[PATCH 2 of 3] unbundle20: retrieve unbundler instances through a factory function

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at fb.com>
# Date 1428361473 25200
#      Mon Apr 06 16:04:33 2015 -0700
# Node ID 37b1e89e2ffcbd8a8851cb7c84404d47c6dc8e56
# Parent  3aea190962e2c2286d70a251b375957e1ab60c01
unbundle20: retrieve unbundler instances through a factory function

To support multiple bundle2 formats, we will need a function returning the
proper unbundler according to the header. We introduce such function and change
the usage in the code base. The function will get smarter in later
changesets.

This is somewhat similar to the dispatching we do for 'HG10' and 'HG11'.

The main target is to allow HG2Y support in an extension to ease transition of
companies using the experimental protocol in production (yeah...) But I've no
doubt this will be useful when playing with a future HG21.

diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -519,10 +519,14 @@ class unpackermixin(object):
     def close(self):
         """close underlying file"""
         if util.safehasattr(self._fp, 'close'):
             return self._fp.close()
 
+def getunbundler(ui, fp, header=None):
+    """return a valid unbundler object for a given header"""
+    return unbundle20(ui, fp, header)
+
 class unbundle20(unpackermixin):
     """interpret a bundle2 stream
 
     This class is fed with a binary stream and yields parts through its
     `iterparts` methods."""
diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -31,11 +31,11 @@ def readbundle(ui, fh, fname, vfs=None):
     if version == '10':
         if alg is None:
             alg = changegroup.readexactly(fh, 2)
         return changegroup.cg1unpacker(fh, alg)
     elif version == '2Y':
-        return bundle2.unbundle20(ui, fh, header=magic + version)
+        return bundle2.getunbundler(ui, fh, header=magic + version)
     else:
         raise util.Abort(_('%s: unknown bundle version %s') % (fname, version))
 
 def buildobsmarkerspart(bundler, markers):
     """add an obsmarker part to the bundler with <markers>
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -112,11 +112,11 @@ class localpeer(peer.peerrepository):
                                 common=common, bundlecaps=bundlecaps, **kwargs)
         if bundlecaps is not None and 'HG2Y' in bundlecaps:
             # When requesting a bundle2, getbundle returns a stream to make the
             # wire level function happier. We need to build a proper object
             # from it in local peer.
-            cg = bundle2.unbundle20(self.ui, cg)
+            cg = bundle2.getunbundler(self.ui, cg)
         return cg
 
     # TODO We might want to move the next two calls into legacypeer and add
     # unbundle instead.
 
@@ -130,11 +130,11 @@ class localpeer(peer.peerrepository):
             if util.safehasattr(ret, 'getchunks'):
                 # This is a bundle20 object, turn it into an unbundler.
                 # This little dance should be dropped eventually when the API
                 # is finally improved.
                 stream = util.chunkbuffer(ret.getchunks())
-                ret = bundle2.unbundle20(self.ui, stream)
+                ret = bundle2.getunbundler(self.ui, stream)
             return ret
         except error.PushRaced, exc:
             raise error.ResponseError(_('push failed:'), str(exc))
 
     def lock(self):
diff --git a/mercurial/wireproto.py b/mercurial/wireproto.py
--- a/mercurial/wireproto.py
+++ b/mercurial/wireproto.py
@@ -362,11 +362,11 @@ class wirepeer(peer.peerrepository):
                                % keytype)
             opts[key] = value
         f = self._callcompressable("getbundle", **opts)
         bundlecaps = kwargs.get('bundlecaps')
         if bundlecaps is not None and 'HG2Y' in bundlecaps:
-            return bundle2.unbundle20(self.ui, f)
+            return bundle2.getunbundler(self.ui, f)
         else:
             return changegroupmod.cg1unpacker(f, 'UN')
 
     def unbundle(self, cg, heads, source):
         '''Send cg (a readable file-like object representing the
@@ -399,11 +399,11 @@ class wirepeer(peer.peerrepository):
             for l in output.splitlines(True):
                 self.ui.status(_('remote: '), l)
         else:
             # bundle2 push. Send a stream, fetch a stream.
             stream = self._calltwowaystream('unbundle', cg, heads=heads)
-            ret = bundle2.unbundle20(self.ui, stream)
+            ret = bundle2.getunbundler(self.ui, stream)
         return ret
 
     def debugwireargs(self, one, two, three=None, four=None, five=None):
         # don't pass optional arguments left at their default value
         opts = {}
diff --git a/tests/test-bundle2-format.t b/tests/test-bundle2-format.t
--- a/tests/test-bundle2-format.t
+++ b/tests/test-bundle2-format.t
@@ -155,11 +155,11 @@ Create an extension to test bundle2 API
   >     try:
   >         tr = None
   >         lock = repo.lock()
   >         tr = repo.transaction('processbundle')
   >         try:
-  >             unbundler = bundle2.unbundle20(ui, sys.stdin)
+  >             unbundler = bundle2.getunbundler(ui, sys.stdin)
   >             op = bundle2.processbundle(repo, unbundler, lambda: tr)
   >             tr.close()
   >         except error.BundleValueError, exc:
   >             raise util.Abort('missing support for %s' % exc)
   >         except error.PushRaced, exc:
@@ -181,11 +181,11 @@ Create an extension to test bundle2 API
   >             file.write(chunk)
   > 
   > @command('statbundle2', [], '')
   > def cmdstatbundle2(ui, repo):
   >     """print statistic on the bundle2 container read from stdin"""
-  >     unbundler = bundle2.unbundle20(ui, sys.stdin)
+  >     unbundler = bundle2.getunbundler(ui, sys.stdin)
   >     try:
   >         params = unbundler.params
   >     except error.BundleValueError, exc:
   >        raise util.Abort('unknown parameters: %s' % exc)
   >     ui.write('options count: %i\n' % len(params))