--- /dev/null
+/* Copyright (C) 2014 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * Partial sweep is not feasible as we don't have a list of items sorted
+ * by age nor any sort of LRU/MRU, completely random replace is not possible
+ * as well.
+ * - Idea - make poor man's LRU with two databases doing following:
+ * - Fill up 1, mark that it's unwritable
+ * - Fill up 2, mark that it's unwritable
+ * - Clear 1, all writes will now go in there
+ * - This gives us LR(written) with resolution 2
+ */
+
+#include <time.h>
+
+#include "lib/module.h"
+#include "lib/context.h"
+#include "lib/cache.h"
+
+/*
+ * Properties.
+ */
+
+/**
+ * Return number of cached records.
+ *
+ * Input: N/A
+ * Output: { result: [int] size }
+ *
+ */
+static char* get_size(struct kr_context *ctx, struct kr_module *module, const char *args)
+{
+ char *result = NULL;
+ const namedb_api_t *storage = kr_cache_storage();
+
+ /* Fetch item count */
+ namedb_txn_t txn;
+ int ret = kr_cache_txn_begin(ctx->cache, &txn, NAMEDB_RDONLY);
+ if (ret == 0) {
+ asprintf(&result, "{ \"result\": %d }", storage->count(&txn));
+ kr_cache_txn_abort(&txn);
+ }
+
+ return result;
+}
+
+/** Return boolean true if a record in the RR set is expired. */
+static int is_expired(struct kr_cache_rrset *rr, uint32_t drift)
+{
+ /* Initialize set. */
+ knot_rdataset_t rrs;
+ rrs.rr_count = rr->count;
+ rrs.data = rr->data;
+
+ for (unsigned i = 0; i < rrs.rr_count; ++i) {
+ const knot_rdata_t *rd = knot_rdataset_at(&rrs, i);
+ if (knot_rdata_ttl(rd) <= drift) {
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * Prune expired/invalid records.
+ *
+ * Input: N/A
+ * Output: { result: [int] nr_pruned }
+ *
+ */
+static char* prune(struct kr_context *ctx, struct kr_module *module, const char *args)
+{
+ const namedb_api_t *storage = kr_cache_storage();
+
+ namedb_txn_t txn;
+ int ret = kr_cache_txn_begin(ctx->cache, &txn, 0);
+ if (ret != 0) {
+ return NULL;
+ }
+
+ /* Iterate cache and find expired records. */
+ int pruned = 0;
+ uint32_t now = time(NULL);
+ namedb_iter_t *it = storage->iter_begin(&txn, 0);
+ while (it) {
+ /* Fetch RR from cache */
+ namedb_val_t key, val;
+ if (storage->iter_key(it, &key) != 0 ||
+ storage->iter_val(it, &val)) {
+ break;
+ }
+ /* Prune expired records. */
+ struct kr_cache_rrset *rr = val.data;
+ if (is_expired(rr, now - rr->timestamp)) {
+ storage->del(&txn, &key);
+ pruned += 1;
+ }
+ it = storage->iter_next(it);
+ }
+
+ /* Commit and format result. */
+ char *result = NULL;
+ if (kr_cache_txn_commit(&txn) != 0) {
+ asprintf(&result, "{ \"result\": %d, \"error\": \"%s\" }", pruned, knot_strerror(ret));
+ } else {
+ asprintf(&result, "{ \"result\": %d }", pruned);
+ }
+
+ return result;
+}
+
+/**
+ * Clear all records.
+ *
+ * Input: N/A
+ * Output: { result: [bool] success }
+ *
+ */
+static char* clear(struct kr_context *ctx, struct kr_module *module, const char *args)
+{
+ namedb_txn_t txn;
+ int ret = kr_cache_txn_begin(ctx->cache, &txn, 0);
+ if (ret != 0) {
+ return NULL;
+ }
+
+ /* Clear cache and commit. */
+ ret = kr_cache_clear(&txn);
+ if (ret == 0) {
+ ret = kr_cache_txn_commit(&txn);
+ } else {
+ kr_cache_txn_abort(&txn);
+ }
+
+ char *result = NULL;
+ asprintf(&result, "{ \"result\": %s }", ret == 0 ? "true" : "false");
+ return result;
+}
+
+/*
+ * Module implementation.
+ */
+
+struct kr_prop *cachectl_props(void)
+{
+ static struct kr_prop prop_list[] = {
+ { &get_size, "size", "Return number of cached records.", },
+ { &prune, "prune", "Prune expired/invalid records.", },
+ { &clear, "clear", "Clear all cache records.", },
+ { NULL, NULL, NULL }
+ };
+ return prop_list;
+}
+
+KR_MODULE_EXPORT(cachectl);
projects / thirdparty / knot-resolver.git / commitdiff
