if device storage is really low, delete the entire cache

app/src/main/AndroidManifest.xml

@@ -267,6 +267,9 @@
         <service
                 android:name=".CleanCacheService"
                 android:exported="false"/>
+        <service
+                android:name=".DeleteCacheService"
+                android:exported="false"/>
         <service android:name=".net.WifiStateChangeService"/>
         <service android:name=".localrepo.SwapService"/>
         <service

app/src/main/java/org/fdroid/fdroid/DeleteCacheService.java

@@ -0,0 +1,44 @@
+package org.fdroid.fdroid;
+
+import android.app.IntentService;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Process;
+import android.support.v4.content.ContextCompat;
+import android.util.Log;
+import org.apache.commons.io.FileUtils;
+
+import java.io.File;
+
+/**
+ * An {@link IntentService} subclass for deleting the full cache for this app.
+ */
+public class DeleteCacheService extends IntentService {
+    public static final String TAG = "DeleteCacheService";
+
+    public DeleteCacheService() {
+        super("DeleteCacheService");
+    }
+
+    public static void deleteAll(Context context) {
+        Intent intent = new Intent(context, DeleteCacheService.class);
+        context.startService(intent);
+    }
+
+    @Override
+    protected void onHandleIntent(Intent intent) {
+        if (intent == null) {
+            return;
+        }
+        Process.setThreadPriority(Process.THREAD_PRIORITY_LOWEST);
+        Log.w(TAG, "Deleting all cached contents!");
+        try {
+            FileUtils.deleteDirectory(getCacheDir());
+            for (File dir : ContextCompat.getExternalCacheDirs(this)) {
+                FileUtils.deleteDirectory(dir);
+            }
+        } catch (Exception e) {
+            // ignored
+        }
+    }
+}

app/src/main/java/org/fdroid/fdroid/receiver/DeviceStorageReceiver.java

@@ -4,6 +4,8 @@ import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import org.fdroid.fdroid.CleanCacheService;
+import org.fdroid.fdroid.DeleteCacheService;
+import org.fdroid.fdroid.Utils;
 
 public class DeviceStorageReceiver extends BroadcastReceiver {
     @Override
@@ -13,7 +15,13 @@ public class DeviceStorageReceiver extends BroadcastReceiver {
         }
         String action = intent.getAction();
         if (Intent.ACTION_DEVICE_STORAGE_LOW.equals(action)) {
-            CleanCacheService.schedule(context);
+            int percentageFree = Utils.getPercent(Utils.getImageCacheDirAvailableMemory(context),
+                    Utils.getImageCacheDirTotalMemory(context));
+            if (percentageFree > 2) {
+                CleanCacheService.start(context);
+            } else {
+                DeleteCacheService.deleteAll(context);
+            }
         }
     }
 }