Initial syncapi storage refactor to share pq/sqlite code (#1030)

* Initial syncapi storage refactor to share pq/sqlite code

This goes down a different route than https://github.com/matrix-org/dendrite/pull/985
which tried to even reduce the boilerplate of `ExecContext` etc. The previous pattern
fails badly when there are subtle differences in parameters and hence the shared
boilerplate to read from `QueryContext` breaks. Rather than attacking it at that level,
the main place where we want to reuse code is for the `syncserver.go` itself - the
database implementation which has lots of complex logic. So instead, this commit:
 - Makes `invites_table.go` an interface.
 - Makes `SyncServerDatasource` use that interface
 - This means some functions are now identical for pq/sqlite, so factor them out
   to a temporary `shared.Database` struct which will grow until it replaces all of
   `SyncServerDatasource`.

* Missing files

2 files changed, 29 insertions, 24 deletions

diff --git a/syncapi/storage/postgres/invites_table.go b/syncapi/storage/postgres/invites_table.go
index ca0c64fb..78ca4d6d 100644
--- a/syncapi/storage/postgres/invites_table.go
+++ b/syncapi/storage/postgres/invites_table.go
@@ -21,6 +21,7 @@ import (
 	"encoding/json"
 
 	"github.com/matrix-org/dendrite/common"
+	"github.com/matrix-org/dendrite/syncapi/storage/tables"
 	"github.com/matrix-org/dendrite/syncapi/types"
 	"github.com/matrix-org/gomatrixserverlib"
 )
@@ -66,28 +67,29 @@ type inviteEventsStatements struct {
 	selectMaxInviteIDStmt         *sql.Stmt
 }
 
-func (s *inviteEventsStatements) prepare(db *sql.DB) (err error) {
-	_, err = db.Exec(inviteEventsSchema)
+func NewPostgresInvitesTable(db *sql.DB) (tables.Invites, error) {
+	s := &inviteEventsStatements{}
+	_, err := db.Exec(inviteEventsSchema)
 	if err != nil {
-		return
+		return nil, err
 	}
 	if s.insertInviteEventStmt, err = db.Prepare(insertInviteEventSQL); err != nil {
-		return
+		return nil, err
 	}
 	if s.selectInviteEventsInRangeStmt, err = db.Prepare(selectInviteEventsInRangeSQL); err != nil {
-		return
+		return nil, err
 	}
 	if s.deleteInviteEventStmt, err = db.Prepare(deleteInviteEventSQL); err != nil {
-		return
+		return nil, err
 	}
 	if s.selectMaxInviteIDStmt, err = db.Prepare(selectMaxInviteIDSQL); err != nil {
-		return
+		return nil, err
 	}
-	return
+	return s, nil
 }
 
-func (s *inviteEventsStatements) insertInviteEvent(
-	ctx context.Context, inviteEvent gomatrixserverlib.HeaderedEvent,
+func (s *inviteEventsStatements) InsertInviteEvent(
+	ctx context.Context, txn *sql.Tx, inviteEvent gomatrixserverlib.HeaderedEvent,
 ) (streamPos types.StreamPosition, err error) {
 	var headeredJSON []byte
 	headeredJSON, err = json.Marshal(inviteEvent)
@@ -105,7 +107,7 @@ func (s *inviteEventsStatements) insertInviteEvent(
 	return
 }
 
-func (s *inviteEventsStatements) deleteInviteEvent(
+func (s *inviteEventsStatements) DeleteInviteEvent(
 	ctx context.Context, inviteEventID string,
 ) error {
 	_, err := s.deleteInviteEventStmt.ExecContext(ctx, inviteEventID)
@@ -114,7 +116,7 @@ func (s *inviteEventsStatements) deleteInviteEvent(
 
 // selectInviteEventsInRange returns a map of room ID to invite event for the
 // active invites for the target user ID in the supplied range.
-func (s *inviteEventsStatements) selectInviteEventsInRange(
+func (s *inviteEventsStatements) SelectInviteEventsInRange(
 	ctx context.Context, txn *sql.Tx, targetUserID string, startPos, endPos types.StreamPosition,
 ) (map[string]gomatrixserverlib.HeaderedEvent, error) {
 	stmt := common.TxStmt(txn, s.selectInviteEventsInRangeStmt)
@@ -143,7 +145,7 @@ func (s *inviteEventsStatements) selectInviteEventsInRange(
 	return result, rows.Err()
 }
 
