From d88341f9db5d2cc09036bab5461d6bcb1e60c7e6 Mon Sep 17 00:00:00 2001
From: Mike Solar <iam@mikesolar.cn>
Date: Fri, 3 Jul 2026 02:46:56 +0800
Subject: [PATCH] Revert OCIO LUT processor generation to synchronous

Background generation caused the UI to freeze indefinitely when
switching LUT files, likely due to a deadlock between the worker
process, the preview autocacher, and the asynchronous set_processor
path. Synchronous generation is fast enough for typical 33^3 .cube
files and keeps the cache invalidation logic simple and safe.

The passthrough fix in OCIOBaseNode::Value() is retained so the
viewer shows the input frame while a processor is being created.
---
 app/node/color/ociolut/ociolut.cpp | 99 ++++--------------------------
 app/node/color/ociolut/ociolut.h   | 29 ---------
 2 files changed, 11 insertions(+), 117 deletions(-)

diff --git a/app/node/color/ociolut/ociolut.cpp b/app/node/color/ociolut/ociolut.cpp
index aea41b933..ed025aa7c 100644
--- a/app/node/color/ociolut/ociolut.cpp
+++ b/app/node/color/ociolut/ociolut.cpp
@@ -155,92 +155,10 @@ void OCIOLutNode::GenerateProcessor()
 	pending_direction_ = direction;
 	pending_generation_++;
 
-	MaybeStartNextTask();
-}
-
-void OCIOLutNode::MaybeStartNextTask()
-{
-	if (task_running_) {
-		return;
-	}
-
-	if (pending_path_.isEmpty()) {
-		return;
-	}
-
-	if (pending_path_ == last_path_ && pending_direction_ == last_direction_ &&
-		last_processor_) {
-		return;
-	}
-
-	task_running_ = true;
-	const int generation = pending_generation_;
-	const QString path = pending_path_;
-	const int direction = pending_direction_;
-	ColorManager *manager = this->manager();
-
-	QThreadPool::globalInstance()->start(
-		new GenerateProcessorTask(this, path, direction, generation, manager));
-}
-
-void OCIOLutNode::SetProcessorResult(ColorProcessorPtr processor,
-									 const QString &path, int direction,
-									 int generation)
-{
-	QMutexLocker locker(&gen_mutex_);
-
-	task_running_ = false;
-
-	if (generation != pending_generation_) {
-		// A newer request was issued while this one was in flight; restart.
-		MaybeStartNextTask();
-		return;
-	}
-
-	if (path != pending_path_ || direction != pending_direction_) {
-		MaybeStartNextTask();
-		return;
-	}
-
-	last_path_ = path;
-	last_direction_ = direction;
-	last_processor_ = processor;
-	set_processor(processor);
-
-	// NOTE: We intentionally do NOT call InvalidateAll() here. A full cache
-	// invalidation of the entire timeline freezes the UI while the preview
-	// autocacher re-renders every frame. The new processor will be picked up
-	// naturally on the next render request (e.g. scrubbing or playback).
-}
-
-OCIOLutNode::GenerateProcessorTask::GenerateProcessorTask(
-	OCIOLutNode *node, const QString &path, int direction, int generation,
-	ColorManager *manager)
-	: node_(node), path_(path), direction_(direction), generation_(generation),
-	  manager_(manager)
-{
-	setAutoDelete(true);
-}
-
-void OCIOLutNode::GenerateProcessorTask::run()
-{
-	ColorProcessorPtr processor = CreateProcessor(path_, direction_, manager_);
-
-	if (node_) {
-		QMetaObject::invokeMethod(
-			node_, "SetProcessorResult", Qt::QueuedConnection,
-			Q_ARG(olive::ColorProcessorPtr, processor), Q_ARG(QString, path_),
-			Q_ARG(int, direction_), Q_ARG(int, generation_));
-	}
-}
-
-ColorProcessorPtr OCIOLutNode::GenerateProcessorTask::CreateProcessor(
-	const QString &path, int direction, ColorManager *manager)
-{
-	if (!manager) {
-		return nullptr;
-	}
-
+	// Synchronous generation: for typical 33^3 .cube files this is well under
+	// 100ms and avoids the complexity and potential deadlocks of background
+	// generation + cache invalidation.
+	ColorProcessorPtr processor;
 	try {
 		OCIO::FileTransformRcPtr transform = OCIO::FileTransform::Create();
 		transform->setSrc(path.toUtf8().constData());
@@ -251,11 +169,16 @@ ColorProcessorPtr OCIOLutNode::GenerateProcessorTask::CreateProcessor(
 				? OCIO::TRANSFORM_DIR_FORWARD
 				: OCIO::TRANSFORM_DIR_INVERSE);
 
-		return ColorProcessor::Create(manager->GetConfig()->getProcessor(transform));
+		processor = ColorProcessor::Create(manager()->GetConfig()->getProcessor(transform));
 	} catch (const std::exception &e) {
 		qWarning() << "OCIO LUT processor error:" << e.what();
-		return nullptr;
+		processor = nullptr;
 	}
+
+	last_path_ = path;
+	last_direction_ = direction;
+	last_processor_ = processor;
+	set_processor(processor);
 }
 
 } // namespace olive
diff --git a/app/node/color/ociolut/ociolut.h b/app/node/color/ociolut/ociolut.h
index 01048ea0c..bf1f9baf7 100644
--- a/app/node/color/ociolut/ociolut.h
+++ b/app/node/color/ociolut/ociolut.h
@@ -22,9 +22,6 @@
 #define OCIOLUTNODE_H
 
 #include <QMutex>
-#include <QPointer>
-#include <QRunnable>
-#include <QThreadPool>
 
 #include "node/color/ociobase/ociobase.h"
 #include "render/colorprocessor.h"
@@ -54,33 +51,8 @@ public:
 protected slots:
 	virtual void ConfigChanged() override;
 
-private slots:
-	void SetProcessorResult(olive::ColorProcessorPtr processor,
-							const QString &path, int direction, int generation);
-
 private:
-	class GenerateProcessorTask : public QRunnable {
-	public:
-		GenerateProcessorTask(OCIOLutNode *node, const QString &path,
-							  int direction, int generation,
-							  ColorManager *manager);
-
-		void run() override;
-
-	private:
-		static ColorProcessorPtr CreateProcessor(const QString &path,
-											 int direction,
-											 ColorManager *manager);
-
-		QPointer<OCIOLutNode> node_;
-		QString path_;
-		int direction_;
-		int generation_;
-		ColorManager *manager_;
-	};
-
 	void GenerateProcessor();
-	void MaybeStartNextTask();
 
 	QMutex gen_mutex_;
 	QString last_path_;
@@ -90,7 +62,6 @@ private:
 	QString pending_path_;
 	int pending_direction_ = -1;
 	int pending_generation_ = 0;
-	bool task_running_ = false;
 };
 
 } // namespace olive