Use a lifecycle aware async task instead of a loader to open collection

AnkiDroid/build.gradle

@@ -108,11 +108,12 @@ task jacocoTestReport(type: JacocoReport, dependsOn: ['testDebugUnitTest', 'crea
 
 dependencies {
     implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation 'com.android.support:appcompat-v7:27.0.2'
+    def support_lib_version = '27.1.1'
+    implementation "com.android.support:appcompat-v7:$support_lib_version"
     // Note: the design support library can be quite buggy, so test everything thoroughly before updating it
-    implementation 'com.android.support:design:27.0.2'
-    implementation 'com.android.support:customtabs:27.0.2'
-    implementation 'com.android.support:recyclerview-v7:27.0.2'
+    implementation "com.android.support:design:$support_lib_version"
+    implementation "com.android.support:customtabs:$support_lib_version"
+    implementation "com.android.support:recyclerview-v7:$support_lib_version"
     implementation 'io.requery:sqlite-android:3.24.0'
     implementation 'android.arch.persistence:db:1.1.1'
     implementation 'com.afollestad.material-dialogs:core:0.9.6.0'

AnkiDroid/src/main/java/com/ichi2/anki/AnkiActivity.java

@@ -15,10 +15,8 @@
 import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentManager;
 import android.support.v4.app.FragmentTransaction;
-import android.support.v4.app.LoaderManager;
 import android.support.v4.app.NotificationCompat;
 import android.support.v4.content.ContextCompat;
-import android.support.v4.content.Loader;
 import android.support.v7.app.AppCompatActivity;
 import android.view.MenuItem;
 import android.view.View;
@@ -38,8 +36,7 @@
 
 import timber.log.Timber;
 
-public class AnkiActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Collection>,
-        SimpleMessageDialog.SimpleMessageDialogListener {
+public class AnkiActivity extends AppCompatActivity implements SimpleMessageDialog.SimpleMessageDialogListener {
 
     public final int SIMPLE_NOTIFICATION_ID = 0;
     public static final int REQUEST_REVIEW = 901;
@@ -97,6 +94,7 @@ public boolean onOptionsItemSelected(MenuItem item) {
 
     // called when the CollectionLoader finishes... usually will be over-ridden
     protected void onCollectionLoaded(Collection col) {
+        hideProgressBar();
     }
 
 
@@ -250,49 +248,25 @@ private void enableActivityAnimation(int animation) {
 
     // Method for loading the collection which is inherited by all AnkiActivitys
     public void startLoadingCollection() {
-        // Initialize the open collection loader
         Timber.d("AnkiActivity.startLoadingCollection()");
-        if (!colIsOpen()) {
-            showProgressBar();
+        if (colIsOpen()) {
+            onCollectionLoaded(getCol());
+            return;
         }
-        getSupportLoaderManager().restartLoader(0, null, this);
-    }
-
-
-    // Kick user back to DeckPicker on collection load error unless this method is overridden
-    protected void onCollectionLoadError() {
-        Intent deckPicker = new Intent(this, DeckPicker.class);
-        deckPicker.putExtra("collectionLoadError", true); // don't currently do anything with this
-        deckPicker.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
-        startActivityWithAnimation(deckPicker, ActivityTransitionAnimation.LEFT);
-    }
-
-
-    // CollectionLoader Listener callbacks
-    @Override
-    public Loader<Collection> onCreateLoader(int id, Bundle args) {
-        // Currently only using one loader, so ignore id
-        return new CollectionLoader(this);
-    }
-
-
-    @Override
-    public void onLoadFinished(Loader<Collection> loader, Collection col) {
-        hideProgressBar();
-        if (col != null && colIsOpen()) {
-            onCollectionLoaded(col);
-        } else {
-            onCollectionLoadError();
-        }
-    }
-
-
-    @Override
-    public void onLoaderReset(Loader<Collection> arg0) {
-        // We don't currently retain any references, so no need to free any data here
+        // Open collection asynchronously if it hasn't already been opened
+        showProgressBar();
+        CollectionLoader.load(this, col -> {
+            if (col != null) {
+                onCollectionLoaded(col);
+            } else {
+                Intent deckPicker = new Intent(this, DeckPicker.class);
+                deckPicker.putExtra("collectionLoadError", true); // don't currently do anything with this
+                deckPicker.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
+                startActivityWithAnimation(deckPicker, ActivityTransitionAnimation.LEFT);
+            }
+        });
     }
 
-
     public void showProgressBar() {
         ProgressBar progressBar = (ProgressBar) findViewById(R.id.progress_bar);
         if (progressBar != null) {

AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.java

@@ -823,7 +823,7 @@ private void onFinishedStartup() {
                 getCol().modSchema();
             } catch (ConfirmModSchemaException e) {
                 // If libanki determines it's necessary to confirm the full sync then show a confirmation dialog
-                // We have to show the dialog via the DialogHandler since this method is called via a Loader
+                // We have to show the dialog via the DialogHandler since this method is called via an async task
                 Resources res = getResources();
                 Message handlerMessage = Message.obtain();
                 handlerMessage.what = DialogHandler.MSG_SHOW_FORCE_FULL_SYNC_DIALOG;
@@ -841,12 +841,10 @@ private void onFinishedStartup() {
         automaticSync();
     }
 
