encoder/{opus,vorbis}: new serial generator replacing g_random_int()

src/encoder/OggSerial.cxx

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2003-2012 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "OggSerial.hxx"
+#include "system/Clock.hxx"
+#include "Compiler.h"
+
+#include <atomic>
+
+static std::atomic_uint next_ogg_serial;
+
+int
+GenerateOggSerial()
+{
+	unsigned serial = ++next_ogg_serial;
+	if (gcc_unlikely(serial < 16)) {
+		/* first-time initialization: seed with a clock value,
+		   which is random enough for our use */
+
+		/* this code is not race-free, but good enough */
+		const unsigned seed = MonotonicClockMS();
+		next_ogg_serial = serial = seed;
+	}
+
+	return serial;
+}
+

src/encoder/OggSerial.hxx

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2003-2012 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_OGG_SERIAL_HXX
+#define MPD_OGG_SERIAL_HXX
+
+/**
+ * Generate the next pseudo-random Ogg serial.
+ */
+int
+GenerateOggSerial();
+
+#endif

src/encoder/OpusEncoderPlugin.cxx

@@ -20,6 +20,7 @@
 #include "config.h"
 #include "OpusEncoderPlugin.hxx"
 #include "OggStream.hxx"
+#include "OggSerial.hxx"
 #include "EncoderAPI.hxx"
 #include "AudioFormat.hxx"
 #include "ConfigError.hxx"
@@ -188,7 +189,7 @@ opus_encoder_open(Encoder *_encoder,
 	encoder->buffer_position = 0;
 	encoder->buffer = (unsigned char *)g_malloc(encoder->buffer_size);
 
-	encoder->stream.Initialize(g_random_int());
+	encoder->stream.Initialize(GenerateOggSerial());
 	encoder->packetno = 0;
 
 	return true;

src/encoder/VorbisEncoderPlugin.cxx

@@ -20,6 +20,7 @@
 #include "config.h"
 #include "VorbisEncoderPlugin.hxx"
 #include "OggStream.hxx"
+#include "OggSerial.hxx"
 #include "EncoderAPI.hxx"
 #include "tag/Tag.hxx"
 #include "AudioFormat.hxx"
@@ -164,7 +165,7 @@ vorbis_encoder_reinit(struct vorbis_encoder *encoder, Error &error)
 
 	vorbis_analysis_init(&encoder->vd, &encoder->vi);
 	vorbis_block_init(&encoder->vd, &encoder->vb);
-	encoder->stream.Initialize(g_random_int());
+	encoder->stream.Initialize(GenerateOggSerial());
 
 	return true;
 }
@@ -294,7 +295,7 @@ vorbis_encoder_tag(Encoder *_encoder, const Tag *tag,
 
 	/* reset ogg_stream_state and begin a new stream */
 
-	encoder->stream.Reinitialize(g_random_int());
+	encoder->stream.Reinitialize(GenerateOggSerial());
 
 	/* send that vorbis_comment to the ogg_stream_state */