Remove need for memory allocation in _alpm_depcmp

Noticed when tweaking testdb, when we run _alpm_depcmp in loops and call it
seven million times, the strdup()/free() combo can add up. Remove the need
for any string duplication by some pointer manipulation and use of strncmp
instead of strcmp. Also kill the function logger and add an escape so we
don't needlessly retrieve the list of provides.

Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 13 insertions, 9 deletions

diff --git a/lib/libalpm/deps.c b/lib/libalpm/deps.c
index 21578293..e37eb02e 100644
--- a/lib/libalpm/deps.c
+++ b/lib/libalpm/deps.c
@@ -322,9 +322,6 @@ static int dep_vercmp(const char *version1, pmdepmod_t mod,
 int _alpm_depcmp(pmpkg_t *pkg, pmdepend_t *dep)
 {
 	alpm_list_t *i;
-
-	ALPM_LOG_FUNC;
-
 	const char *pkgname = alpm_pkg_get_name(pkg);
 	const char *pkgversion = alpm_pkg_get_version(pkg);
 	int satisfy = 0;
@@ -332,22 +329,29 @@ int _alpm_depcmp(pmpkg_t *pkg, pmdepend_t *dep)
 	/* check (pkg->name, pkg->version) */
 	satisfy = (strcmp(pkgname, dep->name) == 0
 			&& dep_vercmp(pkgversion, dep->mod, dep->version));
+	if(satisfy) {
+		return(satisfy);
+	}
 
 	/* check provisions, format : "name=version" */
 	for(i = alpm_pkg_get_provides(pkg); i && !satisfy; i = i->next) {
-		char *provname = strdup(i->data);
-		char *provver = strchr(provname, '=');
+		const char *provision = i->data;
+		const char *provver = strchr(provision, '=');
 
 		if(provver == NULL) { /* no provision version */
 			satisfy = (dep->mod == PM_DEP_MOD_ANY
-					&& strcmp(provname, dep->name) == 0);
+					&& strcmp(provision, dep->name) == 0);
 		} else {
-			*provver = '\0';
+			/* This is a bit tricker than the old code for performance reasons. To
+			 * prevent the need to copy and duplicate strings, strncmp only the name
+			 * portion if they are the same length, since there is a version and
+			 * operator in play here. */
+			size_t namelen = provver - provision;
 			provver += 1;
-			satisfy = (strcmp(provname, dep->name) == 0
+			satisfy = (strlen(dep->name) == namelen
+					&& strncmp(provision, dep->name, namelen) == 0
 					&& dep_vercmp(provver, dep->mod, dep->version));
 		}
-		free(provname);
 	}
 
 	return(satisfy);