[pacman-dev] [PATCH 2/2] Do not replicate files list when removing packages

[Allan McRae]

This saves replicating the list of files in a package that is being
removed which can be quite large.

Signed-off-by: Allan McRae <allan at archlinux.org>
---

The tradeoff here is a slightly less readable loop, but duplicating that list
just struck me as wasteful.

 lib/libalpm/remove.c |   41 +++++++++++++++++++++++------------------
 1 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/lib/libalpm/remove.c b/lib/libalpm/remove.c
index cc6daea..2d75a84 100644
--- a/lib/libalpm/remove.c
+++ b/lib/libalpm/remove.c
@@ -285,8 +285,7 @@ static void unlink_file(pmhandle_t *handle, pmpkg_t *info, const char *filename,
 int _alpm_upgraderemove_package(pmhandle_t *handle,
 		pmpkg_t *oldpkg, pmpkg_t *newpkg)
 {
-	alpm_list_t *skip_remove, *b;
-	alpm_list_t *newfiles, *lp;
+	alpm_list_t *skip_remove, *b, *lp;
 	size_t filenum=0;
 	alpm_list_t *files = alpm_pkg_get_files(oldpkg);
 	const char *pkgname = alpm_pkg_get_name(oldpkg);
@@ -329,11 +328,15 @@ int _alpm_upgraderemove_package(pmhandle_t *handle,
 	_alpm_log(handle, PM_LOG_DEBUG, "removing %ld files\n", (unsigned long)filenum);
 
 	/* iterate through the list backwards, unlinking files */
-	newfiles = alpm_list_reverse(files);
-	for(lp = newfiles; lp; lp = alpm_list_next(lp)) {
-		unlink_file(handle, oldpkg, lp->data, skip_remove, 0);
+	if(files) {
+		alpm_list_t *last = alpm_list_last(files);
+		lp = last;
+		do {
+			unlink_file(handle, oldpkg, lp->data, skip_remove, 0);
+			lp = lp->prev;
+		} while (lp != last);
 	}
-	alpm_list_free(newfiles);
+
 	FREELIST(skip_remove);
 
 db:
@@ -390,7 +393,6 @@ int _alpm_remove_packages(pmhandle_t *handle)
 
 		if(!(trans->flags & PM_TRANS_FLAG_DBONLY)) {
 			alpm_list_t *files = alpm_pkg_get_files(info);
-			alpm_list_t *newfiles;
 			size_t filenum=0;
 
 			for(lp = files; lp; lp = lp->next) {
@@ -409,18 +411,21 @@ int _alpm_remove_packages(pmhandle_t *handle)
 					pkg_count, (pkg_count - targcount + 1));
 
 			/* iterate through the list backwards, unlinking files */
-			newfiles = alpm_list_reverse(files);
-			for(lp = newfiles; lp; lp = alpm_list_next(lp)) {
-				int percent;
-				unlink_file(handle, info, lp->data, NULL, trans->flags & PM_TRANS_FLAG_NOSAVE);
-
-				/* update progress bar after each file */
-				percent = (position * 100) / filenum;
-				PROGRESS(trans, PM_TRANS_PROGRESS_REMOVE_START, info->name,
-						percent, pkg_count, (pkg_count - targcount + 1));
-				position++;
+			if(files) {
+				alpm_list_t *last = alpm_list_last(files);
+				lp = last;
+				do {
+					int percent;
+					unlink_file(handle, info, lp->data, NULL, trans->flags & PM_TRANS_FLAG_NOSAVE);
+
+					/* update progress bar after each file */
+					percent = (position * 100) / filenum;
+					PROGRESS(trans, PM_TRANS_PROGRESS_REMOVE_START, info->name,
+							percent, pkg_count, (pkg_count - targcount + 1));
+					position++;
+					lp = lp->prev;
+				} while (lp != last);
 			}
-			alpm_list_free(newfiles);
 		}
 
 		/* set progress to 100% after we finish unlinking files */
-- 
1.7.5.4