1 files changed, 267 insertions, 0 deletions
diff --git a/internal/db/bundb/drivers.go b/internal/db/bundb/drivers.go
new file mode 100644
index 000000000..14d84e6fa
--- /dev/null
+++ b/internal/db/bundb/drivers.go
@@ -0,0 +1,267 @@
+// 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"
+	"database/sql"
+	"database/sql/driver"
+	"time"
+	_ "unsafe" // linkname shenanigans
+
+	pgx "github.com/jackc/pgx/v5/stdlib"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"modernc.org/sqlite"
+)
+
+var (
+	// global SQL driver instances.
+	postgresDriver = pgx.GetDefaultDriver()
+	sqliteDriver   = getSQLiteDriver()
+)
+
+func init() {
+	sql.Register("pgx-gts", &PostgreSQLDriver{})
+	sql.Register("sqlite-gts", &SQLiteDriver{})
+}
+
+//go:linkname getSQLiteDriver modernc.org/sqlite.newDriver
+func getSQLiteDriver() *sqlite.Driver
+
+// PostgreSQLDriver is our own wrapper around the
+// pgx/stdlib.Driver{} type in order to wrap further
+// SQL driver types with our own err processing.
+type PostgreSQLDriver struct{}
+
+func (d *PostgreSQLDriver) Open(name string) (driver.Conn, error) {
+	c, err := postgresDriver.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	return &PostgreSQLConn{conn: c.(conn)}, nil
+}
+
+type PostgreSQLConn struct{ conn }
+
+func (c *PostgreSQLConn) Begin() (driver.Tx, error) {
+	return c.BeginTx(context.Background(), driver.TxOptions{})
+}
+
+func (c *PostgreSQLConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
+	tx, err := c.conn.BeginTx(ctx, opts)
+	err = processPostgresError(err)
+	return tx, err
+}
+
+func (c *PostgreSQLConn) Prepare(query string) (driver.Stmt, error) {
+	return c.PrepareContext(context.Background(), query)
+}
+
+func (c *PostgreSQLConn) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
+	stmt, err := c.conn.PrepareContext(ctx, query)
+	err = processPostgresError(err)
+	return stmt, err
+}
+
+func (c *PostgreSQLConn) Exec(query string, args []driver.NamedValue) (driver.Result, error) {
+	return c.ExecContext(context.Background(), query, args)
+}
+
+func (c *PostgreSQLConn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
+	result, err := c.conn.ExecContext(ctx, query, args)
+	err = processPostgresError(err)
+	return result, err
+}
+
+func (c *PostgreSQLConn) Query(query string, args []driver.NamedValue) (driver.Rows, error) {
+	return c.QueryContext(context.Background(), query, args)
+}
+
+func (c *PostgreSQLConn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
+	rows, err := c.conn.QueryContext(ctx, query, args)
+	err = processPostgresError(err)
+	return rows, err
+}
+
+func (c *PostgreSQLConn) Close() error {
+	return c.conn.Close()
+}
+
+type PostgreSQLTx struct{ driver.Tx }
+
+func (tx *PostgreSQLTx) Commit() error {
+	err := tx.Tx.Commit()
+	return processPostgresError(err)
+}
+
+func (tx *PostgreSQLTx) Rollback() error {
+	err := tx.Tx.Rollback()
+	return processPostgresError(err)
+}
+
+// SQLiteDriver is our own wrapper around the
+// sqlite.Driver{} type in order to wrap further
+// SQL driver types with our own functionality,
+// e.g. hooks, retries and err processing.
