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

1 files changed, 43 insertions, 0 deletions

diff --git a/src/encoder/OggSerial.cxx b/src/encoder/OggSerial.cxx
new file mode 100644
index 000000000..5659762f2
--- /dev/null
+++ b/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;
+}
+