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>

lib/protocol/bep_fileinfo.go

@@ -19,10 +19,12 @@ import (
 
 // FileInfo.LocalFlags flags
 const (
-	FlagLocalUnsupported = 1 << 0 // The kind is unsupported, e.g. symlinks on Windows
-	FlagLocalIgnored     = 1 << 1 // Matches local ignore patterns
-	FlagLocalMustRescan  = 1 << 2 // Doesn't match content on disk, must be rechecked fully
-	FlagLocalReceiveOnly = 1 << 3 // Change detected on receive only folder
+	FlagLocalUnsupported = 1 << 0 // 1: The kind is unsupported, e.g. symlinks on Windows
+	FlagLocalIgnored     = 1 << 1 // 2: Matches local ignore patterns
+	FlagLocalMustRescan  = 1 << 2 // 4: Doesn't match content on disk, must be rechecked fully
+	FlagLocalReceiveOnly = 1 << 3 // 8: Change detected on receive only folder
+	FlagLocalGlobal      = 1 << 4 // 16: This is the global file version
+	FlagLocalNeeded      = 1 << 5 // 32: We need this file
 
 	// Flags that should result in the Invalid bit on outgoing updates
 	LocalInvalidFlags = FlagLocalUnsupported | FlagLocalIgnored | FlagLocalMustRescan | FlagLocalReceiveOnly
@@ -32,7 +34,7 @@ const (
 	// disk.
 	LocalConflictFlags = FlagLocalUnsupported | FlagLocalIgnored | FlagLocalReceiveOnly
 
-	LocalAllFlags = FlagLocalUnsupported | FlagLocalIgnored | FlagLocalMustRescan | FlagLocalReceiveOnly
+	LocalAllFlags = FlagLocalUnsupported | FlagLocalIgnored | FlagLocalMustRescan | FlagLocalReceiveOnly | FlagLocalGlobal | FlagLocalNeeded
 )
 
 // BlockSizes is the list of valid block sizes, from min to max

lib/protocol/protocol_test.go

@@ -10,10 +10,8 @@ import (
 	"bytes"
 	"context"
 	"encoding/hex"
-	"encoding/json"
 	"errors"
 	"io"
-	"os"
 	"sync"
 	"testing"
 	"time"
@@ -280,28 +278,6 @@ func TestUnmarshalFDPUv16v17(t *testing.T) {
 	}
 }
 
-func testMarshal(t *testing.T, prefix string, m1, m2 proto.Message) bool {
-	buf, err := proto.Marshal(m1)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	err = proto.Unmarshal(buf, m2)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	bs1, _ := json.MarshalIndent(m1, "", "  ")
-	bs2, _ := json.MarshalIndent(m2, "", "  ")
-	if !bytes.Equal(bs1, bs2) {
-		os.WriteFile(prefix+"-1.txt", bs1, 0o644)
-		os.WriteFile(prefix+"-2.txt", bs2, 0o644)
-		return false
-	}
-
-	return true
-}
-
 func TestWriteCompressed(t *testing.T) {
 	for _, random := range []bool{false, true} {
 		buf := new(bytes.Buffer)

lib/protocol/vector.go

@@ -7,6 +7,11 @@
 package protocol
 
 import (
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/syncthing/syncthing/internal/gen/bep"
@@ -20,6 +25,17 @@ type Vector struct {
 	Counters []Counter
 }
 
+func (v *Vector) String() string {
+	var buf strings.Builder
+	for i, c := range v.Counters {
+		if i > 0 {
+			buf.WriteRune(',')
+		}
+		fmt.Fprintf(&buf, "%x:%d", c.ID, c.Value)
+	}
+	return buf.String()
+}
+
 func (v *Vector) ToWire() *bep.Vector {
 	counters := make([]*bep.Counter, len(v.Counters))
 	for i, c := range v.Counters {
@@ -42,6 +58,31 @@ func VectorFromWire(w *bep.Vector) Vector {
 	return v
 }
 
+func VectorFromString(s string) (Vector, error) {
+	pairs := strings.Split(s, ",")
+	var v Vector
+	v.Counters = make([]Counter, len(pairs))
+	for i, pair := range pairs {
+		idStr, valStr, ok := strings.Cut(pair, ":")
+		if !ok {
+			return Vector{}, fmt.Errorf("bad pair %q", pair)
+		}
+		idslice, err := hex.DecodeString(idStr)
+		if err != nil {
+			return Vector{}, fmt.Errorf("bad id in pair %q", pair)
+		}
+		var idbs [8]byte
+		copy(idbs[8-len(idslice):], idslice)
+		id := binary.BigEndian.Uint64(idbs[:])
+		val, err := strconv.ParseUint(valStr, 10, 64)
+		if err != nil {
+			return Vector{}, fmt.Errorf("bad val in pair %q", pair)
+		}
+		v.Counters[i] = Counter{ID: ShortID(id), Value: val}
+	}
+	return v, nil
+}
+
 // Counter represents a single counter in the version vector.
 type Counter struct {
 	ID    ShortID