1 files changed, 89 insertions, 0 deletions
diff --git a/roomserver/storage/postgres/transactions_table.go b/roomserver/storage/postgres/transactions_table.go
new file mode 100644
index 00000000..87c1caca
--- /dev/null
+++ b/roomserver/storage/postgres/transactions_table.go
@@ -0,0 +1,89 @@
+// Copyright 2017-2018 New Vector Ltd
+// Copyright 2019-2020 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"
+)
+
+const transactionsSchema = `
+-- The transactions table holds transaction IDs with sender's info and event ID it belongs to.
+-- This table is used by roomserver to prevent reprocessing of events.
+CREATE TABLE IF NOT EXISTS roomserver_transactions (
+	-- The transaction ID of the event.
+	transaction_id TEXT NOT NULL,
+	-- The session ID of the originating transaction.
+	session_id BIGINT NOT NULL,
+	-- User ID of the sender who authored the event
+	user_id TEXT NOT NULL,
+	-- Event ID corresponding to the transaction
+	-- Required to return event ID to client on a duplicate request.
+	event_id TEXT NOT NULL,
+	-- A transaction ID is unique for a user and device
+	-- This automatically creates an index.
+	PRIMARY KEY (transaction_id, session_id, user_id)
+);
+`
+const insertTransactionSQL = "" +
+	"INSERT INTO roomserver_transactions (transaction_id, session_id, user_id, event_id)" +
+	" VALUES ($1, $2, $3, $4)"
+
+const selectTransactionEventIDSQL = "" +
+	"SELECT event_id FROM roomserver_transactions" +
+	" WHERE transaction_id = $1 AND session_id = $2 AND user_id = $3"
+
+type transactionStatements struct {
+	insertTransactionStmt        *sql.Stmt
+	selectTransactionEventIDStmt *sql.Stmt
+}
+
+func (s *transactionStatements) prepare(db *sql.DB) (err error) {
+	_, err = db.Exec(transactionsSchema)
+	if err != nil {
+		return
+	}
+
+	return statementList{
+		{&s.insertTransactionStmt, insertTransactionSQL},
+		{&s.selectTransactionEventIDStmt, selectTransactionEventIDSQL},
+	}.prepare(db)
+}
+
+func (s *transactionStatements) insertTransaction(
+	ctx context.Context,
+	transactionID string,
+	sessionID int64,
+	userID string,
+	eventID string,
+) (err error) {
+	_, err = s.insertTransactionStmt.ExecContext(
+		ctx, transactionID, sessionID, userID, eventID,
+	)
+	return
+}
+
+func (s *transactionStatements) selectTransactionEventID(
+	ctx context.Context,
+	transactionID string,
+	sessionID int64,
+	userID string,
+) (eventID string, err error) {
+	err = s.selectTransactionEventIDStmt.QueryRowContext(
+		ctx, transactionID, sessionID, userID,
+	).Scan(&eventID)
+	return
+}