Enable request limiter for CreateInstallation, GenerateAuthToken request calls.

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

@@ -34,7 +34,6 @@
 import com.google.firebase.installations.remote.FirebaseInstallationServiceClient;
 import com.google.firebase.installations.remote.InstallationResponse;
 import com.google.firebase.installations.remote.TokenResult;
-import com.google.firebase.installations.time.SystemClock;
 import com.google.firebase.platforminfo.UserAgentPublisher;
 import java.io.IOException;
 import java.util.ArrayList;
@@ -133,7 +132,7 @@ public Thread newThread(Runnable r) {
         new FirebaseInstallationServiceClient(
             firebaseApp.getApplicationContext(), publisher, heartbeatInfo),
         new PersistedInstallation(firebaseApp),
-        new Utils(SystemClock.getInstance()),
+        Utils.getInstance(),
         new IidStore(firebaseApp),
         new RandomFidGenerator());
   }

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

@@ -35,6 +35,10 @@ public enum Status {
      * may be corrected by retrying. We recommend exponential backoff when retrying requests.
      */
     UNAVAILABLE,
+    /**
+     * Firebase servers have received too many requests in a short period of time from the client.
+     */
+    TOO_MANY_REQUESTS,
   }
 
   @NonNull private final Status status;

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

@@ -19,6 +19,7 @@
 import androidx.annotation.Nullable;
 import com.google.firebase.installations.local.PersistedInstallationEntry;
 import com.google.firebase.installations.time.Clock;
+import com.google.firebase.installations.time.SystemClock;
 import java.util.concurrent.TimeUnit;
 import java.util.regex.Pattern;
 
@@ -31,11 +32,30 @@ public final class Utils {
   public static final long AUTH_TOKEN_EXPIRATION_BUFFER_IN_SECS = TimeUnit.HOURS.toSeconds(1);
   private static final String APP_ID_IDENTIFICATION_SUBSTRING = ":";
   private static final Pattern API_KEY_FORMAT = Pattern.compile("\\AA[\\w-]{38}\\z");
+  private static Utils singleton;
   private final Clock clock;
 
-  Utils(Clock clock) {
+  private Utils(Clock clock) {
     this.clock = clock;
   }
+
+  // Factory method that always returns the same Utils instance.
+  public static Utils getInstance() {
+    return getInstance(SystemClock.getInstance());
+  }
+
+  /**
+   * Returns an Utils instance. {@link Utils#getInstance()} defines the clock used. NOTE: If a Utils
+   * instance has already been initialized, the parameter will be ignored and the existing instance
+   * will be returned.
+   */
+  public static Utils getInstance(Clock clock) {
+    if (singleton == null) {
+      singleton = new Utils(clock);
+    }
+    return singleton;
+  }
+
   /**
    * Checks if the FIS Auth token is expired or going to expire in next 1 hour {@link
    * #AUTH_TOKEN_EXPIRATION_BUFFER_IN_SECS}.

firebase-installations/src/main/java/com/google/firebase/installations/remote/FirebaseInstallationServiceClient.java

@@ -97,13 +97,15 @@ public class FirebaseInstallationServiceClient {
   private static final String SDK_VERSION_PREFIX = "a:";
 
   private static final String FIS_TAG = "Firebase-Installations";
+  private boolean shouldServerErrorRetry;
 
   @VisibleForTesting
   static final String PARSING_EXPIRATION_TIME_ERROR_MESSAGE = "Invalid Expiration Timestamp.";
 
   private final Context context;
   private final Provider<UserAgentPublisher> userAgentPublisher;
   private final Provider<HeartBeatInfo> heartbeatInfo;
+  private final RequestLimiter requestLimiter;
 
   public FirebaseInstallationServiceClient(
       @NonNull Context context,
@@ -112,6 +114,7 @@ public FirebaseInstallationServiceClient(
     this.context = context;
     this.userAgentPublisher = publisher;
     this.heartbeatInfo = heartbeatInfo;
+    this.requestLimiter = new RequestLimiter();
   }
 
   /**
@@ -140,10 +143,16 @@ public InstallationResponse createFirebaseInstallation(
       @NonNull String appId,
       @Nullable String iidToken)
       throws FirebaseInstallationsException {
+    if (!requestLimiter.isRequestAllowed()) {
+      throw new FirebaseInstallationsException(
+          "Firebase Installations Service is unavailable. Please try again later.",
+          Status.UNAVAILABLE);
+    }
+
     String resourceName = String.format(CREATE_REQUEST_RESOURCE_NAME_FORMAT, projectID);
-    int retryCount = 0;
     URL url = getFullyQualifiedRequestUri(resourceName);
-    while (retryCount <= MAX_RETRIES) {
+    for (int retryCount = 0; retryCount <= MAX_RETRIES; retryCount++) {
+
       HttpURLConnection httpURLConnection = openHttpURLConnection(url, apiKey);
 
       try {
@@ -158,15 +167,22 @@ public InstallationResponse createFirebaseInstallation(
         writeFIDCreateRequestBodyToOutputStream(httpURLConnection, fid, appId);
 
         int httpResponseCode = httpURLConnection.getResponseCode();
+        requestLimiter.setNextRequestTime(httpResponseCode);
 