+type SQLiteDriver struct{}
+
+func (d *SQLiteDriver) Open(name string) (driver.Conn, error) {
+	c, err := sqliteDriver.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	return &SQLiteConn{conn: c.(conn)}, nil
+}
+
+type SQLiteConn struct{ conn }
+
+func (c *SQLiteConn) Begin() (driver.Tx, error) {
+	return c.BeginTx(context.Background(), driver.TxOptions{})
+}
+
+func (c *SQLiteConn) BeginTx(ctx context.Context, opts driver.TxOptions) (tx driver.Tx, err error) {
+	err = retryOnBusy(ctx, func() error {
+		tx, err = c.conn.BeginTx(ctx, opts)
+		err = processSQLiteError(err)
+		return err
+	})
+	return &SQLiteTx{Context: ctx, Tx: tx}, nil
+}
+
+func (c *SQLiteConn) Prepare(query string) (driver.Stmt, error) {
+	return c.PrepareContext(context.Background(), query)
+}
+
+func (c *SQLiteConn) PrepareContext(ctx context.Context, query string) (stmt driver.Stmt, err error) {
+	err = retryOnBusy(ctx, func() error {
+		stmt, err = c.conn.PrepareContext(ctx, query)
+		err = processSQLiteError(err)
+		return err
+	})
+	return
+}
+
+func (c *SQLiteConn) Exec(query string, args []driver.NamedValue) (driver.Result, error) {
+	return c.ExecContext(context.Background(), query, args)
+}
+
+func (c *SQLiteConn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (result driver.Result, err error) {
+	err = retryOnBusy(ctx, func() error {
+		result, err = c.conn.ExecContext(ctx, query, args)
+		err = processSQLiteError(err)
+		return err
+	})
+	return
+}
+
+func (c *SQLiteConn) Query(query string, args []driver.NamedValue) (driver.Rows, error) {
+	return c.QueryContext(context.Background(), query, args)
+}
+
+func (c *SQLiteConn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (rows driver.Rows, err error) {
+	err = retryOnBusy(ctx, func() error {
+		rows, err = c.conn.QueryContext(ctx, query, args)
+		err = processSQLiteError(err)
+		return err
+	})
+	return
+}
+
+func (c *SQLiteConn) Close() error {
+	// see: https://www.sqlite.org/pragma.html#pragma_optimize
+	const onClose = "PRAGMA analysis_limit=1000; PRAGMA optimize;"
+	_, _ = c.conn.ExecContext(context.Background(), onClose, nil)
+	return c.conn.Close()
+}
+
+type SQLiteTx struct {
+	context.Context
+	driver.Tx
+}
+
+func (tx *SQLiteTx) Commit() (err error) {
+	err = retryOnBusy(tx.Context, func() error {
+		err = tx.Tx.Commit()
+		err = processSQLiteError(err)
+		return err
+	})
+	return
+}
+
+func (tx *SQLiteTx) Rollback() (err error) {
+	err = retryOnBusy(tx.Context, func() error {
+		err = tx.Tx.Rollback()
+		err = processSQLiteError(err)
+		return err
+	})
+	return
+}
+
+type conn interface {
+	driver.Conn
+	driver.ConnPrepareContext
+	driver.ExecerContext
+	driver.QueryerContext
+	driver.ConnBeginTx
+}
+
+// retryOnBusy will retry given function on returned 'errBusy'.
+func retryOnBusy(ctx context.Context, fn func() error) error {
+	var backoff time.Duration
+
+	for i := 0; ; i++ {
+		// Perform func.
+		err := fn()
+
+		if err != errBusy {
+			// May be nil, or may be
+			// some other error, either
+			// way return here.
+			return err
+		}
+
+		// backoff according to a multiplier of 2ms * 2^2n,
+		// up to a maximum possible backoff time of 5 minutes.
+		//
+		// this works out as the following:
+		// 4ms
+		// 16ms
+		// 64ms
+		// 256ms
+		// 1.024s
+		// 4.096s
+		// 16.384s
+		// 1m5.536s
+		// 4m22.144s
+		backoff = 2 * time.Millisecond * (1 << (2*i + 1))
+		if backoff >= 5*time.Minute {
+			break
+		}
+
+		select {
+		// Context cancelled.
+		case <-ctx.Done():
+
+		// Backoff for some time.
+		case <-time.After(backoff):
+		}
+	}
+
+	return gtserror.Newf("%w (waited > %s)", db.ErrBusyTimeout, backoff)
+}