getId() implementation with instrumented tests.

firebase-installations/firebase-installations.gradle

@@ -58,4 +58,6 @@ dependencies {
     androidTestImplementation "com.google.truth:truth:$googleTruthVersion"
     androidTestImplementation 'junit:junit:4.12'
     androidTestImplementation "androidx.annotation:annotation:1.0.0"
+    androidTestImplementation 'org.mockito:mockito-core:2.25.0'
+    androidTestImplementation 'org.mockito:mockito-android:2.25.0'
 }

firebase-installations/src/androidTest/java/com/google/firebase/installations/FirebaseInstallationsInstrumentedTest.java

@@ -14,10 +14,31 @@
 
 package com.google.firebase.installations;
 
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.fail;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.when;
+
+import androidx.test.core.app.ApplicationProvider;
 import androidx.test.runner.AndroidJUnit4;
+import com.google.android.gms.tasks.Tasks;
+import com.google.firebase.FirebaseApp;
+import com.google.firebase.FirebaseOptions;
+import com.google.firebase.installations.local.FiidCache;
+import com.google.firebase.installations.local.FiidCacheEntryValue;
+import com.google.firebase.installations.remote.FirebaseInstallationServiceClient;
+import com.google.firebase.installations.remote.FirebaseInstallationServiceException;
+import com.google.firebase.installations.remote.InstallationResponse;
+import java.util.concurrent.ExecutionException;
+import org.junit.After;
+import org.junit.Before;
 import org.junit.FixMethodOrder;
+import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.MethodSorters;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
 
 /**
  * Instrumented test, which will execute on an Android device.
@@ -26,4 +47,99 @@
  */
 @RunWith(AndroidJUnit4.class)
 @FixMethodOrder(MethodSorters.NAME_ASCENDING)
-public class FirebaseInstallationsInstrumentedTest {}
+public class FirebaseInstallationsInstrumentedTest {
+  private FirebaseApp firebaseApp;
+  @Mock private FirebaseInstallationServiceClient backendClientReturnsOk;
+  @Mock private FirebaseInstallationServiceClient backendClientReturnsError;
+  private FiidCache actualCache;
+  @Mock private FiidCache cacheReturnsError;
+
+  @Before
+  public void setUp() throws FirebaseInstallationServiceException {
+    MockitoAnnotations.initMocks(this);
+    FirebaseApp.clearInstancesForTest();
+    firebaseApp =
+        FirebaseApp.initializeApp(
+            ApplicationProvider.getApplicationContext(),
+            new FirebaseOptions.Builder()
+                .setApplicationId("1:123456789:android:abcdef")
+                .setProjectId("project-id")
+                .setApiKey("api_key")
+                .build());
+    actualCache = new FiidCache(firebaseApp);
+    when(backendClientReturnsOk.createFirebaseInstallation(
+            anyString(), anyString(), anyString(), anyString()))
+        .thenReturn(
+            InstallationResponse.builder()
+                .setName("/projects/123456789/installations/fid")
+                .setRefreshToken("refresh-token")
+                .setAuthToken(
+                    InstallationTokenResult.builder()
+                        .setToken("auth-token")
+                        .setTokenExpirationTimestampMillis(1000L)
+                        .build())
+                .build());
+    when(backendClientReturnsError.createFirebaseInstallation(
+            anyString(), anyString(), anyString(), anyString()))
+        .thenThrow(
+            new FirebaseInstallationServiceException(
+                "SDK Error", FirebaseInstallationServiceException.Status.SERVER_ERROR));
+    when(cacheReturnsError.insertOrUpdateCacheEntry(any())).thenReturn(false);
+    when(cacheReturnsError.readCacheEntryValue()).thenReturn(null);
+  }
+
+  @After
+  public void cleanUp() throws Exception {
+    actualCache.clear();
+  }
+
+  @Test
+  public void testCreateFirebaseInstallation_CacheOk_BackendOk() throws Exception {
+    FirebaseInstallations firebaseInstallations =
+        new FirebaseInstallations(firebaseApp, actualCache, backendClientReturnsOk);
+
+    // No exception, means success.
+    assertThat(Tasks.await(firebaseInstallations.getId())).isNotEmpty();
+    FiidCacheEntryValue entryValue = actualCache.readCacheEntryValue();
+    assertThat(entryValue.getFirebaseInstallationId()).isNotEmpty();
+    assertThat(entryValue.getCacheStatus()).isEqualTo(FiidCache.CacheStatus.REGISTERED);
+  }
+
+  @Test
+  public void testCreateFirebaseInstallation_CacheOk_BackendError() throws Exception {
+    FirebaseInstallations firebaseInstallations =
+        new FirebaseInstallations(firebaseApp, actualCache, backendClientReturnsError);
+
+    // Expect exception
+    try {
+      Tasks.await(firebaseInstallations.getId());
+      fail();
+    } catch (ExecutionException expected) {
+      Throwable cause = expected.getCause();
+      assertThat(cause).isInstanceOf(FirebaseInstallationsException.class);
+      assertThat(((FirebaseInstallationsException) cause).getStatus())
+          .isEqualTo(FirebaseInstallationsException.Status.SDK_INTERNAL_ERROR);
+    }
+
+    FiidCacheEntryValue entryValue = actualCache.readCacheEntryValue();
+    assertThat(entryValue.getFirebaseInstallationId()).isNotEmpty();
+    assertThat(entryValue.getCacheStatus()).isEqualTo(FiidCache.CacheStatus.REGISTER_ERROR);
+  }
+
+  @Test
+  public void testCreateFirebaseInstallation_CacheError_BackendOk() throws InterruptedException {
+    FirebaseInstallations firebaseInstallations =
+        new FirebaseInstallations(firebaseApp, cacheReturnsError, backendClientReturnsOk);
+
+    // Expect exception
+    try {
+      Tasks.await(firebaseInstallations.getId());
+      fail();
+    } catch (ExecutionException expected) {
+      Throwable cause = expected.getCause();
+      assertThat(cause).isInstanceOf(FirebaseInstallationsException.class);
+      assertThat(((FirebaseInstallationsException) cause).getStatus())
+          .isEqualTo(FirebaseInstallationsException.Status.CLIENT_ERROR);
+    }
+  }
+}

