From 78e79ab51780641bb9d5370840691f221ba56b28 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Vavru=C5=A1a?= <marek.vavrusa@nic.cz>
Date: Mon, 5 Oct 2015 18:25:49 +0200
Subject: [PATCH] lib/cache: key format change, code to check versions
the key is now stored in a format friendly to prefix search, the values
also contain one more 16bit field to store rank of the data (to be
utilised later)
---
daemon/bindings.c | 3 ++-
lib/cache.c | 63 ++++++++++++++++++++++++++++++++++++---------
lib/cache.h | 1 +
lib/layer/rrcache.c | 2 +-
4 files changed, 55 insertions(+), 14 deletions(-)
diff --git a/daemon/bindings.c b/daemon/bindings.c
index d5c20d7f5..9221d27c1 100644
--- a/daemon/bindings.c
+++ b/daemon/bindings.c
@@ -328,7 +328,8 @@ static int cache_count(lua_State *L)
lua_error(L);
}
- lua_pushinteger(L, storage->count(&txn.t));
+ /* First key is a version counter, omit it. */
+ lua_pushinteger(L, storage->count(&txn.t) - 1);
kr_cache_txn_abort(&txn);
return 1;
}
diff --git a/lib/cache.c b/lib/cache.c
index f75cd76fd..5fd6ec115 100644
--- a/lib/cache.c
+++ b/lib/cache.c
@@ -29,22 +29,58 @@
#include "lib/defines.h"
#include "lib/utils.h"
+/* Cache version */
+#define KEY_VERSION "V\x01"
/* Key size */
-#define KEY_HSIZE (1 + sizeof(uint16_t))
+#define KEY_HSIZE (sizeof(uint8_t) + sizeof(uint16_t))
#define KEY_SIZE (KEY_HSIZE + KNOT_DNAME_MAXLEN)
-#define txn_api(txn) (txn->owner->api)
+#define txn_api(txn) ((txn)->owner->api)
+
+/** @internal Check cache internal data version. Clear if it doesn't match. */
+static void assert_right_version(struct kr_cache *cache)
+{
+ /* Check cache ABI version */
+ struct kr_cache_txn txn;
+ int ret = kr_cache_txn_begin(cache, &txn, 0);
+ if (ret != 0) {
+ return; /* N/A, doesn't work. */
+ }
+ namedb_val_t key = { KEY_VERSION, 2 };
+ namedb_val_t val = { NULL, 0 };
+ ret = txn_api(&txn)->find(&txn.t, &key, &val, 0);
+ if (ret == 0) { /* Version is OK */
+ kr_cache_txn_abort(&txn);
+ return;
+ }
+ /* Recreate cache and write version key */
+ ret = txn_api(&txn)->count(&txn.t);
+ if (ret > 0) { /* Non-empty cache, purge it. */
+ log_info("[cache] version mismatch, clearing\n");
+ kr_cache_clear(&txn);
+ kr_cache_txn_commit(&txn);
+ ret = kr_cache_txn_begin(cache, &txn, 0);
+ }
+ /* Either purged or empty. */
+ if (ret == 0) {
+ txn_api(&txn)->insert(&txn.t, &key, &val, 0);
+ kr_cache_txn_commit(&txn);
+ }
+}
int kr_cache_open(struct kr_cache *cache, const namedb_api_t *api, void *opts, mm_ctx_t *mm)
{
if (!cache) {
return kr_error(EINVAL);
}
+ /* Open cache */
cache->api = (api == NULL) ? namedb_lmdb_api() : api;
int ret = cache->api->init(&cache->db, mm, opts);
if (ret != 0) {
return ret;
}
memset(&cache->stats, 0, sizeof(cache->stats));
+ /* Check cache ABI version */
+ assert_right_version(cache);
return kr_ok();
}
@@ -99,20 +135,23 @@ void kr_cache_txn_abort(struct kr_cache_txn *txn)
}
}
-/** @internal Composed key as { u8 tag, u8[1-255] name, u16 type } */
+/**
+ * @internal Composed key as { u8 tag, u8[1-255] name, u16 type }
+ * The name is lowercased and label order is reverted for easy prefix search.
+ * e.g. '\x03nic\x02cz\x00' is saved as '\0x00cz\x00nic\x00'
+ */
static size_t cache_key(uint8_t *buf, uint8_t tag, const knot_dname_t *name, uint16_t rrtype)
{
- /* Write tag + type */
- buf[0] = tag;
- memcpy(buf + 1, &rrtype, sizeof(uint16_t));
- buf += KEY_HSIZE;
- /* Write lowercased name */
- int ret = knot_dname_to_wire(buf, name, KNOT_DNAME_MAXLEN);
- if (ret <= 0) {
+ /* Convert to lookup format */
+ int ret = knot_dname_lf(buf, name, NULL);
+ if (ret != 0) {
return 0;
}
- knot_dname_to_lower(buf);
- return KEY_HSIZE + ret;
+ /* Write tag + type */
+ uint8_t name_len = buf[0];
+ buf[0] = tag;
+ memcpy(buf + sizeof(uint8_t) + name_len, &rrtype, sizeof(uint16_t));
+ return name_len + KEY_HSIZE;
}
static struct kr_cache_entry *cache_entry(struct kr_cache_txn *txn, uint8_t tag, const knot_dname_t *name, uint16_t type)
diff --git a/lib/cache.h b/lib/cache.h
index 4408a6bfa..79852f011 100644
--- a/lib/cache.h
+++ b/lib/cache.h
@@ -36,6 +36,7 @@ struct kr_cache_entry
uint32_t timestamp;
uint32_t ttl;
uint16_t count;
+ uint16_t rank;
uint8_t data[];
};
diff --git a/lib/layer/rrcache.c b/lib/layer/rrcache.c
index dde29829e..4c9598f22 100644
--- a/lib/layer/rrcache.c
+++ b/lib/layer/rrcache.c
@@ -47,7 +47,7 @@ static int loot_rr(struct kr_cache_txn *txn, knot_pkt_t *pkt, const knot_dname_t
if (fetch_rrsig) {
ret = kr_cache_peek_rrsig(txn, &cache_rr, &drift);
} else {
- ret = kr_cache_peek_rr(txn, &cache_rr, &drift);
+ ret = kr_cache_peek_rr(txn, &cache_rr, &drift);
}
if (ret != 0) {
return ret;
--
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