[Firebase Segmentation] Add custom installation id cache layer and tests for it.

firebase-segmentation/firebase-segmentation.gradle

@@ -57,7 +57,7 @@ android {
     compileSdkVersion project.targetSdkVersion
 
     defaultConfig {
-        minSdkVersion project.minSdkVersion
+        minSdkVersion 21
         targetSdkVersion project.targetSdkVersion
         multiDexEnabled true
         versionName version
@@ -91,12 +91,17 @@ dependencies {
     implementation 'androidx.multidex:multidex:2.0.0'
     implementation 'com.google.android.gms:play-services-tasks:16.0.1'
 
+    compileOnly "com.google.auto.value:auto-value-annotations:1.6.5"
+    annotationProcessor "com.google.auto.value:auto-value:1.6.2"
+
     testImplementation 'androidx.test:core:1.2.0'
     testImplementation 'junit:junit:4.12'
     testImplementation "org.robolectric:robolectric:$robolectricVersion"
 
-    androidTestImplementation 'androidx.annotation:annotation:1.1.0'
-    androidTestImplementation 'androidx.test:runner:1.2.0'
-    androidTestImplementation 'androidx.test:rules:1.2.0'
+    androidTestImplementation "androidx.annotation:annotation:1.1.0"
     androidTestImplementation 'androidx.test.ext:junit:1.1.1'
+    androidTestImplementation 'androidx.test:rules:1.2.0'
+    androidTestImplementation 'androidx.test:runner:1.2.0'
+    androidTestImplementation "com.google.truth:truth:$googleTruthVersion"
+    androidTestImplementation 'junit:junit:4.12'
 }

firebase-segmentation/src/androidTest/java/com/google/firebase/segmentation/CustomInstallationIdCacheTest.java

@@ -0,0 +1,85 @@
+// Copyright 2019 Google LLC
+//
+// 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.google.firebase.segmentation;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertNull;
+
+import androidx.test.InstrumentationRegistry;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import com.google.firebase.FirebaseApp;
+import com.google.firebase.FirebaseOptions;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Instrumented tests for {@link CustomInstallationIdCache} */
+@RunWith(AndroidJUnit4.class)
+public class CustomInstallationIdCacheTest {
+
+  private FirebaseApp firebaseApp0;
+  private FirebaseApp firebaseApp1;
+  private CustomInstallationIdCache cache;
+
+  @Before
+  public void setUp() {
+    FirebaseApp.clearInstancesForTest();
+    firebaseApp0 =
+        FirebaseApp.initializeApp(
+            InstrumentationRegistry.getContext(),
+            new FirebaseOptions.Builder().setApplicationId("1:123456789:android:abcdef").build());
+    firebaseApp1 =
+        FirebaseApp.initializeApp(
+            InstrumentationRegistry.getContext(),
+            new FirebaseOptions.Builder().setApplicationId("1:987654321:android:abcdef").build(),
+            "firebase_app_1");
+    cache = new CustomInstallationIdCache();
+  }
+
+  @After
+  public void cleanUp() {
+    cache.clear();
+  }
+
+  @Test
+  public void testReadCacheEntry_Null() {
+    assertNull(cache.readCacheEntryValue(firebaseApp0));
+    assertNull(cache.readCacheEntryValue(firebaseApp1));
+  }
+
+  @Test
+  public void testUpdateAndReadCacheEntry() {
+    cache.insertOrUpdateCacheEntry(
+        firebaseApp0,
+        CustomInstallationIdCacheEntryValue.create(
+            "123456", "cAAAAAAAAAA", CustomInstallationIdCache.CacheStatus.PENDING));
+    CustomInstallationIdCacheEntryValue entryValue = cache.readCacheEntryValue(firebaseApp0);
+    assertThat(entryValue.getCustomInstallationId()).isEqualTo("123456");
+    assertThat(entryValue.getFirebaseInstanceId()).isEqualTo("cAAAAAAAAAA");
+    assertThat(entryValue.getCacheStatus())
+        .isEqualTo(CustomInstallationIdCache.CacheStatus.PENDING);
+    assertNull(cache.readCacheEntryValue(firebaseApp1));
+
+    cache.insertOrUpdateCacheEntry(
+        firebaseApp0,
+        CustomInstallationIdCacheEntryValue.create(
+            "123456", "cAAAAAAAAAA", CustomInstallationIdCache.CacheStatus.SYNCED));
+    entryValue = cache.readCacheEntryValue(firebaseApp0);
+    assertThat(entryValue.getCustomInstallationId()).isEqualTo("123456");
+    assertThat(entryValue.getFirebaseInstanceId()).isEqualTo("cAAAAAAAAAA");
+    assertThat(entryValue.getCacheStatus()).isEqualTo(CustomInstallationIdCache.CacheStatus.SYNCED);
+  }
+}

firebase-segmentation/src/main/java/com/google/firebase/segmentation/CustomInstallationIdCache.java

