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Streamline alpm_splitdep() comparisons 

This reduces from 5 to 3 the number of searches needed on the string
looking for a comparison operator, since we can so a second quick
comparison looking for '=' if we find '<' or '>'. It also makes every
search doable with strchr() or memchr() rather than the slower strstr()
method.

In testing, only 10% of splitdep calls (~1600 / 16000) during an -Ss
database load found a version comparison operator, so optimizing the not
found path to be require less work makes sense.

Signed-off-by: Dan McGee <dan@archlinux.org>
This commit is contained in:
Dan McGee 2011-08-28 23:29:53 -05:00
parent b3c0ae5205
commit 499e09734b
1 changed files with 19 additions and 13 deletions
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32
lib/libalpm/deps.c
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@ -410,31 +410,37 @@ alpm_depend_t *_alpm_splitdep(const char *depstring)
{
alpm_depend_t *depend;
const char *ptr, *version = NULL;
size_t deplen;
if(depstring == NULL) {
return NULL;
}
CALLOC(depend, 1, sizeof(alpm_depend_t), return NULL);
deplen = strlen(depstring);
/* Find a version comparator if one exists. If it does, set the type and
* increment the ptr accordingly so we can copy the right strings. */
if((ptr = strstr(depstring, ">="))) {
depend->mod = ALPM_DEP_MOD_GE;
version = ptr + 2;
} else if((ptr = strstr(depstring, "<="))) {
depend->mod = ALPM_DEP_MOD_LE;
version = ptr + 2;
} else if((ptr = strstr(depstring, "="))) {
if((ptr = memchr(depstring, '<', deplen))) {
if(ptr[1] == '=') {
depend->mod = ALPM_DEP_MOD_LE;
version = ptr + 2;
} else {
depend->mod = ALPM_DEP_MOD_LT;
version = ptr + 1;
}
} else if((ptr = memchr(depstring, '>', deplen))) {
if(ptr[1] == '=') {
depend->mod = ALPM_DEP_MOD_GE;
version = ptr + 2;
} else {
depend->mod = ALPM_DEP_MOD_GT;
version = ptr + 1;
}
} else if((ptr = memchr(depstring, '=', deplen))) {
/* Note: we must do =,<,> checks after <=, >= checks */
depend->mod = ALPM_DEP_MOD_EQ;
version = ptr + 1;
} else if((ptr = strstr(depstring, "<"))) {
depend->mod = ALPM_DEP_MOD_LT;
version = ptr + 1;
} else if((ptr = strstr(depstring, ">"))) {
depend->mod = ALPM_DEP_MOD_GT;
version = ptr + 1;
} else {
/* no version specified, leave version and ptr NULL */
depend->mod = ALPM_DEP_MOD_ANY;