renames 'proto_reverse_connect' module to 'proto_rhttp'.
This commits follows this by replacing various custom prefix by 'rhttp_'
to make the code uniform.
Note that 'reverse_' prefix was kept in connection module. This is
because if a new reversable protocol not based on HTTP is implemented,
it may be necessary to reused the same connection function which are
protocol agnostic.
This bug was introduced with 29b76ca ("BUG/MEDIUM: server/log: "mode log"
after server keyword causes crash ")
Indeed, we cannot safely rely on addr_proto being set when str2sa_range()
returns in parse_server() (even if SRV_PARSE_PARSE_ADDR is set), because
proto lookup might be bypassed when FQDN addresses are involved.
Unfortunately, the above patch wrongly assumed that proto would always
be set when SRV_PARSE_PARSE_ADDR was passed to parse_server() (so when
str2sa_range() was called), resulting in invalid postparsing checks being
performed, which could as well lead to crashes with log backends
("mode log" set) because some postparsing init was skipped as a result of
proto not being set and this wasn't expected later in the init code.
To fix this, we now make use of the previous patch to perform server's
address compatibility checks on hints that are always set when
str2sa_range() succesfully returns.
For log backend, we're also adding a complementary test to check if the
address family is of expected type, else we report an error, plus we're
moving the postinit logic in log api since _srv_check_proxy_mode() is
only meant to check proxy mode compatibility and we were abusing it.
This patch depends on:
- "MINOR: tools: make str2sa_range() directly return type hints"
No backport required unless 29b76ca gets backported.
This commit introduces a generic server-side parsing of type-value pair
arguments and allocation of a TLV list via a new keyword called
set-proxy-v2-tlv-fmt.
This allows to 1) forward any TLV type with the help of fc_pp_tlv,
2) generally, send out any TLV type and value via a log format expression.
To have this fully working the connection will need to be updated in
a follow-up commit to actually respect the new server TLV list.
default-server support has also been implemented.
In 9a74a6c ("MAJOR: log: introduce log backends"), a mistake was made:
it was assumed that the proxy mode was already known during server
keyword parsing in parse_server() function, but this is wrong.
Indeed, "mode log" can be declared late in the proxy section. Due to this,
a simple config like this will cause the process to crash:
|backend test
|
| server name 127.0.0.1:8080
| mode log
In order to fix this, we relax some checks in _srv_parse_init() and store
the address protocol from str2sa_range() in server struct, then we set-up
a postparsing function that is to be called after config parsing to
finish the server checks/initialization that depend on the proxy mode
to be known. We achieve this by checking the PR_CAP_LB capability from
the parent proxy to know if we're in such case where the effective proxy
mode is not yet known (it is assumed that other proxies which are implicit
ones don't provide this possibility and thus don't suffer from this
constraint).
Only then, if the capability is not found, we immediately perform the
server checks that depend on the proxy mode, else the check is postponed
and it will automatically be performed during postparsing thanks to the
REGISTER_POST_SERVER_CHECK() hook.
Note that we remove the SRV_PARSE_IN_LOG_BE flag because it was introduced
in the above commit and it is no longer relevant.
No backport needed unless 9a74a6c gets backported.
"log-bufsize" may now be used for a log server (in a log backend) to
configure the bufsize of implicit ring associated to the server (which
defaults to BUFSIZE).
Using "mode log" in a backend section turns the proxy in a log backend
which can be used to log-balance logs between multiple log targets
(udp or tcp servers)
log backends can be used as regular log targets using the log directive
with "backend@be_name" prefix, like so:
| log backend@mybackend local0
A log backend will distribute log messages to servers according to the
log load-balancing algorithm that can be set using the "log-balance"
option from the log backend section. For now, only the roundrobin
algorithm is supported and set by default.
This patch implements the 'curves' keyword on server lines as well as
the 'ssl-default-server-curves' keyword in the global section.
It also add the keyword on the server line in the ssl_curves reg-test.
These keywords allow the configuration of the curves list for a server.
When a thread creates a new session for a server, if none was known yet,
we assign the thread id (hence the reused_sess index) to a shared variable
so that other threads will later be able to find it when they don't have
one yet. For now we only set and clear the pointer upon session creation,
we do not yet pick it.
Note that we could have done it per thread-group, so as to avoid any
cross-thread exchanges, but it's anticipated that this is essentially
used during startup, at a moment where the cost of inter-thread contention
is very low compared to the ability to restart at full speed, which
explains why instead we store a single entry.
The goal will be to permit a thread to update its session while having
it shared with other threads. For now we only place the lock and arrange
the code around it so that this is quite light. For now only the owner
thread uses this lock so there is no contention.
Note that there is a subtlety in the openssl API regarding
i2s_SSL_SESSION() in that it fills the area pointed to by its argument
with a dump of the session and returns a size that's equal to the
previously allocated one. As such, it does modify the shared area even
if that's not obvious at first glance.
Backend idle connections are purged on a recurring occurence during the
process lifetime. An estimated number of needed connections is
calculated and the excess is removed periodically.
