Commit acf1a21e authored by Rusty Russell's avatar Rusty Russell

tdb: cleanup: tdb_nest_lock/tdb_nest_unlock

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: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 1d03cc6d
...@@ -218,43 +218,38 @@ int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len) ...@@ -218,43 +218,38 @@ int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len)
return -1; 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 */ /* lock an offset in the database. */
static int _tdb_lock(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) enum tdb_lock_flags flags)
{ {
struct tdb_lock_type *new_lck; struct tdb_lock_type *new_lck;
int i; int i;
/* a allrecord lock allows us to avoid per chain locks */ if (offset >= lock_offset(tdb->header.hash_size)) {
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;
}
if (list < -1 || list >= (int)tdb->header.hash_size) {
tdb->ecode = TDB_ERR_LOCK; tdb->ecode = TDB_ERR_LOCK;
TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid list %d for ltype=%d\n", TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n",
list, ltype)); offset, ltype));
return -1; return -1;
} }
if (tdb->flags & TDB_NOLOCK) if (tdb->flags & TDB_NOLOCK)
return 0; return 0;
for (i=0; i<tdb->num_lockrecs; i++) { 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) { if (tdb->lockrecs[i].count == 0) {
/* /*
* Can't happen, see tdb_unlock(). It should * Can't happen, see tdb_unlock(). It should
* be an assert. * be an assert.
*/ */
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock: " 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 * Just increment the in-memory struct, posix locks
...@@ -276,13 +271,13 @@ static int _tdb_lock(struct tdb_context *tdb, int list, int ltype, ...@@ -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, /* Since fcntl locks don't nest, we do a lock for the first one,
and simply bump the count for future ones */ 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; return -1;
} }
tdb->num_locks++; 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].count = 1;
tdb->lockrecs[tdb->num_lockrecs].ltype = ltype; tdb->lockrecs[tdb->num_lockrecs].ltype = ltype;
tdb->num_lockrecs += 1; tdb->num_lockrecs += 1;
...@@ -295,7 +290,19 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype) ...@@ -295,7 +290,19 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype)
{ {
int ret; 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) { if (ret) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d " TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
"ltype=%d (%s)\n", list, ltype, strerror(errno))); "ltype=%d (%s)\n", list, ltype, strerror(errno)));
...@@ -306,18 +313,7 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype) ...@@ -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 */ /* 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) int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
{ {
return _tdb_lock(tdb, list, ltype, TDB_LOCK_NOWAIT); /* a allrecord lock allows us to avoid per chain locks */
}
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 */
if (tdb->allrecord_lock.count && if (tdb->allrecord_lock.count &&
(ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) { (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
return 0; return 0;
...@@ -328,17 +324,28 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype, ...@@ -328,17 +324,28 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
return -1; 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) if (tdb->flags & TDB_NOLOCK)
return 0; return 0;
/* Sanity checks */ /* Sanity checks */
if (list < -1 || list >= (int)tdb->header.hash_size) { if (offset >= lock_offset(tdb->header.hash_size)) {
TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: list %d invalid (%d)\n", list, tdb->header.hash_size)); TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->header.hash_size));
return ret; return ret;
} }
for (i=0; i<tdb->num_lockrecs; i++) { for (i=0; i<tdb->num_lockrecs; i++) {
if (tdb->lockrecs[i].list == list) { if (tdb->lockrecs[i].off == offset) {
lck = &tdb->lockrecs[i]; lck = &tdb->lockrecs[i];
break; break;
} }
...@@ -364,8 +371,7 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype, ...@@ -364,8 +371,7 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype,
if (mark_lock) { if (mark_lock) {
ret = 0; ret = 0;
} else { } else {
ret = tdb->methods->brunlock(tdb, ltype, ret = tdb->methods->brunlock(tdb, ltype, offset, 1);
FREELIST_TOP+4*list, 1);
} }
tdb->num_locks--; tdb->num_locks--;
...@@ -395,7 +401,18 @@ static int _tdb_unlock(struct tdb_context *tdb, int list, int ltype, ...@@ -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) 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) ...@@ -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! */ /* 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 tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
{ {
int ret = _tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK, int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
TDB_LOCK_MARK_ONLY); F_WRLCK, TDB_LOCK_MARK_ONLY);
tdb_trace_1rec(tdb, "tdb_chainlock_mark", key); tdb_trace_1rec(tdb, "tdb_chainlock_mark", key);
return ret; return ret;
} }
...@@ -609,7 +626,8 @@ int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key) ...@@ -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) int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
{ {
tdb_trace_1rec(tdb, "tdb_chainlock_unmark", 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) int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
......
...@@ -183,7 +183,7 @@ struct tdb_header { ...@@ -183,7 +183,7 @@ struct tdb_header {
}; };
struct tdb_lock_type { struct tdb_lock_type {
int list; uint32_t off;
uint32_t count; uint32_t count;
uint32_t ltype; uint32_t ltype;
}; };
...@@ -256,6 +256,10 @@ int tdb_munmap(struct tdb_context *tdb); ...@@ -256,6 +256,10 @@ int tdb_munmap(struct tdb_context *tdb);
void tdb_mmap(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(struct tdb_context *tdb, int list, int ltype);
int tdb_lock_nonblock(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_unlock(struct tdb_context *tdb, int list, int ltype);
int tdb_brlock(struct tdb_context *tdb, int tdb_brlock(struct tdb_context *tdb,
int rw_type, tdb_off_t offset, size_t len, int rw_type, tdb_off_t offset, size_t len,
......
...@@ -520,7 +520,7 @@ int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype) ...@@ -520,7 +520,7 @@ int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
if (tdb->num_locks != 0) { if (tdb->num_locks != 0) {
for (i=0;i<tdb->num_lockrecs;i++) { for (i=0;i<tdb->num_lockrecs;i++) {
tdb_brunlock(tdb, tdb->lockrecs[i].ltype, 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_locks = 0;
tdb->num_lockrecs = 0; tdb->num_lockrecs = 0;
......
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