[PATCH] check-concurrency: expose the feature as 'check-concurrent-push-mode'

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at octobus.net>
# Date 1495923158 -7200
#      Sun May 28 00:12:38 2017 +0200
# Node ID 37ac2d3f1c505077f5684635df123a1fc31cf594
# Parent  29558247b00eff8c95c7604032b59cfbab34010d
# EXP-Topic pushrace
# Available At https://www.mercurial-scm.org/repo/users/marmoute/mercurial/
#              hg pull https://www.mercurial-scm.org/repo/users/marmoute/mercurial/ -r 37ac2d3f1c50
check-concurrency: expose the feature as 'check-concurrent-push-mode'

We move the feature to a proper configuration and document it. The config goes
in the 'server' section because it feels like something the server owner would
want to decide. We pick and open field because it seems likely that other
checking levels will emerge in the future. (eg: server like the mozilla-try
server will likely wants a "none" value)

The option name contains 'push' since this affects 'push' only. The option value
'check-related' is preferred over one explicitly containing 'allow' or 'deny'
because the client still have a strong decision power here. Here, the server is
just advising the client on the check mode to use.

diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -1323,7 +1323,8 @@ def getrepocaps(repo, allowpushback=Fals
         caps['obsmarkers'] = supportedformat
     if allowpushback:
         caps['pushback'] = ()
-    if not repo.ui.configbool('experimental', 'checkheads-strict', True):
+    cpmode = repo.ui.config('server', 'concurrent-push-mode', 'strict')
+    if cpmode == 'check-related':
         caps['checkheads'] = ('related',)
     return caps
 
diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -1672,6 +1672,16 @@ Controls generic server settings.
     are highly recommended. Partial clones will still be allowed.
     (default: False)
 
+``concurrent-push-mode``
+    Level of allowed race condition between two pushing client.
+    - 'strict': push is abort if another client touched the repository
+      while the push was preparing. (default)
+    - 'check-related': push is only aborted if it affects head that got also
+      affected while the push was preparing.
+
+    This requires compatible client (version 4.3 and later). Old client will
+    use 'strict'.
+
 ``validate``
     Whether to validate the completeness of pushed changesets by
     checking that all new file revisions specified in manifests are
diff --git a/tests/test-push-race.t b/tests/test-push-race.t
--- a/tests/test-push-race.t
+++ b/tests/test-push-race.t
@@ -111,8 +111,8 @@ We tests multiple cases:
 #if unrelated
 
   $ cat >> $HGRCPATH << EOF
-  > [experimental]
-  > checkheads-strict = no
+  > [server]
+  > concurrent-push-mode = check-related
   > EOF
 
 #endif