Call back from the firebase transport runtime into the event-emitter if there is an updated pseudonymous ID

This then allows the emitter to store the ID and attach it to future events.

Note: Ideally we would not even attach the ID to the event and rather resolve it directly before the http-call. Not sure why this was not done. But this is not really a big issue as long as the ids are very long living. Then we will we only end up with a small amount of events with stale IDs

I thought about how to best implement the callback.

- We can unfortunately not just use a regular Consumer class as the callback has to be persistable.
- Since the firebase transport runtime does not use Hilt's app-wide shared components I don't think we can inject the callback using dagger
- We could use Android functionality like e.g. a BroadcastReceiver, but this is pretty heavy handed

Internal b/490114654

Author: moltmann

transport/transport-api/CHANGELOG.md

@@ -1,5 +1,7 @@
 # Unreleased
 
+- [feature] Support callback when the pseudonymous id was updated
+
 # 4.1.0
 
 - [feature] Support multiple encrypted experiment IDs.

transport/transport-api/src/main/java/com/google/android/datatransport/EventContext.java

@@ -36,6 +36,9 @@ public abstract class EventContext {
   @SuppressWarnings("mutable")
   public abstract List<byte[]> getExperimentIdsEncryptedList();
 
+  @Nullable
+  public abstract String getPseudonymousIdUpdateReceiverClassName();
+
   public static Builder builder() {
     return new AutoValue_EventContext.Builder();
   }
@@ -54,6 +57,9 @@ public abstract static class Builder {
     @NonNull
     public abstract Builder setExperimentIdsEncryptedList(List<byte[]> value);
 
+    @NonNull
+    public abstract Builder setPseudonymousIdUpdateReceiverClassName(String value);
+
     @NonNull
     public abstract EventContext build();
   }

transport/transport-api/src/main/java/com/google/android/datatransport/PseudonymousIdUpdateReceiver.java

@@ -0,0 +1,32 @@
+// Copyright 2026 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.android.datatransport;
+
+import android.content.Context;
+import androidx.annotation.NonNull;
+
+/**
+ * This {@link PseudonymousIdUpdateReceiver} will be receiving pseudonymous id updates from the
+ * transport.
+ *
+ * <p>The constructor needs to take a single {@link Context} parameter.
+ *
+ * <p>Make sure that the constructor and the {@link #setUpdatedPseudonymousId} method are not
+ * removed by Proguard (add @Keep annotation if needed).
+ */
+public interface PseudonymousIdUpdateReceiver {
+  /** Sets the updated pseudonymous id. */
+  void setUpdatedPseudonymousId(@NonNull String updatedPseudonymousId);
+}

transport/transport-backend-cct/CHANGELOG.md

@@ -1,5 +1,7 @@
 # Unreleased
 
+- [feature] Support callback when the pseudonymous id was updated
+
 # 4.1.0
 
 - [feature] Support multiple encrypted experiment IDs.

transport/transport-backend-cct/src/main/java/com/google/android/datatransport/cct/CctTransportBackend.java

@@ -342,6 +342,27 @@ private BatchedLogRequest getRequestBody(BackendRequest backendRequest) {
     return BatchedLogRequest.create(batchedRequests);
   }
 
+  private String getPseudonymousId(HttpURLConnection connection) {
+    String setCookieHeader = connection.getHeaderField("Set-Cookie");
+    if (setCookieHeader != null) {
+      String[] cookieHeaderParts = setCookieHeader.split(";");
+
+      for (String cookieHeaderPart : cookieHeaderParts) {
+        String[] cookieKeyValue = cookieHeaderPart.trim().split("=", 2);
+        if (cookieKeyValue.length != 2) {
+          continue;
+        }
+        String cookieKey = cookieKeyValue[0];
+        String cookieValue = cookieKeyValue[1];
+
+        if (cookieKey.equals("NID")) {
+          return cookieValue;
+        }
+      }
+    }
+    return null;
+  }
+
   private HttpResponse doSend(HttpRequest request) throws IOException {
     Logging.i(LOG_TAG, "Making request to: %s", request.url);
     HttpURLConnection connection = (HttpURLConnection) request.url.openConnection();
@@ -373,10 +394,10 @@ private HttpResponse doSend(HttpRequest request) throws IOException {
           request.requestBody, new BufferedWriter(new OutputStreamWriter(outputStream)));
     } catch (ConnectException | UnknownHostException e) {
       Logging.e(LOG_TAG, "Couldn't open connection, returning with 500", e);
-      return new HttpResponse(500, null, 0);
+      return new HttpResponse(500, null, 0, null);
     } catch (EncodingException | IOException e) {
       Logging.e(LOG_TAG, "Couldn't encode request, returning with 400", e);
-      return new HttpResponse(400, null, 0);
+      return new HttpResponse(400, null, 0, null);
     }
 
