MXFileStore: Be more robust on commit interruption: The metadata file…

… needs to by backuped too.

element-hq/element-ios#376

MatrixSDK/Data/Store/MXFileStore/MXFileStore.h

@@ -38,15 +38,17 @@
                     L accountData
                     L receipts
                 + ...
-            + roomsBackup: This folder contains backup of room files that are modified
-                  during the commit process. It is flushed when the commit completes.
+            L MXFileStore : Information about the stored data
+            + backup : This folder contains backup of files that are modified during
+                  the commit process. It is flushed when the commit completes.
                   This allows to rollback to previous data if the commit process was
                   interrupted.
                 + {syncToken} : the token that corresponds to the backup data
-                    + {roomIdA}
-                    + {roomIdB}
-                    + ...
-            L MXFileStore : Information about the stored data
+                    + rooms
+                        + {roomIdA}
+                        + {roomIdB}
+                        + ...
+                    L MXFileStore
  */
 @interface MXFileStore : MXMemoryStore
 

MatrixSDK/Data/Store/MXFileStore/MXFileStore.m

@@ -24,11 +24,11 @@
 
 NSString *const kMXFileStoreFolder = @"MXFileStore";
 NSString *const kMXFileStoreMedaDataFile = @"MXFileStore";
+NSString *const kMXFileStoreBackupFolder = @"backup";
 
 NSString *const kMXFileStoreSavingMarker = @"savingMarker";
 
 NSString *const kMXFileStoreRoomsFolder = @"rooms";
-NSString *const kMXFileStoreRoomsBackupFolder = @"roomsBackup";
 NSString *const kMXFileStoreRoomMessagesFile = @"messages";
 NSString *const kMXFileStoreRoomStateFile = @"state";
 NSString *const kMXFileStoreRoomAccountDataFile = @"accountData";
@@ -52,6 +52,9 @@ @interface MXFileStore ()
     // The path of the MXFileStore folder
     NSString *storePath;
 
+    // The path of the backup folder
+    NSString *storeBackupPath;
+
     // The path of the temporary file created during saving process.
     NSString *savingMarkerFile;
 
@@ -111,7 +114,9 @@ - (void)openWithCredentials:(MXCredentials*)someCredentials onComplete:(void (^)
     storePath = [[cachePath stringByAppendingPathComponent:kMXFileStoreFolder] stringByAppendingPathComponent:credentials.userId];
     savingMarkerFile = [storePath stringByAppendingPathComponent:kMXFileStoreSavingMarker];
     storeRoomsPath = [storePath stringByAppendingPathComponent:kMXFileStoreRoomsFolder];
-    storeRoomsBackupPath = [storePath stringByAppendingPathComponent:kMXFileStoreRoomsBackupFolder];
+
+    storeBackupPath = [storePath stringByAppendingPathComponent:kMXFileStoreBackupFolder];
+    storeRoomsBackupPath = [storeBackupPath stringByAppendingPathComponent:kMXFileStoreRoomsFolder];
 
     /*
     Mount data corresponding to the account credentials.
@@ -541,6 +546,18 @@ - (NSString*)readReceiptsFileForRoom:(NSString*)roomId forBackup:(BOOL)backup
     return [[self folderForRoom:roomId forBackup:backup] stringByAppendingPathComponent:kMXFileStoreRoomReadReceiptsFile];
 }
 
+- (NSString*)metaDataFileForBackup:(BOOL)backup
+{
+    if (!backup)
+    {
+        return [storePath stringByAppendingPathComponent:kMXFileStoreMedaDataFile];
+    }
+    else
+    {
+        return [storeBackupPath stringByAppendingPathComponent:kMXFileStoreMedaDataFile];
+    }
+}
+
 
 #pragma mark - Storage validity
 - (BOOL)checkStorageValidity
@@ -802,9 +819,18 @@ - (void)saveMetaData
         MXFileStoreMetaData *metaData2 = [metaData copy];
 
         dispatch_async(dispatchQueue, ^(void){
-
-            NSString *metaDataFile = [storePath stringByAppendingPathComponent:kMXFileStoreMedaDataFile];
-            [NSKeyedArchiver archiveRootObject:metaData2 toFile:metaDataFile];
+
+            NSString *file = [self metaDataFileForBackup:NO];
+            NSString *backupFile = [self metaDataFileForBackup:YES];
+
+            // Backup the file
+            if ([[NSFileManager defaultManager] fileExistsAtPath:file])
+            {
+                [[NSFileManager defaultManager] moveItemAtPath:file toPath:backupFile error:nil];
+            }
+
+            // Store new data
+            [NSKeyedArchiver archiveRootObject:metaData2 toFile:file];
         });
     }
 }