Compress trie nodes down to extent maps after loading, to save memory

This commit is contained in:
Paul LeoNerd Evans 2008-11-12 23:58:20 +00:00
parent 754214c200
commit 4a108d4916
1 changed files with 59 additions and 15 deletions

View File

@ -10,7 +10,9 @@
#include <unistd.h>
/* To be efficient at lookups, we store the byte sequence => keyinfo mapping
* in a trie. This avoids a slow linear search though a flat list of sequences
* in a trie. This avoids a slow linear search through a flat list of
* sequences. Because it is likely most nodes will be very sparse, we optimise
* vector to store an extent map after the database is loaded.
*/
typedef enum {
@ -29,7 +31,8 @@ struct trie_node_key {
struct trie_node_arr {
trie_nodetype type;
struct trie_node *arr[256];
unsigned char min, max; /* INCLUSIVE endpoints of the extent range */
struct trie_node *arr[0];
};
typedef struct {
@ -57,17 +60,18 @@ static struct trie_node *new_node_key(termkey_type type, termkey_keysym sym, int
return (struct trie_node*)n;
}
static struct trie_node *new_node_arr(void)
static struct trie_node *new_node_arr(unsigned char min, unsigned char max)
{
struct trie_node_arr *n = malloc(sizeof(struct trie_node_arr));
struct trie_node_arr *n = malloc(sizeof(struct trie_node_arr) + ((int)max-min+1) * sizeof(void*));
if(!n)
return NULL;
n->type = TYPE_ARR;
n->min = min; n->max = max;
unsigned char b;
for(b = 0; b < 255; b++)
n->arr[b] = NULL;
int i;
for(i = min; i <= max; i++)
n->arr[i-min] = NULL;
return (struct trie_node*)n;
}
@ -81,7 +85,9 @@ static struct trie_node *lookup_next(struct trie_node *n, unsigned char b)
case TYPE_ARR:
{
struct trie_node_arr *nar = (struct trie_node_arr*)n;
return nar->arr[b];
if(b < nar->min || b > nar->max)
return NULL;
return nar->arr[b - nar->min];
}
}
@ -96,10 +102,10 @@ static void free_trie(struct trie_node *n)
case TYPE_ARR:
{
struct trie_node_arr *nar = (struct trie_node_arr*)n;
unsigned char b;
for(b = 0; b < 255; b++)
if(nar->arr[b])
free_trie(nar->arr[b]);
int i;
for(i = nar->min; i <= nar->max; i++)
if(nar->arr[i - nar->min])
free_trie(nar->arr[i - nar->min]);
break;
}
}
@ -107,6 +113,37 @@ static void free_trie(struct trie_node *n)
free(n);
}
static struct trie_node *compress_trie(struct trie_node *n)
{
if(!n)
return NULL;
switch(n->type) {
case TYPE_KEY:
return n;
case TYPE_ARR:
{
struct trie_node_arr *nar = (struct trie_node_arr*)n;
unsigned char min, max;
// Find the real bounds
for(min = 0; !nar->arr[min]; min++)
;
for(max = 0xff; !nar->arr[max]; max--)
;
struct trie_node_arr *new = (struct trie_node_arr*)new_node_arr(min, max);
int i;
for(i = min; i <= max; i++)
new->arr[i - min] = compress_trie(nar->arr[i]);
free(nar);
return (struct trie_node*)new;
}
}
return n;
}
static void *new_driver(termkey_t *tk, const char *term)
{
int err;
@ -120,7 +157,7 @@ static void *new_driver(termkey_t *tk, const char *term)
ti->tk = tk;
ti->root = new_node_arr();
ti->root = new_node_arr(0, 0xff);
if(!ti->root)
goto abort_free_ti;
@ -148,6 +185,8 @@ static void *new_driver(termkey_t *tk, const char *term)
goto abort_free_trie;
}
ti->root = compress_trie(ti->root);
return ti;
abort_free_trie:
@ -341,7 +380,7 @@ static int register_seq(termkey_ti *ti, const char *seq, termkey_type type, term
struct trie_node *next;
if(seq[pos+1])
// Intermediate node
next = new_node_arr();
next = new_node_arr(0, 0xff);
else
// Final key node
next = new_node_key(type, sym, modmask, modset);
@ -353,7 +392,12 @@ static int register_seq(termkey_ti *ti, const char *seq, termkey_type type, term
case TYPE_ARR:
{
struct trie_node_arr *nar = (struct trie_node_arr*)p;
nar->arr[b] = next;
if(b < nar->min || b > nar->max) {
fprintf(stderr, "ASSERT FAIL: Trie insert at 0x%02x is outside of extent bounds (0x%02x..0x%02x)\n",
b, nar->min, nar->max);
abort();
}
nar->arr[b - nar->min] = next;
p = next;
break;
}