Changeset: f5f2a0f6507e for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/f5f2a0f6507e
Modified Files:
gdk/gdk_strimps.c
Branch: Dec2023
Log Message:
Fixed a data race in strimps creation.
diffs (82 lines):
diff --git a/gdk/gdk_strimps.c b/gdk/gdk_strimps.c
--- a/gdk/gdk_strimps.c
+++ b/gdk/gdk_strimps.c
@@ -838,10 +838,10 @@ BATsetstrimps(BAT *b)
* in the BAT.
*/
#define STRIMP_COMPLETE(b) \
- (b)->tstrimps != NULL && \
- (b)->tstrimps != (Strimps *)1 && \
- (b)->tstrimps != (Strimps *)2 && \
- (((b)->tstrimps->strimps.free - ((char
*)(b)->tstrimps->bitstrings_base - (b)->tstrimps->strimps.base)) ==
(b)->batCount*sizeof(uint64_t))
+ ((b)->tstrimps != NULL && \
+ (b)->tstrimps != (Strimps *)1 && \
+ (b)->tstrimps != (Strimps *)2 && \
+ (((b)->tstrimps->strimps.free - ((char
*)(b)->tstrimps->bitstrings_base - (b)->tstrimps->strimps.base)) ==
(b)->batCount*sizeof(uint64_t)))
/* Strimp creation.
@@ -886,16 +886,17 @@ STRMPcreate(BAT *b, BAT *s)
pb = b;
}
+ /* First thread to take the lock will read the strimp from disk
+ * or construct the strimp header.
+ */
+ MT_lock_set(&pb->batIdxLock);
+
/* Strimp creation was requested. There are three cases:
* - The strimp is on disk (pb->tstrimps == 1)
* - The strimp needs to be created (pb->tstrimps == 2)
* - Finally the pointer might have been changed to NULL in another
thread.
*/
if (pb->tstrimps == NULL || pb->tstrimps == (Strimps*)1 || pb->tstrimps
== (Strimps*)2) {
- /* First thread to take the lock will read the strimp
- * from disk or construct the strimp header.
- */
- MT_lock_set(&pb->batIdxLock);
/* The strimp needs to be created. The rest of the
* creation code assumes that the pointer to the strimps
* is NULL. Make it so.
@@ -933,10 +934,10 @@ STRMPcreate(BAT *b, BAT *s)
}
pb->tstrimps = r;
}
- MT_lock_unset(&pb->batIdxLock);
}
if (STRIMP_COMPLETE(pb)) {
+ MT_lock_unset(&pb->batIdxLock);
if (pb != b)
BBPunfix(pb->batCacheid);
return GDK_SUCCEED;
@@ -947,6 +948,10 @@ STRMPcreate(BAT *b, BAT *s)
MT_thread_setalgorithm("create strimp index");
r = pb->tstrimps;
STRMPincref(r);
+ if (pb != b) {
+ MT_lock_unset(&pb->batIdxLock);
+ MT_lock_set(&b->batIdxLock);
+ }
dh = (uint64_t *)r->bitstrings_base + b->hseqbase;
canditer_init(&ci, b, s);
@@ -961,13 +966,16 @@ STRMPcreate(BAT *b, BAT *s)
}
bat_iterator_end(&bi);
- MT_lock_set(&b->batIdxLock);
+ if (pb != b) {
+ MT_lock_unset(&b->batIdxLock);
+ MT_lock_set(&pb->batIdxLock);
+ }
r->strimps.free += b->batCount*sizeof(uint64_t);
/* The thread that reaches this point last needs to write the strimp to
disk. */
if ((r->strimps.free - ((char *)r->bitstrings_base - r->strimps.base))
== b->batCount*sizeof(uint64_t)) {
persistStrimp(pb);
}
- MT_lock_unset(&b->batIdxLock);
+ MT_lock_unset(&pb->batIdxLock);
STRMPdecref(r, false);
TRC_DEBUG(ACCELERATOR, "strimp creation took " LLFMT " usec\n",
GDKusec()-t0);
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