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/postgres/queue_edus_table.go

@@ -0,0 +1,198 @@
+// 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 postgres
+
+import (
+	"context"
+	"database/sql"
+
+	"github.com/lib/pq"
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+const queueEDUsSchema = `
+CREATE TABLE IF NOT EXISTS federationsender_queue_edus (
+	-- The type of the event (informational).
+	edu_type TEXT NOT NULL,
+    -- The domain part of the user ID the EDU event is for.
+	server_name TEXT NOT NULL,
+	-- The JSON NID from the federationsender_queue_edus_json table.
+	json_nid BIGINT NOT NULL
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS federationsender_queue_edus_json_nid_idx
+    ON federationsender_queue_edus (json_nid, server_name);
+`
+
+const insertQueueEDUSQL = "" +
+	"INSERT INTO federationsender_queue_edus (edu_type, server_name, json_nid)" +
+	" VALUES ($1, $2, $3)"
+
+const deleteQueueEDUSQL = "" +
+	"DELETE FROM federationsender_queue_edus WHERE server_name = $1 AND json_nid = ANY($2)"
+
+const selectQueueEDUSQL = "" +
+	"SELECT json_nid FROM federationsender_queue_edus" +
+	" WHERE server_name = $1" +
+	" LIMIT $2"
+
+const selectQueueEDUReferenceJSONCountSQL = "" +
+	"SELECT COUNT(*) FROM federationsender_queue_edus" +
+	" WHERE json_nid = $1"
+
+const selectQueueEDUCountSQL = "" +
+	"SELECT COUNT(*) FROM federationsender_queue_edus" +
+	" WHERE server_name = $1"
+
+const selectQueueServerNamesSQL = "" +
+	"SELECT DISTINCT server_name FROM federationsender_queue_edus"
+
+type queueEDUsStatements struct {
+	db                                   *sql.DB
+	insertQueueEDUStmt                   *sql.Stmt
+	deleteQueueEDUStmt                   *sql.Stmt
+	selectQueueEDUStmt                   *sql.Stmt
+	selectQueueEDUReferenceJSONCountStmt *sql.Stmt
+	selectQueueEDUCountStmt              *sql.Stmt
+	selectQueueEDUServerNamesStmt        *sql.Stmt
+}
+
+func NewPostgresQueueEDUsTable(db *sql.DB) (s *queueEDUsStatements, err error) {
+	s = &queueEDUsStatements{
+		db: db,
+	}
+	_, err = s.db.Exec(queueEDUsSchema)
+	if err != nil {
+		return
+	}
+	if s.insertQueueEDUStmt, err = s.db.Prepare(insertQueueEDUSQL); err != nil {
+		return
+	}
+	if s.deleteQueueEDUStmt, err = s.db.Prepare(deleteQueueEDUSQL); err != nil {
+		return
+	}
+	if s.selectQueueEDUStmt, err = s.db.Prepare(selectQueueEDUSQL); err != nil {
+		return
+	}
+	if s.selectQueueEDUReferenceJSONCountStmt, err = s.db.Prepare(selectQueueEDUReferenceJSONCountSQL); err != nil {
+		return
+	}
+	if s.selectQueueEDUCountStmt, err = s.db.Prepare(selectQueueEDUCountSQL); err != nil {
+		return
+	}
+	if s.selectQueueEDUServerNamesStmt, err = s.db.Prepare(selectQueueServerNamesSQL); err != nil {
+		return
+	}
+	return
+}
+
+func (s *queueEDUsStatements) InsertQueueEDU(
+	ctx context.Context,
+	txn *sql.Tx,
+	eduType string,
+	serverName gomatrixserverlib.ServerName,
+	nid int64,
+) error {
+	stmt := sqlutil.TxStmt(txn, s.insertQueueEDUStmt)
+	_, err := stmt.ExecContext(
+		ctx,
+		eduType,    // the EDU type
+		serverName, // destination server name
+		nid,        // JSON blob NID
+	)
+	return err
+}
+
+func (s *queueEDUsStatements) DeleteQueueEDUs(
+	ctx context.Context, txn *sql.Tx,
+	serverName gomatrixserverlib.ServerName,
+	jsonNIDs []int64,
+) error {
+	stmt := sqlutil.TxStmt(txn, s.deleteQueueEDUStmt)
+	_, err := stmt.ExecContext(ctx, serverName, pq.Int64Array(jsonNIDs))
+	return err
+}
+
+func (s *queueEDUsStatements) SelectQueueEDUs(
+	ctx context.Context, txn *sql.Tx,
+	serverName gomatrixserverlib.ServerName,
+	limit int,
+) ([]int64, error) {
+	stmt := sqlutil.TxStmt(txn, s.selectQueueEDUStmt)
+	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, nil
+}
+
+func (s *queueEDUsStatements) SelectQueueEDUReferenceJSONCount(
+	ctx context.Context, txn *sql.Tx, jsonNID int64,
+) (int64, error) {
+	var count int64
+	stmt := sqlutil.TxStmt(txn, s.selectQueueEDUReferenceJSONCountStmt)
+	err := stmt.QueryRowContext(ctx, jsonNID).Scan(&count)
+	if err == sql.ErrNoRows {
+		return -1, nil
+	}
+	return count, err
+}
+
+func (s *queueEDUsStatements) SelectQueueEDUCount(
+	ctx context.Context, txn *sql.Tx, serverName gomatrixserverlib.ServerName,
+) (int64, error) {
+	var count int64
+	stmt := sqlutil.TxStmt(txn, s.selectQueueEDUCountStmt)
+	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
+}
+
+func (s *queueEDUsStatements) SelectQueueEDUServerNames(
+	ctx context.Context, txn *sql.Tx,
+) ([]gomatrixserverlib.ServerName, error) {
+	stmt := sqlutil.TxStmt(txn, s.selectQueueEDUServerNamesStmt)
+	rows, err := stmt.QueryContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "queueFromStmt: rows.close() failed")
+	var result []gomatrixserverlib.ServerName
+	for rows.Next() {
+		var serverName gomatrixserverlib.ServerName
+		if err = rows.Scan(&serverName); err != nil {
+			return nil, err
+		}
+		result = append(result, serverName)
+	}
+
+	return result, rows.Err()
+}