diff options
Diffstat (limited to 'src/util/Serial.cxx')
| -rw-r--r-- | src/util/Serial.cxx | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/src/util/Serial.cxx b/src/util/Serial.cxx new file mode 100644 index 000000000..c91fe62da --- /dev/null +++ b/src/util/Serial.cxx @@ -0,0 +1,46 @@ +/* + * Copyright 2003-2021 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 "Serial.hxx" +#include "Compiler.h" + +#include <atomic> +#include <chrono> + +static std::atomic_uint next_serial; + +int +GenerateSerial() noexcept +{ + unsigned serial = ++next_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 */ + using namespace std::chrono; + const auto now = steady_clock::now().time_since_epoch(); + const auto now_ms = duration_cast<milliseconds>(now); + const unsigned seed = now_ms.count(); + next_serial = serial = seed; + } + + return serial; +} + |