-        if (httpResponseCode == 200) {
+        if (isSuccessfulResponseCode(httpResponseCode)) {
           return readCreateResponse(httpURLConnection);
         }
 
         logFisCommunicationError(httpURLConnection, appId, apiKey, projectID);
 
-        if (httpResponseCode == 429 || (httpResponseCode >= 500 && httpResponseCode < 600)) {
-          retryCount++;
+        if (httpResponseCode == 429) {
+          throw new FirebaseInstallationsException(
+              "Firebase servers have received too many requests from this client in a short "
+                  + "period of time. Please try again later.",
+              Status.TOO_MANY_REQUESTS);
+        }
+
+        if (httpResponseCode >= 500 && httpResponseCode < 600) {
           continue;
         }
 
@@ -175,7 +191,7 @@ public InstallationResponse createFirebaseInstallation(
         // Return empty installation response with BAD_CONFIG response code after max retries
         return InstallationResponse.builder().setResponseCode(ResponseCode.BAD_CONFIG).build();
       } catch (AssertionError | IOException ignored) {
-        retryCount++;
+        continue;
       } finally {
         httpURLConnection.disconnect();
       }
@@ -363,11 +379,17 @@ public TokenResult generateAuthToken(
       @NonNull String projectID,
       @NonNull String refreshToken)
       throws FirebaseInstallationsException {
+    if (!requestLimiter.isRequestAllowed()) {
+      throw new FirebaseInstallationsException(
+          "Firebase Installations Service is unavailable. Please try again later.",
+          Status.UNAVAILABLE);
+    }
+
     String resourceName =
         String.format(GENERATE_AUTH_TOKEN_REQUEST_RESOURCE_NAME_FORMAT, projectID, fid);
-    int retryCount = 0;
     URL url = getFullyQualifiedRequestUri(resourceName);
-    while (retryCount <= MAX_RETRIES) {
+    for (int retryCount = 0; retryCount <= MAX_RETRIES; retryCount++) {
+
       HttpURLConnection httpURLConnection = openHttpURLConnection(url, apiKey);
       try {
         httpURLConnection.setRequestMethod("POST");
@@ -377,8 +399,9 @@ public TokenResult generateAuthToken(
         writeGenerateAuthTokenRequestBodyToOutputStream(httpURLConnection);
 
         int httpResponseCode = httpURLConnection.getResponseCode();
+        requestLimiter.setNextRequestTime(httpResponseCode);
 
-        if (httpResponseCode == 200) {
+        if (isSuccessfulResponseCode(httpResponseCode)) {
           return readGenerateAuthTokenResponse(httpURLConnection);
         }
 
@@ -388,8 +411,14 @@ public TokenResult generateAuthToken(
           return TokenResult.builder().setResponseCode(TokenResult.ResponseCode.AUTH_ERROR).build();
         }
 
-        if (httpResponseCode == 429 || (httpResponseCode >= 500 && httpResponseCode < 600)) {
-          retryCount++;
+        if (httpResponseCode == 429) {
+          throw new FirebaseInstallationsException(
+              "Firebase servers have received too many requests from this client in a short "
+                  + "period of time. Please try again later.",
+              Status.TOO_MANY_REQUESTS);
+        }
+
+        if (httpResponseCode >= 500 && httpResponseCode < 600) {
           continue;
         }
 
@@ -398,7 +427,7 @@ public TokenResult generateAuthToken(
         return TokenResult.builder().setResponseCode(TokenResult.ResponseCode.BAD_CONFIG).build();
         // TODO(b/166168291): Remove code duplication and clean up this class.
       } catch (AssertionError | IOException ignored) {
-        retryCount++;
+        continue;
       } finally {
         httpURLConnection.disconnect();
       }
@@ -408,6 +437,10 @@ public TokenResult generateAuthToken(
         Status.UNAVAILABLE);
   }
 
+  private static boolean isSuccessfulResponseCode(int responseCode) {
+    return responseCode >= 200 && responseCode < 300;
+  }
+
   private static void logBadConfigError() {
     Log.e(
         FIS_TAG,

firebase-installations/src/main/java/com/google/firebase/installations/remote/RequestLimiter.java

@@ -42,10 +42,15 @@ class RequestLimiter {
     this.utils = utils;
   }
 
+  RequestLimiter() {
+    // Util class is injected to ease mocking & testing the system time.
+    this.utils = Utils.getInstance();
+  }
+
   // Based on the response code, calculates the next request time to communicate with the FIS
   // servers.
   public synchronized void setNextRequestTime(int responseCode) {
-    if (isSuccessful(responseCode)) {
+    if (isSuccessfulOrRequiresNewFidCreation(responseCode)) {
       resetBackoffStrategy();
       return;
     }
@@ -77,10 +82,14 @@ private static boolean isRetryableError(int responseCode) {
     return responseCode == 429 || (responseCode >= 500 && responseCode < 600);
   }
 
