diff mercurial/transaction.py @ 23904:d251da5e0e84

transaction: include backup file in the "undo" transaction

Once the transaction is closed, we now write transaction related data for
possible future undo. For now, we only do it for full file "backup" because
their were not handle at all in that case. In the future, we could move all the
current logic to set undo up (that currently exists in localrepository) inside
transaction itself, but it is not strictly requires to solve the current
situation.

--- a/mercurial/transaction.py	Fri Jan 16 19:35:04 2015 -0800
+++ b/mercurial/transaction.py	Fri Jan 16 18:34:14 2015 -0800
@@ -405,6 +405,7 @@
                     self.report("couldn't remote %s: %s\n"
                                 % (vfs.join(b), inst))
         self.entries = []
+        self._writeundo()
         if self.after:
             self.after()
         if self.opener.isfile(self.journal):
@@ -440,6 +441,32 @@
         scope)'''
         self._abort()
 
+    def _writeundo(self):
+        """write transaction data for possible future undo call"""
+        if self.undoname is None:
+            return
+        undobackupfile = self.opener.open("%s.backupfiles" % self.undoname, 'w')
+        undobackupfile.write('%d\n' % version)
+        for l, f, b, c in self._backupentries:
+            if not f:  # temporary file
+                continue
+            if not b:
+                u = ''
+            else:
+                if l not in self._vfsmap and c:
+                    self.report("couldn't remote %s: unknown cache location"
+                                "%s\n" % (b, l))
+                    continue
+                vfs = self._vfsmap[l]
+                base, name = vfs.split(b)
+                assert name.startswith(self.journal), name
+                uname = name.replace(self.journal, self.undoname, 1)
+                u = vfs.reljoin(base, uname)
+                util.copyfile(vfs.join(b), vfs.join(u), hardlink=True)
+            undobackupfile.write("%s\0%s\0%s\0%d\n" % (l, f, u, c))
+        undobackupfile.close()
+
+
     def _abort(self):
         self.count = 0
         self.usages = 0