Begin implementing all the PDU storage stuff in Events land

9 files changed, 485 insertions, 42 deletions

diff --git a/synapse/api/events/__init__.py b/synapse/api/events/__init__.py
index a5a55742e0..b855811b98 100644
--- a/synapse/api/events/__init__.py
+++ b/synapse/api/events/__init__.py
@@ -71,7 +71,9 @@ class SynapseEvent(JsonEncodedObject):
         "outlier",
         "power_level",
         "redacted",
-        "prev_pdus",
+        "prev_events",
+        "hashes",
+        "signatures",
     ]
 
     required_keys = [
diff --git a/synapse/federation/pdu_codec.py b/synapse/federation/pdu_codec.py
index 991aae2a56..2cd591410b 100644
--- a/synapse/federation/pdu_codec.py
+++ b/synapse/federation/pdu_codec.py
@@ -47,7 +47,10 @@ class PduCodec(object):
         kwargs["event_id"] = encode_event_id(pdu.pdu_id, pdu.origin)
         kwargs["room_id"] = pdu.context
         kwargs["etype"] = pdu.pdu_type
-        kwargs["prev_pdus"] = pdu.prev_pdus
+        kwargs["prev_events"] = [
+            encode_event_id(i, o)
+            for i, o in pdu.prev_pdus
+        ]
 
         if hasattr(pdu, "prev_state_id") and hasattr(pdu, "prev_state_origin"):
             kwargs["prev_state"] = encode_event_id(
@@ -78,8 +81,8 @@ class PduCodec(object):
         d["context"] = event.room_id
         d["pdu_type"] = event.type
 
-        if hasattr(event, "prev_pdus"):
-            d["prev_pdus"] = event.prev_pdus
+        if hasattr(event, "prev_events"):
+            d["prev_pdus"] = [decode_event_id(e) for e in event.prev_events]
 
         if hasattr(event, "prev_state"):
             d["prev_state_id"], d["prev_state_origin"] = (
@@ -92,7 +95,7 @@ class PduCodec(object):
         kwargs = copy.deepcopy(event.unrecognized_keys)
         kwargs.update({
             k: v for k, v in d.items()
-            if k not in ["event_id", "room_id", "type"]
+            if k not in ["event_id", "room_id", "type", "prev_events"]
         })
 
         if "origin_server_ts" not in kwargs:
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index a50e19349a..678de0cf50 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -40,6 +40,7 @@ from .stream import StreamStore
 from .pdu import StatePduStore, PduStore, PdusTable
 from .transactions import TransactionStore
 from .keys import KeyStore
+from .event_federation import EventFederationStore
 
 from .state import StateStore
 from .signatures import SignatureStore
@@ -69,6 +70,7 @@ SCHEMAS = [
     "redactions",
     "state",
     "signatures",
+    "event_edges",
 ]
 
 
@@ -83,10 +85,12 @@ class _RollbackButIsFineException(Exception):
     """
     pass
 
+
 class DataStore(RoomMemberStore, RoomStore,
                 RegistrationStore, StreamStore, ProfileStore, FeedbackStore,
                 PresenceStore, PduStore, StatePduStore, TransactionStore,
-                DirectoryStore, KeyStore, StateStore, SignatureStore):
+                DirectoryStore, KeyStore, StateStore, SignatureStore,
+                EventFederationStore, ):
 
     def __init__(self, hs):
         super(DataStore, self).__init__(hs)
@@ -230,6 +234,10 @@ class DataStore(RoomMemberStore, RoomStore,
         elif event.type == RoomRedactionEvent.TYPE:
             self._store_redaction(txn, event)
 
+        outlier = False
+        if hasattr(event, "outlier"):
+            outlier = event.outlier
+
         vals = {
             "topological_ordering": event.depth,
             "event_id": event.event_id,
@@ -237,20 +245,20 @@ class DataStore(RoomMemberStore, RoomStore,
             "room_id": event.room_id,
             "content": json.dumps(event.content),
             "processed": True,
+            "outlier": outlier,
+            "depth": event.depth,
         }
 
         if stream_ordering is not None:
             vals["stream_ordering"] = stream_ordering
 
