Update of /cvsroot/monetdb/pathfinder/runtime
In directory sc8-pr-cvs16:/tmp/cvs-serv21384
Modified Files:
pathfinder.mx
Log Message:
- fix in incremental readonly shred, introduced with value indexing
Index: pathfinder.mx
===================================================================
RCS file: /cvsroot/monetdb/pathfinder/runtime/pathfinder.mx,v
retrieving revision 1.334
retrieving revision 1.335
diff -u -d -r1.334 -r1.335
--- pathfinder.mx 16 Apr 2007 12:06:32 -0000 1.334
+++ pathfinder.mx 17 Apr 2007 13:16:18 -0000 1.335
@@ -542,8 +542,8 @@
# master bat *READS* must protect themselves against *independent* master bat
updates, and
# in particular extends. Such BATextends may reallocate the base address of
the heaps.
-# Thus readers take a nonexclusive locks, and appends (that potentially
extend) take
-# an exclusive extend-lock. We would prefereably have had this per-collection,
but for now
+# Thus readers take a nonexclusive lock, and appends (that potentially extend)
take
+# an exclusive extend-lock. We would preferably have had this per-collection,
but for now
# there is just a global lock for this.
var pf_extend := pflock_get(3); # protects the counter
var pf_extend_cnt := 0; # counter is used by nonexclusive acces (first gets
barrier, last releases)
@@ -883,6 +883,16 @@
master bats. It must also be taken by update transactions that modify
stable portions of the master bats.
+Writers just lock coll_lock short to get exclusive access. Readers can
+follow a non-exclusive mechanism wrt to other readers. This policy
+is used when opening collections (the lock is needed while the remap/rcopy
+isolation is done on the master bats). The non-exclusive variant releases
+the lock immediately, but after insert an entry [shortlock,nil] in the
+shortlock_barrier bat, and remove this when they are done. Exclusive writers
+examine this BAT, and if [shortlock,nil] is present, create a new
+barrier and insert this [shortlock,sema] in the BAT, and block on the
+semaphore. The last reader exiting wakes up all these semaphores.
+
The long lock is taken by updating actions only. Holding it prevents
other updates from proceeding on a commit to that collection. However,
it does allow read-transactions to access the master BATs freely.
@@ -1228,6 +1238,8 @@
var coll_shortlock :=
reverse(ws.fetch(CONT_RUNTIME).fetch(cont)).fetch(RT_LOCK_FREELIST);
lock_set(coll_shortlock);
+ if (ws_log_active)
+ ws_log(ws, nme + " (coll_lock_set) shortlock" + str(ws_logtime
- (ws_logtime := usec())));
lock_set(pf_collbarrier_lock);
if (shortlock_barrier.exist(coll_shortlock,sema_nil)) { # there
are readers in ws_opencoll!!
var barrier := sema_create(0);
@@ -1236,8 +1248,12 @@
lock_unset(pf_collbarrier_lock);
lock_unset(coll_shortlock);
sema_down(barrier); # wait for the readers
+ if (ws_log_active)
+ ws_log(ws, nme + " (coll_lock_set) sema" +
str(ws_logtime - (ws_logtime := usec())));
lock_set(coll_shortlock);
lock_set(pf_collbarrier_lock);
+ if (ws_log_active)
+ ws_log(ws, nme + " (coll_lock_set) shortlock-redo" +
str(ws_logtime - (ws_logtime := usec())));
}
shortlock_barrier.delete(coll_shortlock,barrier);
sema_destroy(barrier);
@@ -1245,8 +1261,6 @@
lock_unset(pf_collbarrier_lock);
ws.fetch(CONT_LOCKED).append(coll_shortlock);
- if (ws_log_active)
- ws_log(ws, nme + " (coll_lock_set) shortlock" + str(ws_logtime
- (ws_logtime := usec())));
checkpoint_protect(ws);
if (ws_log_active)
ws_log(ws, nme + " (coll_lock_set) checkpoint_lock" +
str(ws_logtime - usec()));
@@ -2137,8 +2151,8 @@
var qn_nid := commitbat + "_qn_nid";
var vx_hsh_nid := commitbat + "_vx_hsh_nid";
commitbat := "old_" + commitbat;
- CATCH({ qn_nid.persists(false).rename(commitbat + "_qn_nid");
- vx_hsh_nid.persists(false).rename(commitbat + "_vx_hsh_nid");
}); # delete idx in commit
+ CATCH({ bat(qn_nid).persists(false).rename(commitbat + "_qn_nid");
+ bat(vx_hsh_nid).persists(false).rename(commitbat +
"_vx_hsh_nid"); }); # delete idx in commit
} else {
commitbat := str_nil; # incremental readonly shred, but no index to
delete
}
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