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path: root/lib/tdb/common/lock.c
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2010-03-26tdb: Add a non-blocking version of tdb_transaction_startVolker Lendecke1-2/+3
2010-03-25Fix some nonempty blank linesVolker Lendecke1-2/+2
2010-02-24tdb: handle processes dying during transaction commit.Rusty Russell1-0/+60
tdb transactions were designed to be robust against the machine powering off, but interestingly were never designed to handle the case where an administrator kill -9's a process during commit. Because recovery is only done on tdb_open, processes with the tdb already mapped will simply use it despite it being corrupt and needing recovery. The solution to this is to check for recovery every time we grab a data lock: we could have gained the lock because a process just died. This has no measurable cost: here is the time for tdbtorture -s 0 -n 1 -l 10000: Before: 2.75 2.50 2.81 3.19 2.91 2.53 2.72 2.50 2.78 2.77 = Avg 2.75 After: 2.81 2.57 3.42 2.49 3.02 2.49 2.84 2.48 2.80 2.43 = Avg 2.74 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24patch tdb-refactor-tdb_lock-and-tdb_lock_nonblock.patchRusty Russell1-16/+13
2010-02-24tdb: remove lock opsRusty Russell1-15/+22
Now the transaction code uses the standard allrecord lock, that stops us from trying to grab any per-record locks anyway. We don't need to have special noop lock ops for transactions. This is a nice simplification: if you see brlock, you know it's really going to grab a lock. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24tdb: rename tdb_release_extra_locks() to tdb_release_transaction_locks()Rusty Russell1-10/+7
tdb_release_extra_locks() is too general: it carefully skips over the transaction lock, even though the only caller then drops it. Change this, and rename it to show it's clearly transaction-specific. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-17tdb: tdb_allrecord_lock/tdb_allrecord_unlock/tdb_allrecord_upgradeRusty Russell1-20/+52
Centralize locking of all chains of the tdb; rename _tdb_lockall to tdb_allrecord_lock and _tdb_unlockall to tdb_allrecord_unlock, and tdb_brlock_upgrade to tdb_allrecord_upgrade. Then we use this in the transaction code. Unfortunately, if the transaction code records that it has grabbed the allrecord lock read-only, write locks will fail, so we treat this upgradable lock as a write lock, and mark it as upgradable using the otherwise-unused offset field. One subtlety: now the transaction code is using the allrecord_lock, the tdb_release_extra_locks() function drops it for us, so we no longer need to do it manually in _tdb_transaction_cancel. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24tdb: suppress record write locks when allrecord lock is taken.Rusty Russell1-0/+9
Records themselves get (read) locked by the traversal code against delete. Interestingly, this locking isn't done when the allrecord lock has been taken, though the allrecord lock until recently didn't cover the actual records (it now goes to end of file). The write record lock, grabbed by the delete code, is not suppressed by the allrecord lock. This is now bad: it causes us to punch a hole in the allrecord lock when we release the write record lock. Make this consistent: *no* record locks of any kind when the allrecord lock is taken. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24tdb: cleanup: always grab allrecord lock to infinity.Rusty Russell1-7/+3
We were previously inconsistent with our "global" lock: the transaction code grabbed it from FREELIST_TOP to end of file, and the rest of the code grabbed it from FREELIST_TOP to end of the hash chains. Change it to always grab to end of file for simplicity and so we can merge the two. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-17tdb: remove num_locksRusty Russell1-10/+2
This was redundant before this patch series: it mirrored num_lockrecs exactly. It still does. Also, skip useless branch when locks == 1: unconditional assignment is cheaper anyway. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24tdb: use tdb_nest_lock() for active lock.Rusty Russell1-0/+8
Use our newly-generic nested lock tracking for the active lock. Note that the tdb_have_extra_locks() and tdb_release_extra_locks() functions have to skip over this lock now it is tracked. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-22tdb: use tdb_nest_lock() for open lock.Rusty Russell1-1/+2
This never nests, so it's overkill, but it centralizes the locking into lock.c and removes the ugly flag in the transaction code to track whether we have the lock or not. Note that we have a temporary hack so this places a real lock, despite the fact that we are in a transaction. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-17tdb: use tdb_nest_lock() for transaction lock.Rusty Russell1-31/+23
