filelog: record what's using attributes

filelog and the file storage interface have some attributes that
ideally shouldn't be there. This commit annotates some of those
attributes with their users so we know where to look when it comes
time to removing them.

This exercise exposed a theme: many attributes are used by LFS,
repo upgrade, verify, and special repo types (like bundlerepo). That
points to missing abstractions on file storage to facilitate these
special needs.

Differential Revision: https://phab.mercurial-scm.org/D4661

mercurial/filelog.py

@@ -1,262 +1,278 b''
 # filelog.py - file history class for mercurial
 #
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 from . import (
     error,
     repository,
     revlog,
 )
 from .utils import (
     interfaceutil,
 )
 
 @interfaceutil.implementer(repository.ifilestorage)
 class filelog(object):
     def __init__(self, opener, path):
         self._revlog = revlog.revlog(opener,
                                      '/'.join(('data', path + '.i')),
                                      censorable=True)
-        # full name of the user visible file, relative to the repository root
+        # Full name of the user visible file, relative to the repository root.
+        # Used by LFS.
         self.filename = path
+        # Used by repo upgrade.
         self.index = self._revlog.index
+        # Used by verify.
         self.version = self._revlog.version
+        # Used by changegroup generation.
         self._generaldelta = self._revlog._generaldelta
 
     def __len__(self):
         return len(self._revlog)
 
     def __iter__(self):
         return self._revlog.__iter__()
 
     def revs(self, start=0, stop=None):
         return self._revlog.revs(start=start, stop=stop)
 
     def parents(self, node):
         return self._revlog.parents(node)
 
     def parentrevs(self, rev):
         return self._revlog.parentrevs(rev)
 
     def rev(self, node):
         return self._revlog.rev(node)
 
     def node(self, rev):
         return self._revlog.node(rev)
 
     def lookup(self, node):
         return self._revlog.lookup(node)
 
     def linkrev(self, rev):
         return self._revlog.linkrev(rev)
 
+    # Used by LFS, verify.
     def flags(self, rev):
         return self._revlog.flags(rev)
 
     def commonancestorsheads(self, node1, node2):
         return self._revlog.commonancestorsheads(node1, node2)
 
+    # Used by dagop.blockdescendants().
     def descendants(self, revs):
         return self._revlog.descendants(revs)
 
+    # Used by hgweb.
     def headrevs(self):
         return self._revlog.headrevs()
 
     def heads(self, start=None, stop=None):
         return self._revlog.heads(start, stop)
 
+    # Used by hgweb, children extension.
     def children(self, node):
         return self._revlog.children(node)
 
     def deltaparent(self, rev):
         return self._revlog.deltaparent(rev)
 
     def iscensored(self, rev):
         return self._revlog.iscensored(rev)
 
+    # Used by verify.
     def rawsize(self, rev):
         return self._revlog.rawsize(rev)
 
+    # Might be unused.
     def checkhash(self, text, node, p1=None, p2=None, rev=None):
         return self._revlog.checkhash(text, node, p1=p1, p2=p2, rev=rev)
 
     def revision(self, node, _df=None, raw=False):
         return self._revlog.revision(node, _df=_df, raw=raw)
 
     def revdiff(self, rev1, rev2):
         return self._revlog.revdiff(rev1, rev2)
 
     def emitrevisiondeltas(self, requests):
         return self._revlog.emitrevisiondeltas(requests)
 
     def addrevision(self, revisiondata, transaction, linkrev, p1, p2,
                     node=None, flags=revlog.REVIDX_DEFAULT_FLAGS,
                     cachedelta=None):
         return self._revlog.addrevision(revisiondata, transaction, linkrev,
                                     p1, p2, node=node, flags=flags,
                                     cachedelta=cachedelta)
 
     def addgroup(self, deltas, linkmapper, transaction, addrevisioncb=None):
         return self._revlog.addgroup(deltas, linkmapper, transaction,
                                  addrevisioncb=addrevisioncb)
 
     def getstrippoint(self, minlink):
         return self._revlog.getstrippoint(minlink)
 
     def strip(self, minlink, transaction):
         return self._revlog.strip(minlink, transaction)
 
     def censorrevision(self, tr, node, tombstone=b''):
         return self._revlog.censorrevision(node, tombstone=tombstone)
 
     def files(self):
         return self._revlog.files()
 
