Write metadata updates to a tempfile first and improve error handling

Author: ajungg

core/src/main/java/io/snabble/sdk/MetadataDownloader.java

@@ -45,7 +45,7 @@ public MetadataDownloader(SnabbleSdk sdk,
     }
 
     @Override
-    protected void onDownloadFinished(String content) {
+    protected synchronized void onDownloadFinished(String content) {
         try {
             Map<String, String> urls = new HashMap<>();
             Map<String, String> extras = new HashMap<>();
@@ -68,7 +68,6 @@ protected void onDownloadFinished(String content) {
 
             if (jsonObject.has("metadata")) {
                 this.metadata = jsonObject.get("metadata").getAsJsonObject();
-
             }
 
             if (jsonObject.has("project")) {
@@ -82,7 +81,7 @@ protected void onDownloadFinished(String content) {
 
             updateStorage(content);
             hasData = true;
-        } catch (JsonSyntaxException e){
+        } catch (Exception e) {
             Logger.e(e.getMessage());
         }
     }

utils/src/main/java/io/snabble/sdk/utils/StringDownloader.java

@@ -5,6 +5,7 @@
 import android.content.pm.PackageManager;
 
 import org.apache.commons.io.FileUtils;
+import org.apache.commons.io.FilenameUtils;
 import org.apache.commons.io.IOUtils;
 
 import java.io.File;
@@ -20,6 +21,8 @@
 
 public abstract class StringDownloader extends Downloader {
     private File storageFile = null;
+    private String assetPath;
+    private Context context;
 
     public StringDownloader(OkHttpClient okHttpClient) {
         super(okHttpClient);
@@ -32,10 +35,11 @@ public StringDownloader(OkHttpClient okHttpClient) {
      * uses the app files data unless the app gets updated.
      */
     public void setBundledData(Context context, String assetPath, File storageFile) {
+        this.context = context;
         this.storageFile = storageFile;
+        this.assetPath = assetPath;
 
         try {
-            InputStream bundledDataInputStream = context.getAssets().open(assetPath);
             PackageInfo packageInfo = context.getPackageManager().getPackageInfo(context.getPackageName(), 0);
 
             //you can not check for file modified time in the android assets folder,
@@ -46,28 +50,45 @@ public void setBundledData(Context context, String assetPath, File storageFile)
                 loadFromSavedData();
             } else {
                 Logger.d("Using initial seed: %s", storageFile.getAbsolutePath());
-                onDownloadFinished(IOUtils.toString(bundledDataInputStream, Charset.forName("UTF-8")));
+                loadFromBundledData();
             }
         } catch (IOException | PackageManager.NameNotFoundException e) {
             Logger.e("Could not load saved data: %s", storageFile.getAbsolutePath());
+            loadFromBundledData();
         }
     }
 
     private void loadFromSavedData() throws IOException {
         FileInputStream fis = new FileInputStream(storageFile);
         Logger.d("Using saved data: %s", storageFile.getAbsolutePath());
-        onDownloadFinished(IOUtils.toString(fis, Charset.forName("UTF-8")));
+        String savedData = IOUtils.toString(fis, Charset.forName("UTF-8"));
+        if(savedData != null && savedData.length() > 0){
+            onDownloadFinished(savedData);
+        } else {
+            Logger.d("Data corrupted, using initial seed: %s", storageFile.getAbsolutePath());
+            loadFromBundledData();
+        }
         fis.close();
     }
 
+    private void loadFromBundledData() {
+        try {
+            InputStream bundledDataInputStream = context.getAssets().open(assetPath);
+            onDownloadFinished(IOUtils.toString(bundledDataInputStream, Charset.forName("UTF-8")));
+            bundledDataInputStream.close();
+        } catch (IOException e) {
+            Logger.e("Could not bundled data: %s", e.toString());
+        }
+    }
+
     public void setStorageFile(File storageFile) {
         this.storageFile = storageFile;
 
         if (storageFile.exists()) {
             try {
                 loadFromSavedData();
             } catch (IOException e) {
-                Logger.e("Could not load saved data: %s", storageFile.getAbsolutePath());
+                Logger.e("Could not load saved data: %s", e.toString());
             }
         }
     }
@@ -78,17 +99,22 @@ public void setStorageFile(File storageFile) {
      * Note that app updates are causing the updated data written here to be overwritten again,
      * as it is assumed that new builds always have newer data.
      */
-    public void updateStorage(String content) {
+    public synchronized void updateStorage(String content) {
         if (storageFile != null) {
-            FileUtils.deleteQuietly(storageFile);
-
             try {
-                FileOutputStream fos = new FileOutputStream(storageFile);
+                File tempFile = new File(FilenameUtils.getFullPath(storageFile.getPath())
+                        + FilenameUtils.getBaseName(storageFile.getName())
+                        + "_temp." + FilenameUtils.getExtension(storageFile.getName()));
+
+                FileOutputStream fos = new FileOutputStream(tempFile);
                 IOUtils.write(content, fos, Charset.forName("UTF-8"));
                 fos.close();
+
+                FileUtils.deleteQuietly(storageFile);
+                FileUtils.moveFile(tempFile, storageFile);
                 Logger.d("Updated saved data:%s", storageFile.getAbsolutePath());
             } catch (IOException e) {
-                Logger.e("Could not update saved data %s", storageFile.getAbsolutePath());
+                Logger.e("Could not update saved data %s", e.toString());
             }
         }
     }