-        if hasattr(event, "outlier"):
-            vals["outlier"] = event.outlier
-        else:
-            vals["outlier"] = False
-
         unrec = {
             k: v
             for k, v in event.get_full_dict().items()
-            if k not in vals.keys() and k not in ["redacted", "redacted_because"]
+            if k not in vals.keys() and k not in [
+                "redacted", "redacted_because", "signatures", "hashes",
+                "prev_events",
+            ]
         }
         vals["unrecognized_keys"] = json.dumps(unrec)
 
@@ -264,6 +272,14 @@ class DataStore(RoomMemberStore, RoomStore,
             )
             raise _RollbackButIsFineException("_persist_event")
 
+        self._handle_prev_events(
+            txn,
+            outlier=outlier,
+            event_id=event.event_id,
+            prev_events=event.prev_events,
+            room_id=event.room_id,
+        )
+
         self._store_state_groups_txn(txn, event)
 
         is_state = hasattr(event, "state_key") and event.state_key is not None
@@ -291,6 +307,28 @@ class DataStore(RoomMemberStore, RoomStore,
                 }
             )
 
+        signatures = event.signatures.get(event.origin, {})
+
+        for key_id, signature_base64 in signatures.items():
+            signature_bytes = decode_base64(signature_base64)
+            self._store_event_origin_signature_txn(
+                txn, event.event_id, key_id, signature_bytes,
+            )
+
+        for prev_event_id, prev_hashes in event.prev_events:
+            for alg, hash_base64 in prev_hashes.items():
+                hash_bytes = decode_base64(hash_base64)
+                self._store_prev_event_hash_txn(
+                    txn, event.event_id, prev_event_id, alg, hash_bytes
+                )
+
+        (ref_alg, ref_hash_bytes) = compute_pdu_event_reference_hash(pdu)
+        self._store_pdu_reference_hash_txn(
+            txn, pdu.pdu_id, pdu.origin, ref_alg, ref_hash_bytes
+        )
+
+        self._update_min_depth_for_room_txn(txn, event.room_id, event.depth)
+
     def _store_redaction(self, txn, event):
         txn.execute(
             "INSERT OR IGNORE INTO redactions "
@@ -373,7 +411,7 @@ class DataStore(RoomMemberStore, RoomStore,
         """
         def _snapshot(txn):
             membership_state = self._get_room_member(txn, user_id, room_id)
-            prev_pdus = self._get_latest_pdus_in_context(
+            prev_events = self._get_latest_events_in_room(
                 txn, room_id
             )
 
@@ -388,7 +426,7 @@ class DataStore(RoomMemberStore, RoomStore,
                 store=self,
                 room_id=room_id,
                 user_id=user_id,
-                prev_pdus=prev_pdus,
+                prev_events=prev_events,
                 membership_state=membership_state,
                 state_type=state_type,
                 state_key=state_key,
@@ -404,7 +442,7 @@ class Snapshot(object):
         store (DataStore): The datastore.
         room_id (RoomId): The room of the snapshot.
         user_id (UserId): The user this snapshot is for.
-        prev_pdus (list): The list of PDU ids this snapshot is after.
+        prev_events (list): The list of event ids this snapshot is after.
         membership_state (RoomMemberEvent): The current state of the user in
             the room.
         state_type (str, optional): State type captured by the snapshot
@@ -413,29 +451,29 @@ class Snapshot(object):
             the previous value of the state type and key in the room.
     """
 
-    def __init__(self, store, room_id, user_id, prev_pdus,
+    def __init__(self, store, room_id, user_id, prev_events,
                  membership_state, state_type=None, state_key=None,
                  prev_state_pdu=None):
         self.store = store
         self.room_id = room_id
         self.user_id = user_id
-        self.prev_pdus = prev_pdus
+        self.prev_events = prev_events
         self.membership_state = membership_state
         self.state_type = state_type
         self.state_key = state_key
         self.prev_state_pdu = prev_state_pdu
 
     def fill_out_prev_events(self, event):
-        if hasattr(event, "prev_pdus"):
+        if hasattr(event, "prev_events"):
             return
 
