# HG changeset patch
# User Simon Farnsworth <simonfar@fb.com>
# Date 1476636773 25200
# Node ID 970a4c13ebc320a034bc0aff21e0ef0a84157a92
# Parent  8c05184672ae5ca3deb6e1740c1def961a002dca
evolve: lock the working copy early in next and prev (issue5244)

Both next and prev depend on a consistent working copy, but were waiting to
take the lock until they were ready to alter the working copy.

Take the lock before reading the working copy state, and do not release it
until we're definitely not going to change the working copy.

diff --git a/README b/README
--- a/README
+++ b/README
@@ -60,6 +60,8 @@
 
  - Fix erroneous manifest computation when solving 'bumped' changeset.
  - split: avoid crash on empty commit (issue5191),
+ - next: improve locking to avoid issue with working copy parent (issue5244)
+ - prev: improve locking to avoid issue with working copy parent (issue5244)
 
 5.4.1 -- 2016-08-01
 
diff --git a/hgext/evolve.py b/hgext/evolve.py
--- a/hgext/evolve.py
+++ b/hgext/evolve.py
@@ -2221,10 +2221,13 @@
     """update to parent revision
 
     Displays the summary line of the destination for clarity."""
-    if True:
+    wlock = None
+    dryrunopt = opts['dry_run']
+    if not dryrunopt:
+        wlock = repo.wlock()
+    try:
         wkctx = repo[None]
         wparents = wkctx.parents()
-        dryrunopt = opts['dry_run']
         if len(wparents) != 1:
             raise error.Abort('merge in progress')
         if not opts['merge']:
@@ -2254,7 +2257,6 @@
                 ret = hg.update(repo, p.rev())
                 if not ret:
                     tr = lock = None
-                    wlock = repo.wlock()
                     try:
                         lock = repo.lock()
                         tr = repo.transaction('previous')
@@ -2265,7 +2267,8 @@
                             bmdeactivate(repo)
                         tr.close()
                     finally:
-                        lockmod.release(tr, lock, wlock)
+                        lockmod.release(tr, lock)
+
             displayer.show(p)
             return 0
         else:
@@ -2273,6 +2276,8 @@
                 displayer.show(p)
             ui.warn(_('multiple parents, explicitly update to one\n'))
             return 1
+    finally:
+        lockmod.release(wlock)
 
 @command('^next',
          [('B', 'move-bookmark', False,
@@ -2290,10 +2295,13 @@
 
     Displays the summary line of the destination for clarity.
     """
-    if True:
+    wlock = None
+    dryrunopt = opts['dry_run']
+    if not dryrunopt:
+        wlock = repo.wlock()
+    try:
         wkctx = repo[None]
         wparents = wkctx.parents()
-        dryrunopt = opts['dry_run']
         if len(wparents) != 1:
             raise error.Abort('merge in progress')
         if not opts['merge']:
@@ -2323,7 +2331,6 @@
                 ret = hg.update(repo, c.rev())
                 if not ret:
                     lock = tr = None
-                    wlock = repo.wlock()
                     try:
                         lock = repo.lock()
                         tr = repo.transaction('next')
@@ -2334,7 +2341,7 @@
                             bmdeactivate(repo)
                         tr.close()
                     finally:
-                        lockmod.release(tr, lock, wlock)
+                        lockmod.release(tr, lock)
             displayer.show(c)
             result = 0
         elif children:
@@ -2376,6 +2383,8 @@
                 return result
             return 1
         return result
+    finally:
+        lockmod.release(wlock)
 
 def _reachablefrombookmark(repo, revs, bookmarks):
     """filter revisions and bookmarks reachable from the given bookmark
diff --git a/tests/fake-editor.sh b/tests/fake-editor.sh
new file mode 100755
--- /dev/null
+++ b/tests/fake-editor.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+sleep 5
+echo "new desc" >> $1
diff --git a/tests/test-prev-next.t b/tests/test-prev-next.t
--- a/tests/test-prev-next.t
+++ b/tests/test-prev-next.t
@@ -206,3 +206,34 @@
   move:[5] added d
   atop:[6] added b (3)
   working directory is now at 47ea25be8aea
+
+prev and next should lock properly against other commands
+
+  $ hg init repo
+  $ cd repo
+  $ HGEDITOR=${TESTDIR}/fake-editor.sh
+  $ echo hi > foo
+  $ hg ci -Am 'one'
+  adding foo
+  $ echo bye > foo
+  $ hg ci -Am 'two'
+
+  $ hg amend --edit &
+  $ sleep 1
+  $ hg prev
+  waiting for lock on working directory of $TESTTMP/repo held by '*' (glob)
+  got lock after [4-6] seconds (re)
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  [0] one
+  $ wait
+
+  $ hg amend --edit &
+  $ sleep 1
+  $ hg next --evolve
+  waiting for lock on working directory of $TESTTMP/repo held by '*' (glob)
+  1 new unstable changesets
+  got lock after [4-6] seconds (re)
+  move:[2] two
+  atop:[3] one
+  working directory now at a7d885c75614
+  $ wait