depgraph: tuple display list, avoid copies

TODO: Optimize _show_merge_list to use reference comparison more
instead of == comparison.

diff --git a/pym/_emerge/Scheduler.py b/pym/_emerge/Scheduler.py
index 5930550fa9f93a3bbc3af2a78a22fa1e187d4709..4e8b223fb51c575232c0670b41423f0b0a0f7636 100644 (file)
--- a/pym/_emerge/Scheduler.py
+++ b/pym/_emerge/Scheduler.py
@@ -1830,7 +1830,7 @@ class Scheduler(PollScheduler):
                        mylist = mydepgraph.altlist()
                        if mylist:
                                if "--tree" in self.myopts:
-                                       mylist.reverse()
+                                       mylist = tuple(reversed(mylist))
                                mydepgraph.display(mylist, favorites=self._favorites)
 
                if not success:

diff --git a/pym/_emerge/depgraph.py b/pym/_emerge/depgraph.py
index 7929a78f33072cb204a6a92845c27cab2a0fd973..9c0a966c557f452ec3bbb26e36f786f092567401 100644 (file)
--- a/pym/_emerge/depgraph.py
+++ b/pym/_emerge/depgraph.py
@@ -5704,9 +5704,13 @@ class depgraph(object):
                        except self._serialize_tasks_retry:
                                pass
 
-               retlist = self._dynamic_config._serialized_tasks_cache[:]
+               retlist = self._dynamic_config._serialized_tasks_cache
                if reversed:
+                       # TODO: deprecate the "reversed" parameter (builtin name collision)
+                       retlist = list(retlist)
                        retlist.reverse()
+                       retlist = tuple(retlist)
+
                return retlist
 
        def _implicit_libc_deps(self, mergelist, graph):
@@ -6575,10 +6579,12 @@ class depgraph(object):
                for blocker in unsolvable_blockers:
                        retlist.append(blocker)
 
+               retlist = tuple(retlist)
+
                if unsolvable_blockers and \
                        not self._accept_blocker_conflicts():
                        self._dynamic_config._unsatisfied_blockers_for_display = unsolvable_blockers
-                       self._dynamic_config._serialized_tasks_cache = retlist[:]
+                       self._dynamic_config._serialized_tasks_cache = retlist
                        self._dynamic_config._scheduler_graph = scheduler_graph
                        # Blockers don't trigger the _skip_restart flag, since
                        # backtracking may solve blockers when it solves slot
@@ -6587,7 +6593,7 @@ class depgraph(object):
 
                if self._dynamic_config._slot_collision_info and \
                        not self._accept_blocker_conflicts():
-                       self._dynamic_config._serialized_tasks_cache = retlist[:]
+                       self._dynamic_config._serialized_tasks_cache = retlist
                        self._dynamic_config._scheduler_graph = scheduler_graph
                        raise self._unknown_internal_error()
 
@@ -6641,12 +6647,13 @@ class depgraph(object):
        def _show_merge_list(self):
                if self._dynamic_config._serialized_tasks_cache is not None and \
                        not (self._dynamic_config._displayed_list is not None and \
-                       (self._dynamic_config._displayed_list == self._dynamic_config._serialized_tasks_cache or \
+                       (self._dynamic_config._displayed_list is self._dynamic_config._serialized_tasks_cache or \
+                       self._dynamic_config._displayed_list == self._dynamic_config._serialized_tasks_cache or \
                        self._dynamic_config._displayed_list == \
                                list(reversed(self._dynamic_config._serialized_tasks_cache)))):
-                       display_list = self._dynamic_config._serialized_tasks_cache[:]
+                       display_list = self._dynamic_config._serialized_tasks_cache
                        if "--tree" in self._frozen_config.myopts:
-                               display_list.reverse()
+                               display_list = tuple(reversed(display_list))
                        self.display(display_list)
 
        def _show_unsatisfied_blockers(self, blockers):