From beea3beacba34c11b6b73323f4c3c8590a9aa73e Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Mon, 11 Feb 2013 00:18:40 +0000
Subject: Basic attempt to catch exceptions in the writer thread and pass them
 safely back to the GUI.

---
 src/lib/encoder.cc   |  4 ++++
 src/lib/exceptions.h | 32 ++++++++++++++++++++++++++++++++
 src/lib/writer.cc    | 13 ++++++++++---
 src/lib/writer.h     |  5 +++--
 4 files changed, 49 insertions(+), 5 deletions(-)

(limited to 'src/lib')

diff --git a/src/lib/encoder.cc b/src/lib/encoder.cc
index 0c810d12c..d64622cba 100644
--- a/src/lib/encoder.cc
+++ b/src/lib/encoder.cc
@@ -251,6 +251,10 @@ Encoder::process_video (shared_ptr<Image> image, bool same, boost::shared_ptr<Su
 		return;
 	}
 
+	if (_writer->thrown ()) {
+		_writer->rethrow ();
+	}
+
 	if (_writer->can_fake_write (_video_frames_out)) {
 		_writer->fake_write (_video_frames_out);
 		_have_a_real_frame = false;
diff --git a/src/lib/exceptions.h b/src/lib/exceptions.h
index bf8e85f0b..e757d2506 100644
--- a/src/lib/exceptions.h
+++ b/src/lib/exceptions.h
@@ -17,6 +17,9 @@
 
 */
 
+#ifndef DVDOMATIC_EXCEPTIONS_H
+#define DVDOMATIC_EXCEPTIONS_H
+
 /** @file  src/exceptions.h
  *  @brief Our exceptions.
  */
@@ -24,6 +27,8 @@
 #include <stdexcept>
 #include <sstream>
 #include <cstring>
+#include <boost/exception/all.hpp>
+#include <boost/thread.hpp>
 
 /** @class StringError
  *  @brief A parent class for exceptions using messages held in a std::string
@@ -224,3 +229,30 @@ public:
 		: StringError (s)
 	{}
 };
+
+class ExceptionStore
+{
+public:
+	bool thrown () const {
+		boost::mutex::scoped_lock lm (_mutex);
+		return _exception;
+	}
+	
+	void rethrow () {
+		boost::mutex::scoped_lock lm (_mutex);
+		boost::rethrow_exception (_exception);
+	}
+
+protected:	
+	
+	void store_current () {
+		boost::mutex::scoped_lock lm (_mutex);
+		_exception = boost::current_exception ();
+	}
+
+private:
+	boost::exception_ptr _exception;
+	mutable boost::mutex _mutex;
+};
+
+#endif
diff --git a/src/lib/writer.cc b/src/lib/writer.cc
index 1df8a4301..8a09f254b 100644
--- a/src/lib/writer.cc
+++ b/src/lib/writer.cc
@@ -85,7 +85,7 @@ Writer::Writer (shared_ptr<Film> f)
 
 		_sound_asset_writer = _sound_asset->start_write ();
 	}
-	
+
 	_thread = new boost::thread (boost::bind (&Writer::thread, this));
 }
 
@@ -130,6 +130,7 @@ Writer::write (shared_ptr<const AudioBuffers> audio)
 
 void
 Writer::thread ()
+try
 {
 	while (1)
 	{
@@ -221,7 +222,10 @@ Writer::thread ()
 			--_queued_full_in_memory;
 		}
 	}
-
+}
+catch (...)
+{
+	store_current ();
 }
 
 void
@@ -237,6 +241,10 @@ Writer::finish ()
 	lock.unlock ();
 
 	_thread->join ();
+	if (thrown ()) {
+		rethrow ();
+	}
+	
 	delete _thread;
 	_thread = 0;
 
@@ -361,7 +369,6 @@ Writer::can_fake_write (int frame) const
 	return (frame != 0 && frame < _first_nonexistant_frame);
 }
 
-
 bool
 operator< (QueueItem const & a, QueueItem const & b)
 {
diff --git a/src/lib/writer.h b/src/lib/writer.h
index cee20acb9..beb16c7b9 100644
--- a/src/lib/writer.h
+++ b/src/lib/writer.h
@@ -21,6 +21,7 @@
 #include <boost/shared_ptr.hpp>
 #include <boost/thread.hpp>
 #include <boost/thread/condition.hpp>
+#include "exceptions.h"
 
 class Film;
 class EncodedData;
@@ -59,7 +60,7 @@ public:
 bool operator< (QueueItem const & a, QueueItem const & b);
 bool operator== (QueueItem const & a, QueueItem const & b);
 
-class Writer
+class Writer : public ExceptionStore
 {
 public:
 	Writer (boost::shared_ptr<Film>);
@@ -113,7 +114,7 @@ private:
 	    due to the limit of frames to be held in memory.
 	*/
 	int _pushed_to_disk;
-
+	
 	boost::shared_ptr<libdcp::MonoPictureAsset> _picture_asset;
 	boost::shared_ptr<libdcp::MonoPictureAssetWriter> _picture_asset_writer;
 	boost::shared_ptr<libdcp::SoundAsset> _sound_asset;
-- 
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