comparison mercurial/transaction.py @ 49993:2f348babe30d

transaction: clarify the "quick abort" scenario

Right now, the transaction has a code-pass to do a "quick abort" that skip most¹
(too much) of the logic when the right condition are detected²

We are about to improve this logic in multiple aspect. We clarify the code
first.

The conditional return in `_can_quick_abort` looks a bit weird because we are
about to make them more complex very soon.

[1] actually too much
[2] actually not often enough

49992:420fad6bdec5

        self._count = 0
        self._usages = 0
        self._file.close()
        self._backupsfile.close()

        try:
            if not entries and not self._backupentries:
                if self._backupjournal:
                    self._opener.unlink(self._backupjournal)
                if self._journal:
                    self._opener.unlink(self._journal)
                return

            self._report(_(b"transaction abort!\n"))

            try:
                for cat in sorted(self._abortcallback):
                    self._abortcallback[cat](self)
                # Prevent double usage and help clear cycles.
                self._abortcallback = None
                _playback(
                    self._journal,
                    self._report,
                    self._opener,
                    self._vfsmap,
                    entries,
                    self._backupentries,
                    False,
                    checkambigfiles=self._checkambigfiles,
                )
                self._report(_(b"rollback completed\n"))
            except BaseException as exc:
                self._report(_(b"rollback failed - please run hg recover\n"))
                self._report(
                    _(b"(failure reason: %s)\n") % stringutil.forcebytestr(exc)
                )
        finally:
            self._journal = None
            self._releasefn(self, False)  # notify failure of transaction
            self._releasefn = None  # Help prevent cycles.


BAD_VERSION_MSG = _(
    b"journal was created by a different version of Mercurial\n"
)

49993:2f348babe30d

        self._count = 0
        self._usages = 0
        self._file.close()
        self._backupsfile.close()

        quick = self._can_quick_abort(entries)
        try:
            if quick:
                self._do_quick_abort(entries)
            else:
                self._do_full_abort(entries)
        finally:
            self._journal = None
            self._releasefn(self, False)  # notify failure of transaction
            self._releasefn = None  # Help prevent cycles.

    def _can_quick_abort(self, entries):
        """False if any semantic content have been written on disk

        True if nothing, except temporary files has been writen on disk."""
        if entries:
            return False
        if self._backupentries:
            return False
        return True

    def _do_quick_abort(self, entries):
        """(Silently) do a quick cleanup (see _can_quick_abort)"""
        assert self._can_quick_abort(entries)
        if self._backupjournal:
            self._opener.unlink(self._backupjournal)
        if self._journal:
            self._opener.unlink(self._journal)

    def _do_full_abort(self, entries):
        """(Noisily) rollback all the change introduced by the transaction"""
        self._report(_(b"transaction abort!\n"))
        try:
            for cat in sorted(self._abortcallback):
                self._abortcallback[cat](self)
            # Prevent double usage and help clear cycles.
            self._abortcallback = None
            _playback(
                self._journal,
                self._report,
                self._opener,
                self._vfsmap,
                entries,
                self._backupentries,
                False,
                checkambigfiles=self._checkambigfiles,
            )
            self._report(_(b"rollback completed\n"))
        except BaseException as exc:
            self._report(_(b"rollback failed - please run hg recover\n"))
            self._report(
                _(b"(failure reason: %s)\n") % stringutil.forcebytestr(exc)
            )


BAD_VERSION_MSG = _(
    b"journal was created by a different version of Mercurial\n"
)