Fix a sync deadlock, and add a stress testing example app

android/core/src/main/java/com/mongodb/stitch/android/core/internal/net/AndroidNetworkMonitor.java

@@ -21,6 +21,8 @@
 import android.content.Intent;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
+import android.os.AsyncTask;
+
 import com.mongodb.stitch.core.internal.net.NetworkMonitor;
 
 import java.util.HashSet;
@@ -56,9 +58,39 @@ public synchronized void removeNetworkStateListener(@Nonnull final StateListener
 
   @Override
   public void onReceive(final Context context, final Intent intent) {
-    final Set<StateListener> listenersCopy = new HashSet<>(listeners);
-    for (final StateListener listener : listenersCopy) {
-      listener.onNetworkStateChanged();
+    // Dispatch our network change callback to a background thread,
+    // since our listeners may block the main thread.
+    // See https://developer.android.com/guide/components/broadcasts#effects-process-state
+    final PendingResult pendingResult = goAsync();
+    final NetworkStateChangedTask asyncTask =
+        new NetworkStateChangedTask(pendingResult, new HashSet<>(listeners));
+    asyncTask.execute();
+  }
+
+  private static final class NetworkStateChangedTask extends AsyncTask<Void, Void, Void> {
+    private final Set<StateListener> listeners;
+    private final PendingResult pendingResult;
+
+    private NetworkStateChangedTask(
+        final PendingResult result,
+        final Set<StateListener> listeners
+    ) {
+      this.pendingResult = result;
+      this.listeners = listeners;
+    }
+
+    @Override
+    protected Void doInBackground(final Void... v) {
+      for (final StateListener listener: listeners) {
+        listener.onNetworkStateChanged();
+      }
+      return null;
+    }
+
+    @Override
+    protected void onPostExecute(final Void v) {
+      super.onPostExecute(v);
+      pendingResult.finish();
     }
   }
 }

android/examples/stress-tests/.gitignore

@@ -0,0 +1 @@
+/build

android/examples/stress-tests/build.gradle

@@ -0,0 +1,28 @@
+apply plugin: 'com.android.application'
+apply plugin: 'digital.wup.android-maven-publish'
+apply plugin: 'jacoco-android'
+
+buildscript {
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.3.0'
+        classpath 'digital.wup:android-maven-publish:3.3.0'
+        classpath 'com.dicedmelon.gradle:jacoco-android:0.1.4'
+    }
+}
+
+android {
+    compileSdkVersion target_api
+    defaultConfig {
+        minSdkVersion min_api
+        targetSdkVersion target_api
+    }
+}
+
+dependencies {
+    implementation project(':android:stitch-android-sdk')
+    implementation project(':android:android-services:stitch-android-services-mongodb-remote')
+    implementation "com.android.support:support-v4:${support_library_version}"
+    implementation "com.android.support:appcompat-v7:${support_library_version}"
+    implementation "com.android.support:recyclerview-v7:${support_library_version}"
+    implementation "com.android.support.constraint:constraint-layout:1.1.0"
+}

android/examples/stress-tests/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

android/examples/stress-tests/src/main/AndroidManifest.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.mongodb.stitch.android.examples.stresstests">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

android/examples/stress-tests/src/main/java/com/mongodb/stitch/android/examples/stresstests/MainActivity.java

