fix: iOS clean migration from RNCAsyncStorage_V1 to RTCAsyncStorage_V1 (#64)

Author: reilem

ios/RNCAsyncStorage.m

@@ -17,6 +17,7 @@
 #import <React/RCTUtils.h>
 
 static NSString *const RCTStorageDirectory = @"RCTAsyncLocalStorage_V1";
+static NSString *const RCTOldStorageDirectory = @"RNCAsyncLocalStorage_V1";
 static NSString *const RCTManifestFileName = @"manifest.json";
 static const NSUInteger RCTInlineValueThreshold = 1024;
 
@@ -78,27 +79,38 @@ static void RCTAppendError(NSDictionary *error, NSMutableArray<NSDictionary *> *
   return nil;
 }
 
+static NSString *RCTCreateStorageDirectoryPath(NSString *storageDir) {
+  NSString *storageDirectoryPath;
+#if TARGET_OS_TV
+  storageDirectoryPath = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES).firstObject;
+#else
+  storageDirectoryPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
+#endif
+  storageDirectoryPath = [storageDirectoryPath stringByAppendingPathComponent:storageDir];
+  return storageDirectoryPath;
+}
+
 static NSString *RCTGetStorageDirectory()
 {
   static NSString *storageDirectory = nil;
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
-#if TARGET_OS_TV
-    storageDirectory = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES).firstObject;
-#else
-    storageDirectory = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
-#endif
-    storageDirectory = [storageDirectory stringByAppendingPathComponent:RCTStorageDirectory];
+    storageDirectory = RCTCreateStorageDirectoryPath(RCTStorageDirectory);
   });
   return storageDirectory;
 }
 
+static NSString *RCTCreateManifestFilePath(NSString *storageDirectory)
+{
+  return [RCTCreateStorageDirectoryPath(storageDirectory) stringByAppendingPathComponent:RCTManifestFileName];
+}
+
 static NSString *RCTGetManifestFilePath()
 {
   static NSString *manifestFilePath = nil;
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
-    manifestFilePath = [RCTGetStorageDirectory() stringByAppendingPathComponent:RCTManifestFileName];
+    manifestFilePath = RCTCreateManifestFilePath(RCTStorageDirectory);
   });
   return manifestFilePath;
 }
@@ -168,6 +180,74 @@ static dispatch_queue_t RCTGetMethodQueue()
   return error ? RCTMakeError(@"Failed to delete storage directory.", error, nil) : nil;
 }
 
+static NSDate *RCTManifestModificationDate(NSString *manifestFilePath)
+{
+  NSDictionary *attributes = [[NSFileManager defaultManager] attributesOfItemAtPath:manifestFilePath error:nil];
+  return [attributes fileModificationDate];
+}
+
+/**
+ * Creates an NSException used during Storage Directory Migration.
+ */
+static void RCTStorageDirectoryMigrationLogError(NSString *reason, NSError *error)
+{
+  RCTLogWarn(@"%@: %@", reason, error ? error.description : @"");
+}
+
+static void RCTStorageDirectoryCleanupOld()
+{
+  NSError *error;
+  if (![[NSFileManager defaultManager] removeItemAtPath:RCTCreateStorageDirectoryPath(RCTOldStorageDirectory) error:&error]) {
+    RCTStorageDirectoryMigrationLogError(@"Failed to remove old storage directory during migration", error);
+  }
+}
+
+static void RCTStorageDirectoryMigrate()
+{
+  NSError *error;
+  // Migrate data by copying old storage directory to new storage directory location
+  if (![[NSFileManager defaultManager] copyItemAtPath:RCTCreateStorageDirectoryPath(RCTOldStorageDirectory) toPath:RCTGetStorageDirectory() error:&error]) {
+    RCTStorageDirectoryMigrationLogError(@"Failed to copy old storage directory to new storage directory location during migration", error);
+  } else {
+    // If copying succeeds, remove old storage directory
+    RCTStorageDirectoryCleanupOld();
+  }
+}
+
+/**
+ * This check is added to make sure that anyone coming from pre-1.2.2 does not lose cached data.
+ * Data is migrated from the "RNCAsyncLocalStorage_V1" directory to the "RCTAsyncLocalStorage_V1" directory.
+ */
+static void RCTStorageDirectoryMigrationCheck()
+{
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    NSError *error;
+    BOOL isDir;
+    // If the old directory exists, it means we may need to migrate old data to the new directory
+    if ([[NSFileManager defaultManager] fileExistsAtPath:RCTCreateStorageDirectoryPath(RCTOldStorageDirectory) isDirectory:&isDir] && isDir) {
+      // Check if the new storage directory location already exists
+      if ([[NSFileManager defaultManager] fileExistsAtPath:RCTGetStorageDirectory()]) {
+        // If new storage location exists, check if the new storage has been modified sooner
+        if ([RCTManifestModificationDate(RCTGetManifestFilePath()) compare:RCTManifestModificationDate(RCTCreateManifestFilePath(RCTOldStorageDirectory))] == 1) {
+          // If new location has been modified more recently, simply clean out old data
+          RCTStorageDirectoryCleanupOld();
+        } else {
+          // If old location has been modified more recently, remove new storage and migrate
+          if (![[NSFileManager defaultManager] removeItemAtPath:RCTGetStorageDirectory() error:&error]) {
+            RCTStorageDirectoryMigrationLogError(@"Failed to remove new storage directory during migration", error);
+          } else {
+            RCTStorageDirectoryMigrate();
+          }
+        }
+      } else {
+        // If new storage location doesn't exist, migrate data
+        RCTStorageDirectoryMigrate();
+      }
+    }
+  });
+}
+
 #pragma mark - RNCAsyncStorage
 
 @implementation RNCAsyncStorage
@@ -179,6 +259,20 @@ @implementation RNCAsyncStorage
   NSMutableDictionary<NSString *, NSString *> *_manifest;
 }
 
++ (BOOL)requiresMainQueueSetup
+{
+  return NO;
+}
+
+- (instancetype)init
+{
+  if (!(self = [super init])) {
+    return nil;
+  }
+  RCTStorageDirectoryMigrationCheck();
+  return self;
+}
+
 RCT_EXPORT_MODULE()
 
 - (dispatch_queue_t)methodQueue