# HG changeset patch
# User Jun Wu <quark@fb.com>
# Date 2017-08-16 17:44:06
# Node ID 3cfc9070245fbaa8c4c010327f24d579a416370f
# Parent  8fb5212652ec1a60522c4d5847fde1c54183a7eb

demandimport: disable if chg is being used

In chg's case, making modules lazily loaded could actually slow down things
since chg pre-imports them. Therefore disable demandimport if chg is being
used.

This is not done by setting `HGDEMANDIMPORT` chg client-side because that
has side-effects on child processes (hooks, etc).

Differential Revision: https://phab.mercurial-scm.org/D351

diff --git a/hgdemandimport/__init__.py b/hgdemandimport/__init__.py
--- a/hgdemandimport/__init__.py
+++ b/hgdemandimport/__init__.py
@@ -73,5 +73,7 @@ disable = demandimport.disable
 deactivated = demandimport.deactivated
 
 def enable():
-    if os.environ.get('HGDEMANDIMPORT') != 'disable':
+    # chg pre-imports modules so do not enable demandimport for it
+    if ('CHGINTERNALMARK' not in os.environ
+        and os.environ.get('HGDEMANDIMPORT') != 'disable'):
         demandimport.enable()
diff --git a/mercurial/chgserver.py b/mercurial/chgserver.py
--- a/mercurial/chgserver.py
+++ b/mercurial/chgserver.py
@@ -565,8 +565,11 @@ class chgunixservicehandler(object):
                             self._hashstate, self._baseaddress)
 
 def chgunixservice(ui, repo, opts):
-    # CHGINTERNALMARK is temporarily set by chg client to detect if chg will
-    # start another chg. drop it to avoid possible side effects.
+    # CHGINTERNALMARK is set by chg client. It is an indication of things are
+    # started by chg so other code can do things accordingly, like disabling
+    # demandimport or detecting chg client started by chg client. When executed
+    # here, CHGINTERNALMARK is no longer useful and hence dropped to make
+    # environ cleaner.
     if 'CHGINTERNALMARK' in encoding.environ:
         del encoding.environ['CHGINTERNALMARK']