@@ -0,0 +1,161 @@
+/*
+ * Copyright 2018-present MongoDB, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.mongodb.stitch.android.examples.stresstests;
+
+import android.os.Bundle;
+import android.support.v7.app.AppCompatActivity;
+import android.util.Log;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.TextView;
+
+import com.mongodb.stitch.android.core.Stitch;
+import com.mongodb.stitch.android.core.StitchAppClient;
+import com.mongodb.stitch.android.core.auth.StitchUser;
+import com.mongodb.stitch.android.services.mongodb.remote.RemoteMongoClient;
+import com.mongodb.stitch.android.services.mongodb.remote.RemoteMongoCollection;
+import com.mongodb.stitch.android.services.mongodb.remote.Sync;
+import com.mongodb.stitch.core.auth.providers.anonymous.AnonymousCredential;
+import com.mongodb.stitch.core.services.mongodb.remote.sync.DefaultSyncConflictResolvers;
+
+import java.util.ArrayList;
+import java.util.Locale;
+import java.util.Random;
+
+import org.bson.Document;
+import org.bson.types.ObjectId;
+
+public class MainActivity extends AppCompatActivity {
+
+  private Button addSingleDocButton;
+  private Button addManyDocsButton;
+  private Button clearDocsButton;
+
+  private EditText etManyDocs;
+  private TextView label;
+
+  private StitchAppClient stitchAppClient;
+  private RemoteMongoCollection<Document> coll;
+  private Sync<Document> syncedColl;
+
+  private static final String TAG = MainActivity.class.getName();
+
+  private static final Random RANDOM = new Random();
+
+  private void initializeSync() {
+    stitchAppClient.getAuth().loginWithCredential(new AnonymousCredential()).addOnSuccessListener(
+        stitchUser -> {
+          coll = stitchAppClient
+              .getServiceClient(RemoteMongoClient.factory, "mongodb-atlas")
+              .getDatabase("stress")
+              .getCollection("tests");
+
+          syncedColl = coll.sync();
+          syncedColl.configure(
+              DefaultSyncConflictResolvers.remoteWins(),
+              (documentId, event) -> {
+                Log.i(TAG, String.format("Got event for doc %s: %s", documentId, event));
+                updateLabels();
+              },
+              (documentId, error) -> Log.e(
+                  TAG, String.format("Got sync error for doc %s: %s", documentId, error)
+              )
+          );
+          updateLabels();
+        });
+
+  }
+
+  private void updateLabels() {
+    syncedColl.getSyncedIds().addOnSuccessListener(syncedIds -> label.setText(String.format(
+        Locale.US,
+        "# of synced docs: %d",
+        syncedIds.size()
+    )));
+  }
+
+  private void syncNewDocument() {
+    final StitchUser user = stitchAppClient.getAuth().getUser();
+    if (user == null) {
+      return;
+    }
+    final Document docToInsert = new Document()
+        .append("_id", new ObjectId())
+        .append("owner_id", stitchAppClient.getAuth().getUser().getId())
+        .append("message", String.format(Locale.US, "%d", RANDOM.nextInt()));
+
+    syncedColl.insertOne(docToInsert).addOnCompleteListener(task -> updateLabels());
+  }
+
+  private void syncManyDocuments(final int numberOfDocs) {
+    final StitchUser user = stitchAppClient.getAuth().getUser();
+    if (user == null) {
+      return;
+    }
+
+    final ArrayList<Document> docsToInsert = new ArrayList<>();
+
+    for (int i = 0; i < numberOfDocs; ++i) {
+      final Document docToInsert = new Document()
+          .append("_id", new ObjectId())
+          .append("owner_id", stitchAppClient.getAuth().getUser().getId())
+          .append("message", String.format(Locale.US, "%d", RANDOM.nextInt()));
+
+      docsToInsert.add(docToInsert);
+    }
+
+    syncedColl.insertMany(docsToInsert).addOnCompleteListener(task -> updateLabels());
+  }
+
+  private void clearAllDocuments() {
+    final StitchUser user = stitchAppClient.getAuth().getUser();
+    if (user == null) {
+      return;
+    }
+
+    syncedColl.deleteMany(new Document()).addOnCompleteListener(task -> updateLabels());
+  }
+
+  @Override
+  protected void onCreate(final Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    setContentView(R.layout.activity_main);
+
+    if (!Stitch.hasAppClient("stitch-tests-js-sdk-jntlj")) {
+      Stitch.initializeDefaultAppClient("stitch-tests-js-sdk-jntlj");
+    }
+
+    stitchAppClient = Stitch.getDefaultAppClient();
+    initializeSync();
+
+    addSingleDocButton = findViewById(R.id.button);
+    addManyDocsButton = findViewById(R.id.button3);
+    clearDocsButton = findViewById(R.id.button2);
+    etManyDocs = findViewById(R.id.numInput);
+
+    label = findViewById(R.id.textView);
+
+    addSingleDocButton.setOnClickListener(v -> syncNewDocument());
+
+    addManyDocsButton.setOnClickListener(v -> {
+      final int numberOfDocsToInsert = Integer.decode(etManyDocs.getText().toString());
+      syncManyDocuments(numberOfDocsToInsert);
+    });
+
+    clearDocsButton.setOnClickListener(v -> clearAllDocuments());
+  }
+}

android/examples/stress-tests/src/main/res/drawable-v24/ic_launcher_foreground.xml

@@ -0,0 +1,34 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillType="evenOdd"
+        android:pathData="M32,64C32,64 38.39,52.99 44.13,50.95C51.37,48.37 70.14,49.57 70.14,49.57L108.26,87.69L108,109.01L75.97,107.97L32,64Z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="78.5885"
+                android:endY="90.9159"
+                android:startX="48.7653"
+                android:startY="61.0927"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M66.94,46.02L66.94,46.02C72.44,50.07 76,56.61 76,64L32,64C32,56.61 35.56,50.11 40.98,46.06L36.18,41.19C35.45,40.45 35.45,39.3 36.18,38.56C36.91,37.81 38.05,37.81 38.78,38.56L44.25,44.05C47.18,42.57 50.48,41.71 54,41.71C57.48,41.71 60.78,42.57 63.68,44.05L69.11,38.56C69.84,37.81 70.98,37.81 71.71,38.56C72.44,39.3 72.44,40.45 71.71,41.19L66.94,46.02ZM62.94,56.92C64.08,56.92 65,56.01 65,54.88C65,53.76 64.08,52.85 62.94,52.85C61.8,52.85 60.88,53.76 60.88,54.88C60.88,56.01 61.8,56.92 62.94,56.92ZM45.06,56.92C46.2,56.92 47.13,56.01 47.13,54.88C47.13,53.76 46.2,52.85 45.06,52.85C43.92,52.85 43,53.76 43,54.88C43,56.01 43.92,56.92 45.06,56.92Z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>