diff options
| -rw-r--r-- | PKGBUILD | 2 | ||||
| -rw-r--r-- | command_pyroscope.cc | 178 |
2 files changed, 117 insertions, 63 deletions
@@ -23,7 +23,7 @@ source=("https://github.com/rakshasa/$_pkgname/archive/$pkgver.tar.gz" "ui_pyroscope.h" "ui_pyroscope.patch") md5sums=('b8b4009f95f8543244ae1d23b1810d7c' - 'e7e55ab66fbb8663a466723b8d6b7c10' + 'd44e605a784ec45b0bfafce3676842c4' 'f1539d70c74e5c74d8a15d51675aa26c' '2d34e8c86c1c6ed1354b55ca21819886' 'cef14e9011d4b4af92536b02f8b611c2' diff --git a/command_pyroscope.cc b/command_pyroscope.cc index 14fd8f96defa..ceef0ee0026f 100644 --- a/command_pyroscope.cc +++ b/command_pyroscope.cc @@ -58,9 +58,121 @@ namespace core { int log_messages_fd = -1; }; -#define RANDOM_STATESIZE 128 -static char system_random_state[RANDOM_STATESIZE]; -static struct random_data system_random_data; + +#if RT_HEX_VERSION <= 0x000906 +// will be merged into 0.9.7+ mainline! + +namespace torrent { + +/* uniform_rng - Uniform distribution random number generator. + + This class implements a no-shared-state random number generator that + emits uniformly distributed numbers with high entropy. It solves the + two problems of a simple `random() % limit`, which is a skewed + distribution due to RAND_MAX typically not being evenly divisble by + the limit, and worse, the lower bits of typical PRNGs having extremly + low entropy – the end result are grossly un-random number sequences. + + A `uniform_rng` instance carries its own state, unlike the `random()` + function, and is thus thread-safe when no instance is shared between + threads. It uses `random_r()` and `initstate_r()` from glibc. + */ +class uniform_rng { +public: + uniform_rng(); + + int rand(); + int rand_range(int lo, int hi); + int rand_below(int limit) { return this->rand_range(0, limit-1); } + +private: + char m_state[128]; + struct ::random_data m_data; +}; + + +uniform_rng::uniform_rng() { + unsigned int seed = cachedTime.usec() ^ (getpid() << 16) ^ getppid(); + ::initstate_r(seed, m_state, sizeof(m_state), &m_data); +} + +// return random number in interval [0, RAND_MAX] +int uniform_rng::rand() +{ + int rval; + if (::random_r(&m_data, &rval) == -1) { + throw torrent::input_error("system.random: random_r() failure!"); + } + return rval; +} + +// return random number in interval [lo, hi] +int uniform_rng::rand_range(int lo, int hi) +{ + if (lo > hi) { + throw torrent::input_error("Empty interval passed to rand_range (low > high)"); + } + if (lo < 0 || RAND_MAX < lo) { + throw torrent::input_error("Lower bound of rand_range outside 0..RAND_MAX"); + } + if (hi < 0 || RAND_MAX < hi) { + throw torrent::input_error("Upper bound of rand_range outside 0..RAND_MAX"); + } + + int rval; + const int64_t range = 1 + hi - lo; + const int64_t buckets = RAND_MAX / range; + const int64_t limit = buckets * range; + + /* Create equal size buckets all in a row, then fire randomly towards + * the buckets until you land in one of them. All buckets are equally + * likely. If you land off the end of the line of buckets, try again. */ + do { + rval = this->rand(); + } while (rval >= limit); + + return (int) (lo + (rval / buckets)); +} + +}; // namespace torrent + + +static torrent::uniform_rng system_random_gen; + +/* @DOC + `system.random = [[<lower>,] <upper>]` + + Generate *uniformly* distributed random numbers in the range + defined by `lower`..`upper`. + + The default range with no args is `0`..