     int responseCode = connection.getResponseCode();
@@ -386,10 +407,10 @@ private HttpResponse doSend(HttpRequest request) throws IOException {
 
     if (responseCode == 302 || responseCode == 301 || responseCode == 307) {
       String redirect = connection.getHeaderField("Location");
-      return new HttpResponse(responseCode, new URL(redirect), 0);
+      return new HttpResponse(responseCode, new URL(redirect), 0, null);
     }
     if (responseCode != 200) {
-      return new HttpResponse(responseCode, null, 0);
+      return new HttpResponse(responseCode, null, 0, null);
     }
 
     try (InputStream connStream = connection.getInputStream();
@@ -398,7 +419,7 @@ private HttpResponse doSend(HttpRequest request) throws IOException {
       long nextRequestMillis =
           LogResponse.fromJson(new BufferedReader(new InputStreamReader(inputStream)))
               .getNextRequestWaitMillis();
-      return new HttpResponse(responseCode, null, nextRequestMillis);
+      return new HttpResponse(responseCode, null, nextRequestMillis, getPseudonymousId(connection));
     }
   }
 
@@ -469,7 +490,7 @@ public BackendResponse send(BackendRequest request) {
               });
 
       if (response.code == 200) {
-        return BackendResponse.ok(response.nextRequestMillis);
+        return BackendResponse.ok(response.nextRequestMillis, response.updatedPseudonymousId);
       } else if (response.code >= 500 || response.code == 404) {
         return BackendResponse.transientError();
       } else if (response.code == 400) {
@@ -493,11 +514,17 @@ static final class HttpResponse {
     final int code;
     @Nullable final URL redirectUrl;
     final long nextRequestMillis;
+    @Nullable final String updatedPseudonymousId;
 
-    HttpResponse(int code, @Nullable URL redirectUrl, long nextRequestMillis) {
+    HttpResponse(
+        int code,
+        @Nullable URL redirectUrl,
+        long nextRequestMillis,
+        @Nullable String updatedPseudonymousId) {
       this.code = code;
       this.redirectUrl = redirectUrl;
       this.nextRequestMillis = nextRequestMillis;
+      this.updatedPseudonymousId = updatedPseudonymousId;
     }
   }
 

transport/transport-backend-cct/src/test/java/com/google/android/datatransport/cct/CctTransportBackendTest.java

@@ -292,7 +292,7 @@ public void testCCTSuccessLoggingRequest() {
                         JSON_PAYLOAD_ESCAPED)))
             .withoutHeader("Cookie"));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -391,7 +391,7 @@ public void testCCTSuccessLoggingRequestWithoutEncryptedList() {
                         JSON_PAYLOAD_ESCAPED)))
             .withoutHeader("Cookie"));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -490,7 +490,7 @@ public void testCCTSuccessLoggingRequestWithJustEncryptedList() {
                         JSON_PAYLOAD_ESCAPED)))
             .withoutHeader("Cookie"));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -536,7 +536,7 @@ public void testCCTContainsRightAndroidClientInfo() {
                     String.format(
                         "$[?(@.logRequest[0].clientInfo.androidClientInfo.mccMnc == \"\")]"))));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -570,7 +570,7 @@ public void testCCTContainsRightApplicationBuild() throws NameNotFoundException
                                 ApplicationProvider.getApplicationContext().getPackageName(),
                                 /* flags= */ 0)
                             .versionCode))));
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -806,7 +806,7 @@ public void send_whenBackendRedirects_shouldCorrectlyFollowTheRedirectViaPost()
         postRequestedFor(urlEqualTo("/api/hello"))
             .withHeader("Content-Type", equalTo("application/json")));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -836,7 +836,7 @@ public void send_whenBackendRedirectswith307_shouldCorrectlyFollowTheRedirectVia
         postRequestedFor(urlEqualTo("/api/hello"))
             .withHeader("Content-Type", equalTo("application/json")));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -895,7 +895,7 @@ public void send_CompressedResponseIsUncompressed() throws IOException {
             .withHeader("Content-Type", equalTo("application/json"))
             .withHeader("Content-Encoding", equalTo("gzip")));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -952,7 +952,7 @@ public void send_whenLogSourceIsSetByName_shouldSetItToProperField() throws IOEx
                 matchingJsonPath(
                     String.format("$[?(@.logRequest[1].logSourceName == \"%s\")]", TEST_NAME))));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test
@@ -1006,7 +1006,7 @@ public void send_withEventsOfUnsupportedEncoding_shouldBeSkipped() throws IOExce
                     String.format("$[?(@.logRequest[1].logSourceName == \"%s\")]", TEST_NAME)))
             .withRequestBody(matchingJsonPath("$[?(@.logRequest[1].logEvent.size() == 1)]")));
 
