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Nest: Change nexthop merging order to prefer earlier nexthops

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When nexthop merge limit was applied, the old code used first N nexthops
in the canonical ordering. Now the code prefers nexthops based on the
order or routes in the network.
This commit is contained in:
Ondrej Zajicek (work) 2020-08-27 03:24:04 +02:00
parent 00cf501a0a
commit 5ae13e157f
3 changed files with 60 additions and 19 deletions
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1
nest/route.h
View File

@ -638,6 +638,7 @@ int nexthop__same(struct nexthop *x, struct nexthop *y); /* Compare multipath ne
static inline int nexthop_same(struct nexthop *x, struct nexthop *y)
{ return (x == y) || nexthop__same(x, y); }
struct nexthop *nexthop_merge(struct nexthop *x, struct nexthop *y, int rx, int ry, int max, linpool *lp);
struct nexthop *nexthop_merge2(struct nexthop *x, struct nexthop *y, int ry, int *max, linpool *lp);
static inline void nexthop_link(struct rta *a, struct nexthop *from)
{ memcpy(&a->nh, from, nexthop_size(from)); }
void nexthop_insert(struct nexthop **n, struct nexthop *y);

51
nest/rt-attr.c
View File

@ -285,6 +285,57 @@ nexthop_merge(struct nexthop *x, struct nexthop *y, int rx, int ry, int max, lin
return root;
}
/**
* nexthop_merge2 - merge nexthop lists
* @x: list 1
* @y: list 2
* @ry: reusability of list @y
* @max: max number of added nexthops
* @lp: linpool for allocating nexthops
*
* The nexthop_merge2() function takes two nexthop lists @x and @y and merges
* them, eliminating possible duplicates. It is a variant of nexthop_merge()
* function differing in how @max limit is handled, here it limits just number
* of nexthops added from the second list @y. The @max value is decreased with
* each such nexthop, this return remaining 'unused' limit, which can be used in
* subsequent calls. The list @x is expected to be an accumulator and its
* reusability is implied. New nodes are allocated from linpool @lp.
*/
struct nexthop *
nexthop_merge2(struct nexthop *x, struct nexthop *y, int ry, int *max, linpool *lp)
{
struct nexthop *root = NULL;
struct nexthop **n = &root;
if (*max <= 0)
return x;
while (x || y)
{
int cmp = nexthop_compare_node(x, y);
if (cmp < 0)
{
*n = x;
x = x->next;
}
else if (cmp > 0)
{
*n = ry ? y : nexthop_copy_node(y, lp);
y = (--*max) ? y->next : NULL;
}
else
{
*n = x;
x = x->next;
y = y->next;
}
n = &((*n)->next);
}
*n = NULL;
return root;
}
void
nexthop_insert(struct nexthop **n, struct nexthop *x)
{

23
nest/rt-table.c
View File

@ -849,18 +849,13 @@ rt_notify_accepted(struct channel *c, net *net, rte *new_changed, rte *old_chang
}
static struct nexthop *
nexthop_merge_rta(struct nexthop *nhs, rta *a, linpool *pool, int max)
{
return nexthop_merge(nhs, &(a->nh), 1, 0, max, pool);
}
rte *
rt_export_merged(struct channel *c, net *net, rte **rt_free, ea_list **tmpa, linpool *pool, int silent)
{
// struct proto *p = c->proto;
struct nexthop *nhs = NULL;
rte *best0, *best, *rt0, *rt, *tmp;
int max = c->merge_limit;
best0 = net->routes;
*rt_free = NULL;
@ -870,10 +865,12 @@ rt_export_merged(struct channel *c, net *net, rte **rt_free, ea_list **tmpa, lin
best = export_filter_(c, best0, rt_free, tmpa, pool, silent);
if (!best || !rte_is_reachable(best))
if (!best || !rte_is_reachable(best) || !best0->next)
return best;
for (rt0 = best0->next; rt0; rt0 = rt0->next)
nhs = nexthop_merge2(NULL, &(best->attrs->nh), 0, &max, pool);
for (rt0 = best0->next; rt0 && max; rt0 = rt0->next)
{
if (!rte_mergable(best0, rt0))
continue;
@ -884,22 +881,14 @@ rt_export_merged(struct channel *c, net *net, rte **rt_free, ea_list **tmpa, lin
continue;
if (rte_is_reachable(rt))
nhs = nexthop_merge_rta(nhs, rt->attrs, pool, c->merge_limit);
nhs = nexthop_merge2(nhs, &(rt->attrs->nh), 0, &max, pool);
if (tmp)
rte_free(tmp);
}
if (nhs)
{
nhs = nexthop_merge_rta(nhs, best->attrs, pool, c->merge_limit);
if (nhs->next)
{
best = rte_cow_rta(best, pool);
nexthop_link(best->attrs, nhs);
}
}
if (best != best0)
*rt_free = best;