Rev 4451: Avoid inner function calls to .append() in http://bazaar.launchpad.net/~jameinel/bzr/1.17-annotate-bug387952

[John Arbash Meinel]

At http://bazaar.launchpad.net/~jameinel/bzr/1.17-annotate-bug387952

------------------------------------------------------------
revno: 4451
revision-id: john at arbash-meinel.com-20090616212044-gdm6tfrrg230j72v
parent: john at arbash-meinel.com-20090616211728-3z22kmrhmw62bf8k
committer: John Arbash Meinel <john at arbash-meinel.com>
branch nick: 1.17-annotate-bug387952
timestamp: Tue 2009-06-16 16:20:44 -0500
message:
  Avoid inner function calls to .append()
  instead, pre-allocate a buffer and then extend the output.
-------------- next part --------------
=== modified file 'bzrlib/annotate.py'
--- a/bzrlib/annotate.py	2009-06-16 21:17:28 +0000
+++ b/bzrlib/annotate.py	2009-06-16 21:20:44 +0000
@@ -407,35 +407,34 @@
         # Shortcut the case when the two sides match exactly
         output_lines.extend(annotated_match_subset)
         return
-    append = output_lines.append
     assert len(annotated_match_subset) == len(right_parent_subset)
+    resolved = [None] * len(annotated_match_subset)
     for idx in xrange(len(annotated_match_subset)):
         new_line = annotated_match_subset[idx]
         right_line = right_parent_subset[idx]
         assert new_line[1] == right_line[1]
-        if new_line[0] == right_line[0]:
-            # These have identical annotations, just go with it
-            append(new_line)
-        elif new_line[0] == new_revision_id:
-            # the new annotation claims 'this' modified it, but it just simply
-            # comes from the right parent
-            append(right_line)
+        if new_line[0] == right_line[0] or new_line[0] == new_revision_id:
+            # These have identical annotations, or the right parent supersedes
+            # the 'new' status
+            resolved[idx] = right_line
         else:
             # Both new and right parent lay claim to this line, resolve
             if heads_provider is None:
-                append((new_revision_id, right_line[1]))
+                resolved[idx] = (new_revision_id, right_line[1])
             else:
                 heads = heads_provider.heads((new_line[0], right_line[0]))
                 if len(heads) == 1:
                     for head in heads:
                         break
-                    append((head, new_line[1]))
+                    resolved[idx] = (head, right_line[1])
                 else:
                     # Both claim different origins, get a stable result.
                     # If the result is not stable, there is a risk a
                     # performance degradation as criss-cross merges will
                     # flip-flop the attribution.
-                    append(_break_annotation_tie([new_line, right_line]))
+                    resolved[idx] = _break_annotation_tie(
+                                        [new_line, right_line])
+    output_lines.extend(resolved)
 
 
 def _reannotate_annotated(right_parent_lines, new_lines, new_revision_id,