From b4569632e5036179ce7b54465467c76aa91931b8 Mon Sep 17 00:00:00 2001
From: Avinash Kumar Deepak <avinash8655279@gmail.com>
Date: Wed, 9 Sep 2026 15:18:49 +0530
Subject: [PATCH] fix(java): recover REQ socket after missing reply

---
 ConcoreJavaRuntimeCore.java |  6 +++++-
 TestConcoredockerApi.java   | 30 ++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/ConcoreJavaRuntimeCore.java b/ConcoreJavaRuntimeCore.java
index d371080..3120e1e 100644
--- a/ConcoreJavaRuntimeCore.java
+++ b/ConcoreJavaRuntimeCore.java
@@ -504,6 +504,10 @@ private class ZeroMQPort {
         ZeroMQPort(String portType, String address, int socketType) {
             ZMQ.Context ctx = getZmqContext();
             this.socket = ctx.socket(socketType);
+            if (socketType == ZMQ.REQ) {
+                this.socket.setReqRelaxed(true);
+                this.socket.setReqCorrelate(true);
+            }
             this.socket.setReceiveTimeOut(2000);
             this.socket.setSendTimeOut(2000);
             this.socket.setLinger(0);
@@ -771,4 +775,4 @@ Object parseKeyword() {
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/TestConcoredockerApi.java b/TestConcoredockerApi.java
index d62c8de..90e2085 100644
--- a/TestConcoredockerApi.java
+++ b/TestConcoredockerApi.java
@@ -2,6 +2,8 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.*;
+import org.zeromq.ZMQ;
+import org.zeromq.ZMQException;
 
 /**
  * Tests for concoredocker read(), write(), unchanged(), initVal()
@@ -29,6 +31,7 @@ public static void main(String[] args) {
         testReadParseError();
         testReadTraversalBlocked();
         testWriteTraversalBlocked();
+        testReqCanSendAfterMissingReply();
 
         System.out.println("\n=== Results: " + passed + " passed, " + failed + " failed out of " + (passed + failed) + " tests ===");
         if (failed > 0) {
@@ -251,4 +254,31 @@ static void testWriteTraversalBlocked() {
         concoredocker.write(1, "../escape", Collections.singletonList((Object) 1.0), 0);
         check("write traversal blocked: no escaped file", false, Files.exists(tmp.resolve("escape")));
     }
+
+    static void testReqCanSendAfterMissingReply() {
+        ZMQ.Context context = ZMQ.context(1);
+        ZMQ.Socket peer = context.socket(ZMQ.REP);
+        peer.setReceiveTimeOut(2000);
+        peer.setLinger(0);
+        int port = peer.bindToRandomPort("tcp://127.0.0.1");
+
+        concoredocker.terminateZmq();
+        try {
+            concoredocker.initZmqPort("request", "connect", "tcp://127.0.0.1:" + port, "REQ");
+            concoredocker.write("request", "signal", Collections.singletonList((Object) 1.0), 0);
+            check("REQ peer receives first request", true, peer.recvStr() != null);
+
+            boolean secondWriteSucceeded = true;
+            try {
+                concoredocker.write("request", "signal", Collections.singletonList((Object) 2.0), 0);
+            } catch (ZMQException e) {
+                secondWriteSucceeded = false;
+            }
+            check("REQ can send again when reply is missing", true, secondWriteSucceeded);
+        } finally {
+            concoredocker.terminateZmq();
+            peer.close();
+            context.term();
+        }
+    }
 }