From 2e65e0d16093be6fc709842453eadc5818f8badf Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Tue, 18 Aug 2020 17:26:59 +0100
Subject: [PATCH] Fix redaction deadlocks

---
 .../storage/shared/room_recent_events_updater.go |  6 +++---
 roomserver/storage/shared/storage.go             | 16 ++++++----------
 roomserver/storage/sqlite3/storage.go            |  8 ++++++++
 3 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/roomserver/storage/shared/room_recent_events_updater.go b/roomserver/storage/shared/room_recent_events_updater.go
index 55bc2e914..9b7611d49 100644
--- a/roomserver/storage/shared/room_recent_events_updater.go
+++ b/roomserver/storage/shared/room_recent_events_updater.go
@@ -18,7 +18,7 @@ type roomRecentEventsUpdater struct {
 	currentStateSnapshotNID types.StateSnapshotNID
 }
 
-func NewRoomRecentEventsUpdater(d *Database, ctx context.Context, roomNID types.RoomNID) (types.RoomRecentEventsUpdater, func() error, error) {
+func NewRoomRecentEventsUpdater(d *Database, ctx context.Context, roomNID types.RoomNID, useTxns bool) (types.RoomRecentEventsUpdater, func() error, error) {
 	eventNIDs, lastEventNIDSent, currentStateSnapshotNID, err :=
 		d.RoomsTable.SelectLatestEventsNIDsForUpdate(ctx, nil, roomNID)
 	if err != nil && err != sql.ErrNoRows {
@@ -40,13 +40,13 @@ func NewRoomRecentEventsUpdater(d *Database, ctx context.Context, roomNID types.
 	}
 	var txn *sql.Tx
 	cancel := func() error { return nil }
-	/*
+	if useTxns {
 		txn, err := d.DB.Begin()
 		if err != nil {
 			return nil, nil, fmt.Errorf("d.DB.Begin: %w", err)
 		}
 		cancel = func() error { return txn.Commit() }
-	*/
+	}
 	return &roomRecentEventsUpdater{
 		transaction{ctx, txn}, d, roomNID, stateAndRefs, lastEventIDSent, currentStateSnapshotNID,
 	}, cancel, nil
diff --git a/roomserver/storage/shared/storage.go b/roomserver/storage/shared/storage.go
index a048f9e6a..56bd8354d 100644
--- a/roomserver/storage/shared/storage.go
+++ b/roomserver/storage/shared/storage.go
@@ -353,7 +353,7 @@ func (d *Database) MembershipUpdater(
 func (d *Database) GetLatestEventsForUpdate(
 	ctx context.Context, roomNID types.RoomNID,
 ) (types.RoomRecentEventsUpdater, func() error, error) {
-	return NewRoomRecentEventsUpdater(d, ctx, roomNID)
+	return NewRoomRecentEventsUpdater(d, ctx, roomNID, true)
 }
 
 // nolint:gocyclo
@@ -570,12 +570,10 @@ func (d *Database) handleRedactions(
 			return nil, "", nil
 		}
 
-		err = d.Writer.Do(d.DB, txn, func(txn *sql.Tx) error {
-			return d.RedactionsTable.InsertRedaction(ctx, txn, tables.RedactionInfo{
-				Validated:        false,
-				RedactionEventID: event.EventID(),
-				RedactsEventID:   event.Redacts(),
-			})
+		err = d.RedactionsTable.InsertRedaction(ctx, txn, tables.RedactionInfo{
+			Validated:        false,
+			RedactionEventID: event.EventID(),
+			RedactsEventID:   event.Redacts(),
 		})
 		if err != nil {
 			return nil, "", err
@@ -604,9 +602,7 @@ func (d *Database) handleRedactions(
 		redactedEvent.Event = redactedEvent.Redact()
 	}
 	// overwrite the eventJSON table
-	err = d.Writer.Do(d.DB, txn, func(txn *sql.Tx) error {
-		return d.EventJSONTable.InsertEventJSON(ctx, txn, redactedEvent.EventNID, redactedEvent.JSON())
-	})
+	err = d.EventJSONTable.InsertEventJSON(ctx, txn, redactedEvent.EventNID, redactedEvent.JSON())
 	if err != nil {
 		return nil, "", err
 	}
diff --git a/roomserver/storage/sqlite3/storage.go b/roomserver/storage/sqlite3/storage.go
index 8c79fa666..6a1c3a5ab 100644
--- a/roomserver/storage/sqlite3/storage.go
+++ b/roomserver/storage/sqlite3/storage.go
@@ -16,12 +16,14 @@
 package sqlite3
 
 import (
+	"context"
 	"database/sql"
 
 	"github.com/matrix-org/dendrite/internal/config"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/roomserver/storage/shared"
 	"github.com/matrix-org/dendrite/roomserver/storage/tables"
+	"github.com/matrix-org/dendrite/roomserver/types"
 	_ "github.com/mattn/go-sqlite3"
 )
 
@@ -133,3 +135,9 @@ func Open(dbProperties *config.DatabaseOptions) (*Database, error) {
 	}
 	return &d, nil
 }
+
+func (d *Database) GetLatestEventsForUpdate(
+	ctx context.Context, roomNID types.RoomNID,
+) (types.RoomRecentEventsUpdater, func() error, error) {
+	return shared.NewRoomRecentEventsUpdater(d, ctx, roomNID, false)
+}