unionrepo: dynamically create repository type from base repository

This is basically the same thing we just did for bundlerepo except
for union repositories.

.. api::

   ``unionrepo.unionrepository()`` is no longer usable on its own.

   To instantiate an instance, call ``unionrepo.instance()`` or
   ``unionrepo.makeunionrepository()``.

Differential Revision: https://phab.mercurial-scm.org/D4556

mercurial/unionrepo.py

@@ -1,263 +1,284 b''
 # unionrepo.py - repository class for viewing union of repository changesets
 #
 # Derived from bundlerepo.py
 # Copyright 2006, 2007 Benoit Boissinot <[e-mail]>
 # Copyright 2013 Unity Technologies, Mads Kiilerich <[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.
 
 """Repository class for "in-memory pull" of one local repository to another,
 allowing operations like diff and log with revsets.
 """
 
 from __future__ import absolute_import
 
 from .i18n import _
 from .node import nullid
 
 from . import (
     changelog,
     cmdutil,
     error,
     filelog,
     localrepo,
     manifest,
     mdiff,
     pathutil,
     pycompat,
     revlog,
     util,
     vfs as vfsmod,
 )
 
 class unionrevlog(revlog.revlog):
     def __init__(self, opener, indexfile, revlog2, linkmapper):
         # How it works:
         # To retrieve a revision, we just need to know the node id so we can
         # look it up in revlog2.
         #
         # To differentiate a rev in the second revlog from a rev in the revlog,
         # we check revision against repotiprev.
         opener = vfsmod.readonlyvfs(opener)
         revlog.revlog.__init__(self, opener, indexfile)
         self.revlog2 = revlog2
 
         n = len(self)
         self.repotiprev = n - 1
         self.bundlerevs = set() # used by 'bundle()' revset expression
         for rev2 in self.revlog2:
             rev = self.revlog2.index[rev2]
             # rev numbers - in revlog2, very different from self.rev
             _start, _csize, rsize, base, linkrev, p1rev, p2rev, node = rev
             flags = _start & 0xFFFF
 
             if linkmapper is None: # link is to same revlog
                 assert linkrev == rev2 # we never link back
                 link = n
             else: # rev must be mapped from repo2 cl to unified cl by linkmapper
                 link = linkmapper(linkrev)
 
             if linkmapper is not None: # link is to same revlog
                 base = linkmapper(base)
 
             if node in self.nodemap:
                 # this happens for the common revlog revisions
                 self.bundlerevs.add(self.nodemap[node])
                 continue
 
             p1node = self.revlog2.node(p1rev)
             p2node = self.revlog2.node(p2rev)
 
             # TODO: it's probably wrong to set compressed length to None, but
             # I have no idea if csize is valid in the base revlog context.
             e = (flags, None, rsize, base,
                  link, self.rev(p1node), self.rev(p2node), node)
             self.index.append(e)
             self.nodemap[node] = n
             self.bundlerevs.add(n)
             n += 1
 
     def _chunk(self, rev):
         if rev <= self.repotiprev:
             return revlog.revlog._chunk(self, rev)
         return self.revlog2._chunk(self.node(rev))
 
     def revdiff(self, rev1, rev2):
         """return or calculate a delta between two revisions"""
         if rev1 > self.repotiprev and rev2 > self.repotiprev:
             return self.revlog2.revdiff(
                 self.revlog2.rev(self.node(rev1)),
                 self.revlog2.rev(self.node(rev2)))
         elif rev1 <= self.repotiprev and rev2 <= self.repotiprev:
             return self.baserevdiff(rev1, rev2)
 
         return mdiff.textdiff(self.revision(rev1), self.revision(rev2))
 
     def revision(self, nodeorrev, _df=None, raw=False):
         """return an uncompressed revision of a given node or revision
         number.
         """
         if isinstance(nodeorrev, int):
             rev = nodeorrev
             node = self.node(rev)
         else:
             node = nodeorrev
             rev = self.rev(node)
 
         if node == nullid:
             return ""
 
         if rev > self.repotiprev:
             text = self.revlog2.revision(node)
             self._cache = (node, rev, text)
         else:
             text = self.baserevision(rev)
             # already cached
         return text
 
     def baserevision(self, nodeorrev):
         # Revlog subclasses may override 'revision' method to modify format of
         # content retrieved from revlog. To use unionrevlog with such class one
         # needs to override 'baserevision' and make more specific call here.
         return revlog.revlog.revision(self, nodeorrev)
 
     def baserevdiff(self, rev1, rev2):
         # Exists for the same purpose as baserevision.
         return revlog.revlog.revdiff(self, rev1, rev2)
 
     def addrevision(self, text, transaction, link, p1=None, p2=None, d=None):
         raise NotImplementedError
     def addgroup(self, deltas, transaction, addrevisioncb=None):
         raise NotImplementedError
     def strip(self, rev, minlink):
         raise NotImplementedError
     def checksize(self):
         raise NotImplementedError
 
 class unionchangelog(unionrevlog, changelog.changelog):
     def __init__(self, opener, opener2):
         changelog.changelog.__init__(self, opener)
         linkmapper = None
         changelog2 = changelog.changelog(opener2)
         unionrevlog.__init__(self, opener, self.indexfile, changelog2,
                              linkmapper)
 
