From d30cc19d253a3db784ad10c3084f58cbb52d325a Mon Sep 17 00:00:00 2001
From: Ikalco <73481042+ikalco@users.noreply.github.com>
Date: Sat, 8 Mar 2025 13:24:22 -0600
Subject: renderer: skip ds commits if buffer didn't change (#9556)

this fixes direct scanout glitches by ensuring that attemptDirectScanout doesn't try to recommit the same buffer to AQ
which would cause a pageflip event and the backendRelease to release the same buffer too early
---
 src/protocols/core/Compositor.cpp | 14 ++------------
 src/protocols/types/Buffer.cpp    | 11 ++++++++---
 src/protocols/types/Buffer.hpp    |  2 +-
 3 files changed, 11 insertions(+), 16 deletions(-)

(limited to 'src/protocols')

diff --git a/src/protocols/core/Compositor.cpp b/src/protocols/core/Compositor.cpp
index 06977338..f7af9504 100644
--- a/src/protocols/core/Compositor.cpp
+++ b/src/protocols/core/Compositor.cpp
@@ -439,9 +439,8 @@ void CWLSurfaceResource::unlockPendingState() {
 }
 
 void CWLSurfaceResource::commitPendingState() {
-    static auto PDROP          = CConfigValue<Hyprlang::INT>("render:allow_early_buffer_release");
-    auto const  previousBuffer = current.buffer;
-    current                    = pending;
+    static auto PDROP = CConfigValue<Hyprlang::INT>("render:allow_early_buffer_release");
+    current           = pending;
     pending.damage.clear();
     pending.bufferDamage.clear();
     pending.newBuffer = false;
@@ -495,15 +494,6 @@ void CWLSurfaceResource::commitPendingState() {
             nullptr);
     }
 
-    // for async buffers, we can only release the buffer once we are unrefing it from current.
-    // if the backend took it, ref it with the lambda. Otherwise, the end of this scope will release it.
-    if (previousBuffer && previousBuffer->buffer && !previousBuffer->buffer->isSynchronous()) {
-        if (previousBuffer->buffer->lockedByBackend && !previousBuffer->buffer->hlEvents.backendRelease) {
-            previousBuffer->buffer->lock();
-            previousBuffer->buffer->unlockOnBufferRelease(self);
-        }
-    }
-
     lastBuffer = current.buffer ? current.buffer->buffer : WP<IHLBuffer>{};
 }
 
diff --git a/src/protocols/types/Buffer.cpp b/src/protocols/types/Buffer.cpp
index ea12f017..9fb6294f 100644
--- a/src/protocols/types/Buffer.cpp
+++ b/src/protocols/types/Buffer.cpp
@@ -26,9 +26,14 @@ bool IHLBuffer::locked() {
     return nLocks > 0;
 }
 
-void IHLBuffer::unlockOnBufferRelease(WP<CWLSurfaceResource> surf) {
-    hlEvents.backendRelease = events.backendRelease.registerListener([this](std::any data) {
-        unlock();
+void IHLBuffer::onBackendRelease(const std::function<void()>& fn) {
+    if (hlEvents.backendRelease) {
+        hlEvents.backendRelease->emit(nullptr);
+        Debug::log(LOG, "backendRelease emitted early");
+    }
+
+    hlEvents.backendRelease = events.backendRelease.registerListener([this, fn](std::any) {
+        fn();
         hlEvents.backendRelease.reset();
     });
 }
diff --git a/src/protocols/types/Buffer.hpp b/src/protocols/types/Buffer.hpp
index 7d84dce7..bd02e2db 100644
--- a/src/protocols/types/Buffer.hpp
+++ b/src/protocols/types/Buffer.hpp
@@ -21,7 +21,7 @@ class IHLBuffer : public Aquamarine::IBuffer {
     virtual void                          unlock();
     virtual bool                          locked();
 
-    void                                  unlockOnBufferRelease(WP<CWLSurfaceResource> surf /* optional */);
+    void                                  onBackendRelease(const std::function<void()>& fn);
 
     SP<CTexture>                          texture;
     bool                                  opaque = false;
-- 
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