From 0437d37f232e210b572b51c076ac2b75cf7ff574 Mon Sep 17 00:00:00 2001
From: Clark <clark@signal.org>
Date: Thu, 15 Jun 2023 09:50:22 -0400
Subject: [PATCH] Fix pending retry receipt cache deadlock.

---
 .../securesms/database/PendingRetryReceiptCache.kt  | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/app/src/main/java/org/thoughtcrime/securesms/database/PendingRetryReceiptCache.kt b/app/src/main/java/org/thoughtcrime/securesms/database/PendingRetryReceiptCache.kt
index 7ac9a56d40..65b6f7dc57 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/database/PendingRetryReceiptCache.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/database/PendingRetryReceiptCache.kt
@@ -23,10 +23,15 @@ class PendingRetryReceiptCache @VisibleForTesting constructor(
   fun insert(author: RecipientId, authorDevice: Int, sentTimestamp: Long, receivedTimestamp: Long, threadId: Long) {
     if (!FeatureFlags.retryReceipts()) return
     ensurePopulated()
-
+    val model: PendingRetryReceiptModel = database.insert(author, authorDevice, sentTimestamp, receivedTimestamp, threadId)
     synchronized(pendingRetries) {
-      val model: PendingRetryReceiptModel = database.insert(author, authorDevice, sentTimestamp, receivedTimestamp, threadId)
-      pendingRetries[RemoteMessageId(author, sentTimestamp)] = model
+      val key = RemoteMessageId(author, sentTimestamp)
+      val existing: PendingRetryReceiptModel? = pendingRetries[key]
+
+      // We rely on db unique constraint and auto-incrementing ids for conflict resolution here.
+      if (existing == null || existing.id < model.id) {
+        pendingRetries[key] = model
+      }
     }
   }
 
@@ -54,8 +59,8 @@ class PendingRetryReceiptCache @VisibleForTesting constructor(
 
     synchronized(pendingRetries) {
       pendingRetries.remove(RemoteMessageId(model.author, model.sentTimestamp))
-      database.delete(model)
     }
+    database.delete(model)
   }
 
   fun clear() {