firebase-installations/src/main/java/com/google/firebase/installations/FirebaseInstallations.java

@@ -16,10 +16,18 @@
 
 import androidx.annotation.NonNull;
 import androidx.annotation.VisibleForTesting;
+import androidx.annotation.WorkerThread;
 import com.google.android.gms.common.internal.Preconditions;
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.Tasks;
 import com.google.firebase.FirebaseApp;
+import com.google.firebase.installations.local.FiidCache;
+import com.google.firebase.installations.local.FiidCacheEntryValue;
+import com.google.firebase.installations.remote.FirebaseInstallationServiceClient;
+import com.google.firebase.installations.remote.FirebaseInstallationServiceException;
+import com.google.firebase.installations.remote.InstallationResponse;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
 
 /**
  * Entry point for Firebase Installations.
@@ -35,10 +43,23 @@
 public class FirebaseInstallations implements FirebaseInstallationsApi {
 
   private final FirebaseApp firebaseApp;
+  private final FirebaseInstallationServiceClient serviceClient;
+  private final FiidCache localCache;
+  private final Executor executor;
 
   /** package private constructor. */
   FirebaseInstallations(FirebaseApp firebaseApp) {
+    this(firebaseApp, new FiidCache(firebaseApp), new FirebaseInstallationServiceClient());
+  }
+
+  FirebaseInstallations(
+      FirebaseApp firebaseApp,
+      FiidCache localCache,
+      FirebaseInstallationServiceClient serviceClient) {
     this.firebaseApp = firebaseApp;
+    this.serviceClient = serviceClient;
+    this.executor = Executors.newFixedThreadPool(6);
+    this.localCache = localCache;
   }
 
   /**
@@ -71,7 +92,7 @@ public static FirebaseInstallations getInstance(@NonNull FirebaseApp app) {
   @NonNull
   @Override
   public Task<String> getId() {
-    return Tasks.forResult("fid-is-better-than-iid");
+    return Tasks.call(executor, () -> createFirebaseInstallationId());
   }
 