-func (s *inviteEventsStatements) selectMaxInviteID(
+func (s *inviteEventsStatements) SelectMaxInviteID(
 	ctx context.Context, txn *sql.Tx,
 ) (id int64, err error) {
 	var nullableID sql.NullInt64
diff --git a/syncapi/storage/postgres/syncserver.go b/syncapi/storage/postgres/syncserver.go
index 90976168..9883c362 100644
--- a/syncapi/storage/postgres/syncserver.go
+++ b/syncapi/storage/postgres/syncserver.go
@@ -32,6 +32,7 @@ import (
 	_ "github.com/lib/pq"
 	"github.com/matrix-org/dendrite/common"
 	"github.com/matrix-org/dendrite/eduserver/cache"
+	"github.com/matrix-org/dendrite/syncapi/storage/shared"
 	"github.com/matrix-org/dendrite/syncapi/storage/tables"
 	"github.com/matrix-org/dendrite/syncapi/types"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -54,10 +55,10 @@ type SyncServerDatasource struct {
 	accountData         accountDataStatements
 	events              outputRoomEventsStatements
 	roomstate           currentRoomStateStatements
-	invites             inviteEventsStatements
 	eduCache            *cache.EDUCache
 	topology            outputRoomEventsTopologyStatements
 	backwardExtremities tables.BackwardsExtremities
+	shared              *shared.Database
 }
 
 // NewSyncServerDatasource creates a new sync server database
@@ -79,7 +80,8 @@ func NewSyncServerDatasource(dbDataSourceName string, dbProperties common.DbProp
 	if err = d.roomstate.prepare(d.db); err != nil {
 		return nil, err
 	}
-	if err = d.invites.prepare(d.db); err != nil {
+	invites, err := NewPostgresInvitesTable(d.db)
+	if err != nil {
 		return nil, err
 	}
 	if err = d.topology.prepare(d.db); err != nil {
@@ -90,6 +92,10 @@ func NewSyncServerDatasource(dbDataSourceName string, dbProperties common.DbProp
 		return nil, err
 	}
 	d.eduCache = cache.New()
+	d.shared = &shared.Database{
+		DB:      d.db,
+		Invites: invites,
+	}
 	return &d, nil
 }
 
@@ -340,7 +346,7 @@ func (d *SyncServerDatasource) syncStreamPositionTx(
 	if maxAccountDataID > maxID {
 		maxID = maxAccountDataID
 	}
-	maxInviteID, err := d.invites.selectMaxInviteID(ctx, txn)
+	maxInviteID, err := d.shared.Invites.SelectMaxInviteID(ctx, txn)
 	if err != nil {
 		return 0, err
 	}
@@ -365,7 +371,7 @@ func (d *SyncServerDatasource) syncPositionTx(
 	if maxAccountDataID > maxEventID {
 		maxEventID = maxAccountDataID
 	}
-	maxInviteID, err := d.invites.selectMaxInviteID(ctx, txn)
+	maxInviteID, err := d.shared.Invites.SelectMaxInviteID(ctx, txn)
 	if err != nil {
 		return sp, err
 	}
@@ -662,17 +668,14 @@ func (d *SyncServerDatasource) UpsertAccountData(
 
 func (d *SyncServerDatasource) AddInviteEvent(
 	ctx context.Context, inviteEvent gomatrixserverlib.HeaderedEvent,
-) (types.StreamPosition, error) {
-	return d.invites.insertInviteEvent(ctx, inviteEvent)
+) (sp types.StreamPosition, err error) {
+	return d.shared.AddInviteEvent(ctx, inviteEvent)
 }
 
 func (d *SyncServerDatasource) RetireInviteEvent(
 	ctx context.Context, inviteEventID string,
 ) error {
-	// TODO: Record that invite has been retired in a stream so that we can
-	// notify the user in an incremental sync.
-	err := d.invites.deleteInviteEvent(ctx, inviteEventID)
-	return err
+	return d.shared.RetireInviteEvent(ctx, inviteEventID)
 }
 
 func (d *SyncServerDatasource) SetTypingTimeoutCallback(fn cache.TimeoutCallbackFn) {
@@ -697,7 +700,7 @@ func (d *SyncServerDatasource) addInvitesToResponse(
 	fromPos, toPos types.StreamPosition,
 	res *types.Response,
 ) error {
-	invites, err := d.invites.selectInviteEventsInRange(
+	invites, err := d.shared.Invites.SelectInviteEventsInRange(
 		ctx, txn, userID, fromPos, toPos,
 	)
 	if err != nil {