From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Mon, 4 Sep 2017 10:51:47 +0000 (+0200)
Subject: cache.clear() on LMDB: first try mdb_drop()
X-Git-Tag: v1.4.0~9^2~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4356f93579982b0f59feaa269f1aa2bf2cefa7be;p=thirdparty%2Fknot-resolver.git

cache.clear() on LMDB: first try mdb_drop()

It's certainly a cleaner way.
---

diff --git a/lib/cdb_lmdb.c b/lib/cdb_lmdb.c
index 11d0561e7..ff6c09733 100644
--- a/lib/cdb_lmdb.c
+++ b/lib/cdb_lmdb.c
@@ -327,6 +327,22 @@ static int cdb_clear(knot_db_t *db)
 	/* Always attempt to commit write transactions in-flight. */
 	(void) cdb_sync(db);
 
+	/* First try mdb_drop() to clear the DB; this may fail with ENOSPC. */
+	{
+		MDB_txn *txn = NULL;
+		int ret = txn_get(env, &txn, false);
+		if (ret == kr_ok()) {
+			ret = lmdb_error(mdb_drop(txn, env->dbi, 0));
+			if (ret == kr_ok()) {
+				ret = cdb_sync(db);
+			}
+			if (ret == kr_ok()) {
+				return ret;
+			}
+		}
+		kr_log_info("[cache] clearing error, falling back\n");
+	}
+
 	/* Since there is no guarantee that there will be free
 	 * pages to hold whole dirtied db for transaction-safe clear,
 	 * we simply remove the database files and reopen.