-    assertEquals(BackendResponse.ok(3), response);
+    assertEquals(BackendResponse.ok(3, null), response);
   }
 
   @Test

transport/transport-runtime/CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 
 - [changed] Bumped internal dependencies.
+- [feature] Support callback when the pseudonymous id was updated
 
 # 4.1.0
 

transport/transport-runtime/src/main/java/com/google/android/datatransport/runtime/EventInternal.java

@@ -58,6 +58,9 @@ public byte[] getPayload() {
   @Nullable
   public abstract List<byte[]> getExperimentIdsEncryptedList();
 
+  @Nullable
+  public abstract String getPseudonymousIdUpdateReceiverClassName();
+
   public final Map<String, String> getMetadata() {
     return Collections.unmodifiableMap(getAutoMetadata());
   }
@@ -91,6 +94,7 @@ public Builder toBuilder() {
         .setExperimentIdsClear(getExperimentIdsClear())
         .setExperimentIdsEncrypted(getExperimentIdsEncrypted())
         .setExperimentIdsEncryptedList(getExperimentIdsEncryptedList())
+        .setPseudonymousIdUpdateReceiverClassName(getPseudonymousIdUpdateReceiverClassName())
         .setEncodedPayload(getEncodedPayload())
         .setEventMillis(getEventMillis())
         .setUptimeMillis(getUptimeMillis())
@@ -125,6 +129,8 @@ public abstract static class Builder {
 
     public abstract Builder setExperimentIdsEncryptedList(List<byte[]> value);
 
+    public abstract Builder setPseudonymousIdUpdateReceiverClassName(String value);
+
     protected abstract Map<String, String> getAutoMetadata();
 
     public final Builder addMetadata(String key, String value) {

transport/transport-runtime/src/main/java/com/google/android/datatransport/runtime/TransportRuntime.java

@@ -172,6 +172,10 @@ private EventInternal convert(SendRequest request) {
       if (eventContext.getPseudonymousId() != null) {
         builder.setPseudonymousId(eventContext.getPseudonymousId());
       }
+      if (eventContext.getPseudonymousIdUpdateReceiverClassName() != null) {
+        builder.setPseudonymousIdUpdateReceiverClassName(
+            eventContext.getPseudonymousIdUpdateReceiverClassName());
+      }
       if (eventContext.getExperimentIdsClear() != null) {
         builder.setExperimentIdsClear(eventContext.getExperimentIdsClear());
       }

transport/transport-runtime/src/main/java/com/google/android/datatransport/runtime/backends/BackendResponse.java

@@ -14,6 +14,7 @@
 
 package com.google.android.datatransport.runtime.backends;
 
+import androidx.annotation.Nullable;
 import com.google.auto.value.AutoValue;
 
 /**
@@ -36,19 +37,24 @@ public enum Status {
   /** Time in millis to wait before attempting another request. */
   public abstract long getNextRequestWaitMillis();
 
+  /** Updated pseudonymous id from the backend or {@code null} if there is no update. */
+  @Nullable
+  public abstract String getUpdatedPseudonymousId();
+
   public static BackendResponse transientError() {
-    return new AutoValue_BackendResponse(Status.TRANSIENT_ERROR, -1);
+    return new AutoValue_BackendResponse(Status.TRANSIENT_ERROR, -1, null);
   }
 
   public static BackendResponse fatalError() {
-    return new AutoValue_BackendResponse(Status.FATAL_ERROR, -1);
+    return new AutoValue_BackendResponse(Status.FATAL_ERROR, -1, null);
   }
 
   public static BackendResponse invalidPayload() {
-    return new AutoValue_BackendResponse(Status.INVALID_PAYLOAD, -1);
+    return new AutoValue_BackendResponse(Status.INVALID_PAYLOAD, -1, null);
   }
 
-  public static BackendResponse ok(long nextRequestWaitMillis) {
-    return new AutoValue_BackendResponse(Status.OK, nextRequestWaitMillis);
+  public static BackendResponse ok(
+      long nextRequestWaitMillis, @Nullable String updatedPseudonymousId) {
+    return new AutoValue_BackendResponse(Status.OK, nextRequestWaitMillis, updatedPseudonymousId);
   }
 }