From 8bc31386a5d3ac0eed20cd8425a906bd603ba27d Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Fri, 10 Jul 2026 04:31:51 +0000
Subject: [PATCH] Build eager prefetch sessions under the SignalSessionLock.

---
 .../ApplicationDependencyProvider.java        |  1 +
 .../api/keys/PreKeyRepository.kt              | 27 ++++++++++---------
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/app/src/main/java/org/thoughtcrime/securesms/dependencies/ApplicationDependencyProvider.java b/app/src/main/java/org/thoughtcrime/securesms/dependencies/ApplicationDependencyProvider.java
index a9ad7ab192..33412891f1 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/dependencies/ApplicationDependencyProvider.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/dependencies/ApplicationDependencyProvider.java
@@ -209,6 +209,7 @@ public class ApplicationDependencyProvider implements AppDependencies.Provider {
                                                 protocolStore.aci(),
                                                 new SignalProtocolAddress(pushServiceSocket.getCredentialsProvider().getAci().getLibSignalServiceId(),
                                                                           pushServiceSocket.getCredentialsProvider().getDeviceId()),
+                                                ReentrantSessionLock.INSTANCE,
                                                 PreKeyBatcher.INSTANCE
                                               )
                                             );
diff --git a/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/keys/PreKeyRepository.kt b/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/keys/PreKeyRepository.kt
index 7b9a8757e9..947ce96da0 100644
--- a/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/keys/PreKeyRepository.kt
+++ b/lib/libsignal-service/src/main/java/org/whispersystems/signalservice/api/keys/PreKeyRepository.kt
@@ -32,6 +32,7 @@ class PreKeyRepository(
   private val keysApi: KeysApi,
   private val aciStore: SignalServiceAccountDataStore,
   private val localProtocolAddress: SignalProtocolAddress,
+  private val sessionLock: SignalSessionLock,
   private val batchHelper: BatchHelper
 ) {
 
@@ -134,18 +135,20 @@ class PreKeyRepository(
         val recipient = result.recipient
         var aborted = false
 
-        for (preKey in result.bundles) {
-          val preKeyAddress = SignalProtocolAddress(recipient.identifier, preKey.deviceId)
-          try {
-            SessionBuilder(aciStore, preKeyAddress, localProtocolAddress).process(preKey)
-          } catch (_: UntrustedIdentityException) {
-            Log.i(TAG, "[eagerPrefetch] Untrusted identity for recipient")
-            aborted = true
-            break
-          } catch (_: InvalidKeyException) {
-            Log.i(TAG, "[eagerPrefetch] Invalid pre-key")
-            aborted = true
-            break
+        sessionLock.acquire().use {
+          for (preKey in result.bundles) {
+            val preKeyAddress = SignalProtocolAddress(recipient.identifier, preKey.deviceId)
+            try {
+              SessionBuilder(aciStore, preKeyAddress, localProtocolAddress).process(preKey)
+            } catch (_: UntrustedIdentityException) {
+              Log.i(TAG, "[eagerPrefetch] Untrusted identity for recipient")
+              aborted = true
+              break
+            } catch (_: InvalidKeyException) {
+              Log.i(TAG, "[eagerPrefetch] Invalid pre-key")
+              aborted = true
+              break
+            }
           }
         }