-        event.prev_pdus = [
+        event.prev_events = [
             (p_id, origin, hashes)
-            for p_id, origin, hashes, _ in self.prev_pdus
+            for p_id, origin, hashes, _ in self.prev_events
         ]
 
-        if self.prev_pdus:
-            event.depth = max([int(v) for _, _, _, v in self.prev_pdus]) + 1
+        if self.prev_events:
+            event.depth = max([int(v) for _, _, _, v in self.prev_events]) + 1
         else:
             event.depth = 0
 
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 1192216971..30732caa83 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -193,7 +193,6 @@ class SQLBaseStore(object):
             table, keyvalues, retcols=retcols, allow_none=allow_none
         )
 
-    @defer.inlineCallbacks
     def _simple_select_one_onecol(self, table, keyvalues, retcol,
                                   allow_none=False):
         """Executes a SELECT query on the named table, which is expected to
@@ -204,19 +203,41 @@ class SQLBaseStore(object):
             keyvalues : dict of column names and values to select the row with
             retcol : string giving the name of the column to return
         """
-        ret = yield self._simple_select_one(
+        return self.runInteraction(
+            "_simple_select_one_onecol_txn",
+            self._simple_select_one_onecol_txn,
+            table, keyvalues, retcol, allow_none=allow_none,
+        )
+
+    def _simple_select_one_onecol_txn(self, txn, table, keyvalues, retcol,
+                                      allow_none=False):
+        ret = self._simple_select_onecol_txn(
+            txn,
             table=table,
             keyvalues=keyvalues,
-            retcols=[retcol],
-            allow_none=allow_none
+            retcols=retcol,
         )
 
         if ret:
-            defer.returnValue(ret[retcol])
+            return ret[retcol]
         else:
-            defer.returnValue(None)
+            if allow_none:
+                return None
+            else:
+                raise StoreError(404, "No row found")
+
+    def _simple_select_onecol_txn(self, txn, table, keyvalues, retcol):
+        sql = "SELECT %(retcol)s FROM %(table)s WHERE %(where)s" % {
+            "retcol": retcol,
+            "table": table,
+            "where": " AND ".join("%s = ?" % k for k in keyvalues.keys()),
+        }
+
+        txn.execute(sql, keyvalues.values())
+
+        return [r[0] for r in txn.fetchall()]
+
 
-    @defer.inlineCallbacks
     def _simple_select_onecol(self, table, keyvalues, retcol):
         """Executes a SELECT query on the named table, which returns a list
         comprising of the values of the named column from the selected rows.
@@ -229,19 +250,11 @@ class SQLBaseStore(object):
         Returns:
             Deferred: Results in a list
         """
-        sql = "SELECT %(retcol)s FROM %(table)s WHERE %(where)s" % {
-            "retcol": retcol,
-            "table": table,
-            "where": " AND ".join("%s = ?" % k for k in keyvalues.keys()),
-        }
-
-        def func(txn):
-            txn.execute(sql, keyvalues.values())
-            return txn.fetchall()
-
-        res = yield self.runInteraction("_simple_select_onecol", func)
-
-        defer.returnValue([r[0] for r in res])
+        return self.runInteraction(
+            "_simple_select_onecol",
+            self._simple_select_onecol_txn,
+            table, keyvalues, retcol
+        )
 
