On my Ubuntu installation this removes 15k of duplicate strings,
using a temporary index of about 25k.
Signed-off-by: Alan Jenkins <alan-jenkins@xxxxxxxxxxxxxx>
diff --git a/udev/udev-rules.c b/udev/udev-rules.c
index 810a863..df5ed53 100644
--- a/udev/udev-rules.c
+++ b/udev/udev-rules.c
@@ -16,6 +16,7 @@
*/
#include <stddef.h>
+#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
@@ -30,6 +31,7 @@
#define PREALLOC_TOKEN 2048
#define PREALLOC_STRBUF 32 * 1024
+#define PREALLOC_TRIE 256
struct uid_gid {
unsigned int name_off;
@@ -39,7 +41,16 @@ struct uid_gid {
};
};
-/* KEY=="", KEY!="", KEY+="", KEY="", KEY:="" */
+#define TRIE_CHILD_MAX 10
+
+struct trie_node {
+ unsigned int value_off;
+ size_t value_len;
+ unsigned char child_cur;
+ unsigned char child_key[TRIE_CHILD_MAX];
+ unsigned short child[TRIE_CHILD_MAX];
+};
+
struct udev_rules {
struct udev *udev;
int resolve_names;
@@ -55,6 +66,12 @@ struct udev_rules {
size_t buf_max;
unsigned int buf_count;
+ /* key strings are indexed to avoid wasting space with duplicates */
+ struct trie_node *trie;
+ unsigned short trie_cur;
+ unsigned short trie_max;
+ unsigned short *trie_root;
+
/* during rule parsing, we cache uid/gid lookup results */
struct uid_gid *uids;
unsigned int uids_cur;
@@ -64,6 +81,7 @@ struct udev_rules {
unsigned int gids_max;
};
+/* KEY=="", KEY!="", KEY+="", KEY="", KEY:="" */
enum operation_type {
OP_UNSET,
@@ -392,25 +410,19 @@ static inline void dump_token(struct udev_rules *rules, struct token *token) {}
static inline void dump_rules(struct udev_rules *rules) {}
#endif /* DEBUG */
-/* we could lookup and return existing strings, or tails of strings */
-static int add_string(struct udev_rules *rules, const char *str)
+static int add_new_string(struct udev_rules *rules, const char *str, size_t bytes)
{
- size_t len = strlen(str)+1;
int off;
- /* offset 0 is always '\0' */
- if (str[0] == '\0')
- return 0;
-
/* grow buffer if needed */
- if (rules->buf_cur + len+1 >= rules->buf_max) {
+ if (rules->buf_cur + bytes+1 >= rules->buf_max) {
char *buf;
unsigned int add;
/* double the buffer size */
add = rules->buf_max;
- if (add < len * 8)
- add = len * 8;
+ if (add < bytes * 8)
+ add = bytes * 8;
buf = realloc(rules->buf, rules->buf_max + add);
if (buf == NULL)
@@ -420,15 +432,128 @@ static int add_string(struct udev_rules *rules, const char *str)
rules->buf_max += add;
}
off = rules->buf_cur;
- memcpy(&rules->buf[rules->buf_cur], str, len);
- rules->buf_cur += len;
+ memcpy(&rules->buf[rules->buf_cur], str, bytes);
+ rules->buf_cur += bytes;
rules->buf_count++;
return off;
}
-static int add_token(struct udev_rules *rules, struct token *token)
+static unsigned char trie_child_slot(struct trie_node *node, char key)
{
+ unsigned char child_slot;
+
+ for (child_slot = 0; child_slot < node->child_cur; child_slot++) {
+ if (node->child_key[child_slot] == key)
+ break;
+ }
+
+ return child_slot;
+}
+
+static int add_string(struct udev_rules *rules, const char *str)
+{
+ struct trie_node *child;
+ unsigned short child_off;
+ unsigned short node_off;
+ unsigned char key;
+ size_t len;
+ int depth;
+ unsigned int off;
+
+ len = strlen(str);
+
+ /* offset 0 is always '\0' */
+ if (len == 0)
+ return 0;
+
+ /* strings with spaces are probably commands e.g. modprobe,
+ with unique arguments. */
+ if (strchr(str, ' ') != NULL)
+ return add_new_string(rules, str, len + 1);
+
+ /* descend root - start from last character of str */
+ key = str[len - 1];
+ node_off = rules->trie_root[key];
+ depth = 0;
+
+ /* descend suffix trie */
+ if (node_off != 0) {