Rather than a boutique lock and a separate nest count, use our newly-generic nested lock tracking for the transaction lock. Note that the tdb_have_extra_locks() and tdb_release_extra_locks() functions have to skip over this lock now it is tracked. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-17tdb: cleanup: find_nestlock() helper.Rusty Russell1-28/+23
Factor out two loops which find locks; we are going to introduce a couple more so a helper makes sense. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24tdb: cleanup: tdb_release_extra_locks() helperRusty Russell1-0/+20
Move locking intelligence back into lock.c, rather than open-coding the lock release in transaction.c. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-17tdb: cleanup: tdb_have_extra_locks() helperRusty Russell1-2/+13
In many places we check whether locks are held: add a helper to do this. The _tdb_lockall() case has already checked for the allrecord lock, so the extra work done by tdb_have_extra_locks() is merely redundant. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-17tdb: don't suppress the transaction lock because of the allrecord lock.Rusty Russell1-6/+0
tdb_transaction_lock() and tdb_transaction_unlock() do nothing if we hold the allrecord lock. However, the two locks don't overlap, so this is wrong. This simplification makes the transaction lock a straight-forward nested lock. There are two callers for these functions: 1) The transaction code, which already makes sure the allrecord_lock isn't held. 2) The traverse code, which wants to stop transactions whether it has the allrecord lock or not. There have been deadlocks here before, however this should not bring them back (I hope!) Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-17tdb: cleanup: tdb_nest_lock/tdb_nest_unlockRusty Russell1-43/+61
Because fcntl locks don't nest, we track them in the tdb->lockrecs array and only place/release them when the count goes to 1/0. We only do this for record locks, so we simply place the list number (or -1 for the free list) in the structure. To generalize this: 1) Put the offset rather than list number in struct tdb_lock_type. 2) Rename _tdb_lock() to tdb_nest_lock, make it non-static and move the allrecord check out to the callers (except the mark case which doesn't care). 3) Rename _tdb_unlock() to tdb_nest_unlock(), make it non-static and move the allrecord out to the callers (except mark again). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-17tdb: cleanup: rename global_lock to allrecord_lock.Rusty Russell1-21/+21
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>
2010-02-17tdb: cleanup: split brlock and brunlock methods.Rusty Russell1-73/+162
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>
2009-10-22lib/tdb: wean off TDB_ERRCODE.Rusty Russell1-11/+19
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>
2009-10-22lib/tdb: TDB_TRACE support (for developers)Rusty Russell1-6/+28
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>
2009-07-21tdb: fix locking errorRusty Russell1-1/+1
54a51839ea65aa788b18fce8de0ae4f9ba63e4e7 "Make tdb transaction lock recursive (samba version)" was broken: I "cleaned it up" and prevented it from ever unlocking. To see the problem: $ bin/tdbtorture -s 1248142523 tdb_brlock failed (fd=3) at offset 8 rw_type=1 lck_type=14 len=1 tdb_transaction_lock: failed to get transaction lock tdb_transaction_start failed: Resource deadlock avoided My testcase relied on the *count* being correct, which it was. Fixing that now. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Michael Adam <obnox@samba.org>
2009-07-20Make tdb transaction lock recursive (samba version)Rusty Russell1-4/+13
This patch replaces 6ed27edbcd3ba1893636a8072c8d7a621437daf7 and 1a416ff13ca7786f2e8d24c66addf00883e9cb12, which fixed the bug where traversals inside transactions would release the transaction lock early. This solution is more general, and solves the more minor symptom that nested traversals would also release the transaction lock early. (It was also suggestd in Volker's comment in 6ed27ed). This patch also applies to ctdb, if the traverse.c part is removed (ctdb's tdb code never received the previous two fixes). Tested using the testsuite from ccan (adapted to the samba code). Thanks to Michael Adam for feedback. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Michael Adam <obnox@samba.org>
2008-09-17Move common libraries from root to lib/.Jelmer Vernooij1-0/+553