Before this patch, purge was done directly using the idle then the safe
connection tree of a server instance. This has a major drawback to take
no account of a specific ordre and it may removed functional connections
while leaving ones which will fail on the next reuse.
The problem can be worse when using criteria to differentiate idle
connections such as the SSL SNI. In this case, purge may remove
connections with a high rate of reusing while leaving connections with
criteria never matched once, thus reducing drastically the reuse rate.
To improve this, introduce an alternative storage for idle connection
used in parallel of the idle/safe trees. Now, each connection inserted
in one of this tree is also inserted in the new list at
`srv_per_thread.idle_conn_list`. This guarantees that recently used
connection is present at the end of the list.
During the purge, use this list instead of idle/safe trees. Remove first
connection in front of the list which were not reused recently. This
will ensure that connection that are frequently reused are not purged
and should increase the reuse rate, particularily if distinct idle
connection criterias are in used.
Implement reverse-connect server. This server type cannot instantiate
its own connection on transfer. Instead, it can only reuse connection
from its idle pool. These connections will be populated using the future
'tcp-request session attach-srv' rule.
A reverse-connect has no address. Instead, it uses a new custom server
notation with '@' character prefix. For the moment, only '@reverse' is
defined. An extra check is implemented to ensure server is used in a
HTTP proxy.
This patch introduces the "client-sigalgs" keyword for the server line,
which allows to configure the list of server signature algorithms
negociated during the handshake. Also available as
"ssl-default-server-client-sigalgs" in the global section.
This patch introduces the "sigalgs" keyword for the server line, which
allows to configure the list of server signature algorithms negociated
during the handshake. Also available as "ssl-default-server-sigalgs" in
the global section.
Adding a new event type: SERVER_CHECK.
This event is published when a server's check state ought to be reported.
(check status change or check result)
SERVER_CHECK event is provided as a server event with additional data
carrying relevant check's context such as check's result and health.
Adding a new SERVER event in the event_hdl API.
SERVER_ADMIN is implemented as an advanced server event.
It is published each time the administrative state changes.
(when s->cur_admin changes)
SERVER_ADMIN data is an event_hdl_cb_data_server_admin struct that
provides additional info related to the admin state change, but can
be casted as a regular event_hdl_cb_data_server struct if additional
info is not needed.
Adding a new SERVER event in the event_hdl API.
SERVER_STATE is implemented as an advanced server event.
It is published each time the server's effective state changes.
(when s->cur_state changes)
SERVER_STATE data is an event_hdl_cb_data_server_state struct that
provides additional info related to the server state change, but can
be casted as a regular event_hdl_cb_data_server struct if additional
info is not needed.
Operational and administrative state change causes are not propagated
through srv_update_status(), instead they are directly consumed within
the function to provide additional info during the call when required.
Thus, there is no valid reason for keeping adm and op causes within
server struct. We are wasting space and keeping uneeded complexity.
We now exlicitly pass change type (operational or administrative) and
associated cause to srv_update_status() so that no extra storage is
needed since those values are only relevant from srv_update_status().
This one is greatly inspired by "MINOR: server: change adm_st_chg_cause storage type".
While looking at current srv_op_st_chg_cause usage, it was clear that
the struct needed some cleanup since some leftovers from asynchronous server
state change updates were left behind and resulted in some useless code
duplication, and making the whole thing harder to maintain.
Two observations were made:
- by tracking down srv_set_{running, stopped, stopping} usage,
we can see that the <reason> argument is always a fixed statically
allocated string.
- check-related state change context (duration, status, code...) is
not used anymore since srv_append_status() directly extracts the
values from the server->check. This is pure legacy from when
the state changes were applied asynchronously.
To prevent code duplication, useless string copies and make the reason/cause
more exportable, we store it as an enum now, and we provide
srv_op_st_chg_cause() function to fetch the related description string.
HEALTH and AGENT causes (check related) are now explicitly identified to
make consumers like srv_append_op_chg_cause() able to fetch checks info
from the server itself if they need to.
Even though it doesn't look like it at first glance, this is more like
a cleanup than an actual code improvement:
Given that srv->adm_st_chg_cause has been used to exclusively store
static strings ever since it was implemented, we make the choice to
store it as an enum instead of a fixed-size string within server
struct.
This will allow to save some space in server struct, and will make
it more easily exportable (ie: event handlers) because of the
reduced memory footprint during handling and the ability to later get
the corresponding human-readable message when it's explicitly needed.
This commit does nothing that ought to be mentioned, except that
it adds missing comments and slighty moves some function calls
out of "sensitive" code in preparation of some server code refactors.
Expose proxy_uuid variable in event_hdl_cb_data_server struct to
overcome proxy_name fixed length limitation.
proxy_uuid may be used by the handler to perform proxy lookups.
This should be preferred over lookups relying proxy_name.
(proxy_name is suitable for printing / logging purposes but not for
ID lookups since it has a maximum fixed length)
