added xorshift random generator

data_structures/slrbtree.hpp

@@ -0,0 +1,18 @@
+#ifndef MEMGRAPH_DATA_STRUCTURES_SLRBTREE_HPP
+#define MEMGRAPH_DATA_STRUCTURES_SLRBTREE_HPP
+
+#include <map>
+
+#include "utils/sync/spinlock.hpp"
+
+template <class K, class T>
+class SlRbTree
+{
+public:
+
+private:
+    SpinLock lock;
+    std::map<K, T> tree;
+};
+
+#endif

utils/random/xorshift.hpp

@@ -0,0 +1,39 @@
+#ifndef MEMGRAPH_UTILS_RANDOM_XORSHIFT_HPP
+#define MEMGRAPH_UTILS_RANDOM_XORSHIFT_HPP
+
+#include <cstdlib>
+#include <random>
+
+namespace xorshift
+{
+    static uint64_t x, y, z;
+
+    void init()
+    {
+        // use a slow, more complex rnd generator to initialize a fast one
+        // make sure to call this before requesting any random numbers!
+        std::random_device rd;
+        std::mt19937_64 gen(rd());
+        std::uniform_int_distribution<unsigned long long> dist;
+
+        x = dist(gen);
+        y = dist(gen);
+        z = dist(gen);
+    }
+
+    uint64_t next()
+    {
+        // period 2^96 - 1
+        uint64_t t;
+
+        x ^= x << 16;
+        x ^= x >> 5;
+        x ^= x << 1;
+
+        t = x, x = y, y = z;
+
+        return t ^ x ^ y;
+    }
+}
+
+#endif