Fix cross-thread access to info files. May help with #1618.

5 files changed, 97 insertions, 46 deletions

diff --git a/src/lib/film.cc b/src/lib/film.cc
index dcaa73754..e85543b80 100644
--- a/src/lib/film.cc
+++ b/src/lib/film.cc
@@ -1740,3 +1740,37 @@ Film::marker (dcp::Marker type) const
 	}
 	return i->second;
 }
+
+shared_ptr<InfoFileHandle>
+Film::info_file_handle (DCPTimePeriod period, bool read) const
+{
+	return shared_ptr<InfoFileHandle> (new InfoFileHandle(_info_file_mutex, info_file(period), read));
+}
+
+InfoFileHandle::InfoFileHandle (boost::mutex& mutex, boost::filesystem::path file, bool read)
+	: _lock (mutex)
+	, _file (file)
+{
+	if (read) {
+		_handle = fopen_boost (file, "rb");
+		if (!_handle) {
+			throw OpenFileError (file, errno, OpenFileError::READ);
+		}
+	} else {
+		bool const exists = boost::filesystem::exists (file);
+		if (exists) {
+			_handle = fopen_boost (file, "r+b");
+		} else {
+			_handle = fopen_boost (file, "wb");
+		}
+
+		if (!_handle) {
+			throw OpenFileError (file, errno, exists ? OpenFileError::READ_WRITE : OpenFileError::WRITE);
+		}
+	}
+}
+
+InfoFileHandle::~InfoFileHandle ()
+{
+	fclose (_handle);
+}
diff --git a/src/lib/film.h b/src/lib/film.h
index 6f1294b29..0c1959056 100644
--- a/src/lib/film.h
+++ b/src/lib/film.h
@@ -36,7 +36,9 @@
 #include <dcp/encrypted_kdm.h>
 #include <boost/signals2.hpp>
 #include <boost/enable_shared_from_this.hpp>
+#include <boost/thread.hpp>
 #include <boost/filesystem.hpp>
+#include <boost/thread/mutex.hpp>
 #include <string>
 #include <vector>
 #include <inttypes.h>
@@ -59,8 +61,32 @@ class AudioMapping;
 class Ratio;
 class Job;
 class ScreenKDM;
+class Film;
 struct isdcf_name_test;
 
+class InfoFileHandle
+{
+public:
+	~InfoFileHandle ();
+
+	FILE* get () const {
+		return _handle;
+	}
+
+	boost::filesystem::path file () const {
+		return _file;
+	}
+
+private:
+	friend class Film;
+
+	InfoFileHandle (boost::mutex& mutex, boost::filesystem::path file, bool read);
+
+	boost::mutex::scoped_lock _lock;
+	FILE* _handle;
+	boost::filesystem::path _file;
+};
+
 /** @class Film
  *
  *  @brief A representation of some audio and video content, and details of
@@ -74,7 +100,7 @@ public:
 	explicit Film (boost::optional<boost::filesystem::path> dir);
 	~Film ();
 
-	boost::filesystem::path info_file (dcpomatic::DCPTimePeriod p) const;
+	boost::shared_ptr<InfoFileHandle> info_file_handle (dcpomatic::DCPTimePeriod period, bool read) const;
 	boost::filesystem::path j2c_path (int, Frame, Eyes, bool) const;
 	boost::filesystem::path internal_video_asset_dir () const;
 	boost::filesystem::path internal_video_asset_filename (dcpomatic::DCPTimePeriod p) const;
@@ -369,6 +395,8 @@ private:
 	friend struct ::isdcf_name_test;
 	template <typename> friend class ChangeSignaller;
 
+	boost::filesystem::path info_file (dcpomatic::DCPTimePeriod p) const;
+
 	void signal_change (ChangeType, Property);
 	void signal_change (ChangeType, int);
 	std::string video_identifier () const;
@@ -445,6 +473,8 @@ private:
 	*/
 	bool _tolerant;
 
+	mutable boost::mutex _info_file_mutex;
+
 	boost::signals2::scoped_connection _playlist_change_connection;
 	boost::signals2::scoped_connection _playlist_order_changed_connection;
 	boost::signals2::scoped_connection _playlist_content_change_connection;
diff --git a/src/lib/reel_writer.cc b/src/lib/reel_writer.cc
index 263148902..f6313773e 100644
--- a/src/lib/reel_writer.cc
+++ b/src/lib/reel_writer.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2018 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2019 Carl Hetherington <cth@carlh.net>
 
     This file is part of DCP-o-matic.
 
