From 7c9ae3561df6048f1afc8f87c1f2f72009601f7d Mon Sep 17 00:00:00 2001
From: Chris Eager <chris@signal.org>
Date: Fri, 11 Mar 2022 13:46:59 -0800
Subject: [PATCH] Send delivery receipts asynchronously

---
 .../textsecuregcm/WhisperServerService.java   |  4 ++-
 .../textsecuregcm/push/ReceiptSender.java     | 31 ++++++++++++-------
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java b/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
index c63301c90..3bdf62676 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
@@ -399,6 +399,8 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
         minThreads(availableProcessors).  // mostly this is IO bound so tying to number of processors is tenuous at best
         allowCoreThreadTimeOut(true).
         build();
+    ExecutorService receiptSenderExecutor = environment.lifecycle()
+        .executorService(name(getClass(), "receiptSender-%d")).maxThreads(16).minThreads(16).build();
 
     StripeManager stripeManager = new StripeManager(config.getStripe().getApiKey(), stripeExecutor,
         config.getStripe().getIdempotencyKeyGenerator(), config.getStripe().getBoostDescription());
@@ -468,7 +470,7 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
     TwilioSmsSender          twilioSmsSender    = new TwilioSmsSender(config.getTwilioConfiguration(), dynamicConfigurationManager);
     SmsSender                smsSender          = new SmsSender(twilioSmsSender);
     MessageSender            messageSender      = new MessageSender(apnFallbackManager, clientPresenceManager, messagesManager, gcmSender, apnSender, pushLatencyManager);
-    ReceiptSender            receiptSender      = new ReceiptSender(accountsManager, messageSender);
+    ReceiptSender            receiptSender      = new ReceiptSender(accountsManager, messageSender, receiptSenderExecutor);
     TurnTokenGenerator       turnTokenGenerator = new TurnTokenGenerator(config.getTurnConfiguration());
     RecaptchaClient recaptchaClient = new RecaptchaClient(
         config.getRecaptchaConfiguration().getProjectPath(),
diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/push/ReceiptSender.java b/service/src/main/java/org/whispersystems/textsecuregcm/push/ReceiptSender.java
index 82086054e..ffb8168f3 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/push/ReceiptSender.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/push/ReceiptSender.java
@@ -1,11 +1,13 @@
 /*
- * Copyright 2013-2021 Signal Messenger, LLC
+ * Copyright 2013-2022 Signal Messenger, LLC
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
 package org.whispersystems.textsecuregcm.push;
 
 import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.whispersystems.textsecuregcm.auth.AuthenticatedAccount;
@@ -17,20 +19,23 @@ import org.whispersystems.textsecuregcm.storage.Device;
 
 public class ReceiptSender {
 
-  private final MessageSender   messageSender;
+  private final MessageSender messageSender;
   private final AccountsManager accountManager;
+  private final ExecutorService executor;
 
   private static final Logger logger = LoggerFactory.getLogger(ReceiptSender.class);
 
-  public ReceiptSender(final AccountsManager accountManager, final MessageSender messageSender) {
+  public ReceiptSender(final AccountsManager accountManager, final MessageSender messageSender,
+      final ExecutorService executor) {
     this.accountManager = accountManager;
     this.messageSender = messageSender;
+    this.executor = executor;
   }
 
-  public void sendReceipt(AuthenticatedAccount source, UUID destinationUuid, long messageId) throws NoSuchUserException {
+  public CompletableFuture<Void> sendReceipt(AuthenticatedAccount source, UUID destinationUuid, long messageId) throws NoSuchUserException {
     final Account sourceAccount = source.getAccount();
     if (sourceAccount.getUuid().equals(destinationUuid)) {
-      return;
+      return CompletableFuture.completedFuture(null);
     }
 
     final Account destinationAccount = accountManager.getByAccountIdentifier(destinationUuid)
@@ -45,12 +50,16 @@ public class ReceiptSender {
         .setTimestamp(messageId)
         .setType(Envelope.Type.SERVER_DELIVERY_RECEIPT);
 
-    for (final Device destinationDevice : destinationAccount.getDevices()) {
-      try {
-        messageSender.sendMessage(destinationAccount, destinationDevice, message.build(), false);
-      } catch (final NotPushRegisteredException e) {
-        logger.info("User no longer push registered for delivery receipt: " + e.getMessage());
+    return CompletableFuture.runAsync(() -> {
+      for (final Device destinationDevice : destinationAccount.getDevices()) {
+        try {
+          messageSender.sendMessage(destinationAccount, destinationDevice, message.build(), false);
+        } catch (final NotPushRegisteredException e) {
+          logger.info("User no longer push registered for delivery receipt: " + e.getMessage());
+        } catch (final Exception e) {
+          logger.warn("Could not send delivery receipt", e);
+        }
       }
-    }
+    }, executor);
   }
 }