   /** Returns a auth token(public key) of this Firebase app installation. */
@@ -103,4 +124,105 @@ String getApplicationId() {
   String getName() {
     return firebaseApp.getName();
   }
+
+  /**
+   * Create firebase installation id for the {@link FirebaseApp} on FIS Servers and client side
+   * cache.
+   *
+   * <pre>
+   *     The workflow is:
+   *         check if cache empty or cache status is REGISTER_ERROR
+   *                                 |
+   *                           create random fid
+   *                                 |
+   *               update cache with cache status UNREGISTERED
+   *                                 |
+   *                           send http request to backend
+   *                                 |                  |
+   *  on success: set cache entry status to REGISTERED  |
+   *                                 |                  |
+   *                                 |         on failure: set cache entry status to REGISTER_ERROR
+   *                                 |                     |
+   *                                return          throw exception
+   *
+   *
+   *                      else if cached FID exists
+   *                             |            |
+   *     if cache status is UNREGISTERED      |
+   *                  |                   return cached FID
+   *     send http request to backend
+   *               |               |
+   *  on success: set cache        \
+   *  entry status to REGISTERED   \
+   *                |              \
+   *                |         on failure: set cache entry status to REGISTER_ERROR
+   *                |                     |
+   *              return          throw exception
+   * </pre>
+   */
+  @WorkerThread
+  private String createFirebaseInstallationId() throws FirebaseInstallationsException {
+
+    FiidCacheEntryValue cacheEntryValue = localCache.readCacheEntryValue();
+
+    if (cacheEntryValue == null
+        || cacheEntryValue.getCacheStatus() == FiidCache.CacheStatus.REGISTER_ERROR) {
+      String fid = Utils.createRandomFid();
+
+      boolean firstUpdateCacheResult =
+          localCache.insertOrUpdateCacheEntry(
+              FiidCacheEntryValue.create(fid, FiidCache.CacheStatus.UNREGISTERED, "", "", 0, 0));
+
+      if (!firstUpdateCacheResult) {
+        throw new FirebaseInstallationsException(
+            "Failed to update client side cache.",
+            FirebaseInstallationsException.Status.CLIENT_ERROR);
+      }
+
+      registerAndSaveFID(fid);
+
+      return fid;
+    } else if (!cacheEntryValue.getFirebaseInstallationId().isEmpty()) {
+
+      if (cacheEntryValue.getCacheStatus() == FiidCache.CacheStatus.UNREGISTERED) {
+        registerAndSaveFID(cacheEntryValue.getFirebaseInstallationId());
+      }
+
+      return cacheEntryValue.getFirebaseInstallationId();
+    }
+    return null;
+  }
+
+  /**
+   * Registers the created FID with FIS Servers if the Network is available and update the cache.
+   */
+  private void registerAndSaveFID(String fid) throws FirebaseInstallationsException {
+    try {
+      if (Utils.isNetworkAvailable(firebaseApp.getApplicationContext())) {
+        long creationTime = Utils.getCurrentTimeInSeconds();
+
+        InstallationResponse installationResponse =
+            serviceClient.createFirebaseInstallation(
+                firebaseApp.getOptions().getApiKey(),
+                firebaseApp.getOptions().getProjectId(),
+                fid,
+                getApplicationId());
+
+        localCache.insertOrUpdateCacheEntry(
+            FiidCacheEntryValue.create(
+                fid,
+                FiidCache.CacheStatus.REGISTERED,
+                installationResponse.getAuthToken().getToken(),
+                installationResponse.getRefreshToken(),
+                creationTime,
+                installationResponse.getAuthToken().getTokenExpirationTimestampMillis()));
+      }
+
+    } catch (FirebaseInstallationServiceException exception) {
+      localCache.insertOrUpdateCacheEntry(
+          FiidCacheEntryValue.create(fid, FiidCache.CacheStatus.REGISTER_ERROR, "", "", 0, 0));
+      throw new FirebaseInstallationsException(
+          exception.getMessage(), FirebaseInstallationsException.Status.SDK_INTERNAL_ERROR);
+    }
+  }
 }

firebase-installations/src/main/java/com/google/firebase/installations/Utils.java

@@ -14,6 +14,9 @@
 
 package com.google.firebase.installations;
 
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
 import androidx.annotation.NonNull;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
@@ -92,4 +95,15 @@ private static byte[] getBytesFromUUID(UUID uuid) {
 
     return bb.array();
   }
+
+  public static long getCurrentTimeInSeconds() {
+    return System.currentTimeMillis() / 1000;
+  }
+
+  public static boolean isNetworkAvailable(Context context) {
+    ConnectivityManager connectivityManager =
+        (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
+    return activeNetworkInfo != null && activeNetworkInfo.isConnected();
+  }
 }