-    @Override
-    protected void onCollectionLoadError() {
+    private void showCollectionErrorDialog() {
         getDialogHandler().sendEmptyMessage(DialogHandler.MSG_SHOW_COLLECTION_LOADING_ERROR_DIALOG);
     }
 
-
     public void addNote() {
         Intent intent = new Intent(DeckPicker.this, NoteEditor.class);
         intent.putExtra(NoteEditor.EXTRA_CALLER, NoteEditor.CALLER_DECKPICKER);
@@ -1144,7 +1142,7 @@ public void onPostExecute(DeckTask.TaskData result) {
                 }
                 if (result == null || !result.getBoolean()) {
                     UIUtils.showThemedToast(DeckPicker.this, getResources().getString(R.string.deck_repair_error), true);
-                    onCollectionLoadError();
+                    showCollectionErrorDialog();
                 }
             }
 
@@ -1871,7 +1869,7 @@ public void onPostExecute(TaskData result) {
                 }
                 if (result == null) {
                     Timber.e("null result loading deck counts");
-                    onCollectionLoadError();
+                    showCollectionErrorDialog();
                     return;
                 }
                 List<Sched.DeckDueTreeNode> nodes = (List<Sched.DeckDueTreeNode>) result.getObjArray()[0];

AnkiDroid/src/main/java/com/ichi2/async/CollectionLoader.java

@@ -1,70 +1,57 @@
 package com.ichi2.async;
 
-import android.content.Context;
-import android.support.v4.content.AsyncTaskLoader;
+import android.arch.lifecycle.Lifecycle;
+import android.arch.lifecycle.LifecycleOwner;
+import android.os.AsyncTask;
 
 import com.ichi2.anki.AnkiDroidApp;
 import com.ichi2.anki.CollectionHelper;
 import com.ichi2.libanki.Collection;
 
 import timber.log.Timber;
 
-public class CollectionLoader extends AsyncTaskLoader<Collection> {
+public final class CollectionLoader extends AsyncTask<Void, Void, Collection> {
+    private LifecycleOwner mLifecycleOwner;
+    private Callback mCallback;
 
-    public CollectionLoader(Context context) {
-        super(context);
+    public interface Callback {
+        void execute(Collection col);
+    }
+
+    public static void load(LifecycleOwner lifecycleOwner, Callback callback) {
+        CollectionLoader loader = new CollectionLoader(lifecycleOwner, callback);
+        loader.execute();
+    }
+
+    private CollectionLoader(LifecycleOwner lifecycleOwner, Callback callback) {
+        mLifecycleOwner = lifecycleOwner;
+        mCallback = callback;
     }
 
     @Override
-    public Collection loadInBackground() {
+    protected Collection doInBackground(Void... params) {
+        // Don't touch collection if lockCollection flag is set
+        if (CollectionHelper.getInstance().isCollectionLocked()) {
+            Timber.w("onStartLoading() :: Another thread has requested to keep the collection closed.");
+            return null;
+        }
         // load collection
         try {
             Timber.d("CollectionLoader accessing collection");
-            return CollectionHelper.getInstance().getCol(getContext());
+            return CollectionHelper.getInstance().getCol(AnkiDroidApp.getInstance().getApplicationContext());
         } catch (RuntimeException e) {
             Timber.e(e, "loadInBackground - RuntimeException on opening collection");
             AnkiDroidApp.sendExceptionReport(e, "CollectionLoader.loadInBackground");
             return null;
         }
     }
-
-    @Override
-    public void deliverResult(Collection col) {
-        Timber.d("CollectionLoader.deliverResult()");
-        // Loader has been reset so don't forward data to listener
-        if (isReset()) {
-            if (col != null) {
-                return;
-            }
-        }
-        // Loader is running so forward data to listener
-        if (isStarted()) {
-            super.deliverResult(col);
-        }
-    }
-
+
     @Override
-    protected void onStartLoading() {
-        // Don't touch collection if lockCollection flag is set
-        if (CollectionHelper.getInstance().isCollectionLocked()) {
-            Timber.w("onStartLoading() :: Another thread has requested to keep the collection closed.");
-            return;
+    protected void onPostExecute(Collection col) {
+        super.onPostExecute(col);
+        if (mLifecycleOwner.getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.CREATED)) {
+            mCallback.execute(col);
         }
-        // Since the CollectionHelper only opens if necessary, we can just force every time
-        forceLoad();
-    }
-
-    @Override
-    protected void onStopLoading() {
-        // The Loader has been put in a stopped state, so we should attempt to cancel the current load (if there is one).
-        Timber.d("CollectionLoader.onStopLoading()");
-        cancelLoad();
-    }
-
-    @Override
-    protected void onReset() {
-        // Ensure the loader is stopped.
-        Timber.d("CollectionLoader.onReset()");
-        onStopLoading();
     }
+
 }