From 74387c514701e9fc47ee32f5d9b68fd2d7913071 Mon Sep 17 00:00:00 2001
From: Philippe Normand <philn@igalia.com>
Date: Thu, 23 Feb 2023 00:53:02 -0800
Subject: [PATCH] [GStreamer][WebRTC] Renegotiation signalling improvement
 https://bugs.webkit.org/show_bug.cgi?id=252756

Reviewed by Xabier Rodriguez-Calvar.

When webrtcbin emits its on-negotiation-needed it has already made sure the negotiation is really
needed according to the spec, but our implementation wasn't resetting the corresponding flag
afterwards. We now match the event serial number, similarly to the libwebrtc implementation.

* Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.cpp:
(WebCore::GStreamerMediaEndpoint::onNegotiationNeeded):
* Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.h:
(WebCore::GStreamerMediaEndpoint::isNegotiationNeeded const):
* Source/WebCore/Modules/mediastream/gstreamer/GStreamerPeerConnectionBackend.cpp:
(WebCore::GStreamerPeerConnectionBackend::isNegotiationNeeded const):

Canonical link: https://commits.webkit.org/260731@main
---
 .../mediastream/gstreamer/GStreamerMediaEndpoint.cpp       | 7 ++-----
 .../Modules/mediastream/gstreamer/GStreamerMediaEndpoint.h | 4 ++--
 .../gstreamer/GStreamerPeerConnectionBackend.cpp           | 4 ++--
 3 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.cpp b/Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.cpp
index 313ebbd3f5b4..74ec2473b7a8 100644
--- a/Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.cpp
+++ b/Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.cpp
@@ -1140,13 +1140,10 @@ void GStreamerMediaEndpoint::resume()
 
 void GStreamerMediaEndpoint::onNegotiationNeeded()
 {
-    m_isNegotiationNeeded = true;
-
+    ++m_negotiationNeededEventId;
     callOnMainThread([protectedThis = Ref(*this), this] {
-        if (isStopped())
-            return;
         GST_DEBUG_OBJECT(m_pipeline.get(), "Negotiation needed!");
-        m_peerConnectionBackend.markAsNeedingNegotiation(0);
+        m_peerConnectionBackend.markAsNeedingNegotiation(m_negotiationNeededEventId);
     });
 }
 
diff --git a/Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.h b/Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.h
index b1e9ba285f2b..6e1063afc24f 100644
--- a/Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.h
+++ b/Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.h
@@ -76,7 +76,7 @@ class GStreamerMediaEndpoint : public ThreadSafeRefCounted<GStreamerMediaEndpoin
     void resume();
 
     void gatherDecoderImplementationName(Function<void(String&&)>&&);
-    bool isNegotiationNeeded() const { return m_isNegotiationNeeded; }
+    bool isNegotiationNeeded(uint32_t eventId) const { return eventId == m_negotiationNeededEventId; }
 
     void configureAndLinkSource(RealtimeOutgoingMediaSourceGStreamer&);
 
@@ -176,7 +176,7 @@ class GStreamerMediaEndpoint : public ThreadSafeRefCounted<GStreamerMediaEndpoin
     int m_ptCounter { 96 };
     unsigned m_pendingIncomingStreams { 0 };
     bool m_isInitiator { false };
-    bool m_isNegotiationNeeded { false };
+    uint32_t m_negotiationNeededEventId { 0 };
 
 #if !RELEASE_LOG_DISABLED
     Timer m_statsLogTimer;
diff --git a/Source/WebCore/Modules/mediastream/gstreamer/GStreamerPeerConnectionBackend.cpp b/Source/WebCore/Modules/mediastream/gstreamer/GStreamerPeerConnectionBackend.cpp
index 68d5449300bb..6037b4c4b6cc 100644
--- a/Source/WebCore/Modules/mediastream/gstreamer/GStreamerPeerConnectionBackend.cpp
+++ b/Source/WebCore/Modules/mediastream/gstreamer/GStreamerPeerConnectionBackend.cpp
@@ -365,9 +365,9 @@ void GStreamerPeerConnectionBackend::gatherDecoderImplementationName(Function<vo
     m_endpoint->gatherDecoderImplementationName(WTFMove(callback));
 }
 
-bool GStreamerPeerConnectionBackend::isNegotiationNeeded(uint32_t) const
+bool GStreamerPeerConnectionBackend::isNegotiationNeeded(uint32_t eventId) const
 {
-    return m_endpoint->isNegotiationNeeded();
+    return m_endpoint->isNegotiationNeeded(eventId);
 }
 
 } // namespace WebCore