Merge pull request #2121 from Eitot/feature/database-initialisation

Change Database class initialisation process

Avoid calling most of the database setup code from within the `dispatch_once`
block of the singleton initialiser: prevent objects that are meant to be accessed
on the main thread from being accessed from within that block.
So, most of the database setup has been moved  into a `‑loadDatabaseStore`
method that is called from `‑applicationDidFinishLaunching:`

Author: barijaona

Vienna/Sources/Application/AppController.m

@@ -230,7 +230,8 @@ - (void)installScriptsFolderWatcher {
 -(void)applicationDidFinishLaunching:(NSNotification *)aNot
 {
     // Initialize the database
-    if ((db = [Database sharedManager]) == nil) {
+    db = Database.sharedManager;
+    if (!db || ![db loadDatabaseStore]) {
         [NSApp terminate:nil];
         return;
     }
@@ -954,7 +955,7 @@ -(void)initSortMenu
 	NSMenu * sortSubmenu = [NSMenu new];
 
 	// Add the fields which are sortable to the menu.
-	for (Field * field in [db arrayOfFields]) {
+	for (Field *field in db.fields) {
         if (field.customizationOptions & VNAFieldCustomizationSorting) {
             NSMenuItem *menuItem = [[NSMenuItem alloc] initWithTitle:field.displayName
                                                               action:@selector(changeSortColumn:)
@@ -985,7 +986,7 @@ -(void)initSortMenu
 -(void)initColumnsMenu
 {
 	NSMenu * columnsSubMenu = [NSMenu new];
-	for (Field * field in [db arrayOfFields]) {
+	for (Field *field in db.fields) {
         if (field.customizationOptions & VNAFieldCustomizationVisibility) {
             NSMenuItem *menuItem =
                 [[NSMenuItem alloc] initWithTitle:field.displayName

Vienna/Sources/Database/Database.h

@@ -41,6 +41,22 @@ extern NSNotificationName const VNADatabaseDidDeleteFolderNotification;
 
 @property (class, readonly, nonatomic) Database *sharedManager NS_SWIFT_NAME(shared);
 
+/**
+ Loads the database store.
+
+ This method performs these operations in order:
+  1. Retrieve and create if necessary the database path.
+  2. Load the database queue and ask if necessary to relocate the database.
+  3. Perform a SQLite3 `quick_check` and alert if issues are found.
+  4. Depending on the database version:
+     - perform a database migration,
+     - alert that the database is too old or
+     - set up an initial database.
+ @return `YES` if the database is loaded and has the current version or `NO`
+   if any of the operations failed.
+ */
+- (BOOL)loadDatabaseStore;
+
 @property(nonatomic) Folder * trashFolder;
 @property(nonatomic) Folder * searchFolder;
 @property (copy, nonatomic) NSString *searchString;
@@ -55,8 +71,7 @@ extern NSNotificationName const VNADatabaseDidDeleteFolderNotification;
 -(void)close;
 
 // Fields functions
--(void)addField:(NSString *)name type:(NSInteger)type sqlField:(NSString *)sqlField visible:(BOOL)visible width:(NSInteger)width;
--(NSArray *)arrayOfFields;
+@property (readonly, nonatomic) NSArray<Field *> *fields;
 -(Field *)fieldByName:(NSString *)name;
 
 // Folder functions