lib/db: Refactor key handling (ref #5198) (#5199)

This breaks out the key generation stuff into a separate type. It's
cleaner on its own, and it prepares for future stuff.

lib/db/leveldb_test.go

@@ -7,7 +7,6 @@
 package db
 
 import (
-	"bytes"
 	"os"
 	"testing"
 
@@ -15,58 +14,6 @@ import (
 	"github.com/syncthing/syncthing/lib/protocol"
 )
 
-func TestDeviceKey(t *testing.T) {
-	fld := []byte("folder6789012345678901234567890123456789012345678901234567890123")
-	dev := []byte("device67890123456789012345678901")
-	name := []byte("name")
-
-	db := OpenMemory()
-	db.folderIdx.ID(fld)
-	db.deviceIdx.ID(dev)
-
-	key := db.deviceKey(fld, dev, name)
-
-	fld2 := db.deviceKeyFolder(key)
-	if !bytes.Equal(fld2, fld) {
-		t.Errorf("wrong folder %q != %q", fld2, fld)
-	}
-	dev2 := db.deviceKeyDevice(key)
-	if !bytes.Equal(dev2, dev) {
-		t.Errorf("wrong device %q != %q", dev2, dev)
-	}
-	name2 := db.deviceKeyName(key)
-	if !bytes.Equal(name2, name) {
-		t.Errorf("wrong name %q != %q", name2, name)
-	}
-}
-
-func TestGlobalKey(t *testing.T) {
-	fld := []byte("folder6789012345678901234567890123456789012345678901234567890123")
-	name := []byte("name")
-
-	db := OpenMemory()
-	db.folderIdx.ID(fld)
-
-	key := db.globalKey(fld, name)
-
-	fld2, ok := db.globalKeyFolder(key)
-	if !ok {
-		t.Error("should have been found")
-	}
-	if !bytes.Equal(fld2, fld) {
-		t.Errorf("wrong folder %q != %q", fld2, fld)
-	}
-	name2 := db.globalKeyName(key)
-	if !bytes.Equal(name2, name) {
-		t.Errorf("wrong name %q != %q", name2, name)
-	}
-
-	_, ok = db.globalKeyFolder([]byte{1, 2, 3, 4, 5})
-	if ok {
-		t.Error("should not have been found")
-	}
-}
-
 func TestDropIndexIDs(t *testing.T) {
 	db := OpenMemory()
 
@@ -287,11 +234,11 @@ func TestUpdate0to3(t *testing.T) {
 
 	db.updateSchema0to1()
 
-	if _, ok := db.getFile(db.deviceKey(folder, protocol.LocalDeviceID[:], []byte(slashPrefixed))); ok {
+	if _, ok := db.getFile(db.keyer.GenerateDeviceFileKey(nil, folder, protocol.LocalDeviceID[:], []byte(slashPrefixed))); ok {
 		t.Error("File prefixed by '/' was not removed during transition to schema 1")
 	}
 
-	if _, err := db.Get(db.globalKey(folder, []byte(invalid)), nil); err != nil {
+	if _, err := db.Get(db.keyer.GenerateGlobalVersionKey(nil, folder, []byte(invalid)), nil); err != nil {
 		t.Error("Invalid file wasn't added to global list")
 	}