`RAND_MAX`. Providing + just one argument sets an *exclusive* upper bound, and two + args define an *inclusive* range. + + An example use-case is adding jitter to time values that you + later check with `elapsed.greater`, to avoid load spikes and + similar effects of clustered time triggers. +*/ +torrent::Object apply_random(rpc::target_type target, const torrent::Object::list_type& args) { + int64_t lo = 0, hi = RAND_MAX; + + torrent::Object::list_const_iterator itr = args.begin(); + if (args.size() > 2) { + throw torrent::input_error("system.random accepts at most two arguments!"); + } + if (args.size() > 1) { + lo = (itr++)->as_value(); + hi = (itr++)->as_value(); + } else if (args.size() > 0) { + hi = (itr++)->as_value() - 1; + } + + return (int64_t) system_random_gen.rand_range(lo, hi); +} + +// #else +// #include "torrent/utils/uniform_rng.h" +#endif // return the "main" tracker for this download item @@ -184,61 +296,6 @@ torrent::Object apply_compare(rpc::target_type target, const torrent::Object::li } -/* @DOC - `system.random = [[<lower>,] <upper>]` - - Generate *uniformly* distributed random numbers in the range - defined by `lower`..`upper`. - - The default range is `0`..`RAND_MAX`, providing just one - argument sets the upper bound. The range is inclusive. - - An example use-case is adding jitter to time values that you - later check with `elapsed.greater`, to avoid load spikes and - similar effects of clustered time triggers. -*/ -torrent::Object apply_random(rpc::target_type target, const torrent::Object::list_type& args) { - int64_t lo = 0, hi = RAND_MAX; - - torrent::Object::list_const_iterator itr = args.begin(); - if (args.size() > 0) { - hi = (itr++)->as_value(); - } - if (args.size() > 1) { - lo = hi; - hi = (itr++)->as_value(); - } - if (args.size() > 2) { - throw torrent::input_error("system.random accepts at most two arguments!"); - } - if (lo > hi) { - throw torrent::input_error("Empty interval passed to system.random (low > high)!"); - } - if (lo < 0 || RAND_MAX < lo) { - throw torrent::input_error("Lower bound of system.random range outside 0..RAND_MAX!"); - } - if (hi < 0 || RAND_MAX < hi) { - throw torrent::input_error("Upper bound of system.random range outside 0..RAND_MAX!"); - } - - int32_t rval; - const int64_t range = 1 + hi - lo; - const int64_t buckets = RAND_MAX / range; - const int64_t limit = buckets * range; - - /* Create equal size buckets all in a row, then fire randomly towards - * the buckets until you land in one of them. All buckets are equally - * likely. If you land off the end of the line of buckets, try again. */ - do { - if (random_r(&system_random_data, &rval) == -1) { - throw torrent::input_error("system.random: random_r() failure!"); - } - } while (rval >= limit); - - return (int64_t) lo + (rval / buckets); -} - - static std::map<int, std::string> bound_commands[ui::DownloadList::DISPLAY_MAX_SIZE]; /* @DOC @@ -469,9 +526,6 @@ torrent::Object cmd_ui_current_view() { void initialize_command_pyroscope() { - unsigned int seed = cachedTime.usec() ^ (getpid() << 16) ^ getppid(); - initstate_r(seed, system_random_state, RANDOM_STATESIZE, &system_random_data); - // Backports from 0.9.2 #if (API_VERSION < 3) // https://github.com/rakshasa/rtorrent/commit/b28f2ea8070 @@ -487,10 +541,10 @@ void initialize_command_pyroscope() { // these are merged into 0.9.7+ mainline! CMD2_ANY_STRING("system.env", _cxxstd_::bind(&cmd_system_env, _cxxstd_::placeholders::_2)); CMD2_ANY("ui.current_view", _cxxstd_::bind(&cmd_ui_current_view)); + CMD2_ANY_LIST("system.random", &apply_random); #endif CMD2_ANY_LIST("compare", &apply_compare); - CMD2_ANY_LIST("system.random", &apply_random); CMD2_ANY("ui.bind_key", &apply_ui_bind_key); CMD2_DL("d.tracker_domain", _cxxstd_::bind(&cmd_d_tracker_domain, _cxxstd_::placeholders::_1)); CMD2_ANY_STRING("log.messages", _cxxstd_::bind(&cmd_log_messages, _cxxstd_::placeholders::_2)); |