gotosocial/internal/db/bundb/marker.go

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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package bundb
import (
"context"
"errors"
"fmt"
"time"
"github.com/superseriousbusiness/gotosocial/internal/db"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/state"
"github.com/uptrace/bun"
)
type markerDB struct {
db *DB
state *state.State
}
/*
MARKER FUNCTIONS
*/
func (m *markerDB) GetMarker(ctx context.Context, accountID string, name gtsmodel.MarkerName) (*gtsmodel.Marker, error) {
marker, err := m.state.Caches.GTS.Marker().Load(
"AccountID.Name",
func() (*gtsmodel.Marker, error) {
var marker gtsmodel.Marker
if err := m.db.NewSelect().
Model(&marker).
Where("? = ? AND ? = ?", bun.Ident("account_id"), accountID, bun.Ident("name"), name).
Scan(ctx); err != nil {
return nil, err
}
return &marker, nil
},
accountID,
name,
)
if err != nil {
return nil, err // already processed
}
return marker, nil
}
func (m *markerDB) UpdateMarker(ctx context.Context, marker *gtsmodel.Marker) error {
prevMarker, err := m.GetMarker(ctx, marker.AccountID, marker.Name)
if err != nil && !errors.Is(err, db.ErrNoEntries) {
return fmt.Errorf("UpdateMarker: error fetching previous version of marker: %w", err)
}
marker.UpdatedAt = time.Now()
if prevMarker != nil {
marker.Version = prevMarker.Version + 1
}
return m.state.Caches.GTS.Marker().Store(marker, func() error {
if prevMarker == nil {
if _, err := m.db.NewInsert().
Model(marker).
Exec(ctx); err != nil {
return err
}
return nil
}
// Optimistic concurrency control: start a transaction, try to update a row with a previously retrieved version.
// If the update in the transaction fails to actually change anything, another update happened concurrently, and
// this update should be retried by the caller, which in this case involves sending HTTP 409 to the API client.
return m.db.RunInTx(ctx, func(tx Tx) error {
result, err := tx.NewUpdate().
Model(marker).
WherePK().
Where("? = ?", bun.Ident("version"), prevMarker.Version).
Exec(ctx)
if err != nil {
return err
}
rowsAffected, err := result.RowsAffected()
if err != nil {
return err
}
if rowsAffected == 0 {
// Will trigger a rollback, although there should be no changes to roll back.
return db.ErrAlreadyExists
} else if rowsAffected > 1 {
// This shouldn't happen.
return db.ErrNoEntries
}
return nil
})
})
}