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libalias: Switch to efficient data structure for outgoing traffic

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Current data structure is using a hash of unordered lists.  Those
unordered lists are quite efficient, because the least recently
inserted entries are most likely to be used again.  In order to avoid
long search times in other cases, the lists are hashed into many
buckets.  Unfortunatly a search for a miss needs an exhaustive
inspection and a careful definition of the hash.

Splay trees offer a similar feature - almost O(1) for access of the
least recently used entries), and amortized O(ln(n) - for almost all
other cases.  Get rid of the hash.

Discussed with:	Dimitry Luhtionov
MFC after:	1 week
Differential Revision: https://reviews.freebsd.org/D30516
This commit is contained in:
Lutz Donnerhacke 2021-05-27 23:42:54 +02:00
parent d989935b5b
commit 935fc93af1
2 changed files with 36 additions and 49 deletions
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81
sys/netinet/libalias/alias_db.c
View File

@ -324,11 +324,11 @@ struct alias_link {
/* Linked list of pointers for input and output lookup tables */
union {
struct {
LIST_ENTRY(alias_link) in;
LIST_ENTRY(alias_link) out;
SPLAY_ENTRY(alias_link) out;
LIST_ENTRY (alias_link) in;
} all;
struct {
LIST_ENTRY(alias_link) list;
LIST_ENTRY (alias_link) list;
} pptp;
};
struct {
@ -389,8 +389,6 @@ Lookup table starting points:
/* Local prototypes */
static struct group_in *
StartPointIn(struct libalias *, struct in_addr, u_short, int, int);
static u_int
StartPointOut(struct in_addr, struct in_addr, u_short, u_short, int);
static int SeqDiff(u_long, u_long);
#ifndef NO_FW_PUNCH
@ -408,6 +406,24 @@ static void UninitPacketAliasLog(struct libalias *);
void SctpShowAliasStats(struct libalias *la);
/* Splay handling */
static inline int
cmp_out(struct alias_link *a, struct alias_link *b) {
int i = a->src_port - b->src_port;
if (i != 0) return (i);
i = a->src_addr.s_addr - b->src_addr.s_addr;
if (i != 0) return (i);
i = a->dst_addr.s_addr - b->dst_addr.s_addr;
if (i != 0) return (i);
i = a->dst_port - b->dst_port;
if (i != 0) return (i);
i = a->link_type - b->link_type;
return (i);
}
SPLAY_PROTOTYPE(splay_out, alias_link, all.out, cmp_out);
SPLAY_GENERATE(splay_out, alias_link, all.out, cmp_out);
#define INGUARD \
if (grp->alias_port != alias_port || \
grp->link_type != link_type || \
@ -449,21 +465,6 @@ StartPointIn(struct libalias *la,
}
#undef INGUARD
static u_int
StartPointOut(struct in_addr src_addr, struct in_addr dst_addr,
u_short src_port, u_short dst_port, int link_type)
{
u_int n;
n = src_addr.s_addr;
n += dst_addr.s_addr;
n += src_port;
n += dst_port;
n += link_type;
return (n % LINK_TABLE_OUT_SIZE);
}
static int
SeqDiff(u_long x, u_long y)
{
@ -893,7 +894,7 @@ DeleteLink(struct alias_link **plnk, int deletePermanent)
} while ((curr = next) != head);
} else {
/* Adjust output table pointers */
LIST_REMOVE(lnk, all.out);
SPLAY_REMOVE(splay_out, &la->linkSplayOut, lnk);
}
/* Adjust input table pointers */
@ -956,7 +957,6 @@ AddLink(struct libalias *la, struct in_addr src_addr, struct in_addr dst_addr,
struct in_addr alias_addr, u_short src_port, u_short dst_port,
int alias_port_param, int link_type)
{
u_int start_point;
struct alias_link *lnk;
LIBALIAS_LOCK_ASSERT(la);
@ -1085,9 +1085,7 @@ AddLink(struct libalias *la, struct in_addr src_addr, struct in_addr dst_addr,
}
/* Set up pointers for output lookup table */
start_point = StartPointOut(src_addr, dst_addr,
src_port, dst_port, link_type);
LIST_INSERT_HEAD(&la->linkTableOut[start_point], lnk, all.out);
SPLAY_INSERT(splay_out, &la->linkSplayOut, lnk);
/* Set up pointers for input lookup table */
if (lnk->flags & LINK_PARTIALLY_SPECIFIED)
@ -1140,35 +1138,25 @@ ReLink(struct alias_link *old_lnk,
return (new_lnk);
}
#define OUTGUARD \
if (lnk->src_port != src_port || \
lnk->src_addr.s_addr != src_addr.s_addr || \
lnk->dst_addr.s_addr != dst_addr.s_addr || \
lnk->dst_port != dst_port || \
lnk->link_type != link_type) \
continue;
static struct alias_link *
_SearchLinkOut(struct libalias *la, struct in_addr src_addr,
struct in_addr dst_addr,
u_short src_port,
u_short dst_port,
int link_type) {
u_int i;
struct alias_link *lnk;
struct alias_link needle = {
.src_addr = src_addr,
.dst_addr = dst_addr,
.src_port = src_port,
.dst_port = dst_port,
.link_type = link_type
};
i = StartPointOut(src_addr, dst_addr, src_port, dst_port, link_type);
LIST_FOREACH(lnk, &la->linkTableOut[i], all.out) {
OUTGUARD;
return (UseLink(la, lnk));
}
return (NULL);
lnk = SPLAY_FIND(splay_out, &la->linkSplayOut, &needle);
return (UseLink(la, lnk));
}
#undef OUTGUARD
static struct alias_link *
_FindLinkOut(struct libalias *la, struct in_addr src_addr,
struct in_addr dst_addr,
@ -2333,7 +2321,7 @@ LibAliasAddServer(struct libalias *la, struct alias_link *lnk, struct in_addr ad
if (head == NULL) {
server->next = server;
/* not usable for outgoing connections */
LIST_REMOVE(lnk, all.out);
SPLAY_REMOVE(splay_out, &la->linkSplayOut, lnk);
} else {
struct server *s;
@ -2502,8 +2490,7 @@ LibAliasInit(struct libalias *la)
LibAliasTime = time(NULL);
#endif
for (i = 0; i < LINK_TABLE_OUT_SIZE; i++)
LIST_INIT(&la->linkTableOut[i]);
SPLAY_INIT(&la->linkSplayOut);
for (i = 0; i < LINK_TABLE_IN_SIZE; i++)
LIST_INIT(&la->groupTableIn[i]);
LIST_INIT(&la->pptpList);

4
sys/netinet/libalias/alias_local.h
View File

@ -48,6 +48,7 @@
#ifndef _ALIAS_LOCAL_H_
#define _ALIAS_LOCAL_H_
#include <sys/tree.h>
#include <sys/types.h>
#include <sys/sysctl.h>
@ -66,7 +67,6 @@
#endif
/* Sizes of input and output link tables */
#define LINK_TABLE_OUT_SIZE 4001
#define LINK_TABLE_IN_SIZE 4001
#define GET_ALIAS_PORT -1
@ -100,7 +100,7 @@ struct libalias {
/* Lookup table of pointers to chains of link records.
* Each link record is doubly indexed into input and
* output lookup tables. */
LIST_HEAD (, alias_link) linkTableOut[LINK_TABLE_OUT_SIZE];
SPLAY_HEAD(splay_out, alias_link) linkSplayOut;
LIST_HEAD (, group_in) groupTableIn[LINK_TABLE_IN_SIZE];
LIST_HEAD (, alias_link) pptpList;
/* HouseKeeping */