Initial Store & Forward Implementation (#2917)

This adds store & forward relays into dendrite for p2p.
A few things have changed:
- new relay api serves new http endpoints for s&f federation
- updated outbound federation queueing which will attempt to forward
using s&f if appropriate
- database entries to track s&f relays for other nodes

relayapi/storage/sqlite3/relay_queue_table.go

@@ -0,0 +1,168 @@
+// Copyright 2022 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 sqlite3
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+const relayQueueSchema = `
+CREATE TABLE IF NOT EXISTS relayapi_queue (
+	-- The transaction ID that was generated before persisting the event.
+	transaction_id TEXT NOT NULL,
+	-- The domain part of the user ID the m.room.member event is for.
+	server_name TEXT NOT NULL,
+	-- The JSON NID from the relayapi_queue_json table.
+	json_nid BIGINT NOT NULL
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS relayapi_queue_queue_json_nid_idx
+	ON relayapi_queue (json_nid, server_name);
+CREATE INDEX IF NOT EXISTS relayapi_queue_json_nid_idx
+	ON relayapi_queue (json_nid);
+CREATE INDEX IF NOT EXISTS relayapi_queue_server_name_idx
+	ON relayapi_queue (server_name);
+`
+
+const insertQueueEntrySQL = "" +
+	"INSERT INTO relayapi_queue (transaction_id, server_name, json_nid)" +
+	" VALUES ($1, $2, $3)"
+
+const deleteQueueEntriesSQL = "" +
+	"DELETE FROM relayapi_queue WHERE server_name = $1 AND json_nid IN ($2)"
+
+const selectQueueEntriesSQL = "" +
+	"SELECT json_nid FROM relayapi_queue" +
+	" WHERE server_name = $1" +
+	" ORDER BY json_nid" +
+	" LIMIT $2"
+
+const selectQueueEntryCountSQL = "" +
+	"SELECT COUNT(*) FROM relayapi_queue" +
+	" WHERE server_name = $1"
+
+type relayQueueStatements struct {
+	db                        *sql.DB
+	insertQueueEntryStmt      *sql.Stmt
+	selectQueueEntriesStmt    *sql.Stmt
+	selectQueueEntryCountStmt *sql.Stmt
+	// deleteQueueEntriesStmt *sql.Stmt - prepared at runtime due to variadic
+}
+
+func NewSQLiteRelayQueueTable(
+	db *sql.DB,
+) (s *relayQueueStatements, err error) {
+	s = &relayQueueStatements{
+		db: db,
+	}
+	_, err = db.Exec(relayQueueSchema)
+	if err != nil {
+		return
+	}
+
+	return s, sqlutil.StatementList{
+		{&s.insertQueueEntryStmt, insertQueueEntrySQL},
+		{&s.selectQueueEntriesStmt, selectQueueEntriesSQL},
+		{&s.selectQueueEntryCountStmt, selectQueueEntryCountSQL},
+	}.Prepare(db)
+}
+
+func (s *relayQueueStatements) InsertQueueEntry(
+	ctx context.Context,
+	txn *sql.Tx,
+	transactionID gomatrixserverlib.TransactionID,
+	serverName gomatrixserverlib.ServerName,
+	nid int64,
+) error {
+	stmt := sqlutil.TxStmt(txn, s.insertQueueEntryStmt)
+	_, err := stmt.ExecContext(
+		ctx,
+		transactionID, // the transaction ID that we initially attempted
+		serverName,    // destination server name
+		nid,           // JSON blob NID
+	)
+	return err
+}
+
+func (s *relayQueueStatements) DeleteQueueEntries(
+	ctx context.Context,
+	txn *sql.Tx,
+	serverName gomatrixserverlib.ServerName,
+	jsonNIDs []int64,
+) error {
+	deleteSQL := strings.Replace(deleteQueueEntriesSQL, "($2)", sqlutil.QueryVariadicOffset(len(jsonNIDs), 1), 1)
+	deleteStmt, err := txn.Prepare(deleteSQL)
+	if err != nil {
+		return fmt.Errorf("s.deleteQueueEntries s.db.Prepare: %w", err)
+	}
+
+	params := make([]interface{}, len(jsonNIDs)+1)
+	params[0] = serverName
+	for k, v := range jsonNIDs {
+		params[k+1] = v
+	}
+
+	stmt := sqlutil.TxStmt(txn, deleteStmt)
+	_, err = stmt.ExecContext(ctx, params...)
+	return err
+}
+
+func (s *relayQueueStatements) SelectQueueEntries(
+	ctx context.Context,
+	txn *sql.Tx,
+	serverName gomatrixserverlib.ServerName,
+	limit int,
+) ([]int64, error) {
+	stmt := sqlutil.TxStmt(txn, s.selectQueueEntriesStmt)
+	rows, err := stmt.QueryContext(ctx, serverName, limit)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "queueFromStmt: rows.close() failed")
+	var result []int64
+	for rows.Next() {
+		var nid int64
+		if err = rows.Scan(&nid); err != nil {
+			return nil, err
+		}
+		result = append(result, nid)
+	}
+
+	return result, rows.Err()
+}
+
+func (s *relayQueueStatements) SelectQueueEntryCount(
+	ctx context.Context,
+	txn *sql.Tx,
+	serverName gomatrixserverlib.ServerName,
+) (int64, error) {
+	var count int64
+	stmt := sqlutil.TxStmt(txn, s.selectQueueEntryCountStmt)
+	err := stmt.QueryRowContext(ctx, serverName).Scan(&count)
+	if err == sql.ErrNoRows {
+		// It's acceptable for there to be no rows referencing a given
+		// JSON NID but it's not an error condition. Just return as if
+		// there's a zero count.
+		return 0, nil
+	}
+	return count, err
+}