@@ -134,41 +134,27 @@ ReelWriter::ReelWriter (
 void
 ReelWriter::write_frame_info (Frame frame, Eyes eyes, dcp::FrameInfo info) const
 {
-	FILE* file = 0;
-	boost::filesystem::path info_file = _film->info_file (_period);
-
-	bool const read = boost::filesystem::exists (info_file);
-
-	if (read) {
-		file = fopen_boost (info_file, "r+b");
-	} else {
-		file = fopen_boost (info_file, "wb");
-	}
-
-	if (!file) {
-		throw OpenFileError (info_file, errno, read ? OpenFileError::READ_WRITE : OpenFileError::WRITE);
-	}
-	dcpomatic_fseek (file, frame_info_position (frame, eyes), SEEK_SET);
-	checked_fwrite (&info.offset, sizeof (info.offset), file, info_file);
-	checked_fwrite (&info.size, sizeof (info.size), file, info_file);
-	checked_fwrite (info.hash.c_str(), info.hash.size(), file, info_file);
-	fclose (file);
+	shared_ptr<InfoFileHandle> handle = _film->info_file_handle(_period, false);
+	dcpomatic_fseek (handle->get(), frame_info_position(frame, eyes), SEEK_SET);
+	checked_fwrite (&info.offset, sizeof(info.offset), handle->get(), handle->file());
+	checked_fwrite (&info.size, sizeof (info.size), handle->get(), handle->file());
+	checked_fwrite (info.hash.c_str(), info.hash.size(), handle->get(), handle->file());
 }
 
 dcp::FrameInfo
-ReelWriter::read_frame_info (FILE* file, Frame frame, Eyes eyes) const
+ReelWriter::read_frame_info (shared_ptr<InfoFileHandle> info, Frame frame, Eyes eyes) const
 {
-	dcp::FrameInfo info;
-	dcpomatic_fseek (file, frame_info_position (frame, eyes), SEEK_SET);
-	checked_fread (&info.offset, sizeof(info.offset), file, _film->info_file(_period));
-	checked_fread (&info.size, sizeof(info.size), file, _film->info_file(_period));
+	dcp::FrameInfo frame_info;
+	dcpomatic_fseek (info->get(), frame_info_position(frame, eyes), SEEK_SET);
+	checked_fread (&frame_info.offset, sizeof(frame_info.offset), info->get(), info->file());
+	checked_fread (&frame_info.size, sizeof(frame_info.size), info->get(), info->file());
 
 	char hash_buffer[33];
-	checked_fread (hash_buffer, 32, file, _film->info_file(_period));
+	checked_fread (hash_buffer, 32, info->get(), info->file());
 	hash_buffer[32] = '\0';
-	info.hash = hash_buffer;
+	frame_info.hash = hash_buffer;
 
-	return info;
+	return frame_info;
 }
 
 long
@@ -213,17 +199,20 @@ ReelWriter::check_existing_picture_asset ()
 		LOG_GENERAL ("Opened existing asset at %1", asset.string());
 	}
 
-	/* Offset of the last dcp::FrameInfo in the info file */
-	int const n = (boost::filesystem::file_size (_film->info_file(_period)) / _info_size) - 1;
-	LOG_GENERAL ("The last FI is %1; info file is %2, info size %3", n, boost::filesystem::file_size (_film->info_file(_period)), _info_size);
+	shared_ptr<InfoFileHandle> info_file;
 
