--- a/mercurial/wireproto.py	Tue May 19 10:13:43 2015 -0700
+++ b/mercurial/wireproto.py	Thu May 21 10:27:22 2015 -0700
@@ -744,73 +744,27 @@
 def _allowstream(ui):
     return ui.configbool('server', 'uncompressed', True, untrusted=True)
 
-def _walkstreamfiles(repo):
-    # this is it's own function so extensions can override it
-    return repo.store.walk()
-
 @wireprotocommand('stream_out')
 def stream(repo, proto):
     '''If the server supports streaming clone, it advertises the "stream"
     capability with a value representing the version and flags of the repo
     it is serving. Client checks to see if it understands the format.
-
-    The format is simple: the server writes out a line with the amount
-    of files, then the total amount of bytes to be transferred (separated
-    by a space). Then, for each file, the server first writes the filename
-    and file size (separated by the null character), then the file contents.
     '''
-
     if not _allowstream(repo.ui):
         return '1\n'
 
-    entries = []
-    total_bytes = 0
-    try:
-        # get consistent snapshot of repo, lock during scan
-        lock = repo.lock()
-        try:
-            repo.ui.debug('scanning\n')
-            for name, ename, size in _walkstreamfiles(repo):
-                if size:
-                    entries.append((name, size))
-                    total_bytes += size
-        finally:
-            lock.release()
-    except error.LockError:
-        return '2\n' # error: 2
-
-    def streamer(repo, entries, total):
-        '''stream out all metadata files in repository.'''
-        yield '0\n' # success
-        repo.ui.debug('%d files, %d bytes to transfer\n' %
-                      (len(entries), total_bytes))
-        yield '%d %d\n' % (len(entries), total_bytes)
+    def getstream(it):
+        yield '0\n'
+        for chunk in it:
+            yield chunk
 
-        sopener = repo.svfs
-        oldaudit = sopener.mustaudit
-        debugflag = repo.ui.debugflag
-        sopener.mustaudit = False
-
-        try:
-            for name, size in entries:
-                if debugflag:
-                    repo.ui.debug('sending %s (%d bytes)\n' % (name, size))
-                # partially encode name over the wire for backwards compat
-                yield '%s\0%d\n' % (store.encodedir(name), size)
-                if size <= 65536:
-                    fp = sopener(name)
-                    try:
-                        data = fp.read(size)
-                    finally:
-                        fp.close()
-                    yield data
-                else:
-                    for chunk in util.filechunkiter(sopener(name), limit=size):
-                        yield chunk
-        finally:
-            sopener.mustaudit = oldaudit
-
-    return streamres(streamer(repo, entries, total_bytes))
+    try:
+        # LockError may be raised before the first result is yielded. Don't
+        # emit output until we're sure we got the lock successfully.
+        it = exchange.generatestreamclone(repo)
+        return streamres(getstream(it))
+    except error.LockError:
+        return '2\n'
 
 @wireprotocommand('unbundle', 'heads')
 def unbundle(repo, proto, heads):