From d47ff9b7c78da8de5e1cc7619aa0bbc185dd6e4a Mon Sep 17 00:00:00 2001
From: Jonathan Klabunde Tomer <125505367+jkt-signal@users.noreply.github.com>
Date: Thu, 2 Nov 2023 16:20:19 -0700
Subject: [PATCH] don't make empty transactions

---
 .../textsecuregcm/storage/RepeatedUseSignedPreKeyStore.java   | 4 ++++
 .../whispersystems/textsecuregcm/storage/KeysManagerTest.java | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/storage/RepeatedUseSignedPreKeyStore.java b/service/src/main/java/org/whispersystems/textsecuregcm/storage/RepeatedUseSignedPreKeyStore.java
index f1ec9b961..2e61e2fc7 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/storage/RepeatedUseSignedPreKeyStore.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/storage/RepeatedUseSignedPreKeyStore.java
@@ -88,6 +88,10 @@ public abstract class RepeatedUseSignedPreKeyStore<K extends SignedPreKey<?>> {
    * @return a future that completes once all keys have been stored
    */
   public CompletableFuture<Void> store(final UUID identifier, final Map<Byte, K> signedPreKeysByDeviceId) {
+    if (signedPreKeysByDeviceId.isEmpty()) {
+      return CompletableFuture.completedFuture(null);
+    }
+
     final Timer.Sample sample = Timer.start();
 
     return dynamoDbAsyncClient.transactWriteItems(TransactWriteItemsRequest.builder()
diff --git a/service/src/test/java/org/whispersystems/textsecuregcm/storage/KeysManagerTest.java b/service/src/test/java/org/whispersystems/textsecuregcm/storage/KeysManagerTest.java
index 54d8118ad..da6a5ef04 100644
--- a/service/src/test/java/org/whispersystems/textsecuregcm/storage/KeysManagerTest.java
+++ b/service/src/test/java/org/whispersystems/textsecuregcm/storage/KeysManagerTest.java
@@ -265,6 +265,9 @@ class KeysManagerTest {
         "storing new last-resort keys should leave untouched ones alone");
     assertEquals(4L, keysManager.getLastResort(ACCOUNT_UUID, deviceId3).join().get().keyId(),
         "storing new last-resort keys should overwrite old ones");
+
+    keysManager.storePqLastResort(ACCOUNT_UUID, Map.of()).join();
+    assertEquals(3, keysManager.getPqEnabledDevices(ACCOUNT_UUID).join().size(), "storing zero last-resort keys should be a no-op");
   }
 
   @Test