Add CowTree for storing chunk index data

Also, add a a real implementation of LeafStore, with persistence.

5 files changed, 114 insertions, 1 deletions

diff --git a/obnamlib/__init__.py b/obnamlib/__init__.py
index 9590fe7a..21428777 100644
--- a/obnamlib/__init__.py
+++ b/obnamlib/__init__.py
@@ -187,7 +187,9 @@ from .fmt_ga import (
     GAChunkStore,
     GAChunkIndexes,
     InMemoryLeafStore,
+    LeafStore,
     CowLeaf,
+    CowTree,
 )
 
 
diff --git a/obnamlib/fmt_ga/__init__.py b/obnamlib/fmt_ga/__init__.py
index 394d3c31..8797948a 100644
--- a/obnamlib/fmt_ga/__init__.py
+++ b/obnamlib/fmt_ga/__init__.py
@@ -17,8 +17,9 @@
 
 from .client_list import GAClientList
 from .chunk_store import GAChunkStore
-from .leaf_store import InMemoryLeafStore
+from .leaf_store import InMemoryLeafStore, LeafStore
 from .leaf import CowLeaf
+from .cowtree import CowTree
 from .indexes import GAChunkIndexes
 from .dirobj import GADirectory, GAImmutableError, create_gadirectory_from_dict
 from .tree import GATree
diff --git a/obnamlib/fmt_ga/cowtree.py b/obnamlib/fmt_ga/cowtree.py
new file mode 100644
index 00000000..7500b089
--- /dev/null
+++ b/obnamlib/fmt_ga/cowtree.py
@@ -0,0 +1,41 @@
+# Copyright 2016  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+import obnamlib
+
+
+class CowTree(object):
+
+    def __init__(self):
+        self._store = None
+        self._leaf = obnamlib.CowLeaf()
+
+    def set_leaf_store(self, leaf_store):
+        self._store = leaf_store
+
+    def set_list_node(self, leaf_id):
+        self._leaf = self._store.get_leaf(leaf_id)
+
+    def lookup(self, key):
+        return self._leaf.lookup(key)
+
+    def insert(self, key, value):
+        self._leaf.insert(key, value)
+
+    def commit(self):
+        return self._store.put_leaf(self._leaf)
diff --git a/obnamlib/fmt_ga/cowtree_tests.py b/obnamlib/fmt_ga/cowtree_tests.py
new file mode 100644
index 00000000..7e8dd114
--- /dev/null
+++ b/obnamlib/fmt_ga/cowtree_tests.py
@@ -0,0 +1,49 @@
+# Copyright 2016  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+import unittest
+
+import obnamlib
+
+
+class CowTreeTests(unittest.TestCase):
+
+    def setUp(self):
+        self.ls = obnamlib.InMemoryLeafStore()
+        self.cow = obnamlib.CowTree()
+        self.cow.set_leaf_store(self.ls)
+
+    def test_lookup_returns_none_if_key_is_missing(self):
+        self.assertEqual(self.cow.lookup(42), None)
+
+    def test_returns_keyvalue_that_has_been_inserted(self):
+        key = 'fookey'
+        value = 'barvalue'
+        self.cow.insert(key, value)
+        self.assertEqual(self.cow.lookup(key), value)
+
+    def test_commits_changes_persistently(self):
+        key = 'fookey'
+        value = 'barvalue'
+        self.cow.insert(key, value)
+        list_id = self.cow.commit()
+
+        cow2 = obnamlib.CowTree()
+        cow2.set_leaf_store(self.ls)
+        cow2.set_list_node(list_id)
+        self.assertEqual(cow2.lookup(key), value)
diff --git a/obnamlib/fmt_ga/leaf_store.py b/obnamlib/fmt_ga/leaf_store.py
index 5a3a8627..b5cb5120 100644
--- a/obnamlib/fmt_ga/leaf_store.py
+++ b/obnamlib/fmt_ga/leaf_store.py
@@ -16,6 +16,9 @@
 # =*= License: GPL-3+ =*=
 
 
+import obnamlib
+
+
 class LeafStoreInterface(object):  # pragma: no cover
 
     def put_leaf(self, leaf):
@@ -38,3 +41,20 @@ class InMemoryLeafStore(LeafStoreInterface):
 
     def get_leaf(self, leaf_id):
         return self._leaves.get(leaf_id, None)
+
+
+class LeafStore(LeafStoreInterface):  # pragma: no cover
+
+    def __init__(self):
+        self._blob_store = None
+
+    def set_blob_store(self, blob_store):
+        self._blob_store = blob_store
+
+    def put_leaf(self, leaf):
+        return self._blob_store.put_blob(leaf.as_dict())
+
+    def get_leaf(self, leaf_id):
+        leaf = obnamlib.CowLeaf()
+        leaf.from_dict(self._blob_store.get_blob(leaf_id))
+        return leaf