test: add a push race case where each client replaces a different head

We check case where the raced push replace one head while the racing push
replaces another unrelated one.

That second test also make sure we synchronise all repositories to the same
state between tests. That will help us when allowing some sort of concurrent
pushes.

tests/test-push-race.t

@@ -1,191 +1,280 b''
 ============================================================================================
 Test cases where there are race condition between two clients pushing to the same repository
 ============================================================================================
 
 This file tests cases where two clients push to a server at the same time. The
 "raced" client is done preparing it push bundle when the "racing" client
 perform its push. The "raced" client starts its actual push after the "racing"
 client push is fully complete.
 
 A set of extension and shell functions ensures this scheduling.
 
   $ cat >> delaypush.py << EOF
   > """small extension orchestrate push race
   > 
   > Client with the extensions will create a file when ready and get stuck until
   > a file is created."""
   > 
   > import atexit
   > import errno
   > import os
   > import time
   > 
   > from mercurial import (
   >     exchange,
   >     extensions,
   > )
   > 
   > def delaypush(orig, pushop):
   >     # notify we are done preparing
   >     readypath = pushop.repo.ui.config('delaypush', 'ready-path', None)
   >     if readypath is not None:
   >         with open(readypath, 'w') as r:
   >             r.write('foo')
   >         pushop.repo.ui.status('wrote ready: %s\n' % readypath)
   >     # now wait for the other process to be done
   >     watchpath = pushop.repo.ui.config('delaypush', 'release-path', None)
   >     if watchpath is not None:
   >         pushop.repo.ui.status('waiting on: %s\n' % watchpath)
   >         limit = 100
   >         while 0 < limit and not os.path.exists(watchpath):
   >             limit -= 1
   >             time.sleep(0.1)
   >         if limit <= 0:
   >             repo.ui.warn('exiting without watchfile: %s' % watchpath)
   >         else:
   >             # delete the file at the end of the push
   >             def delete():
   >                 try:
   >                     os.unlink(watchpath)
   >                 except OSError as exc:
   >                     if exc.errno != errno.ENOENT:
   >                         raise
   >             atexit.register(delete)
   >     return orig(pushop)
   > 
   > def uisetup(ui):
   >     extensions.wrapfunction(exchange, '_pushbundle2', delaypush)
   > EOF
 
   $ waiton () {
   >     # wait for a file to be created (then delete it)
   >     count=100
   >     while [ ! -f $1 ] ;
   >     do
   >         sleep 0.1;
   >         count=`expr $count - 1`;
   >         if [ $count -lt 0 ];
   >         then
   >              break
   >         fi;
   >     done
   >     [ -f $1 ] || echo "ready file still missing: $1"
   >     rm -f $1
   > }
 
   $ release () {
   >     # create a file and wait for it be deleted
   >     count=100
   >     touch $1
   >     while [ -f $1 ] ;
   >     do
   >         sleep 0.1;
   >         count=`expr $count - 1`;
   >         if [ $count -lt 0 ];
   >         then
   >              break
   >         fi;
   >     done
   >     [ ! -f $1 ] || echo "delay file still exist: $1"
   > }
 
   $ cat >> $HGRCPATH << EOF
   > [ui]
   > ssh = python "$TESTDIR/dummyssh"
   > # simplify output
   > logtemplate = {node|short} {desc} ({branch})
   > [alias]
   > graph = log -G --rev 'sort(all(), "topo")'
   > EOF
 
 Setup
 -----
 
 create a repo with one root
 
   $ hg init server
   $ cd server
   $ echo root > root
   $ hg ci -Am "C-ROOT"
   adding root
   $ cd ..
 
 clone it in two clients
 
   $ hg clone ssh://user@dummy/server client-racy
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
   updating to branch default
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg clone ssh://user@dummy/server client-other
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
   updating to branch default
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
 setup one to allow race on push
 
   $ cat >> client-racy/.hg/hgrc << EOF
   > [extensions]
   > delaypush = $TESTTMP/delaypush.py
   > [delaypush]
   > ready-path = $TESTTMP/readyfile
   > release-path = $TESTTMP/watchfile
   > EOF
 
 Simple race, both try to push to the server at the same time
 ------------------------------------------------------------
 
 Both try to replace the same head
 
 #  a
 #  | b
 #  |/
 #  *
 
 Creating changesets
 
   $ echo b > client-other/a
   $ hg -R client-other/ add client-other/a
   $ hg -R client-other/ commit -m "C-A"
   $ echo b > client-racy/b
   $ hg -R client-racy/ add client-racy/b
   $ hg -R client-racy/ commit -m "C-B"
 
 Pushing
 
   $ hg -R client-racy push -r 'tip' > ./push-log 2>&1 &
 
   $ waiton $TESTTMP/readyfile
 
   $ hg -R client-other push -r 'tip'
   pushing to ssh://user@dummy/server
   searching for changes
   remote: adding changesets
   remote: adding manifests
   remote: adding file changes
   remote: added 1 changesets with 1 changes to 1 files
 
   $ release $TESTTMP/watchfile
 
 Check the result of the push
 
   $ cat ./push-log
   pushing to ssh://user@dummy/server
   searching for changes
   wrote ready: $TESTTMP/readyfile
   waiting on: $TESTTMP/watchfile
   abort: push failed:
   'repository changed while pushing - please try again'
 
   $ hg -R server graph
   o  98217d5a1659 C-A (default)
   |
   @  842e2fac6304 C-ROOT (default)
   
+
+Pushing on two different heads
+------------------------------
+
+Both try to replace a different head
+
+#  a b
+#  | |
+#  * *
+#  |/
+#  *
+
+(resync-all)
+
+  $ hg -R ./server pull ./client-racy
+  pulling from ./client-racy
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files (+1 heads)
+  (run 'hg heads' to see heads, 'hg merge' to merge)
+  $ hg -R ./client-other pull
+  pulling from ssh://user@dummy/server
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files (+1 heads)
+  (run 'hg heads' to see heads, 'hg merge' to merge)
+  $ hg -R ./client-racy pull
+  pulling from ssh://user@dummy/server
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files (+1 heads)
+  (run 'hg heads' to see heads, 'hg merge' to merge)
+
+  $ hg -R server graph
+  o  a9149a1428e2 C-B (default)
+  |
+  | o  98217d5a1659 C-A (default)
+  |/
+  @  842e2fac6304 C-ROOT (default)
+  
+
+Creating changesets
+
+  $ echo aa >> client-other/a
+  $ hg -R client-other/ commit -m "C-C"
+  $ echo bb >> client-racy/b
+  $ hg -R client-racy/ commit -m "C-D"
+
+Pushing
+
+  $ hg -R client-racy push -r 'tip' > ./push-log 2>&1 &
+
+  $ waiton $TESTTMP/readyfile
+
+  $ hg -R client-other push -r 'tip'
+  pushing to ssh://user@dummy/server
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
+
+  $ release $TESTTMP/watchfile
+
+Check the result of the push
+
+  $ cat ./push-log
+  pushing to ssh://user@dummy/server
+  searching for changes
+  wrote ready: $TESTTMP/readyfile
+  waiting on: $TESTTMP/watchfile
+  abort: push failed:
+  'repository changed while pushing - please try again'
+
+  $ hg -R server graph
+  o  51c544a58128 C-C (default)
+  |
+  o  98217d5a1659 C-A (default)
+  |
+  | o  a9149a1428e2 C-B (default)
+  |/
+  @  842e2fac6304 C-ROOT (default)
+