# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 1411889802 25200
# Node ID 4c6198737ad8fd0d3c4aaedb347355649de35599
# Parent  c4d63f6740b8d371386bdba0030a2b3e196cf517
transaction: allow generating file outside of store

We allow a vfs argument to `addfilegenerator`. This allows generating files outside
of the store directory like bookmarks. However, this is not really working since
we do not have the infrastructure to backup and restore files outside of store.
By chance, the bookmark file is already backed up by another mechanism so we can
restrict this new feature to bookmarks (which is our only interest here) and
proceed.

diff -r c4d63f6740b8 -r 4c6198737ad8 mercurial/transaction.py
--- a/mercurial/transaction.py	Wed Oct 01 21:40:44 2014 -0500
+++ b/mercurial/transaction.py	Sun Sep 28 00:36:42 2014 -0700
@@ -144,7 +144,7 @@
         self.file.flush()
 
     @active
-    def addbackup(self, file, hardlink=True):
+    def addbackup(self, file, hardlink=True, vfs=None):
         """Adds a backup of the file to the transaction
 
         Calling addbackup() creates a hardlink backup of the specified file
@@ -158,8 +158,10 @@
         if file in self.map or file in self.backupmap:
             return
         backupfile = "%s.backup.%s" % (self.journal, file)
-        if self.opener.exists(file):
-            filepath = self.opener.join(file)
+        if vfs is None:
+            vfs = self.opener
+        if vfs.exists(file):
+            filepath = vfs.join(file)
             backuppath = self.opener.join(backupfile)
             util.copyfiles(filepath, backuppath, hardlink=hardlink)
         else:
@@ -176,7 +178,7 @@
         self.backupsfile.flush()
 
     @active
-    def addfilegenerator(self, genid, filenames, genfunc, order=0):
+    def addfilegenerator(self, genid, filenames, genfunc, order=0, vfs=None):
         """add a function to generates some files at transaction commit
 
         The `genfunc` argument is a function capable of generating proper
@@ -195,7 +197,10 @@
         The `order` argument may be used to control the order in which multiple
         generator will be executed.
         """
-        self._filegenerators[genid] = (order, filenames, genfunc)
+        # For now, we are unable to do proper backup and restore of custom vfs
+        # but for bookmarks that are handled outside this mechanism.
+        assert vfs is None or filenames == ('bookmarks',)
+        self._filegenerators[genid] = (order, filenames, genfunc, vfs)
 
     @active
     def find(self, file):
@@ -239,16 +244,19 @@
     def close(self):
         '''commit the transaction'''
         # write files registered for generation
-        for order, filenames, genfunc in sorted(self._filegenerators.values()):
+        for entry in sorted(self._filegenerators.values()):
+            order, filenames, genfunc, vfs = entry
+            if vfs is None:
+                vfs = self.opener
             files = []
             try:
                 for name in filenames:
                     # Some files are already backed up when creating the
                     # localrepo. Until this is properly fixed we disable the
                     # backup for them.
-                    if name not in ('phaseroots',):
+                    if name not in ('phaseroots', 'bookmarks'):
                         self.addbackup(name)
-                    files.append(self.opener(name, 'w', atomictemp=True))
+                    files.append(vfs(name, 'w', atomictemp=True))
                 genfunc(*files)
             finally:
                 for f in files: