changeset 39702:3d22aef3ecd5

transaction: make entries a private attribute (API)

This attribute is tracking changes to append-only files. It is
an implementation detail and should not be exposed as part of
the public interface.

But code in repair was accessing it, so it seemingly does belong
as part of the public API. But that code in repair is making
assumptions about how storage works and is grossly wrong when
alternate storage backends are in play. We'll need some kind of
"strip" API at the storage layer that knows how to handle things
in a storage-agnostic manner. I don't think accessing a private
attribute on the transaction is any worse than what this code
is already doing. So I'm fine with violating the abstraction for
transactions.

And with this change, all per-instance attributes on transaction
have been made private except for "changes" and "hookargs." Both
are used by multiple consumers and look like they need to be
part of the public interface.

.. api::

   Various attributes of ``transaction.transaction`` are now ``_``
   prefixed to indicate they shouldn't be used by external
   consumers.

Differential Revision: https://phab.mercurial-scm.org/D4634

--- a/mercurial/repair.py	Mon Sep 17 16:19:55 2018 -0700
+++ b/mercurial/repair.py	Mon Sep 17 16:29:12 2018 -0700
@@ -190,7 +190,11 @@
     with ui.uninterruptable():
         try:
             with repo.transaction("strip") as tr:
-                offset = len(tr.entries)
+                # TODO this code violates the interface abstraction of the
+                # transaction and makes assumptions that file storage is
+                # using append-only files. We'll need some kind of storage
+                # API to handle stripping for us.
+                offset = len(tr._entries)
 
                 tr.startgroup()
                 cl.strip(striprev, tr)
@@ -200,8 +204,8 @@
                     repo.file(fn).strip(striprev, tr)
                 tr.endgroup()
 
-                for i in pycompat.xrange(offset, len(tr.entries)):
-                    file, troffset, ignore = tr.entries[i]
+                for i in pycompat.xrange(offset, len(tr._entries)):
+                    file, troffset, ignore = tr._entries[i]
                     with repo.svfs(file, 'a', checkambig=True) as fp:
                         fp.truncate(troffset)
                     if troffset == 0:

--- a/mercurial/transaction.py	Mon Sep 17 16:19:55 2018 -0700
+++ b/mercurial/transaction.py	Mon Sep 17 16:29:12 2018 -0700
@@ -129,7 +129,7 @@
         vfsmap[''] = opener  # set default value
         self._vfsmap = vfsmap
         self._after = after
-        self.entries = []
+        self._entries = []
         self._map = {}
         self._journal = journalname
         self._undoname = undoname
@@ -230,8 +230,8 @@
         """add a append-only entry to memory and on-disk state"""
         if file in self._map or file in self._backupmap:
             return
-        self.entries.append((file, offset, data))
-        self._map[file] = len(self.entries) - 1
+        self._entries.append((file, offset, data))
+        self._map[file] = len(self._entries) - 1
         # add enough data to the journal to do the truncate
         self._file.write("%s\0%d\n" % (file, offset))
         self._file.flush()
@@ -352,7 +352,7 @@
     @active
     def find(self, file):
         if file in self._map:
-            return self.entries[self._map[file]]
+            return self._entries[self._map[file]]
         if file in self._backupmap:
             return self._backupentries[self._backupmap[file]]
         return None
@@ -367,7 +367,7 @@
         if file not in self._map:
             raise KeyError(file)
         index = self._map[file]
-        self.entries[index] = (file, offset, data)
+        self._entries[index] = (file, offset, data)
         self._file.write("%s\0%d\n" % (file, offset))
         self._file.flush()
 
@@ -486,7 +486,7 @@
                     # Abort may be raise by read only opener
                     self._report("couldn't remove %s: %s\n"
                                  % (vfs.join(b), inst))
-        self.entries = []
+        self._entries = []
         self._writeundo()
         if self._after:
             self._after()
@@ -564,7 +564,7 @@
         self._backupsfile.close()
 
         try:
-            if not self.entries and not self._backupentries:
+            if not self._entries and not self._backupentries:
                 if self._backupjournal:
                     self._opener.unlink(self._backupjournal)
                 if self._journal:
@@ -579,7 +579,7 @@
                 # Prevent double usage and help clear cycles.
                 self._abortcallback = None
                 _playback(self._journal, self._report, self._opener,
-                          self._vfsmap, self.entries, self._backupentries,
+                          self._vfsmap, self._entries, self._backupentries,
                           False, checkambigfiles=self._checkambigfiles)
                 self._report(_("rollback completed\n"))
             except BaseException: