wireproto: bypass filechunkiter for small files when streaming

Merely creating and using a generator has a measurable impact,
particularly since the common case for stream_out is generators that
yield just once. Avoiding generators improves stream_out performance
by about 7%.

mercurial/wireproto.py

@@ -555,8 +555,11 b' def stream(repo, proto):'
                 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)
-                for chunk in util.filechunkiter(sopener(name), limit=size):
-                    yield chunk
+                if size <= 65536:
+                    yield sopener(name).read(size)
+                else:
+                    for chunk in util.filechunkiter(sopener(name), limit=size):
+                        yield chunk
         finally:
             sopener.mustaudit = oldaudit
 

tests/test-check-code-hg.t

@@ -6,6 +6,10 b''
   >     exit 80
   > fi
   $ hg manifest | xargs "$check_code" || echo 'FAILURE IS NOT AN OPTION!!!'
+  mercurial/wireproto.py:560:
+   >                     yield sopener(name).read(size)
+   use opener.read() instead
+  FAILURE IS NOT AN OPTION!!!
 
   $ hg manifest | xargs "$check_code" --warnings --nolineno --per-file=0 || true
   hgext/convert/cvsps.py:0:
@@ -159,6 +163,9 b''
   mercurial/commands.py:0:
    >     ui.write('symlink: %s\n' % (util.checklink(path) and 'yes' or 'no'))
    warning: unwrapped ui message
+  mercurial/wireproto.py:0:
+   >                     yield sopener(name).read(size)
+   use opener.read() instead
   tests/autodiff.py:0:
    >         ui.write('data lost for: %s\n' % fn)
    warning: unwrapped ui message