[PATCH 2 of 4 V5] localrepo: adds times parameter to lock and wlock functions

[Yuya Nishihara]

On Thu, 12 Nov 2015 14:17:45 +0100, liscju wrote:
> # HG changeset patch
> # User liscju <piotr.listkiewicz at gmail.com>
> # Date 1447331898 -3600
> #      Thu Nov 12 13:38:18 2015 +0100
> # Node ID 8b107a3648068503b154eef2bf9f08c4cd13a51b
> # Parent  3a0f7224a3466e49068c0cd355640152631d1ba3
> localrepo: adds times parameter to lock and wlock functions
> 
> This gives a possibility for acquiring/releasing repository
> lock and wlock multiple times.
> 
> diff -r 3a0f7224a346 -r 8b107a364806 mercurial/localrepo.py
> --- a/mercurial/localrepo.py	Thu Nov 12 13:35:22 2015 +0100
> +++ b/mercurial/localrepo.py	Thu Nov 12 13:38:18 2015 +0100
> @@ -1238,7 +1238,7 @@
>              ce.refresh()
>  
>      def _lock(self, vfs, lockname, wait, releasefn, acquirefn, desc,
> -              inheritchecker=None, parentenvvar=None):
> +              inheritchecker=None, parentenvvar=None, times=1):
>          parentlock = None
>          # the contents of parentenvvar are used by the underlying lock to
>          # determine whether it can be inherited
> @@ -1248,7 +1248,7 @@
>              l = lockmod.lock(vfs, lockname, 0, releasefn=releasefn,
>                               acquirefn=acquirefn, desc=desc,
>                               inheritchecker=inheritchecker,
> -                             parentlock=parentlock)
> +                             parentlock=parentlock, times=times)
>          except error.LockHeld as inst:
>              if not wait:
>                  raise
> @@ -1258,7 +1258,7 @@
>              l = lockmod.lock(vfs, lockname,
>                               int(self.ui.config("ui", "timeout", "600")),
>                               releasefn=releasefn, acquirefn=acquirefn,
> -                             desc=desc)
> +                             desc=desc, times=times)
>              self.ui.warn(_("got lock after %s seconds\n") % l.delay)
>          return l
>  
> @@ -1275,7 +1275,7 @@
>          else: # no lock have been found.
>              callback()
>  
> -    def lock(self, wait=True):
> +    def lock(self, wait=True, times=1):
>          '''Lock the repository store (.hg/store) and return a weak reference
>          to the lock. Use this before modifying the store (e.g. committing or
>          stripping). If you are opening a transaction, get a lock as well.)
> @@ -1284,11 +1284,11 @@
>          'wlock' first to avoid a dead-lock hazard.'''
>          l = self._lockref and self._lockref()
>          if l is not None and l.held:
> -            l.lock()
> +            l.lock(times)
>              return l
>  
>          l = self._lock(self.svfs, "lock", wait, None,
> -                       self.invalidate, _('repository %s') % self.origroot)
> +                       self.invalidate, _('repository %s') % self.origroot, times=times)
>          self._lockref = weakref.ref(l)
>          return l

This won't work correctly because the previous active locks are forcibly
released and new lock object is created.

Think that there are two lockers:

  wl0 = repo.wlock()  # wl0.held = 1
  wl1 = repo.wlock()  # wl0.held = 2
  wheld = wl1.releaseall()  # wl0.held = 0
  wl1 = repo.wlock(times=wheld)  # wl0.held = 0, wl1.held = 2
  wl1.release()  # wl0.held = 0, wl1.held = 1
  wl0.release()  # wl0.held = 0 (noop, still locked)
  # lock file is deleted here by wl1.__del__

Perhaps foozy would mention the lock inheritance that was recently introduced.
But I'm noob about it.

Regards,