manifest_xml: use a set instead of (sorted) list in projectsDiff

The logic in projectsDiff performs various operations which
suggest that a set is more appropriate than a list:
 - membership lookup ("in")
 - removal

Also, sorting can be performed on the the remaining elements at the
end (which will usually involve a much smaller number of elements).

(The performance gain is invisible in comparison to the time being
spent performing git operations).

Cosmetic chance:
 - the definition of 'fromProj' is moved to be used in more places
 - the values in diff["added"] are added with a single call to extend

Change-Id: I5ed22ba73b50650ca2d3a49a1ae81f02be3b3055
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/383434
Tested-by: Sylvain Desodt <sylvain.desodt@gmail.com>
Reviewed-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Sylvain Desodt <sylvain.desodt@gmail.com>

1 files changed, 5 insertions, 6 deletions

diff --git a/manifest_xml.py b/manifest_xml.py
index d944b409..458dfb7d 100644
--- a/manifest_xml.py
+++ b/manifest_xml.py
@@ -2210,7 +2210,7 @@ https://gerrit.googlesource.com/git-repo/+/HEAD/docs/manifest-format.md
         toProjects = manifest.paths
 
         fromKeys = sorted(fromProjects.keys())
-        toKeys = sorted(toProjects.keys())
+        toKeys = set(toProjects.keys())
 
         diff = {
             "added": [],
@@ -2221,13 +2221,13 @@ https://gerrit.googlesource.com/git-repo/+/HEAD/docs/manifest-format.md
         }
 
         for proj in fromKeys:
+            fromProj = fromProjects[proj]
             if proj not in toKeys:
-                diff["removed"].append(fromProjects[proj])
-            elif not fromProjects[proj].Exists:
+                diff["removed"].append(fromProj)
+            elif not fromProj.Exists:
                 diff["missing"].append(toProjects[proj])
                 toKeys.remove(proj)
             else:
-                fromProj = fromProjects[proj]
                 toProj = toProjects[proj]
                 try:
                     fromRevId = fromProj.GetCommitRevisionId()
@@ -2239,8 +2239,7 @@ https://gerrit.googlesource.com/git-repo/+/HEAD/docs/manifest-format.md
                         diff["changed"].append((fromProj, toProj))
                 toKeys.remove(proj)
 
-        for proj in toKeys:
-            diff["added"].append(toProjects[proj])
+        diff["added"].extend(toProjects[proj] for proj in sorted(toKeys))
 
         return diff