IF YOU WOULD LIKE TO GET AN ACCOUNT, please write an
email to Administrator. User accounts are meant only to access repo
and report issues and/or generate pull requests.
This is a purpose-specific Git hosting for
BaseALT
projects. Thank you for your understanding!
Только зарегистрированные пользователи имеют доступ к сервису!
Для получения аккаунта, обратитесь к администратору.
This adds optional support for locking based on
shared robust mutexes.
The caller can use the TDB_MUTEX_LOCKING flag
together with TDB_CLEAR_IF_FIRST after verifying
with tdb_runtime_check_for_robust_mutexes() that
it's supported by the current system.
The caller should be aware that using TDB_MUTEX_LOCKING
implies some limitations, e.g. it's not possible to
have multiple read chainlocks on a given hash chain
from multiple processes.
Note: that this doesn't make tdb thread safe!
Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>
Pair-Programmed-With: Michael Adam <obnox@samba.org>
Signed-off-by: Volker Lendecke <vl@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
When in tdb_store we re-use a dead record reactivated from the
target hash chain itself, we currently leave it in its place in
the chain. When we re-use a dead record from a different chain or
from the freelist instead, we insert it at the beginning of the
target chain.
This patch changes the behaviour to always newly store a
record at the beginning of the hash chain. This removes
a special case and hence simplifies the allocation code.
On the other hand side, it introduces two additioal tdb_ofs_write
calls for the in-chain-case.
Note the subtelty of the patch that by moving the case of the candidate
record's chain as new case "i=0" into the for loop, we also reverse the
order of the two steps in the for-loop body (non blocking freelist alloc
and searching for dead record in a chain) in order to keep the overall
order of execution identical.
Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Michael Adam <obnox@samba.org>
Autobuild-Date(master): Wed Apr 9 10:37:08 CEST 2014 on sn-devel-104
In a metadata-intensive benchmark we have seen the locking.tdb freelist to be
one of the central contention points. This patch removes most of the contention
on the freelist. Ages ago we already reduced freelist contention by using the
even much older DEAD records: If TDB_VOLATILE is set, don't directly put
deleted records on the freelist, but just mark a few of them just as DEAD. The
next new record can them re-use that space without consulting the freelist.
This patch builds upon the DEAD records: If we need space and the freelist is
busy, instead of doing a blocking wait on the freelist, start looking into
other chains for DEAD records and steal them from there. This way every hash
chain becomes a small freelist. Just wander around the hash chains as long as
the freelist is still busy.
With this patch and the tdb mutex patch (following hopefully some time soon)
you can see a heavily busy clustered smbd run without locking.tdb futex
syscalls.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Will be used soon to unlink a dead record from a chain
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
This aligns the tdb_find_dead API with the tdb_allocate API and thus makes it a
bit easier to understand, at least for me.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Hash chains are (or can be made) short enough that a full search for the
best-fitting dead record is feasible. The freelist can become much longer,
there we don't do the full search but accept records which are too large.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
If the freelist is heavily contended, we should avoid accessing it
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
tdb_purge_dead can change the next pointer of "rec" if we purge the record
right behind the current record to be deleted. Just overwrite the magic,
not the whole record with stale data.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
by using the same variable as hash as in the lock.
Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Sat Feb 15 03:21:07 CET 2014 on sn-devel-104
Make the lock/unlock bracket more obvious by extracting
locking (and finding) from the special cases to the top
of the function. This also lets us take lock and find
the record outside the special case branches (use dead
records or not).
There is a small semantic change implied:
In the dead records case, the record to delete is looked
up before the current dead records are potentially purged.
Hence, if the record to delete is not found, the dead
records are also not purge. This does not make a big
difference though, because purging is only delayed until
directly befor the next record to delete is in fact found.
Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
header.hash_size was the only thing we ever referenced outside of
tdb_open_ex and its direct callees. So this shrinks the tdb_context by
164 bytes.
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Tue Feb 5 13:18:28 CET 2013 on sn-devel-104
TDB2 testing revealed that tdb1 doesn't do this. It's minor, but fix it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Autobuild-User: Rusty Russell <rusty@rustcorp.com.au>
Autobuild-Date: Tue Aug 16 10:47:41 CEST 2011 on sn-devel-104
Commit 207a213c/24fed55d purported to fix the problem of signals during
tdb_new_database (which could cause a spurious short write, hence a failure).
However, the code is wrong: newdb+written is not correct.
Fix this by introducing a general tdb_write_all() and using it here and in
the tracing code.
Cc: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is pure overhead, but it centralizes the locking. Realloc (esp. as
most implementations are lazy) is fast compared to the fnctl anyway.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The word global is overloaded in tdb. The global_lock inside struct
tdb_context is used to indicate we hold a lock across all the chains.
Rename it to allrecord_lock.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is taken from the CCAN code base: rather than using tdb_brlock for
locking and unlocking, we split it into brlock and brunlock functions.
For extra debugging information, brunlock says what kind of lock it is
unlocking (even though fnctl locks don't need this). This requires an
extra argument to tdb_transaction_unlock() so we know whether the
lock was upgraded to a write lock or not.
We also use a "flags" argument tdb_brlock:
1) TDB_LOCK_NOWAIT replaces lck_type = F_SETLK (vs F_SETLKW).
2) TDB_LOCK_MARK_ONLY replaces setting TDB_MARK_LOCK bit in ltype.
3) TDB_LOCK_PROBE replaces the "probe" argument.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We need to keep TDB_ALLOW_NESTING as default behavior,
so that existing code continues to work.
However we may change the default together with a major version
number change in future.
metze
It was a regrettable hack which I used to reduce line count in tdb; in fact it caused confusion as can be seen in this patch.
In particular, ecode now needs to be set before TDB_LOG anyway, and having it exposed in
the header is useless (the struct tdb_context isn't defined, so it's doubly useless).
Also, we should never set errno, as io.c was doing.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
When TDB_TRACE is defined (in tdb_private.h), verbose tracing of tdb operations is enabled.
This can be replayed using "replay_trace" from http://ccan.ozlabs.org/info/tdb.
The majority of this patch comes from moving internal functions to _<funcname> to
avoid double-tracing. There should be no additional overhead for the normal (!TDB_TRACE)
case.
Note that the verbose traces compress really well with rzip.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The tdb_repack() function repacks a TDB so that it has a single
freelist entry. The file doesn't shrink, but it does remove all
freelist fragmentation. This code originated in the CTDB vacuuming
code, but will now be used in ldb to cope with fragmentation from
re-indexing