-	FILE* info_file = fopen_boost (_film->info_file(_period), "rb");
-	if (!info_file) {
+	try {
+		info_file = _film->info_file_handle (_period, true);
+	} catch (OpenFileError) {
 		LOG_GENERAL_NC ("Could not open film info file");
 		fclose (asset_file);
 		return 0;
 	}
 
+	/* Offset of the last dcp::FrameInfo in the info file */
+	int const n = (boost::filesystem::file_size(info_file->file()) / _info_size) - 1;
+	LOG_GENERAL ("The last FI is %1; info file is %2, info size %3", n, boost::filesystem::file_size(info_file->file()), _info_size);
+
 	Frame first_nonexistant_frame;
 	if (_film->three_d ()) {
 		/* Start looking at the last left frame */
@@ -246,7 +235,6 @@ ReelWriter::check_existing_picture_asset ()
 	LOG_GENERAL ("Proceeding with first nonexistant frame %1", first_nonexistant_frame);
 
 	fclose (asset_file);
-	fclose (info_file);
 
 	return first_nonexistant_frame;
 }
@@ -655,7 +643,7 @@ ReelWriter::write (PlayerText subs, TextType type, optional<DCPTextTrack> track,
 }
 
 bool
-ReelWriter::existing_picture_frame_ok (FILE* asset_file, FILE* info_file, Frame frame) const
+ReelWriter::existing_picture_frame_ok (FILE* asset_file, shared_ptr<InfoFileHandle> info_file, Frame frame) const
 {
 	LOG_GENERAL ("Checking existing picture frame %1", frame);
 
diff --git a/src/lib/reel_writer.h b/src/lib/reel_writer.h
index b96bcfc68..8649ea37f 100644
--- a/src/lib/reel_writer.h
+++ b/src/lib/reel_writer.h
@@ -33,6 +33,7 @@ namespace dcpomatic {
 class Film;
 class Job;
 class AudioBuffers;
+class InfoFileHandle;
 struct write_frame_info_test;
 
 namespace dcp {
@@ -89,7 +90,7 @@ public:
 		return _first_nonexistant_frame;
 	}
 
-	dcp::FrameInfo read_frame_info (FILE* file, Frame frame, Eyes eyes) const;
+	dcp::FrameInfo read_frame_info (boost::shared_ptr<InfoFileHandle> info, Frame frame, Eyes eyes) const;
 
 private:
 
@@ -98,7 +99,7 @@ private:
 	void write_frame_info (Frame frame, Eyes eyes, dcp::FrameInfo info) const;
 	long frame_info_position (Frame frame, Eyes eyes) const;
 	Frame check_existing_picture_asset ();
-	bool existing_picture_frame_ok (FILE* asset_file, FILE* info_file, Frame frame) const;
+	bool existing_picture_frame_ok (FILE* asset_file, boost::shared_ptr<InfoFileHandle> info_file, Frame frame) const;
 
 	boost::shared_ptr<const Film> _film;
 
diff --git a/src/lib/writer.cc b/src/lib/writer.cc
index 5b24d7491..9a0f83a22 100644
--- a/src/lib/writer.cc
+++ b/src/lib/writer.cc
@@ -217,16 +217,14 @@ Writer::fake_write (Frame frame, Eyes eyes)
 	size_t const reel = video_reel (frame);
 	Frame const reel_frame = frame - _reels[reel].start ();
 
-	FILE* file = fopen_boost (_film->info_file(_reels[reel].period()), "rb");
-	if (!file) {
-		throw ReadFileError (_film->info_file(_reels[reel].period()));
-	}
-	dcp::FrameInfo info = _reels[reel].read_frame_info (file, reel_frame, eyes);
-	fclose (file);
-
 	QueueItem qi;
 	qi.type = QueueItem::FAKE;
-	qi.size = info.size;
+
+	{
+		shared_ptr<InfoFileHandle> info_file = _film->info_file_handle(_reels[reel].period(), true);
+		qi.size = _reels[reel].read_frame_info(info_file, reel_frame, eyes).size;
+	}
+
 	qi.reel = reel;
 	qi.frame = reel_frame;
 	if (_film->three_d() && eyes == EYES_BOTH) {