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_edus.go

@@ -0,0 +1,143 @@
+// 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"
+	"errors"
+	"fmt"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+// AssociateEDUWithDestination creates an association that the
+// destination queues will use to determine which JSON blobs to send
+// to which servers.
+func (d *Database) AssociateEDUWithDestination(
+	ctx context.Context,
+	serverName gomatrixserverlib.ServerName,
+	receipt *Receipt,
+) error {
+	return sqlutil.WithTransaction(d.DB, func(txn *sql.Tx) error {
+		for _, nid := range receipt.nids {
+			if err := d.FederationSenderQueueEDUs.InsertQueueEDU(
+				ctx,        // context
+				txn,        // SQL transaction
+				"",         // TODO: EDU type for coalescing
+				serverName, // destination server name
+				nid,        // NID from the federationsender_queue_json table
+			); err != nil {
+				return fmt.Errorf("InsertQueueEDU: %w", err)
+			}
+		}
+		return nil
+	})
+}
+
+// GetNextTransactionEDUs retrieves events from the database for
+// the next pending transaction, up to the limit specified.
+func (d *Database) GetNextTransactionEDUs(
+	ctx context.Context,
+	serverName gomatrixserverlib.ServerName,
+	limit int,
+) (
+	edus []*gomatrixserverlib.EDU,
+	receipt *Receipt,
+	err error,
+) {
+	err = sqlutil.WithTransaction(d.DB, func(txn *sql.Tx) error {
+		nids, err := d.FederationSenderQueueEDUs.SelectQueueEDUs(ctx, txn, serverName, limit)
+		if err != nil {
+			return fmt.Errorf("SelectQueueEDUs: %w", err)
+		}
+
+		receipt = &Receipt{
+			nids: nids,
+		}
+
+		blobs, err := d.FederationSenderQueueJSON.SelectQueueJSON(ctx, txn, nids)
+		if err != nil {
+			return fmt.Errorf("SelectQueueJSON: %w", err)
+		}
+
+		for _, blob := range blobs {
+			var event gomatrixserverlib.EDU
+			if err := json.Unmarshal(blob, &event); err != nil {
+				return fmt.Errorf("json.Unmarshal: %w", err)
+			}
+			edus = append(edus, &event)
+		}
+
+		return nil
+	})
+	return
+}
+
+// CleanEDUs cleans up all specified EDUs. This is done when a
+// transaction was sent successfully.
+func (d *Database) CleanEDUs(
+	ctx context.Context,
+	serverName gomatrixserverlib.ServerName,
+	receipt *Receipt,
+) error {
+	if receipt == nil {
+		return errors.New("expected receipt")
+	}
+
+	return sqlutil.WithTransaction(d.DB, func(txn *sql.Tx) error {
+		if err := d.FederationSenderQueueEDUs.DeleteQueueEDUs(ctx, txn, serverName, receipt.nids); err != nil {
+			return err
+		}
+
+		var deleteNIDs []int64
+		for _, nid := range receipt.nids {
+			count, err := d.FederationSenderQueueEDUs.SelectQueueEDUReferenceJSONCount(ctx, txn, nid)
+			if err != nil {
+				return fmt.Errorf("SelectQueueEDUReferenceJSONCount: %w", err)
+			}
+			if count == 0 {
+				deleteNIDs = append(deleteNIDs, nid)
+			}
+		}
+
+		if len(deleteNIDs) > 0 {
+			if err := d.FederationSenderQueueJSON.DeleteQueueJSON(ctx, txn, deleteNIDs); err != nil {
+				return fmt.Errorf("DeleteQueueJSON: %w", err)
+			}
+		}
+
+		return nil
+	})
+}
+
+// GetPendingEDUCount returns the number of EDUs waiting to be
+// sent for a given servername.
+func (d *Database) GetPendingEDUCount(
+	ctx context.Context,
+	serverName gomatrixserverlib.ServerName,
+) (int64, error) {
+	return d.FederationSenderQueueEDUs.SelectQueueEDUCount(ctx, nil, serverName)
+}
+
+// GetPendingServerNames returns the server names that have EDUs
+// waiting to be sent.
+func (d *Database) GetPendingEDUServerNames(
+	ctx context.Context,
+) ([]gomatrixserverlib.ServerName, error) {
+	return d.FederationSenderQueueEDUs.SelectQueueEDUServerNames(ctx, nil)
+}