From b00ae8eec1ef0aa5094fca7fad918a437603eb12 Mon Sep 17 00:00:00 2001
From: Harshvardhan Gupta <95761669+Harsh5488@users.noreply.github.com>
Date: Wed, 10 Jul 2024 14:40:17 +0530
Subject: [PATCH] fix: make sendBuffer thread safe (#769)

Clearing the buffer upon timeout could lead to:

```
java.util.ConcurrentModificationException
	at java.base/java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:970)
	at java.base/java.util.LinkedList$ListItr.next(LinkedList.java:892)
	at io.socket.client.Socket$6$1.run(Socket.java:232)
	at java.base/java.util.TimerThread.mainLoop(Timer.java:556)
	at java.base/java.util.TimerThread.run(Timer.java:506)
```

Related:

- https://github.com/socketio/socket.io-client-java/issues/710
- https://github.com/socketio/socket.io-client-java/issues/727
- https://github.com/socketio/socket.io-client-java/pull/758
- https://github.com/socketio/socket.io-client-java/issues/759
---
 src/main/java/io/socket/client/Socket.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/java/io/socket/client/Socket.java b/src/main/java/io/socket/client/Socket.java
index 49bc378..7e131d0 100644
--- a/src/main/java/io/socket/client/Socket.java
+++ b/src/main/java/io/socket/client/Socket.java
@@ -61,8 +61,8 @@ public class Socket extends Emitter {
     private Map<String, String> auth;
     private Map<Integer, Ack> acks = new HashMap<>();
     private Queue<On.Handle> subs;
-    private final Queue<List<Object>> receiveBuffer = new LinkedList<>();
-    private final Queue<Packet<JSONArray>> sendBuffer = new LinkedList<>();
+    private final Queue<List<Object>> receiveBuffer = new ConcurrentLinkedQueue<>();
+    private final Queue<Packet<JSONArray>> sendBuffer = new ConcurrentLinkedQueue<>();
 
     private ConcurrentLinkedQueue<Listener> onAnyIncomingListeners = new ConcurrentLinkedQueue<>();
     private ConcurrentLinkedQueue<Listener> onAnyOutgoingListeners = new ConcurrentLinkedQueue<>();