From 43aea02df6cf0d3a606cc201ed09db61b5bad26c Mon Sep 17 00:00:00 2001
From: =?utf8?q?Marek=20Vavru=C5=A1a?= <marek.vavrusa@nic.cz>
Date: Thu, 4 Jun 2015 00:42:06 +0200
Subject: [PATCH] lib/cache: improve cache materialization

---
 lib/cache.c         | 35 +++++++++++++++++------------------
 lib/cache.h         |  5 +++--
 lib/layer/rrcache.c | 14 ++++++++------
 3 files changed, 28 insertions(+), 26 deletions(-)

diff --git a/lib/cache.c b/lib/cache.c
index 9f639d6d0..b5df16282 100644
--- a/lib/cache.c
+++ b/lib/cache.c
@@ -241,35 +241,34 @@ int kr_cache_peek_rr(struct kr_cache_txn *txn, knot_rrset_t *rr, uint32_t *times
 	return kr_error(ENOENT);
 }
 
-knot_rrset_t kr_cache_materialize(const knot_rrset_t *src, uint32_t drift, mm_ctx_t *mm)
+int kr_cache_materialize(knot_rrset_t *dst, const knot_rrset_t *src, uint32_t drift, mm_ctx_t *mm)
 {
 	assert(src);
 
-	/* Make RRSet copy. */
-	knot_rrset_t copy;
-	knot_rrset_init(&copy, NULL, src->type, src->rclass);
-	copy.owner = knot_dname_copy(src->owner, mm);
-	if (!copy.owner) {
-		return copy;
+	/* Make RRSet copy */
+	knot_rrset_init(dst, NULL, src->type, src->rclass);
+	dst->owner = knot_dname_copy(src->owner, mm);
+	if (!dst->owner) {
+		return kr_error(ENOMEM);
 	}
 
+	knot_rdata_t *rd = knot_rdataset_at(&src->rrs, 0);
+	knot_rdata_t *rd_dst = NULL;
 	for (uint16_t i = 0; i < src->rrs.rr_count; ++i) {
-		knot_rdata_t *rd = knot_rdataset_at(&src->rrs, i);
 		if (knot_rdata_ttl(rd) > drift) {
-			if (knot_rdataset_add(&copy.rrs, rd, mm) != 0) {
-				knot_rrset_clear(&copy, mm);
-				return copy;
+			/* Append record */
+			if (knot_rdataset_add(&dst->rrs, rd, mm) != 0) {
+				knot_rrset_clear(dst, mm);
+				return kr_error(ENOMEM);
 			}
+			/* Fixup TTL from absolute time */
+			rd_dst = knot_rdataset_at(&dst->rrs, dst->rrs.rr_count - 1);
+			knot_rdata_set_ttl(rd_dst, knot_rdata_ttl(rd) - drift);
 		}
+		rd += knot_rdata_array_size(knot_rdata_rdlen(rd));
 	}
 
-	/* Update TTLs. */
-	for (uint16_t i = 0; i < copy.rrs.rr_count; ++i) {
-		knot_rdata_t *rd = knot_rdataset_at(&copy.rrs, i);
-		knot_rdata_set_ttl(rd, knot_rdata_ttl(rd) - drift);
-	}
-
-	return copy;
+	return kr_ok();
 }
 
 int kr_cache_insert_rr(struct kr_cache_txn *txn, const knot_rrset_t *rr, uint32_t timestamp)
diff --git a/lib/cache.h b/lib/cache.h
index 1b7c48526..9981aba4f 100644
--- a/lib/cache.h
+++ b/lib/cache.h
@@ -165,12 +165,13 @@ int kr_cache_peek_rr(struct kr_cache_txn *txn, knot_rrset_t *rr, uint32_t *times
 
 /**
  * Clone read-only RRSet and adjust TTLs.
+ * @param dst destination for materialized RRSet
  * @param src read-only RRSet (its rdataset may be changed depending on the result)
  * @param drift time passed between cache time and now
  * @param mm memory context
- * @return materialized (or empty) RRSet
+ * @return 0 or an errcode
  */
-knot_rrset_t kr_cache_materialize(const knot_rrset_t *src, uint32_t drift, mm_ctx_t *mm);
+int kr_cache_materialize(knot_rrset_t *dst, const knot_rrset_t *src, uint32_t drift, mm_ctx_t *mm);
 
 /**
  * Insert RRSet into cache, replacing any existing data.
diff --git a/lib/layer/rrcache.c b/lib/layer/rrcache.c
index 1557bca36..1618029c6 100644
--- a/lib/layer/rrcache.c
+++ b/lib/layer/rrcache.c
@@ -54,13 +54,15 @@ static int loot_rr(struct kr_cache_txn *txn, knot_pkt_t *pkt, const knot_dname_t
 	}
 
 	/* Update packet answer */
-	knot_rrset_t rr_copy = kr_cache_materialize(&cache_rr, timestamp, &pkt->mm);
-	ret = knot_pkt_put(pkt, KNOT_COMPR_HINT_NONE, &rr_copy, KNOT_PF_FREE);
-	if (ret != 0) {
-		knot_rrset_clear(&rr_copy, &pkt->mm);
-		return ret;
+	knot_rrset_t rr_copy;
+	ret = kr_cache_materialize(&rr_copy, &cache_rr, timestamp, &pkt->mm);
+	if (ret == 0) {
+		ret = knot_pkt_put(pkt, KNOT_COMPR_HINT_QNAME, &rr_copy, KNOT_PF_FREE);
+		if (ret != 0) {
+			knot_rrset_clear(&rr_copy, &pkt->mm);
+		}
 	}
-	return kr_ok();
+	return ret;
 }
 
 static int loot_cache_set(struct kr_cache_txn *txn, knot_pkt_t *pkt, const knot_dname_t *qname,
-- 
2.47.3