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We have the same function in tevent, no need to duplicate code. More lines just
due to clang-format.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri Mar 22 06:07:42 UTC 2024 on atb-devel-224
This is useful when we want to wakeup the next watcher
without modifying the record.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
This can be used if the decision of using dbwrap_watched_watch_skip_alerting()
needs to be reverted...
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
If a watcher was already selected for a wakeup notification reset it...
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
This gives a nice speed up, as it's unlikely for the waiters to hit
contention.
The following test with 256 commections all looping with open/close
on the same inode (share root) is improved drastically:
smbtorture //127.0.0.1/m -Uroot%test smb2.create.bench-path-contention-shared \
--option='torture:bench_path=' \
--option="torture:timelimit=60" \
--option="torture:nprocs=256"
From some like this:
open[num/s=8800,avslat=0.021445,minlat=0.000095,maxlat=0.179786]
close[num/s=8800,avslat=0.021658,minlat=0.000044,maxlat=0.179819]
to:
open[num/s=10223,avslat=0.017922,minlat=0.000083,maxlat=0.106759]
close[num/s=10223,avslat=0.017694,minlat=0.000040,maxlat=0.107345]
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Autobuild-User(master): Ralph Böhme <slow@samba.org>
Autobuild-Date(master): Tue Jul 26 14:32:35 UTC 2022 on sn-devel-184
In case of a highly contended record we will have a lot of watchers,
which will all race to get g_lock_lock() to finish.
If g_lock_unlock() wakes them all, e.g. 250 of them, we get a thundering
herd, were 249 will only find that one of them as able to get the lock
and re-add their watcher entry (not unlikely in a different order).
With this commit we only wake the first watcher and let it remove
itself once it no longer wants to monitor the record content
(at that time it will wake the new first watcher).
It means the woken watcher doesn't have to race with all others
and also means order of watchers is kept, which means that we
most likely get a fair latency distribution for all watchers.
The following test with 256 commections all looping with open/close
on the same inode (share root) is improved drastically:
smbtorture //127.0.0.1/m -Uroot%test smb2.create.bench-path-contention-shared \
--option='torture:bench_path=' \
--option="torture:timelimit=60" \
--option="torture:nprocs=256"
From some like this:
open[num/s=80,avslat=2.793862,minlat=0.004097,maxlat=46.597053]
close[num/s=80,avslat=2.387326,minlat=0.023875,maxlat=50.878165]
to:
open[num/s=8800,avslat=0.021445,minlat=0.000095,maxlat=0.179786]
close[num/s=8800,avslat=0.021658,minlat=0.000044,maxlat=0.179819]
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
The destructor triggered by dbwrap_watched_watch_recv() will
remove the watcher instance via a dedicated dbwrap_do_locked(),
just calling dbwrap_watched_watch_remove_instance() inside.
But the typical caller triggers a dbwrap_do_locked() again after
dbwrap_watched_watch_recv() returned. Which means we call
dbwrap_do_locked() twice.
We now allow dbwrap_watched_watch_recv() to return the existing
instance id (if it still exists) and removes the destructor.
That way the caller can pass the given instance id to
dbwrap_watched_watch_remove_instance() from within its own dbwrap_do_locked(),
when it decides to leave the queue, because it's happy with the new
state of the record. In order to get the best performance
dbwrap_watched_watch_remove_instance() should be called before any
dbwrap_record_storev() or dbwrap_record_delete(),
because that will only trigger a single low level storev/delete.
If the caller found out that the state of the record doesn't meet the
expectations and the callers wants to continue watching the
record (from its current position, most likely the first one),
dbwrap_watched_watch_remove_instance() can be skipped and the
instance id can be passed to dbwrap_watched_watch_send() again,
in order to resume waiting on the existing instance.
Currently the watcher instance were always removed (most likely from
the first position) and re-added (to the last position), which may
cause unfair latencies.
In order to improve the overhead of adding a new watcher instance
the caller can call dbwrap_watched_watch_add_instance() before
any dbwrap_record_storev() or dbwrap_record_delete(), which
will only result in a single low level storev/delete.
The returned instance id is then passed to dbwrap_watched_watch_send(),
within the same dbwrap_do_locked() run.
It also adds a way to avoid alerting any callers during
the current dbwrap_do_locked() run.
Layers above may only want to wake up watchers
during specific situations and while it's useless to wake
others in other situations.
This will soon be used to add more fairness to the g_lock code.
Note that this commit only prepares the api for the above to be useful,
the instance returned by dbwrap_watched_watch_recv() is most likely 0,
which means the watcher entry was already removed, but that will change
in the following commits.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
The new dbwrap_watched_watch_remove_instance() will just remove ourself
from the in memory array and let db_watched_record_fini() call
dbwrap_watched_record_storev() in order to write the modified version
into the low level backend record.
For now there's no change in behavior, but it allows us to change it
soon....
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
It means we only have one code path storing the low level record
and that's dbwrap_watched_record_storev on the main record.
