From 1b24f625ea4ee77f3c4796ec2233d059f8c7977e Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Wed, 3 Feb 2021 20:16:06 +0000
Subject: [PATCH] Give compile time warning for libwebsockets
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If it is compiled without external poll support.

Closes #2060. Thanks to Yannic Schröder.
---
 ChangeLog.txt                   | 2 ++
 src/mosquitto_broker_internal.h | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/ChangeLog.txt b/ChangeLog.txt
index db224ae5..214974b0 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -5,6 +5,8 @@ Broker:
   because plugins should never be allocating their own instance of this
   struct, and currently none of the struct members are used for anything, so a
   plugin should not be accessing them.
+- Give compile time warning if libwebsockets compiled without external poll
+  support. Closes #2060.
 
 Clients:
 - Fix possible loss of data in `mosquitto_pub -l` when sending multiple long
diff --git a/src/mosquitto_broker_internal.h b/src/mosquitto_broker_internal.h
index 5b88710f..894e7500 100644
--- a/src/mosquitto_broker_internal.h
+++ b/src/mosquitto_broker_internal.h
@@ -25,6 +25,9 @@ Contributors:
 
 #ifdef WITH_WEBSOCKETS
 #  include <libwebsockets.h>
+#  if LWS_LIBRARY_VERSION_NUMBER >= 3002000 && !defined(LWS_WITH_EXTERNAL_POLL)
+#    warning "libwebsockets is not compiled with LWS_WITH_EXTERNAL_POLL support. Websocket performance will be unusable."
+#  endif
 #endif
 
 #include "mosquitto_internal.h"