+ while (1) {
+ struct trie_node *node = &rules->trie[node_off];
+ unsigned char child_slot;
+
+ depth++;
+ off = node->value_off + node->value_len - len;
+
+ /* match against current node */
+ if (depth == len ||
+ (node->value_len >= len &&
+ memcmp(&rules->buf[off], str, len) == 0))
+ {
+ return off;
+ }
+ /* lookup child node */
+ key = str[len - 1 - depth];
+ child_slot = trie_child_slot(node, key);
+
+ if(child_slot == node->child_cur)
+ break;
+
+ node_off = node->child[child_slot];
+ }
+ }
+
+ /* string not found, add it */
+ off = add_new_string(rules, str, len + 1);
+
+ /* grow trie storage if needed */
+ if (rules->trie_cur >= rules->trie_max) {
+ struct trie_node *trie;
+ unsigned short add;
+
+ /* double the buffer size */
+ add = rules->trie_max;
+ if (add < 8)
+ add = 8;
+
+ trie = realloc(rules->trie, (rules->trie_max + add) * sizeof(struct trie_node));
+ if (trie == NULL)
+ return -1;
+ dbg(rules->udev, "extend string index nodes from %u to %u\n", rules->trie_max, rules->trie_max + add);
+ rules->trie = trie;
+ rules->trie_max += add;
+ }
+
+ /* insert new child node */
+ child_off = rules->trie_cur;
+ if (depth == 0) {
+ rules->trie_root[key] = child_off;
+ } else {
+ struct trie_node *parent = &rules->trie[node_off];
+ unsigned char child_slot = parent->child_cur;
+
+ /* no space in parent, we can't index this string, nevermind */
+ if (child_slot == TRIE_CHILD_MAX)
+ return off;
+
+ parent->child[child_slot] = child_off;
+ parent->child_key[child_slot] = key;
+ parent->child_cur = child_slot + 1;
+ }
+
+ /* allocate and construct the child node */
+ rules->trie_cur++;
+ child = &rules->trie[child_off];
+ memset(child, 0x00, sizeof(struct trie_node));
+ child->value_off = off;
+ child->value_len = len;
+
+ return off;
+}
+
+static int add_token(struct udev_rules *rules, struct token *token)
+{
/* grow buffer if needed */
if (rules->token_cur+1 >= rules->token_max) {
struct token *tokens;
@@ -1607,9 +1732,16 @@ struct udev_rules *udev_rules_new(struct udev *udev, int resolve_names)
if (rules->buf == NULL)
return NULL;
rules->buf_max = PREALLOC_STRBUF;
+ rules->trie = malloc(PREALLOC_TRIE * sizeof(struct trie_node));
+ if (rules->trie == NULL)
+ return NULL;
+ rules->trie_max = PREALLOC_TRIE;
+ rules->trie_root = calloc(UCHAR_MAX + 1, sizeof(unsigned short));
/* offset 0 is always '\0' */
rules->buf[0] = '\0';
rules->buf_cur = 1;
+ /* offset 0 is reserved for the null trie node */
+ rules->trie_cur = 1;
dbg(udev, "prealloc %zu bytes tokens (%u * %zu bytes), %zu bytes buffer\n",
rules->token_max * sizeof(struct token), rules->token_max, sizeof(struct token), rules->buf_max);
@@ -1725,6 +1857,16 @@ struct udev_rules *udev_rules_new(struct udev *udev, int resolve_names)
}
info(udev, "shrunk to %zu bytes tokens (%u * %zu bytes), %zu bytes buffer\n",
rules->token_max * sizeof(struct token), rules->token_max, sizeof(struct token), rules->buf_max);
+ info(udev, "used %zu bytes of string index nodes (%hu * %zu bytes)\n",
+ rules->trie_cur * sizeof(struct trie_node), rules->trie_cur, sizeof(struct trie_node));
+
+ /* cleanup trie */
+ free(rules->trie);
+ rules->trie = NULL;
+ rules->trie_cur = 0;
+ rules->trie_max = 0;
+ free(rules->trie_root);
+ rules->trie_root = NULL;
/* cleanup uid/gid cache */
free(rules->uids);
@@ -1746,6 +1888,8 @@ void udev_rules_unref(struct udev_rules *rules)
return;
free(rules->tokens);
free(rules->buf);
+ free(rules->trie);
+ free(rules->trie_root);
free(rules->uids);
free(rules->gids);
free(rules);
--
To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
