# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 2014-04-11 13:43:01
# Node ID 0bea9db7543bb15f08275b700d7e5e478cc73e54
# Parent  d7e233df48e62d19c1487b2f7c0e38ac4912dcaa

bundle2: add a "check:heads" handler

This part is intended to hold the same role as the `heads` argument of the
unbundle function. The client fill it with the known heads at bundle time and
the server will abort if its heads changed.

diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -657,3 +657,17 @@ def handlechangegroup(op, inpart):
     ret = int(p['return'])
     op.records.add('changegroup', {'return': ret}, int(p['in-reply-to']))
 
+@parthandler('check:heads')
+def handlechangegroup(op, inpart):
+    """check that head of the repo did not change
+
+    This is used to detect a push race when using unbundle.
+    This replaces the "heads" argument of unbundle."""
+    h = inpart.read(20)
+    heads = []
+    while len(h) == 20:
+        heads.append(h)
+        h = inpart.read(20)
+    assert not h
+    if heads != op.repo.heads():
+        raise exchange.PushRaced()