     def _simple_select_list(self, table, keyvalues, retcols):
         """Executes a SELECT query on the named table, which may return zero or
diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py
new file mode 100644
index 0000000000..27ad9aea4d
--- /dev/null
+++ b/synapse/storage/event_federation.py
@@ -0,0 +1,143 @@
+# -*- coding: utf-8 -*-
+# Copyright 2014 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ._base import SQLBaseStore
+from twisted.internet import defer
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+class EventFederationStore(SQLBaseStore):
+
+    def _get_latest_events_in_room(self, txn, room_id):
+        self._simple_select_onecol_txn(
+            txn,
+            table="event_forward_extremities",
+            keyvalues={
+                "room_id": room_id,
+            },
+            retcol="event_id",
+        )
+
+        results = []
+        for pdu_id, origin, depth in txn.fetchall():
+            hashes = self._get_pdu_reference_hashes_txn(txn, pdu_id, origin)
+            sha256_bytes = hashes["sha256"]
+            prev_hashes = {"sha256": encode_base64(sha256_bytes)}
+            results.append((pdu_id, origin, prev_hashes, depth))
+
+    def _get_min_depth_interaction(self, txn, room_id):
+        min_depth = self._simple_select_one_onecol_txn(
+            txn,
+            table="room_depth",
+            keyvalues={"room_id": room_id,},
+            retcol="min_depth",
+            allow_none=True,
+        )
+
+        return int(min_depth) if min_depth is not None else None
+
+    def _update_min_depth_for_room_txn(self, txn, room_id, depth):
+        min_depth = self._get_min_depth_interaction(txn, room_id)
+
+        do_insert = depth < min_depth if min_depth else True
+
+        if do_insert:
+            self._simple_insert_txn(
+                txn,
+                table="room_depth",
+                values={
+                    "room_id": room_id,
+                    "min_depth": depth,
+                },
+                or_replace=True,
+            )
+
+    def _handle_prev_events(self, txn, outlier, event_id, prev_events,
+                            room_id):
+        for e_id in prev_events:
+            # TODO (erikj): This could be done as a bulk insert
+            self._simple_insert_txn(
+                txn,
+                table="event_edges",
+                values={
+                    "event_id": event_id,
+                    "prev_event": e_id,
+                    "room_id": room_id,
+                }
+            )
+
+        # Update the extremities table if this is not an outlier.
+        if not outlier:
+            for e_id in prev_events:
+                # TODO (erikj): This could be done as a bulk insert
+                self._simple_delete_txn(
+                    txn,
+                    table="event_forward_extremities",
+                    keyvalues={
+                        "event_id": e_id,
+                        "room_id": room_id,
+                    }
+                )
+
+
+
+            # We only insert as a forward extremity the new pdu if there are no
+            # other pdus that reference it as a prev pdu
+            query = (
+                "INSERT INTO %(table)s (event_id, room_id) "
+                "SELECT ?, ? WHERE NOT EXISTS ("
+                "SELECT 1 FROM %(event_edges)s WHERE "
+                "prev_event_id = ? "
+                ")"
+            ) % {
+                "table": "event_forward_extremities",
+                "event_edges": "event_edges",
+            }
+
+            logger.debug("query: %s", query)
+
+            txn.execute(query, (event_id, room_id, event_id))
+
+            # Insert all the prev_pdus as a backwards thing, they'll get
+            # deleted in a second if they're incorrect anyway.
+            for e_id in prev_events:
+                # TODO (erikj): This could be done as a bulk insert
+                self._simple_insert_txn(
+                    txn,
+                    table="event_backward_extremities",
+                    values={
+                        "event_id": e_id,
+                        "room_id": room_id,
+                    }
+                )
+
