ref: cef9f9cc57105139c4157fdfb14036c724271271
parent: a3a707822d301c6c1e3cfd164c35e67463406397
author: Ori Bernstein <[email protected]>
date: Tue Feb 5 19:42:58 EST 2013
Document decdegree()'s subtlety.
It's tricky, the way that we use worklists as sets, but
only here.
--- a/6/ra.c
+++ b/6/ra.c
@@ -556,6 +556,18 @@
enablemove(s, m);
for (n = 0; adjiter(s, m, &n); n++)
enablemove(s, n);
+
+ /* Subtle:
+ *
+ * If this code is being called from coalesce(),
+ * then the degree could have been bumped up only
+ * temporarily. This means that the node can already
+ * be on wlfreeze or wlsimp.
+ *
+ * Therefore, if we don't find it on wlspill, we assert
+ * that the node is already on the list that we'd be
+ * moving it to.
+ */
found = wlhas(s->wlspill, s->nwlspill, m, &idx);
if (found)
ldel(&s->wlspill, &s->nwlspill, idx);