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tdb: cleanup: tdb_nest_lock/tdb_nest_unlock

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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>

(Imported from commit 5d9de604d9)

(This used to be ctdb commit 28576ddbd9bf91049db8a4f9e9e7856ac5b8f48a)
This commit is contained in:
Rusty Russell 2010-04-22 13:53:51 +09:30
parent 9a1c172139
commit dca3421b60
3 changed files with 67 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

104
ctdb/lib/tdb/common/lock.c
View File

@ -218,43 +218,38 @@ int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len)
return -1;
}
/* list -1 is the alloc list, otherwise a hash chain. */
static tdb_off_t lock_offset(int list)
{
return FREELIST_TOP + 4*list;
}
/* lock a list in the database. list -1 is the alloc list */
static int _tdb_lock(struct tdb_context *tdb, int list, int ltype,
enum tdb_lock_flags flags)
/* lock an offset in the database. */
int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
enum tdb_lock_flags flags)
{
struct tdb_lock_type *new_lck;
int i;
/* a allrecord lock allows us to avoid per chain locks */
if (tdb->allrecord_lock.count &&
(ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
return 0;
}
if (tdb->allrecord_lock.count) {
if (offset >= lock_offset(tdb->header.hash_size)) {
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
if (list < -1 || list >= (int)tdb->header.hash_size) {
tdb->ecode = TDB_ERR_LOCK;
TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid list %d for ltype=%d\n",
list, ltype));
TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n",
offset, ltype));
return -1;
}
if (tdb->flags & TDB_NOLOCK)
return 0;
for (i=0; i<tdb->num_lockrecs; i++) {
if (tdb->lockrecs[i].list == list) {
if (tdb->lockrecs[i].off == offset) {
if (tdb->lockrecs[i].count == 0) {
/*
* Can't happen, see tdb_unlock(). It should
* be an assert.
*/
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock: "
"lck->count == 0 for list %d", list));
"lck->count == 0 for offset %u",
offset));
}
/*
* Just increment the in-memory struct, posix locks
@ -276,13 +271,13 @@ static int _tdb_lock(struct tdb_context *tdb, int list, int ltype,
/* Since fcntl locks don't nest, we do a lock for the first one,
and simply bump the count for future ones */
if (tdb->methods->brlock(tdb, ltype, FREELIST_TOP+4*list, 1, flags)) {
if (tdb->methods->brlock(tdb, ltype, offset, 1, flags)) {
return -1;
}
tdb->num_locks++;
tdb->lockrecs[tdb->num_lockrecs].list = list;
tdb->lockrecs[tdb->num_lockrecs].off = offset;
tdb->lockrecs[tdb->num_lockrecs].count = 1;
tdb->lockrecs[tdb->num_lockrecs].ltype = ltype;
tdb->num_lockrecs += 1;
@ -295,7 +290,19 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype)
{
int ret;
ret = _tdb_lock(tdb, list, ltype, TDB_LOCK_WAIT);
/* a allrecord lock allows us to avoid per chain locks */
if (tdb->allrecord_lock.count &&
(ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
return 0;
}
if (tdb->allrecord_lock.count) {
tdb->ecode = TDB_ERR_LOCK;
ret = -1;
} else {
ret = tdb_nest_lock(tdb, lock_offset(list), ltype,
TDB_LOCK_WAIT);
}
if (ret) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
"ltype=%d (%s)\n", list, ltype, strerror(errno)));
@ -306,18 +313,7 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype)
/* lock a list in the database. list -1 is the alloc list. non-blocking lock */
int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
{
return _tdb_lock(tdb, list, ltype, TDB_LOCK_NOWAIT);
}
static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
bool mark_lock)
{
int ret = -1;
int i;
struct tdb_lock_type *lck = NULL;
/* a global lock allows us to avoid per chain locks */
/* a allrecord lock allows us to avoid per chain locks */
if (tdb->allrecord_lock.count &&
(ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
return 0;
@ -328,17 +324,28 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
return -1;
}
return tdb_nest_lock(tdb, lock_offset(list), ltype, TDB_LOCK_NOWAIT);
}
int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
bool mark_lock)
{
int ret = -1;
int i;
struct tdb_lock_type *lck = NULL;
if (tdb->flags & TDB_NOLOCK)
return 0;
/* Sanity checks */
if (list < -1 || list >= (int)tdb->header.hash_size) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: list %d invalid (%d)\n", list, tdb->header.hash_size));
if (offset >= lock_offset(tdb->header.hash_size)) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->header.hash_size));
return ret;
}
for (i=0; i<tdb->num_lockrecs; i++) {
if (tdb->lockrecs[i].list == list) {
if (tdb->lockrecs[i].off == offset) {
lck = &tdb->lockrecs[i];
break;
}
@ -364,8 +371,7 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
if (mark_lock) {
ret = 0;
} else {
ret = tdb->methods->brunlock(tdb, ltype,
FREELIST_TOP+4*list, 1);
ret = tdb->methods->brunlock(tdb, ltype, offset, 1);
}
tdb->num_locks--;
@ -395,7 +401,18 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
{
return _tdb_unlock(tdb, list, ltype, false);
/* a global lock allows us to avoid per chain locks */
if (tdb->allrecord_lock.count &&
(ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
return 0;
}
if (tdb->allrecord_lock.count) {
tdb->ecode = TDB_ERR_LOCK;
return -1;
}
return tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
}
/*
@ -599,8 +616,8 @@ int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key)
/* mark a chain as locked without actually locking it. Warning! use with great caution! */
int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
{
int ret = _tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK,
TDB_LOCK_MARK_ONLY);
int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
F_WRLCK, TDB_LOCK_MARK_ONLY);
tdb_trace_1rec(tdb, "tdb_chainlock_mark", key);
return ret;
}
@ -609,7 +626,8 @@ int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
{
tdb_trace_1rec(tdb, "tdb_chainlock_unmark", key);
return _tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK, true);
return tdb_nest_unlock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
F_WRLCK, true);
}
int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)

6
ctdb/lib/tdb/common/tdb_private.h
View File

@ -151,7 +151,7 @@ struct tdb_header {
};
struct tdb_lock_type {
int list;
uint32_t off;
uint32_t count;
uint32_t ltype;
};
@ -224,6 +224,10 @@ int tdb_munmap(struct tdb_context *tdb);
void tdb_mmap(struct tdb_context *tdb);
int tdb_lock(struct tdb_context *tdb, int list, int ltype);
int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype);
int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
enum tdb_lock_flags flags);
int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
bool mark_lock);
int tdb_unlock(struct tdb_context *tdb, int list, int ltype);
int tdb_brlock(struct tdb_context *tdb,
int rw_type, tdb_off_t offset, size_t len,

2
ctdb/lib/tdb/common/transaction.c
View File

@ -631,7 +631,7 @@ static int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
if (tdb->num_locks != 0) {
for (i=0;i<tdb->num_lockrecs;i++) {
tdb_brunlock(tdb, tdb->lockrecs[i].ltype,
FREELIST_TOP+4*tdb->lockrecs[i].list, 1);
tdb->lockrecs[i].off, 1);
}
tdb->num_locks = 0;
tdb->num_lockrecs = 0;