-  // Response codes classified as success for FIS API. Read more on FIS response codes:
-  // go/fis-api-error-code-classification.
-  private static boolean isSuccessful(int responseCode) {
-    return responseCode >= 200 && responseCode < 300;
+  // 2xx Response codes are classified as success for FIS API. Also, FIS GenerateAuthToken endpoint
+  // responds with 401 & 404 for auth config errors which requires clients to follow up with a
+  // request to create a new FID. So, we don't limit the next requests for 401 & 404 response codes
+  // as well. Read more on FIS response codes: go/fis-api-error-code-classification.
+  private static boolean isSuccessfulOrRequiresNewFidCreation(int responseCode) {
+    return ((responseCode >= 200 && responseCode < 300)
+        || responseCode == 401
+        || responseCode == 404);
   }
 
   // Decides whether a network request to FIS servers is allowed to execute.

firebase-installations/src/test/java/com/google/firebase/installations/FirebaseInstallationsTest.java

@@ -152,8 +152,7 @@ public void setUp() {
     persistedInstallation.clearForTesting();
 
     fakeClock = new FakeClock(5000000L);
-    utils = new Utils(fakeClock);
-
+    utils = Utils.getInstance(fakeClock);
     firebaseInstallations =
         new FirebaseInstallations(
             executor,
@@ -523,7 +522,9 @@ public void testGetId_expiredAuthTokenThrowsException_statusUpdated() throws Exc
         PersistedInstallationEntry.INSTANCE.withRegisteredFid(
             TEST_FID_1,
             TEST_REFRESH_TOKEN,
-            utils.currentTimeInSecs(),
+            utils.currentTimeInSecs()
+                - TEST_TOKEN_EXPIRATION_TIMESTAMP
+                + TimeUnit.MINUTES.toSeconds(30),
             TEST_AUTH_TOKEN,
             TEST_TOKEN_EXPIRATION_TIMESTAMP));
 
@@ -562,7 +563,10 @@ public void testGetId_expiredAuthToken_refreshesAuthToken() throws Exception {
         PersistedInstallationEntry.INSTANCE.withRegisteredFid(
             TEST_FID_1,
             TEST_REFRESH_TOKEN,
-            utils.currentTimeInSecs(),
+            // Set expiration time to 30 minutes from now (within refresh period)
+            utils.currentTimeInSecs()
+                - TEST_TOKEN_EXPIRATION_TIMESTAMP
+                + TimeUnit.MINUTES.toSeconds(30),
             TEST_AUTH_TOKEN,
             TEST_TOKEN_EXPIRATION_TIMESTAMP));
 
@@ -582,9 +586,6 @@ public void testGetId_expiredAuthToken_refreshesAuthToken() throws Exception {
     String fid = onCompleteListener.await();
     assertWithMessage("getId Task failed").that(fid).isEqualTo(TEST_FID_1);
 
-    // Waiting for Task that registers FID on the FIS Servers
-    executor.awaitTermination(500, TimeUnit.MILLISECONDS);
-
     TestOnCompleteListener<InstallationTokenResult> onCompleteListener2 =
         new TestOnCompleteListener<>();
     Task<InstallationTokenResult> task = firebaseInstallations.getToken(false);
@@ -749,7 +750,10 @@ public void testGetAuthToken_expiredAuthToken_fetchedNewTokenFromFIS() throws Ex
         PersistedInstallationEntry.INSTANCE.withRegisteredFid(
             TEST_FID_1,
             TEST_REFRESH_TOKEN,
-            utils.currentTimeInSecs(),
+            // Set expiration time to 30 minutes from now (within refresh period)
+            utils.currentTimeInSecs()
+                - TEST_TOKEN_EXPIRATION_TIMESTAMP
+                + TimeUnit.MINUTES.toSeconds(30),
             TEST_AUTH_TOKEN,
             TEST_TOKEN_EXPIRATION_TIMESTAMP));
 
@@ -780,7 +784,10 @@ public void testGetAuthToken_multipleCallsDoNotForceRefresh_fetchedNewTokenOnce(
         PersistedInstallationEntry.INSTANCE.withRegisteredFid(
             TEST_FID_1,
             TEST_REFRESH_TOKEN,
-            utils.currentTimeInSecs(),
+            // Set expiration time to 30 minutes from now (within refresh period)
+            utils.currentTimeInSecs()
+                - TEST_TOKEN_EXPIRATION_TIMESTAMP
+                + TimeUnit.MINUTES.toSeconds(30),
             TEST_AUTH_TOKEN,
             TEST_TOKEN_EXPIRATION_TIMESTAMP));