Rev 5108: Another policy object. in http://bzr.arbash-meinel.com/branches/bzr/lp/2.2.0b2-contained-pack

[John Arbash Meinel]

At http://bzr.arbash-meinel.com/branches/bzr/lp/2.2.0b2-contained-pack

------------------------------------------------------------
revno: 5108
revision-id: john at arbash-meinel.com-20100309180751-y6i1eub2mbkabjw6
parent: john at arbash-meinel.com-20100309174226-210ezid8ioe8575n
committer: John Arbash Meinel <john at arbash-meinel.com>
branch nick: 2.2.0b2-contained-pack
timestamp: Tue 2010-03-09 12:07:51 -0600
message:
  Another policy object.
  
  I'm worried I'm going a bit overboard, but it is also nice to have the
  discrete units of logic self-contained, rather than always being
  aggregated into a single class.
-------------- next part --------------
=== modified file 'bzrlib/pack_collection.py'
--- a/bzrlib/pack_collection.py	2010-03-09 17:42:26 +0000
+++ b/bzrlib/pack_collection.py	2010-03-09 18:07:51 +0000
@@ -461,16 +461,29 @@
         """Return a byte string that can be used to initialize indexes."""
         raise NotImplementedError(self.get_index_memo)
 
-    @classmethod
-    def from_index_memo(cls, collection, name, memo):
-        """Return a new Pack instance, initialized from the given index memo.
+
+class PackPolicy(object):
+    """Description of how we want to manage pack files.
+    
+    This handles stuff like 'do we write to one directory, and then rename to
+    another (upload/ vs packs/)'. Or do we just use one location, etc.
+    """
+
+    _pack_class = Pack # XXX: ExistingPack?
+
+    def __init__(self):
+        pass
+
+    def open_pack_from_memo(self, name, memo):
+        """Return a Pack instance, initialized from the given index memo.
 
         :param collection: A PackCollection that this pack is associated with
+        :param name: The 'name' associated with this memo (eg, pack filename)
         :param memo: A memo that was returned by 'get_index_memo' at some point
             previously.
         :return: A Pack instance
         """
-        raise NotImplementedError(cls.from_index_memo)
+        raise NotImplementedError(self.create_pack_from_memo)
 
 
 class PackCollection(object):
@@ -484,8 +497,8 @@
 
     # TODO: _new_pack_class
 
-    def __init__(self, memo_tracker, pack_class):
-        self._pack_class = pack_class
+    def __init__(self, memo_tracker, pack_policy):
+        self.pack_policy = pack_policy
         self.memo_tracker = memo_tracker
         self.memo_tracker.update_policy = PackCollectionUpdatePolicy(self)
         self._packs = {}
@@ -496,7 +509,7 @@
 
     def _add_pack_from_memo(self, name, value):
         assert name not in self._packs
-        pack = self._pack_class.from_index_memo(self, name, value)
+        pack = self.pack_policy.open_pack_from_memo(name, value)
         self._packs[name] = pack
         # TODO: Do something with the aggregate indexes
         for name, index in pack.get_indexes().iteritems():

=== modified file 'bzrlib/tests/test_pack_collection.py'
--- a/bzrlib/tests/test_pack_collection.py	2010-03-09 17:42:26 +0000
+++ b/bzrlib/tests/test_pack_collection.py	2010-03-09 18:07:51 +0000
@@ -431,23 +431,24 @@
                          ], policy.log)
 
 
-class TestPack(pack_collection.Pack):
-    """A class which defines a couple indexes, and exposes them."""
+class SingleTransportPackPolicy(pack_collection.PackPolicy):
+    """Packs are created and finished in a single transport location.
+
+    Indexes are also located in the same transport.
+    """
 
     _index_class = btree_index.BTreeGraphIndex
 
-    def get_index_memo(self):
-        return bencode.bencode(self._index_info)
+    def __init__(self, transport):
+        self.transport = transport
 
-    @classmethod
-    def from_index_memo(cls, collection, name, memo):
+    def open_pack_from_memo(self, name, memo):
         info = bencode.bdecode(memo)
         assert isinstance(info, dict)
-        p = cls(name)
+        p = pack_collection.Pack(name)
         for index_name, info in info.iteritems():
             size, = info
-            trans = collection.memo_tracker.index_policy.transport
-            index = cls._index_class(trans, name, size=size)
+            index = self._index_class(self.transport, name, size=size)
             p._indexes[index_name] = index
         p._index_info = info
         return p
@@ -463,7 +464,8 @@
 
     def test_init_from_empty_tracker(self):
         tracker = self.make_tracker()
-        collection = pack_collection.PackCollection(tracker, TestPack)
+        collection = pack_collection.PackCollection(tracker,
+            SingleTransportPackPolicy(self.get_transport()))
         self.assertEqual({}, collection._packs)
         self.assertEqual({}, collection._aggregate_indexes)
 
@@ -471,5 +473,6 @@
         memo = bencode.bencode({'t_index': (1024,)})
         tracker = self.make_tracker()
         tracker.add_memo('t-pack', memo)
-        collection = pack_collection.PackCollection(tracker, TestPack)
+        collection = pack_collection.PackCollection(tracker,
+            SingleTransportPackPolicy(self.get_transport()))
         self.assertEqual(['t-pack'], sorted(collection._packs.keys()))