From 94ad27de1f8c13b837582019247de31182cd26a4 Mon Sep 17 00:00:00 2001
From: Jan Kadlec <jan.kadlec@nic.cz>
Date: Tue, 8 Apr 2014 16:50:40 +0200
Subject: [PATCH] new_node: Added more comments for changeset processing.
---
src/knot/updates/xfr-in.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)
diff --git a/src/knot/updates/xfr-in.c b/src/knot/updates/xfr-in.c
index a74fdcfda..f218ca071 100644
--- a/src/knot/updates/xfr-in.c
+++ b/src/knot/updates/xfr-in.c
@@ -44,6 +44,11 @@
static void rrs_list_clear(list_t *l, mm_ctx_t *mm)
{
+ /*
+ * Frees data that are in the tree that will not be used, these are:
+ * - actual data inside knot_rrs_t. (the rest is part of the node)
+ * - arrays allocated for additional nodes. (nodes are kept)
+ */
ptrnode_t *n;
node_t *nxt;
WALK_LIST_DELSAFE(n, nxt, *l) {
@@ -670,6 +675,7 @@ void xfrin_rollback_update(knot_changesets_t *chgs,
static int xfrin_replace_rrs_with_copy(knot_node_t *node,
uint16_t type)
{
+ // Find data to copy.
struct rr_data *data = NULL;
for (uint16_t i = 0; i < node->rrset_count; ++i) {
if (node->rrs[i].type == type) {
@@ -677,6 +683,8 @@ static int xfrin_replace_rrs_with_copy(knot_node_t *node,
}
}
assert(data);
+
+ // Create new data.
knot_rrs_t *rrs = &data->rrs;
void *copy = malloc(knot_rrs_size(rrs));
if (copy == NULL) {
@@ -685,8 +693,12 @@ static int xfrin_replace_rrs_with_copy(knot_node_t *node,
memcpy(copy, rrs->data, knot_rrs_size(rrs));
- // Clear additional from node in new tree.
+ /*
+ * Clear additional array from node in new tree. It's callers
+ * responsibility to store it for cleanup.
+ */
data->additional = NULL;
+ // Store new data into node RRS.
rrs->data = copy;
return KNOT_EOK;
@@ -703,10 +715,12 @@ static void clear_new_rrs(knot_node_t *node, uint16_t type)
static bool can_remove(const knot_node_t *node, const knot_rrset_t *rr)
{
if (node == NULL) {
+ // Node does not exist, cannot remove anything.
return false;
}
const knot_rrs_t *node_rrs = knot_node_rrs(node, rr->type);
if (node_rrs == NULL) {
+ // Node does not have this type at all.
return false;
}
@@ -714,9 +728,12 @@ static bool can_remove(const knot_node_t *node, const knot_rrset_t *rr)
for (uint16_t i = 0; i < rr->rrs.rr_count; ++i) {
knot_rr_t *rr_cmp = knot_rrs_rr(&rr->rrs, i);
if (knot_rrs_member(node_rrs, rr_cmp, compare_ttls)) {
+ // At least one RR matches.
return true;
}
}
+
+ // Node does have the type, but no RRs match.
return false;
}
@@ -766,6 +783,7 @@ static int remove_rr(knot_node_t *node, const knot_rrset_t *rr,
}
knot_rrs_t *changed_rrs = knot_node_get_rrs(node, rr->type);
+ // Subtract changeset RRS from node RRS.
ret = knot_rrs_subtract(changed_rrs, &rr->rrs, NULL);
if (ret != KNOT_EOK) {
clear_new_rrs(node, rr->type);
@@ -773,13 +791,14 @@ static int remove_rr(knot_node_t *node, const knot_rrset_t *rr,
}
if (changed_rrs->rr_count > 0) {
+ // Subtraction left some data in RRSet, store it for rollback.
ret = add_new_data(chset, changed_rrs->data);
if (ret != KNOT_EOK) {
knot_rrs_clear(changed_rrs, NULL);
return ret;
}
} else {
- // Removed last RR in RRSet, remove it from node.
+ // RRSet is empty now, remove it from node, all data freed.
knot_node_remove_rrset(node, rr->type);
}
@@ -823,7 +842,7 @@ static int add_rr(knot_node_t *node, const knot_rrset_t *rr,
return ret;
}
- // Store old RRS for cleanup.
+ // Store old RRS and additional for cleanup.
ret = add_old_data(chset, old_data, old_additional);
if (ret != KNOT_EOK) {
clear_new_rrs(node, rr->type);
@@ -845,8 +864,8 @@ static int add_rr(knot_node_t *node, const knot_rrset_t *rr,
}
}
+ // Get changed RRS and store for possible rollback.
knot_rrs_t *rrs = knot_node_get_rrs(node, rr->type);
- // Store new RRS for rollback
int ret = add_new_data(chset, rrs->data);
if (ret != KNOT_EOK) {
knot_rrs_clear(rrs, NULL);
--
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