Changeset: d0d459b6e7fa for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/d0d459b6e7fa
Modified Files:
gdk/gdk_batop.c
Branch: Mar2025
Log Message:
When unsharing a string heap, reinsert strings if view significantly smaller.
diffs (86 lines):
diff --git a/gdk/gdk_batop.c b/gdk/gdk_batop.c
--- a/gdk/gdk_batop.c
+++ b/gdk/gdk_batop.c
@@ -30,7 +30,6 @@ unshare_varsized_heap(BAT *b)
Heap *h = GDKmalloc(sizeof(Heap));
if (h == NULL)
return GDK_FAIL;
- MT_thread_setalgorithm("unshare vheap");
*h = (Heap) {
.parentid = b->batCacheid,
.farmid = BBPselectfarm(b->batRole, TYPE_str, varheap),
@@ -38,6 +37,74 @@ unshare_varsized_heap(BAT *b)
};
strconcat_len(h->filename, sizeof(h->filename),
BBP_physical(b->batCacheid), ".theap", NULL);
+ /* if parent bat is much larger (currently more than
+ * twice) than the view, we copy the strings
+ * individually so that the resulting vheap is reduced
+ * in size
+ * we do this only if there are no other references to
+ * the bat since we're changing the offset heap and the
+ * values are going to be temporarily incorrect */
+ MT_lock_set(&GDKswapLock(b->batCacheid));
+ if (BBP_refs(b->batCacheid) == 1 &&
+ BATcount(BBP_desc(b->tvheap->parentid)) > 2 * BATcount(b)) {
+ MT_thread_setalgorithm("unshare vheap reinsert
strings");
+ MT_lock_set(&b->theaplock);
+ strHeap(h, b->batCapacity);
+ Heap *oh = b->tvheap;
+ b->tvheap = h;
+ var_t o;
+ switch (b->twidth) {
+ case 1:
+ for (BUN i = 0; i < b->batCount; i++) {
+ o = (var_t) ((uint8_t *)
b->theap->base)[i] + GDK_VAROFFSET;
+ if (strPut(b, &o, oh->base + o) ==
(var_t) -1)
+ goto bailout;
+ ((uint8_t *) b->theap->base)[i] =
(uint8_t) (o - GDK_VAROFFSET);
+ }
+ break;
+ case 2:
+ for (BUN i = 0; i < b->batCount; i++) {
+ o = (var_t) ((uint16_t *)
b->theap->base)[i] + GDK_VAROFFSET;
+ if (strPut(b, &o, oh->base + o) ==
(var_t) -1)
+ goto bailout;
+ ((uint16_t *) b->theap->base)[i] =
(uint16_t) (o - GDK_VAROFFSET);
+ }
+ break;
+#if SIZEOF_VAR_T == 8
+ case 4:
+ for (BUN i = 0; i < b->batCount; i++) {
+ o = (var_t) ((uint32_t *)
b->theap->base)[i];
+ if (strPut(b, &o, oh->base + o) ==
(var_t) -1)
+ goto bailout;
+ ((uint32_t *) b->theap->base)[i] =
(uint32_t) o;
+ }
+ break;
+#endif
+ case SIZEOF_VAR_T:
+ for (BUN i = 0; i < b->batCount; i++) {
+ o = ((var_t *) b->theap->base)[i];
+ if (strPut(b, &o, oh->base + o) ==
(var_t) -1)
+ goto bailout;
+ ((var_t *) b->theap->base)[i] = o;
+ }
+ break;
+ default:
+ MT_UNREACHABLE();
+ }
+ MT_lock_unset(&b->theaplock);
+ MT_lock_unset(&GDKswapLock(b->batCacheid));
+ BBPrelease(oh->parentid);
+ HEAPdecref(oh, false);
+ return GDK_SUCCEED;
+ bailout:
+ MT_lock_unset(&b->theaplock);
+ MT_lock_unset(&GDKswapLock(b->batCacheid));
+ BBPrelease(oh->parentid);
+ HEAPdecref(oh, false);
+ return GDK_FAIL;
+ }
+ MT_lock_unset(&GDKswapLock(b->batCacheid));
+ MT_thread_setalgorithm("unshare vheap by copying");
if (HEAPcopy(h, b->tvheap, 0) != GDK_SUCCEED) {
HEAPfree(h, true);
GDKfree(h);
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