@@ -0,0 +1,132 @@
+// Copyright 2019 Google LLC
+//
+// 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.google.firebase.segmentation;
+
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+import com.google.android.gms.common.internal.Preconditions;
+import com.google.firebase.FirebaseApp;
+
+class CustomInstallationIdCache {
+
+  // Status of each cache entry
+  // NOTE: never change the ordinal of the enum values because the enum values are stored in cache
+  // as their ordinal numbers.
+  enum CacheStatus {
+    // Cache entry is synced to Firebase backend
+    SYNCED,
+    // Cache entry is waiting for Firebase backend response or pending internal retry for retryable
+    // errors.
+    PENDING,
+    // Cache entry is not accepted by Firebase backend.
+    ERROR
+  }
+
+  private static final String LOCAL_DB_NAME = "CustomInstallationIdCache";
+  private static final String TABLE_NAME = "InstallationIdMapping";
+
+  private static final String GMP_APP_ID_COLUMN_NAME = "GmpAppId";
+  private static final String FIREBASE_APP_NAME_COLUMN_NAME = "AppName";
+  private static final String CUSTOM_INSTALLATION_ID_COLUMN_NAME = "Cid";
+  private static final String INSTANCE_ID_COLUMN_NAME = "Iid";
+  private static final String CACHE_STATUS_COLUMN = "Status";
+
+  private static final String QUERY_WHERE_CLAUSE =
+      String.format(
+          "%s = ? " + "AND " + "%s = ?", GMP_APP_ID_COLUMN_NAME, FIREBASE_APP_NAME_COLUMN_NAME);
+
+  private final SQLiteDatabase localDb;
+
+  CustomInstallationIdCache() {
+    // Since different FirebaseApp in the same Android application should have the same application
+    // context and same dir path, so that use the context of the default FirebaseApp to create/open
+    // the database.
+    localDb =
+        SQLiteDatabase.openOrCreateDatabase(
+            FirebaseApp.getInstance()
+                    .getApplicationContext()
+                    .getNoBackupFilesDir()
+                    .getAbsolutePath()
+                + "/"
+                + LOCAL_DB_NAME,
+            null);
+
+    localDb.execSQL(
+        String.format(
+            "CREATE TABLE IF NOT EXISTS %s(%s TEXT NOT NULL, %s TEXT NOT NULL, "
+                + "%s TEXT NOT NULL, %s TEXT NOT NULL, %s INTEGER NOT NULL, PRIMARY KEY (%s, %s));",
+            TABLE_NAME,
+            GMP_APP_ID_COLUMN_NAME,
+            FIREBASE_APP_NAME_COLUMN_NAME,
+            CUSTOM_INSTALLATION_ID_COLUMN_NAME,
+            INSTANCE_ID_COLUMN_NAME,
+            CACHE_STATUS_COLUMN,
+            GMP_APP_ID_COLUMN_NAME,
+            FIREBASE_APP_NAME_COLUMN_NAME));
+  }
+
+  @Nullable
+  CustomInstallationIdCacheEntryValue readCacheEntryValue(FirebaseApp firebaseApp) {
+    String gmpAppId = firebaseApp.getOptions().getApplicationId();
+    String appName = firebaseApp.getName();
+    Cursor cursor =
+        localDb.query(
+            TABLE_NAME,
+            new String[] {
+              CUSTOM_INSTALLATION_ID_COLUMN_NAME, INSTANCE_ID_COLUMN_NAME, CACHE_STATUS_COLUMN
+            },
+            QUERY_WHERE_CLAUSE,
+            new String[] {gmpAppId, appName},
+            null,
+            null,
+            null);
+    CustomInstallationIdCacheEntryValue value = null;
+    while (cursor.moveToNext()) {
+      Preconditions.checkArgument(
+          value == null, "Multiple cache entries found for " + "firebase app %s", appName);
+      value =
+          CustomInstallationIdCacheEntryValue.create(
+              cursor.getString(cursor.getColumnIndex(CUSTOM_INSTALLATION_ID_COLUMN_NAME)),
+              cursor.getString(cursor.getColumnIndex(INSTANCE_ID_COLUMN_NAME)),
+              CacheStatus.values()[cursor.getInt(cursor.getColumnIndex(CACHE_STATUS_COLUMN))]);
+    }
+    return value;
+  }
+
+  void insertOrUpdateCacheEntry(
+      FirebaseApp firebaseApp, CustomInstallationIdCacheEntryValue entryValue) {
+    localDb.execSQL(
+        String.format(
+            "INSERT OR REPLACE INTO %s(%s, %s, %s, %s, %s) VALUES(%s, %s, %s, %s, %s)",
+            TABLE_NAME,
+            GMP_APP_ID_COLUMN_NAME,
+            FIREBASE_APP_NAME_COLUMN_NAME,
+            CUSTOM_INSTALLATION_ID_COLUMN_NAME,
+            INSTANCE_ID_COLUMN_NAME,
+            CACHE_STATUS_COLUMN,
+            "\"" + firebaseApp.getOptions().getApplicationId() + "\"",
+            "\"" + firebaseApp.getName() + "\"",
+            "\"" + entryValue.getCustomInstallationId() + "\"",
+            "\"" + entryValue.getFirebaseInstanceId() + "\"",
+            entryValue.getCacheStatus().ordinal()));
+  }
+
+  @VisibleForTesting
+  void clear() {
+    localDb.execSQL(String.format("DROP TABLE IF EXISTS %s", TABLE_NAME));
+  }
+}

firebase-segmentation/src/main/java/com/google/firebase/segmentation/CustomInstallationIdCacheEntryValue.java

@@ -0,0 +1,37 @@
+// Copyright 2019 Google LLC
+//
+// 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.google.firebase.segmentation;
+
+import com.google.auto.value.AutoValue;
+import com.google.firebase.segmentation.CustomInstallationIdCache.CacheStatus;
+
+/**
+ * This class represents a cache entry value in {@link CustomInstallationIdCache}, which contains a
+ * Firebase instance id, a custom installation id and the cache status of this entry.
+ */
+@AutoValue
+abstract class CustomInstallationIdCacheEntryValue {
+  abstract String getCustomInstallationId();
+
+  abstract String getFirebaseInstanceId();
+
+  abstract CacheStatus getCacheStatus();
+
+  static CustomInstallationIdCacheEntryValue create(
+      String customInstallationId, String firebaseInstanceId, CacheStatus cacheStatus) {
+    return new AutoValue_CustomInstallationIdCacheEntryValue(
+        customInstallationId, firebaseInstanceId, cacheStatus);
+  }
+}