[autoroller] All commits in updates(), only roll interesting ones.

recipe_engine/autoroll_impl/candidate_algorithm.py

 # Copyright 2017 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 import sys
 import time
 
 from recipe_engine import package
 
 from .commit_list import CommitList
@@ skipping 13 matching lines @@
   """
   return {
     project_id: CommitList.from_repo_spec(repo_spec)
     for project_id, repo_spec in deps.iteritems()
   }
 
 
 def find_best_rev(repos):
   """Returns the project_id of the best repo to roll.
 
-  "Best" is determined by "moves the least amount of commits, globally". There
-  are two ways that rolling a repo can move commits:
+  "Best" is determined by "is an interesting commit and moves the least amount
+  of commits, globally".
+
+  "Interesting" means "the commit modifies one or more recipe related files",
+  and is defined by CommitMetadata.roll_candidate.
+
+  There are two ways that rolling a repo can move commits:
 
     1) As dependencies. Rolling repo A that depends on (B, C) will take
        a penalty for each commit that B and C need to move in order to be
        compatible with the new A revision.
 
     2) As dependees. Rolling repo A which is depended on by (B, C) will take
        a penalty for each commit that B and C need to move in order to be
        compatible with the new A revision.
 
   Each repo is analyzed with these two rules and a score is computed. The score
@@ skipping 24 matching lines @@
   Returns (str) - The project_id of the repo to advance next.
   """
   # The project_ids of all the repos that can move
   repo_set = set(repos)
 
   best_project_id = None
   best_score = ()  # (# commits moved, timestamp)
 
   for project_id, clist in repos.iteritems():
     assert isinstance(clist, CommitList)
-    candidate = clist.next
+    candidate, movement_score = clist.next_roll_candidate
     if not candidate:
       continue
 
     unaccounted_repos = set(repo_set)
 
-    movement_score = 0
     # first, determine if rolling this repo will force other repos to move.
     for d_pid, dep in candidate.spec.deps.iteritems():
       unaccounted_repos.discard(d_pid)
       movement_score += repos[d_pid].dist_to(dep.revision)
 
     # Next, see if any unaccounted_repos depend on this repo.
     for pid in unaccounted_repos:
       movement_score += repos[pid].dist_compatible_with(pid, candidate.revision)
 
     score = (movement_score, candidate.commit_timestamp)
@@ skipping 100 matching lines @@
 
   # not on py3 so we can't use print(..., flush=True) :(
   sys.stdout.write('finding roll candidates... ')
   sys.stdout.flush()
 
   repos = get_commitlists(package_spec.deps)
   ret_good, ret_bad = _get_roll_candidates_impl(context, package_spec, repos)
 
   print('found %d/%d good/bad candidates in %0.2f seconds' % (
     len(ret_good), len(ret_bad), time.time()-start))
+  sys.stdout.flush()
   return ret_good, ret_bad, repos