+            # Also delete from the backwards extremities table all ones that
+            # reference pdus that we have already seen
+            query = (
+                "DELETE FROM %(event_back)s as b WHERE EXISTS ("
+                "SELECT 1 FROM %(events)s AS events "
+                "WHERE "
+                "b.event_id = events.event_id "
+                "AND not events.outlier "
+                ")"
+            ) % {
+                "event_back": "event_backward_extremities",
+                "events": "events",
+            }
+            txn.execute(query)
\ No newline at end of file
diff --git a/synapse/storage/schema/event_edges.sql b/synapse/storage/schema/event_edges.sql
new file mode 100644
index 0000000000..6a28314ece
--- /dev/null
+++ b/synapse/storage/schema/event_edges.sql
@@ -0,0 +1,51 @@
+
+CREATE TABLE IF NOT EXISTS event_forward_extremities(
+    event_id TEXT,
+    room_id TEXT,
+    CONSTRAINT uniqueness UNIQUE (event_id, room_id) ON CONFLICT REPLACE
+);
+
+CREATE INDEX IF NOT EXISTS ev_extrem_room ON event_forward_extremities(room_id);
+CREATE INDEX IF NOT EXISTS ev_extrem_id ON event_forward_extremities(event_id);
+--
+
+CREATE TABLE IF NOT EXISTS event_backward_extremities(
+    event_id TEXT,
+    room_id TEXT,
+    CONSTRAINT uniqueness UNIQUE (event_id, room_id) ON CONFLICT REPLACE
+);
+
+CREATE INDEX IF NOT EXISTS ev_b_extrem_room ON event_backward_extremities(room_id);
+CREATE INDEX IF NOT EXISTS ev_b_extrem_id ON event_backward_extremities(event_id);
+--
+
+CREATE TABLE IF NOT EXISTS event_edges(
+    event_id TEXT,
+    prev_event_id TEXT,
+    room_id TEXT,
+    CONSTRAINT uniqueness UNIQUE (event_id, prev_event_id, room_id)
+);
+
+CREATE INDEX IF NOT EXISTS ev_edges_id ON event_edges(event_id);
+CREATE INDEX IF NOT EXISTS ev_edges_prev_id ON event_edges(prev_event_id);
+--
+
+
+CREATE TABLE IF NOT EXISTS room_depth(
+    room_id TEXT,
+    min_depth INTEGER,
+    CONSTRAINT uniqueness UNIQUE (room_id)
+);
+
+CREATE INDEX IF NOT EXISTS room_depth_room ON room_depth(room_id);
+--
+
+create TABLE IF NOT EXISTS event_destinations(
+    event_id TEXT,
+    destination TEXT,
+    delivered_ts INTEGER DEFAULT 0, -- or 0 if not delivered
+    CONSTRAINT uniqueness UNIQUE (event_id, destination) ON CONFLICT REPLACE
+);
+
+CREATE INDEX IF NOT EXISTS event_destinations_id ON event_destinations(event_id);
+--
\ No newline at end of file
diff --git a/synapse/storage/schema/event_signatures.sql b/synapse/storage/schema/event_signatures.sql
new file mode 100644
index 0000000000..5491c7ecec
--- /dev/null
+++ b/synapse/storage/schema/event_signatures.sql
@@ -0,0 +1,65 @@
+/* Copyright 2014 OpenMarket Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+CREATE TABLE IF NOT EXISTS event_content_hashes (
+    event_id TEXT,
+    algorithm TEXT,
+    hash BLOB,
+    CONSTRAINT uniqueness UNIQUE (event_id, algorithm)
+);
+
+CREATE INDEX IF NOT EXISTS event_content_hashes_id ON event_content_hashes(
+    event_id
+);
+
+
+CREATE TABLE IF NOT EXISTS event_reference_hashes (
+    event_id TEXT,
+    algorithm TEXT,
+    hash BLOB,
+    CONSTRAINT uniqueness UNIQUE (event_id, algorithm)
+);
+
+CREATE INDEX IF NOT EXISTS event_reference_hashes_id ON event_reference_hashes (
+    event_id
+);
+
+
+CREATE TABLE IF NOT EXISTS event_origin_signatures (
+    event_id TEXT,
+    origin TEXT,
+    key_id TEXT,
+    signature BLOB,
+    CONSTRAINT uniqueness UNIQUE (event_id, key_id)
+);
+
+CREATE INDEX IF NOT EXISTS event_origin_signatures_id ON event_origin_signatures (
+    event_id
+);
+
+
+CREATE TABLE IF NOT EXISTS event_edge_hashes(
+    event_id TEXT,
+    prev_event_id TEXT,
+    algorithm TEXT,
+    hash BLOB,
+    CONSTRAINT uniqueness UNIQUE (
+        event_id, prev_event_id, algorithm
+    )
+);
+
+CREATE INDEX IF NOT EXISTS event_edge_hashes_id ON event_edge_hashes(
+    event_id
+);
diff --git a/synapse/storage/schema/im.sql b/synapse/storage/schema/im.sql
index 3aa83f5c8c..8d6f655993 100644
--- a/synapse/storage/schema/im.sql
+++ b/synapse/storage/schema/im.sql
@@ -23,6 +23,7 @@ CREATE TABLE IF NOT EXISTS events(
     unrecognized_keys TEXT,
     processed BOOL NOT NULL,
     outlier BOOL NOT NULL,
+    depth INTEGER DEFAULT 0 NOT NULL,
     CONSTRAINT ev_uniq UNIQUE (event_id)
 );
 
