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Replaces the algorithm for building balanced trees.

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Changes the time complexity of the algorithm from O(n^2) to O(n*log(n)).
This speeds up loading of huge DEC-IX config from 128 s to 15 s. It also
makes the code significantly simpler.
This commit is contained in:
Ondrej Zajicek 2010-02-17 21:53:07 +01:00
parent 14f6aca480
commit dfd48621d1
4 changed files with 63 additions and 69 deletions
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5
filter/filter.c
View file

@ -164,6 +164,11 @@ val_compare(struct f_val v1, struct f_val v2)
}
}
int
tree_compare(const void *p1, const void *p2)
{
return val_compare((* (struct f_tree **) p1)->from, (* (struct f_tree **) p2)->from);
}
void
f_prefix_get_bounds(struct f_prefix *px, int *l, int *h)

1
filter/filter.h
View file

@ -91,6 +91,7 @@ void f_prefix_get_bounds(struct f_prefix *px, int *l, int *h);
void f_prefix_get_bounds(struct f_prefix *px, int *l, int *h);
int val_compare(struct f_val v1, struct f_val v2);
int tree_compare(const void *p1, const void *p2);
void val_print(struct f_val v);
#define F_NOP 0

15
filter/test.conf
View file

@ -131,6 +131,9 @@ prefix px;
ip p;
pair pp;
int set is;
int set is1;
int set is2;
int set is3;
prefix set pxs;
string s;
{
@ -156,6 +159,18 @@ string s;
print " must be true: ", defined(1), ",", defined(1.2.3.4), ",", 1 != 2, ",", 1 <= 2;
print " data types: must be false: ", 1 ~ [ 2, 3, 4 ], ",", 5 ~ is, ",", 1.2.3.4 ~ [ 1.2.3.3, 1.2.3.5 ], ",", (1,2) > (2,2), ",", (1,1) > (1,1), ",", 1.0.0.0/9 ~ [ 1.0.0.0/8- ], ",", 1.2.0.0/17 ~ [ 1.0.0.0/8{ 15 , 16 } ], ",", true && false;
is1 = [2, 3, 5, 8, 11, 15, 17, 19];
is2 = [19, 17, 15, 11, 8, 5, 3, 2];
is3 = [5, 17, 2, 11, 8, 15, 3, 19];
print " must be true: ", 2 ~ is1, " ", 2 ~ is2, " ", 2 ~ is3;
print " must be false: ", 4 ~ is1, " ", 4 ~ is2, " ", 4 ~ is3;
print " must be false: ", 10 ~ is1, " ", 10 ~ is2, " ", 10 ~ is3;
print " must be true: ", 15 ~ is1, " ", 15 ~ is2, " ", 15 ~ is3;
print " must be false: ", 18 ~ is1, " ", 18 ~ is2, " ", 18 ~ is3;
print " must be true: ", 19 ~ is1, " ", 19 ~ is2, " ", 19 ~ is3;
print " must be false: ", 20 ~ is1, " ", 20 ~ is2, " ", 20 ~ is3;
px = 1.2.0.0/18;
print "Testing prefixes: 1.2.0.0/18 = ", px;
print " must be true: ", 192.168.0.0/16 ~ 192.168.0.0/16, " ", 192.168.0.0/17 ~ 192.168.0.0/16, " ", 192.168.254.0/24 ~ 192.168.0.0/16;

111
filter/tree.c
View file

@ -6,61 +6,11 @@
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include "lib/alloca.h"
#include "nest/bird.h"
#include "conf/conf.h"
#include "filter/filter.h"
/*
* find_nth - finds n-th element in linked list. Don't be confused by types, it is really a linked list.
*/
static struct f_tree *
find_nth(struct f_tree *from, int nth)
{
struct f_tree *pivot;
int lcount = 0, rcount = 0;
struct f_tree *left, *right, *next;
pivot = from;
left = right = NULL;
next = from->right;
while (from = next) {
next = from->right;
if (val_compare(pivot->from, from->from)==1) {
from->right = left;
left = from;
lcount++;
} else {
from->right = right;
right = from;
rcount++;
}
}
if (lcount == nth)
return pivot;
if (lcount < nth)
return find_nth(right, nth-lcount-1);
return find_nth(left, nth);
}
/*
* find_median - Gets list linked by @left, finds its median, trashes pointers in @right.
*/
static struct f_tree *
find_median(struct f_tree *from)
{
struct f_tree *t = from;
int cnt = 0;
if (!from)
return NULL;
do {
t->right = t->left;
cnt++;
} while (t = t->left);
return find_nth(from, cnt/2);
}
/**
* find_tree
* @t: tree to search in
@ -87,6 +37,23 @@ find_tree(struct f_tree *t, struct f_val val)
return find_tree(t->left, val);
}
static struct f_tree *
build_tree_rec(struct f_tree **buf, int l, int h)
{
struct f_tree *n;
int pos;
if (l >= h)
return NULL;
pos = (l+h)/2;
n = buf[pos];
n->left = build_tree_rec(buf, l, pos);
n->right = build_tree_rec(buf, pos+1, h);
return n;
}
/**
* build_tree
* @from: degenerated tree (linked by @tree->left) to be transformed into form suitable for find_tree()
@ -96,29 +63,35 @@ find_tree(struct f_tree *t, struct f_val val)
struct f_tree *
build_tree(struct f_tree *from)
{
struct f_tree *median, *t = from, *next, *left = NULL, *right = NULL;
struct f_tree *tmp, *root;
struct f_tree **buf;
int len, i;
median = find_median(from);
if (!median)
if (from == NULL)
return NULL;
do {
next = t->left;
if (t == median)
continue;
len = 0;
for (tmp = from; tmp != NULL; tmp = tmp->left)
len++;
if (val_compare(median->from, t->from)==1) {
t->left = left;
left = t;
} else {
t->left = right;
right = t;
}
} while(t = next);
if (len <= 1024)
buf = alloca(len * sizeof(struct f_tree *));
else
buf = malloc(len * sizeof(struct f_tree *));
median->left = build_tree(left);
median->right = build_tree(right);
return median;
/* Convert a degenerated tree into an sorted array */
i = 0;
for (tmp = from; tmp != NULL; tmp = tmp->left)
buf[i++] = tmp;
qsort(buf, len, sizeof(struct f_tree *), tree_compare);
root = build_tree_rec(buf, 0, len);
if (len > 1024)
free(buf);
return root;
}
struct f_tree *