D4329: dagop: port revlogdag.linearize() to standalone function

[indygreg (Gregory Szorc)]

indygreg created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  The code should functionally be identical.
  
  We also port the one consumer in changegroup to use the new
  standalone function.
  
  After this commit, dagutil is no longer used!

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D4329

AFFECTED FILES
  mercurial/changegroup.py
  mercurial/dagop.py

CHANGE DETAILS

diff --git a/mercurial/dagop.py b/mercurial/dagop.py
--- a/mercurial/dagop.py
+++ b/mercurial/dagop.py
@@ -738,3 +738,40 @@
     headrevs.discard(node.nullrev)
 
     return headrevs
+
+def linearize(revs, parentsfn):
+    """Linearize and topologically sort a list of revisions.
+
+    The linearization process tires to create long runs of revs where a child
+    rev comes immediately after its first parent. This is done by visiting the
+    heads of the revs in inverse topological order, and for each visited rev,
+    visiting its second parent, then its first parent, then adding the rev
+    itself to the output list.
+
+    Returns a list of revision numbers.
+    """
+    visit = list(sorted(headrevs(revs, parentsfn), reverse=True))
+    finished = set()
+    result = []
+
+    while visit:
+        rev = visit.pop()
+        if rev < 0:
+            rev = -rev - 1
+
+            if rev not in finished:
+                result.append(rev)
+                finished.add(rev)
+
+        else:
+            visit.append(-rev - 1)
+
+            for prev in parentsfn(rev):
+                if prev == node.nullrev or prev not in revs or prev in finished:
+                    continue
+
+                visit.append(prev)
+
+    assert len(result) == len(revs)
+
+    return result
diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -24,7 +24,7 @@
 )
 
 from . import (
-    dagutil,
+    dagop,
     error,
     match as matchmod,
     mdiff,
@@ -587,8 +587,8 @@
     # for generaldelta revlogs, we linearize the revs; this will both be
     # much quicker and generate a much smaller bundle
     if (store._generaldelta and reorder is None) or reorder:
-        dag = dagutil.revlogdag(store)
-        return dag.linearize(set(store.rev(n) for n in nodes))
+        revs = set(store.rev(n) for n in nodes)
+        return dagop.linearize(revs, store.parentrevs)
     else:
         return sorted([store.rev(n) for n in nodes])
 



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