chore: switch database engine to sqlite (fixes #9954) (#9965)

Switch the database from LevelDB to SQLite, for greater stability and
simpler code.

Co-authored-by: Tommy van der Vorst <tommy@pixelspark.nl>
Co-authored-by: bt90 <btom1990@googlemail.com>

internal/db/counts.go

@@ -0,0 +1,73 @@
+// Copyright (C) 2014 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package db
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/syncthing/syncthing/lib/protocol"
+)
+
+type Counts struct {
+	Files       int
+	Directories int
+	Symlinks    int
+	Deleted     int
+	Bytes       int64
+	Sequence    int64             // zero for the global state
+	DeviceID    protocol.DeviceID // device ID for remote devices, or special values for local/global
+	LocalFlags  uint32            // the local flag for this count bucket
+}
+
+func (c Counts) Add(other Counts) Counts {
+	return Counts{
+		Files:       c.Files + other.Files,
+		Directories: c.Directories + other.Directories,
+		Symlinks:    c.Symlinks + other.Symlinks,
+		Deleted:     c.Deleted + other.Deleted,
+		Bytes:       c.Bytes + other.Bytes,
+		Sequence:    c.Sequence + other.Sequence,
+		DeviceID:    protocol.EmptyDeviceID,
+		LocalFlags:  c.LocalFlags | other.LocalFlags,
+	}
+}
+
+func (c Counts) TotalItems() int {
+	return c.Files + c.Directories + c.Symlinks + c.Deleted
+}
+
+func (c Counts) String() string {
+	var flags strings.Builder
+	if c.LocalFlags&protocol.FlagLocalNeeded != 0 {
+		flags.WriteString("Need")
+	}
+	if c.LocalFlags&protocol.FlagLocalIgnored != 0 {
+		flags.WriteString("Ignored")
+	}
+	if c.LocalFlags&protocol.FlagLocalMustRescan != 0 {
+		flags.WriteString("Rescan")
+	}
+	if c.LocalFlags&protocol.FlagLocalReceiveOnly != 0 {
+		flags.WriteString("Recvonly")
+	}
+	if c.LocalFlags&protocol.FlagLocalUnsupported != 0 {
+		flags.WriteString("Unsupported")
+	}
+	if c.LocalFlags != 0 {
+		flags.WriteString(fmt.Sprintf("(%x)", c.LocalFlags))
+	}
+	if flags.Len() == 0 {
+		flags.WriteString("---")
+	}
+	return fmt.Sprintf("{Device:%v, Files:%d, Dirs:%d, Symlinks:%d, Del:%d, Bytes:%d, Seq:%d, Flags:%s}", c.DeviceID, c.Files, c.Directories, c.Symlinks, c.Deleted, c.Bytes, c.Sequence, flags.String())
+}
+
+// Equal compares the numbers only, not sequence/dev/flags.
+func (c Counts) Equal(o Counts) bool {
+	return c.Files == o.Files && c.Directories == o.Directories && c.Symlinks == o.Symlinks && c.Deleted == o.Deleted && c.Bytes == o.Bytes
+}