Changeset: 31591e782aca for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/31591e782aca
Modified Files:
gdk/gdk_strimps.c
Branch: strimps_update
Log Message:
Some cleanup
diffs (89 lines):
diff --git a/gdk/gdk_strimps.c b/gdk/gdk_strimps.c
--- a/gdk/gdk_strimps.c
+++ b/gdk/gdk_strimps.c
@@ -569,7 +569,6 @@ STRMPfilter(BAT *b, BAT *s, const char *
static void
BATstrimpsync(BAT *b)
{
- // BAT *b = arg;
lng t0 = 0;
Heap *hp;
int fd;
@@ -577,7 +576,6 @@ BATstrimpsync(BAT *b)
TRC_DEBUG_IF(ACCELERATOR) t0 = GDKusec();
- // MT_lock_set(&b->batIdxLock);
if ((hp = &b->tstrimps->strimps)) {
if (HEAPsave(hp, hp->filename, NULL, true, hp->free, NULL) ==
GDK_SUCCEED) {
if (hp->storage == STORE_MEM) {
@@ -615,7 +613,6 @@ BATstrimpsync(BAT *b)
BATgetId(b), GDKusec() - t0, failed);
}
}
- // MT_lock_unset(&b->batIdxLock);
BBPunfix(b->batCacheid);
}
@@ -626,14 +623,10 @@ persistStrimp(BAT *b)
&& b->batInserted == b->batCount
&& !b->theap->dirty
&& !GDKinmemory(b->theap->farmid)) {
- // MT_Id tid;
BBPfix(b->batCacheid);
char name[MT_NAME_LEN];
snprintf(name, sizeof(name), "strimpsync%d", b->batCacheid);
BATstrimpsync(b);
- /* if (MT_create_thread(&tid, BATstrimpsync, b, */
- /* MT_THR_DETACHED, name) < 0) */
- /* BBPunfix(b->batCacheid); */
} else
TRC_DEBUG(ACCELERATOR, "persistStrimp(" ALGOBATFMT "): NOT
persisting strimp\n", ALGOBATPAR(b));
}
@@ -752,7 +745,22 @@ BATsetstrimps(BAT *b)
((b->tstrimps->strimps.free - ((char
*)b->tstrimps->bitstrings_base - b->tstrimps->strimps.base)) ==
b->batCount*sizeof(uint64_t))
-
+/* Strimp creation.
+ *
+ * First we attempt to take the index lock of the BAT. The first thread
+ * that succeeds, checks if the strimp already exists on disk and
+ * attempts to read it. If this succeeds then strimp creation is
+ * complete. If it does not either because the strimp does not exist or
+ * because it is outdated (if for example there is a version mismatch),
+ * the same thread that still holds the lock attempts to create the
+ * strimp header and heap. If this fails then we cannot have a strimp on
+ * this BAT and we report a failure after releasing the lock.
+ *
+ * If the strimp header is suceessfully created, then we release the
+ * lock and allow the rest of the threads to compute the bitstrings of
+ * the slice they have been assigned.
+ *
+ */
gdk_return
STRMPcreate(BAT *b, BAT *s)
{
@@ -779,7 +787,14 @@ STRMPcreate(BAT *b, BAT *s)
pb = b;
}
+ /* Strimp creation was requested. There are two cases:
+ - The strimp is on disk (pb->tstrimps == 1)
+ - The strimp needs to be created (pb->tstrimps == 2)
+ */
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);
if (pb->tstrimps == (Strimps *)2)
pb->tstrimps = NULL;
@@ -901,7 +916,6 @@ STRMPfree(BAT *b)
}
}
-/* Parallel creation. does not wok*/
#if 0
/* Update the strimp by computing a bitstring and adding it to the heap.
This will probably be useful later when strimps take updates into
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