diff mercurial/localrepo.py @ 39765:3e801ffd7269

filelog: custom filelog to be used with narrow repos

Narrow repos may have file revisions whose copy/rename metadata
references files not in the store. This can pose problems when
consumers attempt to access a missing referenced file revision.

The narrow extension hacks around this problem by implementing a
derived filelog type that provides custom implementations of
renamed(), size(), and cmp() which handle renames against files not
in the narrow spec by silently removing the rename metadata.

While silently dropping metadata isn't the most robust solution,
it is the easiest to implement.

This commit ports the custom narrow filelog class to core.

When a narrow repo is constructed, its ifilestorage creation
function will automatically use the new filelog type. This means
the extra logic is 0 cost for non-narrow repos and shouldn't
interfere with their operation.

Differential Revision: https://phab.mercurial-scm.org/D4643

--- a/mercurial/localrepo.py	Tue Sep 18 15:29:42 2018 -0700
+++ b/mercurial/localrepo.py	Thu Sep 13 16:02:22 2018 -0700
@@ -743,9 +743,22 @@
 
         return filelog.filelog(self.svfs, path)
 
[e-mail](repository.ilocalrepositoryfilestorage)
+class revlognarrowfilestorage(object):
+    """File storage when using revlogs and narrow files."""
+
+    def file(self, path):
+        if path[0] == b'/':
+            path = path[1:]
+
+        return filelog.narrowfilelog(self.svfs, path, self.narrowmatch())
+
 def makefilestorage(requirements, **kwargs):
     """Produce a type conforming to ``ilocalrepositoryfilestorage``."""
-    return revlogfilestorage
+    if repository.NARROW_REQUIREMENT in requirements:
+        return revlognarrowfilestorage
+    else:
+        return revlogfilestorage
 
 # List of repository interfaces and factory functions for them. Each
 # will be called in order during ``makelocalrepository()`` to iteratively