     def baserevision(self, nodeorrev):
         # Although changelog doesn't override 'revision' method, some extensions
         # may replace this class with another that does. Same story with
         # manifest and filelog classes.
         return changelog.changelog.revision(self, nodeorrev)
 
     def baserevdiff(self, rev1, rev2):
         return changelog.changelog.revdiff(self, rev1, rev2)
 
 class unionmanifest(unionrevlog, manifest.manifestrevlog):
     def __init__(self, opener, opener2, linkmapper):
         manifest.manifestrevlog.__init__(self, opener)
         manifest2 = manifest.manifestrevlog(opener2)
         unionrevlog.__init__(self, opener, self.indexfile, manifest2,
                              linkmapper)
 
     def baserevision(self, nodeorrev):
         return manifest.manifestrevlog.revision(self, nodeorrev)
 
     def baserevdiff(self, rev1, rev2):
         return manifest.manifestrevlog.revdiff(self, rev1, rev2)
 
 class unionfilelog(filelog.filelog):
     def __init__(self, opener, path, opener2, linkmapper, repo):
         filelog.filelog.__init__(self, opener, path)
         filelog2 = filelog.filelog(opener2, path)
         self._revlog = unionrevlog(opener, self.indexfile,
                                    filelog2._revlog, linkmapper)
         self._repo = repo
         self.repotiprev = self._revlog.repotiprev
         self.revlog2 = self._revlog.revlog2
 
     def baserevision(self, nodeorrev):
         return filelog.filelog.revision(self, nodeorrev)
 
     def baserevdiff(self, rev1, rev2):
         return filelog.filelog.revdiff(self, rev1, rev2)
 
     def iscensored(self, rev):
         """Check if a revision is censored."""
         if rev <= self.repotiprev:
             return filelog.filelog.iscensored(self, rev)
         node = self.node(rev)
         return self.revlog2.iscensored(self.revlog2.rev(node))
 
 class unionpeer(localrepo.localpeer):
     def canpush(self):
         return False
 
-class unionrepository(localrepo.localrepository):
-    def __init__(self, ui, path, path2):
-        localrepo.localrepository.__init__(self, ui, path)
+class unionrepository(object):
+    """Represents the union of data in 2 repositories.
+
+    Instances are not usable if constructed directly. Use ``instance()``
+    or ``makeunionrepository()`` to create a usable instance.
+    """
+    def __init__(self, repo2, url):
+        self.repo2 = repo2
+        self._url = url
+
         self.ui.setconfig('phases', 'publish', False, 'unionrepo')
 
-        self._url = 'union:%s+%s' % (util.expandpath(path),
-                                     util.expandpath(path2))
-        self.repo2 = localrepo.localrepository(ui, path2)
-
     @localrepo.unfilteredpropertycache
     def changelog(self):
         return unionchangelog(self.svfs, self.repo2.svfs)
 
     def _clrev(self, rev2):
         """map from repo2 changelog rev to temporary rev in self.changelog"""
         node = self.repo2.changelog.node(rev2)
         return self.changelog.rev(node)
 
     def _constructmanifest(self):
         return unionmanifest(self.svfs, self.repo2.svfs,
                              self.unfiltered()._clrev)
 
     def url(self):
         return self._url
 
     def file(self, f):
         return unionfilelog(self.svfs, f, self.repo2.svfs,
                             self.unfiltered()._clrev, self)
 
     def close(self):
         self.repo2.close()
 
     def cancopy(self):
         return False
 
     def peer(self):
         return unionpeer(self)
 
     def getcwd(self):
         return pycompat.getcwd() # always outside the repo
 
 def instance(ui, path, create, intents=None, createopts=None):
     if create:
         raise error.Abort(_('cannot create new union repository'))
     parentpath = ui.config("bundle", "mainreporoot")
     if not parentpath:
         # try to find the correct path to the working directory repo
         parentpath = cmdutil.findrepo(pycompat.getcwd())
         if parentpath is None:
             parentpath = ''
     if parentpath:
         # Try to make the full path relative so we get a nice, short URL.
         # In particular, we don't want temp dir names in test outputs.
         cwd = pycompat.getcwd()
         if parentpath == cwd:
             parentpath = ''
         else:
             cwd = pathutil.normasprefix(cwd)
             if parentpath.startswith(cwd):
                 parentpath = parentpath[len(cwd):]
     if path.startswith('union:'):
         s = path.split(":", 1)[1].split("+", 1)
         if len(s) == 1:
             repopath, repopath2 = parentpath, s[0]
         else:
             repopath, repopath2 = s
     else:
         repopath, repopath2 = parentpath, path
-    return unionrepository(ui, repopath, repopath2)
+
+    return makeunionrepository(ui, repopath, repopath2)
+
+def makeunionrepository(ui, repopath1, repopath2):
+    """Make a union repository object from 2 local repo paths."""
+    repo1 = localrepo.instance(ui, repopath1, create=False)
+    repo2 = localrepo.instance(ui, repopath2, create=False)
+
+    url = 'union:%s+%s' % (util.expandpath(repopath1),
+                           util.expandpath(repopath2))
+
+    class derivedunionrepository(unionrepository, repo1.__class__):
+        pass
+
+    repo = repo1
+    repo.__class__ = derivedunionrepository
+    unionrepository.__init__(repo1, repo2, url)
+
+    return repo