obsmarker: add `date` as an explicit field

obsmarker: add `date` as an explicit field

The markers are now 5-item tuples (concluded by the date). The obsstore.fields
contents have been updated accordingly.

There is no change to the on-disk format yet, so the date has to be extracted
every time we read binary markers and re-injected each team we write them. This
introduces a slowdown that will be solved when a new version of the format is
added. Such a slowdown was already introduced by the evolve extension anyway.

--- a/mercurial/obsolete.py	Tue Aug 12 01:49:38 2014 -0700
+++ b/mercurial/obsolete.py	Tue Aug 19 10:01:06 2014 -0700
@@ -168,7 +168,12 @@
                                'short, %d bytes expected, got %d')
                              % (mdsize, len(metadata)))
         off += mdsize
-        yield (pre, sucs, flags, metadata)
+        try:
+            date = util.parsedate(decodemeta(metadata).pop('date', '0 0'))
+        except util.Abort:
+            date = (0., 0)
+
+        yield (pre, sucs, flags, metadata, date)
 
 def encodemeta(meta):
     """Return encoded metadata string to string mapping.
@@ -223,8 +228,7 @@
 
     def date(self):
         """Creation date as (unixtime, offset)"""
-        parts = self.metadata()['date'].split(' ')
-        return (float(parts[0]), int(parts[1]))
+        return self._data[4]
 
     def flags(self):
         """The flags field of the marker"""
@@ -238,7 +242,7 @@
     - successors[x] -> set(markers on successors edges of x)
     """
 
-    fields = ('prec', 'succs', 'flag', 'meta')
+    fields = ('prec', 'succs', 'flag', 'meta', 'date')
 
     def __init__(self, sopener):
         # caches for various obsolescence related cache
@@ -277,10 +281,12 @@
         """
         if metadata is None:
             metadata = {}
-        if 'date' not in metadata:
-            if date is None:
+        if date is None:
+            if 'date' in metadata:
+                # as a courtesy for out-of-tree extensions
+                date = util.parsedate(metadata.pop('date'))
+            else:
                 date = util.makedate()
-            metadata['date'] = "%d %d" % date
         if len(prec) != 20:
             raise ValueError(prec)
         for succ in succs:
@@ -288,7 +294,8 @@
                 raise ValueError(succ)
         if prec in succs:
             raise ValueError(_('in-marker cycle with %s') % node.hex(prec))
-        marker = (str(prec), tuple(succs), int(flag), encodemeta(metadata))
+        marker = (str(prec), tuple(succs), int(flag), encodemeta(metadata),
+                  date)
         return bool(self.add(transaction, [marker]))
 
     def add(self, transaction, markers):
@@ -352,7 +359,10 @@
 
 
 def _encodeonemarker(marker):
-    pre, sucs, flags, metadata = marker
+    pre, sucs, flags, metadata, date = marker
+    metadata = decodemeta(metadata)
+    metadata['date'] = '%d %i' % date
+    metadata = encodemeta(metadata)
     nbsuc = len(sucs)
     format = _fmfixed + (_fmnode * nbsuc)
     data = [nbsuc, len(metadata), flags, pre]