It avoids the nested dbwrap_do_locked() and only uses
dbwrap_parse_record() and talloc_memdup() when needed.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
dbwrap_watched_record_storev() will handle the high level storev and
delete, it will find out if we can remove the record as there's no value
and also no watchers to be stored.
This is no real change for now as dbwrap_watched_record_wakeup() will
always exits with wrec->watchers.count = 0, but that will change in the next
commits.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
We will soon have records with just a number of watchers, but without
payload. These records should not be visible during traverse.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
It will also delete the low level record in case there are no watchers
should be stored and no data buffers are given.
This is no real change for now as dbwrap_watched_record_wakeup() will
always exit with wrec->watchers.count = 0, but that will change in the next
commits.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
dbwrap backends are unlikely to be able to store
UINT32_MAX*DBWRAP_WATCHER_BUF_LENGTH in a single record
and most likely also not with the whole database!
DBWRAP_MAX_WATCHERS = INT32_MAX/DBWRAP_WATCHER_BUF_LENGTH should be
enough and makes further changes easier as we don't need to care
about size_t overflows.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This is never set...
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
At the end of the dbwrap_watched_watch_recv() all temporary state should
be destroyed. It also means dbwrap_watched_watch_state_destructor() was
triggered.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Async function always have their 'state' context for temporary memory.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This will help in the next commits.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This will be used in other places soon.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This reduces quite some complexity and will make further changes
(which will follow soon) easier.
Review with git show --patience
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This is no change in behavior, because:
- The first dbwrap_do_locked(dbwrap_watched_record_wakeup_fn), is
called at the start of dbwrap_watched_record_{storev,delete}().
That means the nested dbwrap_do_locked() will pass the
exact value same (unchanged) value to dbwrap_watched_record_wakeup_fn.
- After the first change we have either removed the whole backend
record in dbwrap_watched_record_delete or dbwrap_watched_record_storev()
removed all watchers and store num_watchers = 0.
- With that any further updates will have no watchers in the backend
record, so dbwrap_do_locked(dbwrap_watched_record_wakeup_fn) will
never do anything useful. It only burns cpu time any may cause memory
fragmentation.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
That makes it easier to understand that db_watched_record_init() and
db_watched_record_fini() wrap any caller activity on the record,
either during do_locked or between fetch_locked and the related
destructor.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
The code to construct a struct db_watched_record is mostly common
between dbwrap_watched_fetch_locked() and dbwrap_watched_do_locked_fn().
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
dbwrap_watched_do_locked_{storev,delete}() was now exactly the
same as dbwrap_watched_{storev,delete}().
We only need to know if dbwrap_watched_record_wakeup() is called from
within dbwrap_watched_do_locked_fn().
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Both dbwrap_watched_record_storev() and dbwrap_watched_record_delete()
call dbwrap_watched_record_wakeup() as their first action.
So the behavior stays the same, but dbwrap_watched_do_locked_storev()
and dbwrap_watched_do_locked_delete() are not trivial and we
have the wakeup logic isolated in dbwrap_watched_record_wakeup() only.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This allows safe casting off rec->private_data to get
struct db_watched_record. And that works fetch_locked and do_locked
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This makes it much clearer to me what it actually is.
Keeping the initial_value with struct db_watched_record will also
simplify further changes.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
We get to the main 'struct db_record' via wrec->rec where needed.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
We should avoid doing shortcuts if not needed.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
We can use a local variable in dbwrap_watched_do_locked_fn.
As 'wrec' should have the same lifetime as 'rec'.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
There's no real reason to pass struct dbwrap_watched_do_locked_state
anymore. The only difference is that we can't use
talloc_get_type_abort().
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
We should try to avoid using dbwrap_watched_do_locked_state in low
level code.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
For the do_locked case they have the same scope, but having
it on db_watched_record will simplify further changes.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This makes it much easier to understand...
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
These functions operate on struct db_watched_record.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
struct db_watched_record is the private data of
the struct db_record produced by the struct db_context that
uses struct db_watched_ctx.
db_watched_subrec had nothing really todo with the
sub record we got back from db_watched_ctx->backend.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
This matches db_tdb_do_locked() and the fetch_locked based fallback in
dbwrap_do_locked().
Calling dbwrap_record_get_value() is not allowed from within
dbwrap_do_locked()!
Now that rec.value is only internal, use it to remember the initial
payload value. This will simplify further code changes as it
makes the fetch_locked case.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
When we (need) to ignore an error from dbwrap_do_locked() within
dbwrap_watched_watch_state_destructor(), we better print this
with log level 1 instead of 10.
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
We should not map any error from ctdbd_init_async_connection() to EIO.
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Jul 1 18:34:17 UTC 2022 on sn-devel-184
The subsequent messaging_ctdb_connection() will fail an assert if messaging is
not up and running, maybe it's a bit better to add a check if
global_messaging_context() actually succeeded.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14787
Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
It's a bit shocking how many references we have to global
contexts. Make this a bit more obvious.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
locking.tdb will not have a LOCK_ORDER anymore, this will be done by
the code in g_lock.c. We need to allow opening a database with dbwrap
without having a lock order.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
