MINOR: pattern: add pat_ref_purge_older() to purge old entries
This function will be usable to purge at most a specified number of old
entries from a reference. Entries are declared old if their generation
number is in the past compared to the one passed in argument. This will
ease removal of early entries when new ones have been appended.
We also call malloc_trim() when available, at the end of the series,
because this is one place where there is a lot of memory to save. Reloads
of 1M IP addresses used in an ACL made the process grow up to 1.7 GB RSS
after 10 reloads and roughly stabilize there without this call, versus
only 260 MB when the call is present. Sadly there is no direct equivalent
for jemalloc, which stabilizes around 800MB-1GB.
diff --git a/src/pattern.c b/src/pattern.c
index 5613512..b0b136b 100644
--- a/src/pattern.c
+++ b/src/pattern.c
@@ -1984,6 +1984,70 @@
return !!pat_ref_load(ref, ref->curr_gen, pattern, sample, -1, err);
}
+/* This function purges all elements from <ref> that are older than generation
+ * <oldest>. It will not purge more than <budget> entries at once, in order to
+ * remain responsive. If budget is negative, no limit is applied.
+ * The caller must already hold the PATREF_LOCK on <ref>. The function will
+ * take the PATEXP_LOCK on all expressions of the pattern as needed. It returns
+ * non-zero on completion, or zero if it had to stop before the end after
+ * <budget> was depleted.
+ */
+int pat_ref_purge_older(struct pat_ref *ref, unsigned int oldest, int budget)
+{
+ struct pat_ref_elt *elt, *elt_bck;
+ struct bref *bref, *bref_bck;
+ struct pattern_expr *expr;
+ int done;
+
+ list_for_each_entry(expr, &ref->pat, list)
+ HA_RWLOCK_WRLOCK(PATEXP_LOCK, &expr->lock);
+
+ /* all expr are locked, we can safely remove all pat_ref */
+
+ /* assume completion for e.g. empty lists */
+ done = 1;
+ list_for_each_entry_safe(elt, elt_bck, &ref->head, list) {
+ if ((int)(elt->gen_id - oldest) >= 0)
+ continue;
+
+ if (budget >= 0 && !budget--) {
+ done = 0;
+ break;
+ }
+
+ /*
+ * we have to unlink all watchers from this reference pattern. We must
+ * not relink them if this elt was the last one in the list.
+ */
+ list_for_each_entry_safe(bref, bref_bck, &elt->back_refs, users) {
+ LIST_DEL(&bref->users);
+ LIST_INIT(&bref->users);
+ if (elt->list.n != &ref->head)
+ LIST_ADDQ(&LIST_ELEM(elt->list.n, typeof(elt), list)->back_refs, &bref->users);
+ bref->ref = elt->list.n;
+ }
+
+ /* delete the storage for all representations of this pattern. */
+ pat_delete_gen(ref, elt);
+
+ LIST_DEL(&elt->list);
+ free(elt->pattern);
+ free(elt->sample);
+ free(elt);
+ }
+
+ list_for_each_entry(expr, &ref->pat, list)
+ HA_RWLOCK_WRUNLOCK(PATEXP_LOCK, &expr->lock);
+
+#if defined(HA_HAVE_MALLOC_TRIM)
+ if (done) {
+ malloc_trim(0);
+ }
+#endif
+
+ return done;
+}
+
/* This function prunes <ref>, replaces all references by the references
* of <replace>, and reindexes all the news values.
*