From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Wed, 3 Jan 2018 08:57:27 +0000 (+0100)
Subject: clear cache if overfull
X-Git-Tag: v2.0.0~6^2~41
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=819bcae16246fed28ee10abe2b207d3401dd6fb5;p=thirdparty%2Fknot-resolver.git

clear cache if overfull

I somehow forgot to migrate that behavior when rewriting cache :-/
---

diff --git a/lib/cache/entry_list.c b/lib/cache/entry_list.c
index 70553e5df..f2c40b3ca 100644
--- a/lib/cache/entry_list.c
+++ b/lib/cache/entry_list.c
@@ -184,6 +184,19 @@ int entry_h_splice(
 	knot_db_val_t val = { .len = storage_size, .data = NULL };
 	int ret = cache_op(cache, write, &key, &val, 1);
 	if (ret || !val.data || !val.len) {
+		/* Clear cache if overfull.  It's nontrivial to do better with LMDB.
+		 * LATER: some garbage-collection mechanism. */
+		if (ret == kr_error(ENOSPC)) {
+			ret = kr_cache_clear(cache);
+			const char *msg = "[cache] clearing because overfull, ret = %d\n";
+			if (ret) {
+				kr_log_error(msg, ret);
+			} else {
+				kr_log_info(msg, ret);
+				ret = kr_error(ENOSPC);
+			}
+			return ret;
+		}
 		assert(ret); /* otherwise "succeeding" but `val` is bad */
 		VERBOSE_MSG(qry, "=> failed backend write, ret = %d\n", ret);
 		return kr_error(ret ? ret : ENOSPC);
diff --git a/lib/cdb_lmdb.c b/lib/cdb_lmdb.c
index af2495961..cfbfc3847 100644
--- a/lib/cdb_lmdb.c
+++ b/lib/cdb_lmdb.c
@@ -56,20 +56,21 @@ struct lmdb_env
 /** @brief Convert LMDB error code. */
 static int lmdb_error(int error)
 {
+	/* _BAD_TXN may happen with overfull DB,
+	 * even during mdb_get with a single fork :-/ */
+	if (error == MDB_BAD_TXN) {
+		kr_log_info("[cache] MDB_BAD_TXN, probably overfull\n");
+		error = ENOSPC;
+	}
 	switch (error) {
 	case MDB_SUCCESS:
 		return kr_ok();
 	case MDB_NOTFOUND:
 		return kr_error(ENOENT);
-
 	case ENOSPC:
 	case MDB_MAP_FULL:
 	case MDB_TXN_FULL:
-	case MDB_BAD_TXN:
-		/* _BAD_TXN in practice happens with overfull DB,
-		 * even during mdb_get with a single fork :-/ */
 		return kr_error(ENOSPC);
-
 	default:
 		kr_log_error("[cache] LMDB error: %s\n", mdb_strerror(error));
 		assert(false);