From f6ca4bac51595555916f7403ae178680791f824c Mon Sep 17 00:00:00 2001
From: Tom Englund <tomenglund26@gmail.com>
Date: Thu, 20 Mar 2025 11:39:55 +0100
Subject: [PATCH] syncobj: restore SHM buffer reset (#9675)

reset shm buffers early to mitigate stuttering animations, also reuse
the monitors eglSync and store the eglsync per monitor. this however
reintroduces flickering in dbeaver nonsyncobj application.
---
 src/helpers/Monitor.hpp           |  2 ++
 src/protocols/core/Compositor.cpp |  8 +++-----
 src/render/Renderer.cpp           | 14 ++++++--------
 3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/src/helpers/Monitor.hpp b/src/helpers/Monitor.hpp
index a5ccdbb9..b55f0116 100644
--- a/src/helpers/Monitor.hpp
+++ b/src/helpers/Monitor.hpp
@@ -57,6 +57,7 @@ struct SMonitorRule {
 
 class CMonitor;
 class CSyncTimeline;
+class CEGLSync;
 
 class CMonitorState {
   public:
@@ -141,6 +142,7 @@ class CMonitor {
     SP<CSyncTimeline>              inTimeline;
     SP<CSyncTimeline>              outTimeline;
     Hyprutils::OS::CFileDescriptor inFence;
+    SP<CEGLSync>                   eglSync;
     uint64_t                       commitSeq = 0;
 
     PHLMONITORREF                  self;
diff --git a/src/protocols/core/Compositor.cpp b/src/protocols/core/Compositor.cpp
index a9fe33db..a3576c7e 100644
--- a/src/protocols/core/Compositor.cpp
+++ b/src/protocols/core/Compositor.cpp
@@ -471,12 +471,10 @@ void CWLSurfaceResource::commitPendingState(SSurfaceState& state) {
             nullptr);
     }
 
-    // release the buffer if it's synchronous as update() has done everything thats needed
+    // release the buffer if it's synchronous (SHM) as update() has done everything thats needed
     // so we can let the app know we're done.
-    // if (!syncobj && current.buffer && current.buffer->buffer && current.buffer->buffer->isSynchronous()) {
-    // dropCurrentBuffer(); // lets not drop it at all, it will get dropped on next commit if a new buffer arrives.
-    // solves flickering on nonsyncobj apps on explicit sync.
-    // }
+    if (current.buffer && current.buffer->buffer && current.buffer->buffer->isSynchronous())
+        dropCurrentBuffer();
 }
 
 void CWLSurfaceResource::updateCursorShm(CRegion damage) {
diff --git a/src/render/Renderer.cpp b/src/render/Renderer.cpp
index 62e4b77d..b76d67e5 100644
--- a/src/render/Renderer.cpp
+++ b/src/render/Renderer.cpp
@@ -1526,21 +1526,19 @@ bool CHyprRenderer::commitPendingAndDoExplicitSync(PHLMONITOR pMonitor) {
         return ok;
 
     Debug::log(TRACE, "Explicit: {} presented", explicitPresented.size());
-    auto sync = g_pHyprOpenGL->createEGLSync(pMonitor->inFence.get());
 
-    if (!sync)
-        Debug::log(TRACE, "Explicit: can't add sync, EGLSync failed");
+    if (!pMonitor->eglSync)
+        Debug::log(TRACE, "Explicit: can't add sync, monitor has no EGLSync");
     else {
         for (auto const& e : explicitPresented) {
             if (!e->current.buffer || !e->current.buffer->buffer || !e->current.buffer->buffer->syncReleaser)
                 continue;
 
-            e->current.buffer->buffer->syncReleaser->addReleaseSync(sync);
+            e->current.buffer->buffer->syncReleaser->addReleaseSync(pMonitor->eglSync);
         }
     }
 
     explicitPresented.clear();
-    pMonitor->output->state->resetExplicitFences();
 
     return ok;
 }
@@ -2257,13 +2255,13 @@ void CHyprRenderer::endRender() {
         auto explicitOptions = getExplicitSyncSettings(PMONITOR->output);
 
         if (PMONITOR->inTimeline && explicitOptions.explicitEnabled && explicitOptions.explicitKMSEnabled) {
-            auto sync = g_pHyprOpenGL->createEGLSync();
-            if (!sync) {
+            PMONITOR->eglSync = g_pHyprOpenGL->createEGLSync();
+            if (!PMONITOR->eglSync) {
                 Debug::log(ERR, "renderer: couldn't create an EGLSync for out in endRender");
                 return;
             }
 
-            bool ok = PMONITOR->inTimeline->importFromSyncFileFD(PMONITOR->commitSeq, sync->fd());
+            bool ok = PMONITOR->inTimeline->importFromSyncFileFD(PMONITOR->commitSeq, PMONITOR->eglSync->fd());
             if (!ok) {
                 Debug::log(ERR, "renderer: couldn't import from sync file fd in endRender");
                 return;