[pacman-dev] [PATCH] Streamline alpm_splitdep() comparisons

[Dan McGee]

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 <d...@archlinux.org>
---
 lib/libalpm/deps.c |   32 +++++++++++++++++++-------------
 1 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/lib/libalpm/deps.c b/lib/libalpm/deps.c
index e268157..639f14b 100644
--- a/lib/libalpm/deps.c
+++ b/lib/libalpm/deps.c
@@ -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;
-- 
1.7.6.1