From 013e69988ffdbed1d3c684a536c0d4b79c7de680 Mon Sep 17 00:00:00 2001
From: David Edmundson <kde@davidedmundson.co.uk>
Date: Fri, 10 May 2024 14:35:11 +0000
Subject: [PATCH] Reconnect Pipewire on Failure

Our connection to pipewire can go down if the pipewire service restarts, it's on us to tear down and reconnect.
To ensure Streams can tear down on their own properly, this patch leaves existing streams with a defunct connection
and creates a new connection for new streams, sharing the connection between them.

This also implicitly fixes the case for distributions without working socket activation.

BUG: 483137
---
 src/plugins/screencast/pipewirecore.cpp      |  7 ++++++
 src/plugins/screencast/pipewirecore.h        |  4 ++++
 src/plugins/screencast/screencastmanager.cpp | 24 ++++++++++++++++----
 src/plugins/screencast/screencastmanager.h   |  4 +++-
 4 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/src/plugins/screencast/pipewirecore.cpp b/src/plugins/screencast/pipewirecore.cpp
index 077854c65e..085d059537 100644
--- a/src/plugins/screencast/pipewirecore.cpp
+++ b/src/plugins/screencast/pipewirecore.cpp
@@ -48,6 +48,7 @@ void PipeWireCore::onCoreError(void *data, uint32_t id, int seq, int res, const
     qCWarning(KWIN_SCREENCAST) << "PipeWire remote error: " << message;
     if (id == PW_ID_CORE && res == -EPIPE) {
         PipeWireCore *pw = static_cast<PipeWireCore *>(data);
+        pw->m_valid = false;
         Q_EMIT pw->pipewireFailed(QString::fromUtf8(message));
     }
 }
@@ -91,9 +92,15 @@ bool PipeWireCore::init()
     }
 
     pw_core_add_listener(pwCore, &coreListener, &pwCoreEvents, this);
+    m_valid = true;
     return true;
 }
 
+bool PipeWireCore::isValid() const
+{
+    return m_valid;
+}
+
 } // namespace KWin
 
 #include "moc_pipewirecore.cpp"
diff --git a/src/plugins/screencast/pipewirecore.h b/src/plugins/screencast/pipewirecore.h
index cb20ba8b52..f66dc0edb2 100644
--- a/src/plugins/screencast/pipewirecore.h
+++ b/src/plugins/screencast/pipewirecore.h
@@ -28,6 +28,7 @@ public:
     ~PipeWireCore();
 
     bool init();
+    bool isValid() const;
 
     static std::shared_ptr<PipeWireCore> self();
 
@@ -41,6 +42,9 @@ public:
 
 Q_SIGNALS:
     void pipewireFailed(const QString &message);
+
+private:
+    bool m_valid = false;
 };
 
 } // namespace KWin
diff --git a/src/plugins/screencast/screencastmanager.cpp b/src/plugins/screencast/screencastmanager.cpp
index 87c84e93f3..e0b009c3b7 100644
--- a/src/plugins/screencast/screencastmanager.cpp
+++ b/src/plugins/screencast/screencastmanager.cpp
@@ -27,9 +27,9 @@ namespace KWin
 
 ScreencastManager::ScreencastManager()
     : m_screencast(new ScreencastV1Interface(waylandServer()->display(), this))
-    , m_core(new PipeWireCore)
 {
-    m_core->init();
+    getPipewireConnection();
+
     connect(m_screencast, &ScreencastV1Interface::windowScreencastRequested, this, &ScreencastManager::streamWindow);
     connect(m_screencast, &ScreencastV1Interface::outputScreencastRequested, this, &ScreencastManager::streamWaylandOutput);
     connect(m_screencast, &ScreencastV1Interface::virtualOutputScreencastRequested, this, &ScreencastManager::streamVirtualOutput);
@@ -46,7 +46,7 @@ void ScreencastManager::streamWindow(ScreencastStreamV1Interface *waylandStream,
         return;
     }
 
-    auto stream = new ScreenCastStream(new WindowScreenCastSource(window), m_core, this);
+    auto stream = new ScreenCastStream(new WindowScreenCastSource(window), getPipewireConnection(), this);
     stream->setObjectName(window->desktopFileName());
     stream->setCursorMode(mode, 1, window->clientGeometry());
 
@@ -88,7 +88,7 @@ void ScreencastManager::streamOutput(ScreencastStreamV1Interface *waylandStream,
         return;
     }
 
-    auto stream = new ScreenCastStream(new OutputScreenCastSource(streamOutput), m_core, this);
+    auto stream = new ScreenCastStream(new OutputScreenCastSource(streamOutput), getPipewireConnection(), this);
     stream->setObjectName(streamOutput->name());
     stream->setCursorMode(mode, streamOutput->scale(), streamOutput->geometry());
 
@@ -112,7 +112,7 @@ void ScreencastManager::streamRegion(ScreencastStreamV1Interface *waylandStream,
     }
 
     auto source = new RegionScreenCastSource(geometry, scale);
-    auto stream = new ScreenCastStream(source, m_core, this);
+    auto stream = new ScreenCastStream(source, getPipewireConnection(), this);
     stream->setObjectName(rectToString(geometry));
     stream->setCursorMode(mode, scale, geometry);
 
@@ -135,6 +135,20 @@ void ScreencastManager::integrateStreams(ScreencastStreamV1Interface *waylandStr
     }
 }
 
+std::shared_ptr<PipeWireCore> ScreencastManager::getPipewireConnection()
+{
+    if (m_pipewireConnectionCache && m_pipewireConnectionCache->isValid()) {
+        return m_pipewireConnectionCache;
+    } else {
+        std::shared_ptr<PipeWireCore> pipeWireCore = std::make_shared<PipeWireCore>();
+        if (pipeWireCore->init()) {
+            m_pipewireConnectionCache = pipeWireCore;
+        }
+        // return a valid object even if init fails
+        return pipeWireCore;
+    }
+}
+
 } // namespace KWin
 
 #include "moc_screencastmanager.cpp"
diff --git a/src/plugins/screencast/screencastmanager.h b/src/plugins/screencast/screencastmanager.h
index 059e64b545..436040dea9 100644
--- a/src/plugins/screencast/screencastmanager.h
+++ b/src/plugins/screencast/screencastmanager.h
@@ -46,8 +46,10 @@ private:
 
     void integrateStreams(ScreencastStreamV1Interface *waylandStream, ScreenCastStream *stream);
 
+    std::shared_ptr<PipeWireCore> getPipewireConnection();
+
     ScreencastV1Interface *m_screencast;
-    std::shared_ptr<PipeWireCore> m_core;
+    std::shared_ptr<PipeWireCore> m_pipewireConnectionCache;
 };
 
 } // namespace KWin