refactoring to prepare for real-time export

* add a threaded TmpFile Writer
* update API calls to that process_export_fw() can be used as
  process_function

The idea is to re-use export infrastructure from normalization:
export to a tmp-file and then encode target formats after that.

2 files changed, 172 insertions, 1 deletions

diff --git a/libs/audiographer/audiographer/sndfile/tmp_file.h b/libs/audiographer/audiographer/sndfile/tmp_file.h
index 296fcdf057..c53557beda 100644
--- a/libs/audiographer/audiographer/sndfile/tmp_file.h
+++ b/libs/audiographer/audiographer/sndfile/tmp_file.h
@@ -35,7 +35,7 @@ class TmpFile : public SndfileWriter<T>, public SndfileReader<T>
 	~TmpFile()
 	{
 		/* explicitly close first, some OS (yes I'm looking at you windows)
-		 * cannot delet files that are still open
+		 * cannot delete files that are still open
 		 */
 		if (!filename.empty()) {
 			SndfileBase::close();
diff --git a/libs/audiographer/audiographer/sndfile/tmp_file_rt.h b/libs/audiographer/audiographer/sndfile/tmp_file_rt.h
new file mode 100644
index 0000000000..ec1f85c773
--- /dev/null
+++ b/libs/audiographer/audiographer/sndfile/tmp_file_rt.h
@@ -0,0 +1,171 @@
+#ifndef AUDIOGRAPHER_TMP_FILE_RT_H
+#define AUDIOGRAPHER_TMP_FILE_RT_H
+
+#include <cstdio>
+#include <string>
+
+#include <glib.h>
+#include "pbd/gstdio_compat.h"
+#include "pbd/ringbuffer.h"
+
+#include "audiographer/flag_debuggable.h"
+#include "audiographer/sink.h"
+#include "sndfile_reader.h"
+
+namespace AudioGrapher
+{
+
+/// A temporary file deleted after this class is destructed
+template<typename T = DefaultSampleType>
+class TmpFileRt
+	: public virtual SndfileReader<T>
+  , public virtual SndfileBase
+  , public Sink<T>
+  , public FlagDebuggable<>
+{
+  public:
+
+	/// \a filename_template must match the requirements for mkstemp, i.e. end in "XXXXXX"
+	TmpFileRt (char * filename_template, int format, ChannelCount channels, framecnt_t samplerate)
+		: SndfileHandle (g_mkstemp(filename_template), true, SndfileBase::ReadWrite, format, channels, samplerate)
+		, filename (filename_template)
+  , _rb (samplerate * channels)
+	{
+		init ();
+	}
+
+	using SndfileHandle::operator=;
+
+	~TmpFileRt()
+	{
+		end_write ();
+		/* explicitly close first, some OS (yes I'm looking at you windows)
+		 * cannot delete files that are still open
+		 */
+		if (!filename.empty()) {
+			SndfileBase::close();
+			std::remove(filename.c_str());
+		}
+		pthread_mutex_destroy (&_disk_thread_lock);
+		pthread_cond_destroy  (&_data_ready);
+	}
+
+	framecnt_t get_frames_written() const { return frames_written; }
+	void       reset_frames_written_count() { frames_written = 0; }
+
+	/// Writes data to file
+	void process (ProcessContext<T> const & c)
+	{
+		check_flags (*this, c);
+
+		if (SndfileReader<T>::throw_level (ThrowStrict) && c.channels() != channels()) {
+			throw Exception (*this, boost::str (boost::format
+				("Wrong number of channels given to process(), %1% instead of %2%")
+				% c.channels() % channels()));
+		}
+
+		if (SndfileReader<T>::throw_level (ThrowProcess) && _rb.write_space() < c.frames()) {
+			throw Exception (*this, boost::str (boost::format
+				("Could not write data to ringbuffer/output file (%1%)")
+				% strError()));
+		}
+
+		_rb.write (c.data(), c.frames());
+
+		if (pthread_mutex_trylock (&_disk_thread_lock) == 0) {
+			pthread_cond_signal (&_data_ready);
+			pthread_mutex_unlock (&_disk_thread_lock);
+		}
+
+		if (c.has_flag(ProcessContext<T>::EndOfInput)) {
+			end_write (); // XXX not rt-safe -- TODO add API call to flush
+			FileWritten (filename);
+		}
+	}
+
+	using Sink<T>::process;
+
+	PBD::Signal1<void, std::string> FileWritten;
+
+	void disk_thread ()
+	{
+		const size_t chunksize = 8192; // samples
+		T *framebuf = (T*) malloc (chunksize * sizeof (T));
+
+		pthread_mutex_lock (&_disk_thread_lock);
+
+		while (1) {
+			if (!_capture) {
+				break;
+			}
+			if (_rb.read_space () >= chunksize) {
+				_rb.read (framebuf, chunksize);
+				framecnt_t const written = write (framebuf, chunksize);
+				assert (written == chunksize);
+				frames_written += written;
+			}
+			pthread_cond_wait (&_data_ready, &_disk_thread_lock);
+		}
+
+		// flush ringbuffer
+		while (_rb.read_space () > 0) {
+			size_t remain = std::min ((size_t)_rb.read_space (), chunksize);
+			_rb.read (framebuf, remain);
+			framecnt_t const written = write (framebuf, remain);
+			frames_written += written;
+		}
+		writeSync();
+
+		pthread_mutex_unlock (&_disk_thread_lock);
+		free (framebuf);
+	}
+
+  protected:
+	std::string filename;
+	framecnt_t frames_written;
+
+	bool _capture;
+	RingBuffer<T> _rb;
+
+	pthread_mutex_t _disk_thread_lock;
+	pthread_cond_t  _data_ready;
+	pthread_t _thread_id;
+
+	static void * _disk_thread (void *arg)
+	{
+		TmpFileRt *d = static_cast<TmpFileRt *>(arg);
+		d->disk_thread ();
+		pthread_exit (0);
+		return 0;
+	}
+
+	void end_write () {
+		pthread_mutex_lock (&_disk_thread_lock);
+		if (!_capture) {
+			pthread_mutex_unlock (&_disk_thread_lock);
+			return;
+		}
+		_capture = false;
+		pthread_cond_signal (&_data_ready);
+		pthread_mutex_unlock (&_disk_thread_lock);
+		pthread_join (_thread_id, NULL);
+	}
+
+	void init()
+	{
+		frames_written = 0;
+		_capture = true;
+		add_supported_flag (ProcessContext<T>::EndOfInput);
+		pthread_mutex_init (&_disk_thread_lock, 0);
+		pthread_cond_init  (&_data_ready, 0);
+
+		pthread_create (&_thread_id, NULL, _disk_thread, this);
+	}
+
+	private:
+	TmpFileRt (TmpFileRt const & other) : SndfileHandle (other) {}
+};
+
+} // namespace
+
+#endif // AUDIOGRAPHER_TMP_FILE_RT_H