From 3517cb889c4e1d348033bc6aeeeaa0189296827d Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Mon, 1 Oct 2018 22:02:25 +0200
Subject: [PATCH] Make for somewhat cleaner shutdown.

---
 jpeg_frame_view.cpp | 20 +++++++++++++++-----
 jpeg_frame_view.h   |  5 +++++
 main.cpp            | 21 ++++++++++++++++-----
 3 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/jpeg_frame_view.cpp b/jpeg_frame_view.cpp
index ef1cded..bc71d00 100644
--- a/jpeg_frame_view.cpp
+++ b/jpeg_frame_view.cpp
@@ -44,12 +44,14 @@ struct LRUFrame {
 	size_t last_used;
 };
 
+thread JPEGFrameView::jpeg_decoder_thread;
 mutex cache_mu;
 map<JPEGID, LRUFrame, JPEGIDLexicalOrder> cache;  // Under cache_mu.
 condition_variable any_pending_decodes, cache_updated;
 deque<pair<JPEGID, JPEGFrameView *>> pending_decodes;  // Under cache_mu.
 atomic<size_t> event_counter{0};
 extern QGLWidget *global_share_widget;
+extern atomic<bool> should_quit;
 
 shared_ptr<Frame> decode_jpeg(const string &filename)
 {
@@ -193,20 +195,21 @@ shared_ptr<Frame> decode_jpeg_with_cache(JPEGID id, CacheMissBehavior cache_miss
 	return frame;
 }
 
-void jpeg_decoder_thread()
+void jpeg_decoder_thread_func()
 {
 	size_t num_decoded = 0, num_dropped = 0;
 
 	pthread_setname_np(pthread_self(), "JPEGDecoder");
-	for ( ;; ) {
+	while (!should_quit.load()) {
 		JPEGID id;
 		JPEGFrameView *dest;
 		CacheMissBehavior cache_miss_behavior = DECODE_IF_NOT_IN_CACHE;
 		{
 			unique_lock<mutex> lock(cache_mu);  // TODO: Perhaps under another lock?
 			any_pending_decodes.wait(lock, [] {
-				return !pending_decodes.empty();
+				return !pending_decodes.empty() || should_quit.load();
 			});
+			if (should_quit.load()) break;
 			id = pending_decodes.front().first;
 			dest = pending_decodes.front().second;
 			pending_decodes.pop_front();
@@ -229,8 +232,9 @@ void jpeg_decoder_thread()
 			// put directly into the cache from VideoStream.
 			unique_lock<mutex> lock(cache_mu);
 			cache_updated.wait(lock, [id] {
-				return cache.count(id) != 0;
+				return cache.count(id) != 0 || should_quit.load();
 			});
+			if (should_quit.load()) break;
 			found_in_cache = true;  // Don't count it as a decode.
 
 			auto it = cache.find(id);
@@ -267,6 +271,12 @@ void jpeg_decoder_thread()
 	}
 }
 
+void JPEGFrameView::shutdown()
+{
+	any_pending_decodes.notify_all();
+	jpeg_decoder_thread.join();
+}
+
 JPEGFrameView::JPEGFrameView(QWidget *parent)
 	: QGLWidget(parent, global_share_widget) {
 }
@@ -304,7 +314,7 @@ void JPEGFrameView::initializeGL()
 	static once_flag once;
 	call_once(once, [] {
 		resource_pool = new ResourcePool;
-		std::thread(&jpeg_decoder_thread).detach();
+		jpeg_decoder_thread = std::thread(jpeg_decoder_thread_func);
 	});
 
 	ImageFormat inout_format;
diff --git a/jpeg_frame_view.h b/jpeg_frame_view.h
index 7c41b78..d0cd47c 100644
--- a/jpeg_frame_view.h
+++ b/jpeg_frame_view.h
@@ -11,6 +11,7 @@
 #include <movit/ycbcr_input.h>
 
 #include <memory>
+#include <thread>
 
 #include "jpeg_frame.h"
 
@@ -44,6 +45,8 @@ public:
 	void setDecodedFrame(std::shared_ptr<Frame> frame);
 	void set_overlay(const std::string &text);  // Blank for none.
 
+	static void shutdown();
+
 signals:
 	void clicked();
 
@@ -72,6 +75,8 @@ private:
 	bool overlay_input_needs_refresh = false;
 
 	int gl_width, gl_height;
+
+	static std::thread jpeg_decoder_thread;
 };
 
 #endif  // !defined(_JPEG_FRAME_VIEW_H)
diff --git a/main.cpp b/main.cpp
index 42b1867..dc80bc2 100644
--- a/main.cpp
+++ b/main.cpp
@@ -4,6 +4,7 @@
 #include <stdint.h>
 #include <sys/types.h>
 
+#include <atomic>
 #include <chrono>
 #include <condition_variable>
 #include <memory>
@@ -37,7 +38,8 @@ extern "C" {
 using namespace std;
 using namespace std::chrono;
 
-std::mutex RefCountedGLsync::fence_lock;
+mutex RefCountedGLsync::fence_lock;
+atomic<bool> should_quit{false};
 
 int64_t start_pts = -1;
 
@@ -101,12 +103,18 @@ int main(int argc, char **argv)
 	MainWindow mainWindow;
 	mainWindow.show();
 
+	init_jpeg_vaapi();
+
 	load_existing_frames();
-	thread(record_thread_func).detach();
+	thread record_thread(record_thread_func);
 
-	init_jpeg_vaapi();
+	int ret = app.exec();
 
-	return app.exec();
+	should_quit = true;
+	record_thread.join();
+	JPEGFrameView::shutdown();
+
+	return ret;
 }
 
 void load_existing_frames()
@@ -163,13 +171,16 @@ int record_thread_func()
 	int64_t last_pts = -1;
 	int64_t pts_offset;
 
-	for ( ;; ) {
+	while (!should_quit.load()) {
 		AVPacket pkt;
 		unique_ptr<AVPacket, decltype(av_packet_unref)*> pkt_cleanup(
 			&pkt, av_packet_unref);
 		av_init_packet(&pkt);
 		pkt.data = nullptr;
 		pkt.size = 0;
+
+		// TODO: Make it possible to abort av_read_frame() (use an interrupt callback);
+		// right now, should_quit will be ignored if it's hung on I/O.
 		if (av_read_frame(format_ctx.get(), &pkt) != 0) {
 			break;
 		}
-- 
2.39.2