add {,ep,msp}pfrd policies

Percentage Free Random Distribution

Chooses a random branch based on the available space percentage free.

IE: if branch A has 1G free and branch B has 2G then B should be chosen
twice as often.

src/rnd.cpp

@@ -0,0 +1,55 @@
+/*
+  ISC License
+
+  Copyright (c) 2020, Antonio SJ Musumeci <trapexit@spawn.link>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "rnd.hpp"
+
+#include "wyhash.h"
+
+#include <stdint.h>
+#include <sys/time.h>
+
+static uint64_t G_SEED;
+static RND      G_RND;
+
+RND::RND()
+{
+  struct timeval tv;
+
+  gettimeofday(&tv,NULL);
+
+  G_SEED = ((tv.tv_sec << 32) | (tv.tv_usec));
+}
+
+uint64_t
+RND::rand64(void)
+{
+  return wyrand(&G_SEED);
+}
+
+uint64_t
+RND::rand64(const uint64_t max_)
+{
+  return (wyrand(&G_SEED) % max_);
+}
+
+uint64_t
+RND::rand64(const uint64_t min_,
+            const uint64_t max_)
+{
+  return (min_ + (wyrand(&G_SEED) % (max_ - min_)));
+}