diff --git a/synapse/storage/signatures.py b/synapse/storage/signatures.py
index 82be946d3f..b8f8fd44cb 100644
--- a/synapse/storage/signatures.py
+++ b/synapse/storage/signatures.py
@@ -153,3 +153,130 @@ class SignatureStore(SQLBaseStore):
             "algorithm": algorithm,
             "hash": buffer(hash_bytes),
         })
+
+    ## Events ##
+
+    def _get_event_content_hashes_txn(self, txn, event_id):
+        """Get all the hashes for a given Event.
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+        Returns:
+            A dict of algorithm -> hash.
+        """
+        query = (
+            "SELECT algorithm, hash"
+            " FROM event_content_hashes"
+            " WHERE event_id = ?"
+        )
+        txn.execute(query, (event_id, ))
+        return dict(txn.fetchall())
+
+    def _store_event_content_hash_txn(self, txn, event_id, algorithm,
+                                    hash_bytes):
+        """Store a hash for a Event
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+            algorithm (str): Hashing algorithm.
+            hash_bytes (bytes): Hash function output bytes.
+        """
+        self._simple_insert_txn(txn, "event_content_hashes", {
+            "event_id": event_id,
+            "algorithm": algorithm,
+            "hash": buffer(hash_bytes),
+        })
+
+    def _get_event_reference_hashes_txn(self, txn, event_id):
+        """Get all the hashes for a given PDU.
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+        Returns:
+            A dict of algorithm -> hash.
+        """
+        query = (
+            "SELECT algorithm, hash"
+            " FROM event_reference_hashes"
+            " WHERE event_id = ?"
+        )
+        txn.execute(query, (event_id, ))
+        return dict(txn.fetchall())
+
+    def _store_event_reference_hash_txn(self, txn, event_id, algorithm,
+                                      hash_bytes):
+        """Store a hash for a PDU
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+            algorithm (str): Hashing algorithm.
+            hash_bytes (bytes): Hash function output bytes.
+        """
+        self._simple_insert_txn(txn, "event_reference_hashes", {
+            "event_id": event_id,
+            "algorithm": algorithm,
+            "hash": buffer(hash_bytes),
+        })
+
+
+    def _get_event_origin_signatures_txn(self, txn, event_id):
+        """Get all the signatures for a given PDU.
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+        Returns:
+            A dict of key_id -> signature_bytes.
+        """
+        query = (
+            "SELECT key_id, signature"
+            " FROM event_origin_signatures"
+            " WHERE event_id = ? "
+        )
+        txn.execute(query, (event_id, ))
+        return dict(txn.fetchall())
+
+    def _store_event_origin_signature_txn(self, txn, event_id, origin, key_id,
+                                          signature_bytes):
+        """Store a signature from the origin server for a PDU.
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+            origin (str): origin of the Event.
+            key_id (str): Id for the signing key.
+            signature (bytes): The signature.
+        """
+        self._simple_insert_txn(txn, "event_origin_signatures", {
+            "event_id": event_id,
+            "origin": origin,
+            "key_id": key_id,
+            "signature": buffer(signature_bytes),
+        })
+
+    def _get_prev_event_hashes_txn(self, txn, event_id):
+        """Get all the hashes for previous PDUs of a PDU
+        Args:
+            txn (cursor):
+            event_id (str): Id for the Event.
+        Returns:
+            dict of (pdu_id, origin) -> dict of algorithm -> hash_bytes.
+        """
+        query = (
+            "SELECT prev_event_id, algorithm, hash"
+            " FROM event_edge_hashes"
+            " WHERE event_id = ?"
+        )
+        txn.execute(query, (event_id, ))
+        results = {}
+        for prev_event_id, algorithm, hash_bytes in txn.fetchall():
+            hashes = results.setdefault(prev_event_id, {})
+            hashes[algorithm] = hash_bytes
+        return results
+
+    def _store_prev_event_hash_txn(self, txn, event_id, prev_event_id,
+                                 algorithm, hash_bytes):
+        self._simple_insert_txn(txn, "event_edge_hashes", {
+            "event_id": event_id,
+            "prev_event_id": prev_event_id,
+            "algorithm": algorithm,
+            "hash": buffer(hash_bytes),
+        })
\ No newline at end of file