Deduplicate FS database, EDU persistence table (#1207)

* Deduplicate FS database, add some EDU persistence groundwork

* Extend TransactionWriter to use optional existing transaction, use that for FS SQLite database writes

* Fix build due to bad keyserver import

* Working EDU persistence

* gocyclo, unsurprisingly

* Remove unused

* Update copyright notices

federationsender/storage/shared/storage.go

@@ -0,0 +1,138 @@
+// Copyright 2020 The Matrix.org Foundation C.I.C.
+//
+// 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.
+
+package shared
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"fmt"
+
+	"github.com/matrix-org/dendrite/federationsender/storage/tables"
+	"github.com/matrix-org/dendrite/federationsender/types"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type Database struct {
+	DB                          *sql.DB
+	FederationSenderQueuePDUs   tables.FederationSenderQueuePDUs
+	FederationSenderQueueEDUs   tables.FederationSenderQueueEDUs
+	FederationSenderQueueJSON   tables.FederationSenderQueueJSON
+	FederationSenderJoinedHosts tables.FederationSenderJoinedHosts
+	FederationSenderRooms       tables.FederationSenderRooms
+}
+
+// An Receipt contains the NIDs of a call to GetNextTransactionPDUs/EDUs.
+// We don't actually export the NIDs but we need the caller to be able
+// to pass them back so that we can clean up if the transaction sends
+// successfully.
+type Receipt struct {
+	nids []int64
+}
+
+func (e *Receipt) Empty() bool {
+	return len(e.nids) == 0
+}
+
+func (e *Receipt) String() string {
+	j, _ := json.Marshal(e.nids)
+	return string(j)
+}
+
+// UpdateRoom updates the joined hosts for a room and returns what the joined
+// hosts were before the update, or nil if this was a duplicate message.
+// This is called when we receive a message from kafka, so we pass in
+// oldEventID and newEventID to check that we haven't missed any messages or
+// this isn't a duplicate message.
+func (d *Database) UpdateRoom(
+	ctx context.Context,
+	roomID, oldEventID, newEventID string,
+	addHosts []types.JoinedHost,
+	removeHosts []string,
+) (joinedHosts []types.JoinedHost, err error) {
+	err = sqlutil.WithTransaction(d.DB, func(txn *sql.Tx) error {
+		err = d.FederationSenderRooms.InsertRoom(ctx, txn, roomID)
+		if err != nil {
+			return err
+		}
+
+		lastSentEventID, err := d.FederationSenderRooms.SelectRoomForUpdate(ctx, txn, roomID)
+		if err != nil {
+			return err
+		}
+
+		if lastSentEventID == newEventID {
+			// We've handled this message before, so let's just ignore it.
+			// We can only get a duplicate for the last message we processed,
+			// so its enough just to compare the newEventID with lastSentEventID
+			return nil
+		}
+
+		if lastSentEventID != "" && lastSentEventID != oldEventID {
+			return types.EventIDMismatchError{
+				DatabaseID: lastSentEventID, RoomServerID: oldEventID,
+			}
+		}
+
+		joinedHosts, err = d.FederationSenderJoinedHosts.SelectJoinedHostsWithTx(ctx, txn, roomID)
+		if err != nil {
+			return err
+		}
+
+		for _, add := range addHosts {
+			err = d.FederationSenderJoinedHosts.InsertJoinedHosts(ctx, txn, roomID, add.MemberEventID, add.ServerName)
+			if err != nil {
+				return err
+			}
+		}
+		if err = d.FederationSenderJoinedHosts.DeleteJoinedHosts(ctx, txn, removeHosts); err != nil {
+			return err
+		}
+		return d.FederationSenderRooms.UpdateRoom(ctx, txn, roomID, newEventID)
+	})
+	return
+}
+
+// GetJoinedHosts returns the currently joined hosts for room,
+// as known to federationserver.
+// Returns an error if something goes wrong.
+func (d *Database) GetJoinedHosts(
+	ctx context.Context, roomID string,
+) ([]types.JoinedHost, error) {
+	return d.FederationSenderJoinedHosts.SelectJoinedHosts(ctx, roomID)
+}
+
+// GetAllJoinedHosts returns the currently joined hosts for
+// all rooms known to the federation sender.
+// Returns an error if something goes wrong.
+func (d *Database) GetAllJoinedHosts(ctx context.Context) ([]gomatrixserverlib.ServerName, error) {
+	return d.FederationSenderJoinedHosts.SelectAllJoinedHosts(ctx)
+}
+
+// StoreJSON adds a JSON blob into the queue JSON table and returns
+// a NID. The NID will then be used when inserting the per-destination
+// metadata entries.
+func (d *Database) StoreJSON(
+	ctx context.Context, js string,
+) (*Receipt, error) {
+	nid, err := d.FederationSenderQueueJSON.InsertQueueJSON(ctx, nil, js)
+	if err != nil {
+		return nil, fmt.Errorf("d.insertQueueJSON: %w", err)
+	}
+	return &Receipt{
+		nids: []int64{nid},
+	}, nil
+}