exchange: return bundle info from getbundlechunks() (API)

exchange: return bundle info from getbundlechunks() (API)

We generally want a mechanism to pass information about the
generated bundle back to callers (in addition to the byte stream).
Ideally we would return a bundler from this function and have the
caller code to an interface. But the bundling APIs are not great
and getbundlechunks() is the best API we have for obtaining bundle
contents in a unified manner.

We change getbundlechunks() to return a dict that we can use to
communicate metadata.

We populate that dict with the bundle version number to demonstrate
some value.

.. api::

   exchange.getbundlechunks() now returns a 2-tuple instead of just
   an iterator.

Differential Revision: https://phab.mercurial-scm.org/D1925

--- a/mercurial/exchange.py	Sat Jan 20 15:26:31 2018 -0800
+++ b/mercurial/exchange.py	Sat Jan 20 13:41:57 2018 -0800
@@ -1727,9 +1727,11 @@
     Could be a bundle HG10 or a bundle HG20 depending on bundlecaps
     passed.
 
-    Returns an iterator over raw chunks (of varying sizes).
+    Returns a 2-tuple of a dict with metadata about the generated bundle
+    and an iterator over raw chunks (of varying sizes).
     """
     kwargs = pycompat.byteskwargs(kwargs)
+    info = {}
     usebundle2 = bundle2requested(bundlecaps)
     # bundle10 case
     if not usebundle2:
@@ -1740,10 +1742,12 @@
             raise ValueError(_('unsupported getbundle arguments: %s')
                              % ', '.join(sorted(kwargs.keys())))
         outgoing = _computeoutgoing(repo, heads, common)
-        return changegroup.makestream(repo, outgoing, '01', source,
-                                      bundlecaps=bundlecaps)
+        info['bundleversion'] = 1
+        return info, changegroup.makestream(repo, outgoing, '01', source,
+                                            bundlecaps=bundlecaps)
 
     # bundle20 case
+    info['bundleversion'] = 2
     b2caps = {}
     for bcaps in bundlecaps:
         if bcaps.startswith('bundle2='):
@@ -1759,7 +1763,7 @@
         func(bundler, repo, source, bundlecaps=bundlecaps, b2caps=b2caps,
              **pycompat.strkwargs(kwargs))
 
-    return bundler.getchunks()
+    return info, bundler.getchunks()
 
 @getbundle2partsgenerator('stream')
 def _getbundlestream(bundler, repo, source, bundlecaps=None,

--- a/mercurial/localrepo.py	Sat Jan 20 15:26:31 2018 -0800
+++ b/mercurial/localrepo.py	Sat Jan 20 13:41:57 2018 -0800
@@ -197,7 +197,7 @@
                   **kwargs):
         chunks = exchange.getbundlechunks(self._repo, source, heads=heads,
                                           common=common, bundlecaps=bundlecaps,
-                                          **kwargs)
+                                          **kwargs)[1]
         cb = util.chunkbuffer(chunks)
 
         if exchange.bundle2requested(bundlecaps):

--- a/mercurial/wireproto.py	Sat Jan 20 15:26:31 2018 -0800
+++ b/mercurial/wireproto.py	Sat Jan 20 13:41:57 2018 -0800
@@ -877,8 +877,8 @@
                     _('server has pull-based clones disabled'),
                     hint=_('remove --pull if specified or upgrade Mercurial'))
 
-        chunks = exchange.getbundlechunks(repo, 'serve',
-                                          **pycompat.strkwargs(opts))
+        info, chunks = exchange.getbundlechunks(repo, 'serve',
+                                                **pycompat.strkwargs(opts))
     except error.Abort as exc:
         # cleanly forward Abort error to the client
         if not exchange.bundle2requested(opts.get('bundlecaps')):