+    # Used by verify.
     def checksize(self):
         return self._revlog.checksize()
 
     def read(self, node):
         t = self.revision(node)
         if not t.startswith('\1\n'):
             return t
         s = t.index('\1\n', 2)
         return t[s + 2:]
 
     def add(self, text, meta, transaction, link, p1=None, p2=None):
         if meta or text.startswith('\1\n'):
             text = revlog.packmeta(meta, text)
         return self.addrevision(text, transaction, link, p1, p2)
 
     def renamed(self, node):
         if self.parents(node)[0] != revlog.nullid:
             return False
         t = self.revision(node)
         m = revlog.parsemeta(t)[0]
         # copy and copyrev occur in pairs. In rare cases due to bugs,
         # one can occur without the other.
         if m and "copy" in m and "copyrev" in m:
             return (m["copy"], revlog.bin(m["copyrev"]))
         return False
 
     def size(self, rev):
         """return the size of a given revision"""
 
         # for revisions with renames, we have to go the slow way
         node = self.node(rev)
         if self.renamed(node):
             return len(self.read(node))
         if self.iscensored(rev):
             return 0
 
         # XXX if self.read(node).startswith("\1\n"), this returns (size+4)
         return self._revlog.size(rev)
 
     def cmp(self, node, text):
         """compare text with a given file revision
 
         returns True if text is different than what is stored.
         """
 
         t = text
         if text.startswith('\1\n'):
             t = '\1\n\1\n' + text
 
         samehashes = not self._revlog.cmp(node, t)
         if samehashes:
             return False
 
         # censored files compare against the empty file
         if self.iscensored(self.rev(node)):
             return text != ''
 
         # renaming a file produces a different hash, even if the data
         # remains unchanged. Check if it's the case (slow):
         if self.renamed(node):
             t2 = self.read(node)
             return t2 != text
 
         return True
 
+    # TODO these aren't part of the interface and aren't internal methods.
+    # Callers should be fixed to not use them.
+
+    # Used by LFS.
     @property
     def filename(self):
         return self._revlog.filename
 
     @filename.setter
     def filename(self, value):
         self._revlog.filename = value
 
-    # TODO these aren't part of the interface and aren't internal methods.
-    # Callers should be fixed to not use them.
+    # Used by bundlefilelog, unionfilelog.
     @property
     def indexfile(self):
         return self._revlog.indexfile
 
     @indexfile.setter
     def indexfile(self, value):
         self._revlog.indexfile = value
 
+    # Used by LFS, repo upgrade.
     @property
     def opener(self):
         return self._revlog.opener
 
+    # Used by repo upgrade.
     def clone(self, tr, destrevlog, **kwargs):
         if not isinstance(destrevlog, filelog):
             raise error.ProgrammingError('expected filelog to clone()')
 
         return self._revlog.clone(tr, destrevlog._revlog, **kwargs)
 
 class narrowfilelog(filelog):
     """Filelog variation to be used with narrow stores."""
 
     def __init__(self, opener, path, narrowmatch):
         super(narrowfilelog, self).__init__(opener, path)
         self._narrowmatch = narrowmatch
 
     def renamed(self, node):
         res = super(narrowfilelog, self).renamed(node)
 
         # Renames that come from outside the narrowspec are problematic
         # because we may lack the base text for the rename. This can result
         # in code attempting to walk the ancestry or compute a diff
         # encountering a missing revision. We address this by silently
         # removing rename metadata if the source file is outside the
         # narrow spec.
         #
         # A better solution would be to see if the base revision is available,
         # rather than assuming it isn't.
         #
         # An even better solution would be to teach all consumers of rename
         # metadata that the base revision may not be available.
         #
         # TODO consider better ways of doing this.
         if res and not self._narrowmatch(res[0]):
             return None
 
         return res
 
     def size(self, rev):
         # Because we have a custom renamed() that may lie, we need to call
         # the base renamed() to report accurate results.
         node = self.node(rev)
         if super(narrowfilelog, self).renamed(node):
             return len(self.read(node))
         else:
             return super(narrowfilelog, self).size(rev)
 
     def cmp(self, node, text):
         different = super(narrowfilelog, self).cmp(node, text)
 
         # Because renamed() may lie, we may get false positives for
         # different content. Check for this by comparing against the original
         # renamed() implementation.
         if different:
             if super(narrowfilelog, self).renamed(node):
                 t2 = self.read(node)
                 return t2 != text
 
         return different