dirstate: initial creation of a test file to check dirstate race read

More problems to solve… yeah ! (I guess)

tests/test-dirstate-read-race.t

@@ -0,0 +1,143 b''
+==============================================================================
+Check potential race conditions between a dirstate's read and other operations
+==============================================================================
+
+Some commands, like `hg status`, do not need to take the wlock but need to
+access dirstate data.
+Other commands might update the dirstate data while this happens.
+
+This can create issues if repository data is read in the wrong order, or for
+the dirstate-v2 format where the data is contained in multiple files.
+
+This test file is meant to test various cases where such parallel operations
+happen and make sure the reading process behaves fine. We do so with a `hg
+status` command since it is probably the most advanced of such read-only
+command.
+
+It bears simililarity with `tests/test-dirstate-status-race.t ` but tests a
+different type of race.
+
+Setup
+=====
+
+  $ directories="dir dir/nested dir2"
+  $ first_files="dir/nested/a dir/b dir/c dir/d dir2/e f"
+  $ second_files="g dir/nested/h dir/i dir/j dir2/k dir2/l dir/nested/m"
+  $ extra_files="dir/n dir/o p q"
+
+  $ hg init reference-repo
+  $ cd reference-repo
+  $ mkdir -p dir/nested dir2
+  $ touch -t 200001010000 $first_files $directories
+  $ hg commit -Aqm "recreate a bunch of files to facilitate dirstate-v2 append"
+  $ touch -t 200001010010 $second_files $directories
+  $ hg commit -Aqm "more files to have two commit"
+  $ hg log -G -v
+  @  changeset:   1:9a86dcbfb938
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  files:       dir/i dir/j dir/nested/h dir/nested/m dir2/k dir2/l g
+  |  description:
+  |  more files to have two commit
+  |
+  |
+  o  changeset:   0:4f23db756b09
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     files:       dir/b dir/c dir/d dir/nested/a dir2/e f
+     description:
+     recreate a bunch of files to facilitate dirstate-v2 append
+  
+  
+  $ hg manifest
+  dir/b
+  dir/c
+  dir/d
+  dir/i
+  dir/j
+  dir/nested/a
+  dir/nested/h
+  dir/nested/m
+  dir2/e
+  dir2/k
+  dir2/l
+  f
+  g
+
+Add some unknown files and refresh the dirstate
+
+  $ touch -t 200001010020 $extra_files
+  $ hg add dir/o
+  $ hg remove dir/nested/m
+
+  $ hg st --config devel.dirstate.v2.data_update_mode=force-new
+  A dir/o
+  R dir/nested/m
+  ? dir/n
+  ? p
+  ? q
+  $ hg debugstate
+  n 644          0 2000-01-01 00:00:00 dir/b
+  n 644          0 2000-01-01 00:00:00 dir/c
+  n 644          0 2000-01-01 00:00:00 dir/d
+  n 644          0 2000-01-01 00:10:00 dir/i
+  n 644          0 2000-01-01 00:10:00 dir/j
+  n 644          0 2000-01-01 00:00:00 dir/nested/a
+  n 644          0 2000-01-01 00:10:00 dir/nested/h
+  r ?????????????????????????????????? dir/nested/m (glob)
+  a ?????????????????????????????????? dir/o (glob)
+  n 644          0 2000-01-01 00:00:00 dir2/e
+  n 644          0 2000-01-01 00:10:00 dir2/k
+  n 644          0 2000-01-01 00:10:00 dir2/l
+  n 644          0 2000-01-01 00:00:00 f
+  n 644          0 2000-01-01 00:10:00 g
+  $ hg debugstate > ../reference
+  $ cd ..
+
+Actual Testing
+==============
+
+Race with a `hg add`
+-------------------
+
+  $ cp -a reference-repo race-with-add
+  $ cd race-with-add
+
+spin a `hg status` with some caches to update
+
+  $ hg st >$TESTTMP/status-race-lock.out 2>$TESTTMP/status-race-lock.log \
+  > --config rhg.on-unsupported=abort \
+  > --config devel.sync.dirstate.pre-read-file=$TESTTMP/status-race-lock \
+  > &
+  $ $RUNTESTDIR/testlib/wait-on-file 5 $TESTTMP/status-race-lock.waiting
+
+Add a file
+
+  $ hg add dir/n $d2args
+  $ touch $TESTTMP/status-race-lock
+  $ wait
+
+The file should in a "added" state
+
+  $ hg status
+  A dir/n
+  A dir/o
+  R dir/nested/m
+  ? p
+  ? q
+
+The status process should return a consistent result and not crash.
+
+  $ cat $TESTTMP/status-race-lock.out
+  A dir/n
+  A dir/o
+  R dir/nested/m
+  ? p
+  ? q
+  $ cat $TESTTMP/status-race-lock.log
+
+final cleanup
+
+  $ rm $TESTTMP/status-race-lock $TESTTMP/status-race-lock.waiting
+  $ cd ..