X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/8cc10fffe7fb2db4e9a0d530a8fa4e9a24e5262c..6c7b494f8d1203fb34e01e349b339a70a68daa7a:/include/xbt/random.hpp

diff --git a/include/xbt/random.hpp b/include/xbt/random.hpp
index 84e8182a36..7d4e4ef30b 100644
--- a/include/xbt/random.hpp
+++ b/include/xbt/random.hpp
@@ -1,4 +1,4 @@
-/* Copyright (c) 2019. The SimGrid Team. All rights reserved.               */
+/* Copyright (c) 2019-2020. The SimGrid Team. All rights reserved.               */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
@@ -6,14 +6,164 @@
 #ifndef SIMGRID_XBT_RANDOM_HPP
 #define SIMGRID_XBT_RANDOM_HPP
 
+#include "xbt/base.h"
+#include <fstream>
+#include <iostream>
 #include <random>
+#include <string>
 
 namespace simgrid {
 namespace xbt {
 namespace random {
-int uniform_int(int, int);
-double uniform_real(double, double);
-double exponential(double);
+
+/** A random number generator.
+ *
+ * It uses a std::mersenne_twister_engine (std::mt19937) and provides several distributions.
+ * This interface is implemented by StdRandom and XbtRandom.
+ */
+class XBT_PUBLIC Random {
+public:
+  std::mt19937 mt19937_gen; // the random number engine
+
+  /** @brief Build a new random number generator with default seed */
+  Random() = default;
+  /** @brief Build a new random number generator with given seed */
+  explicit Random(int seed) : mt19937_gen(seed) {}
+
+  virtual ~Random() = default;
+
+  /**
+   * @brief Sets the seed of the Mersenne-Twister RNG
+   */
+  void set_seed(int seed) { mt19937_gen.seed(seed); }
+
+  /**
+   * @brief Read the state of the Mersenne-Twister RNG from a file
+   */
+  bool read_state(const std::string& filename);
+
+  /**
+   * @brief Write the state of the Mersenne-Twister RNG to a file
+   */
+  bool write_state(const std::string& filename) const;
+
+  /**
+   * @brief Draws an integer number uniformly in range [min, max] (min and max included)
+   *
+   * @param min Minimum value
+   * @param max Maximum value
+   */
+  virtual int uniform_int(int min, int max) = 0;
+
+  /**
+   * @brief Draws a real number uniformly in range [min, max) (min included, and max excluded)
+   *
+   * @param min Minimum value
+   * @param max Maximum value
+   */
+  virtual double uniform_real(double min, double max) = 0;
+
+  /**
+   * @brief Draws a real number according to the given exponential distribution
+   *
+   * @param lambda Parameter of the exponential law
+   */
+  virtual double exponential(double lambda) = 0;
+
+  /**
+   * @brief Draws a real number according to the given normal distribution
+   *
+   * @param mean Mean of the normal distribution
+   * @param sd Standard deviation of the normal distribution
+   */
+  virtual double normal(double mean, double sd) = 0;
+};
+
+/** A random number generator using the C++ standard library.
+ *
+ * Caution: reproducibility is not guaranteed across different implementations.
+ */
+class XBT_PUBLIC StdRandom : public Random {
+public:
+  StdRandom() = default;
+  explicit StdRandom(int seed) : Random(seed) {}
+
+  int uniform_int(int min, int max) override;
+  double uniform_real(double min, double max) override;
+  double exponential(double lambda) override;
+  double normal(double mean, double sd) override;
+};
+
+/** A reproducible random number generator.
+ *
+ * Uses our own implementation of distributions to ensure reproducibility.
+ */
+class XBT_PUBLIC XbtRandom : public Random {
+public:
+  XbtRandom() = default;
+  explicit XbtRandom(int seed) : Random(seed) {}
+
+  int uniform_int(int min, int max) override;
+  double uniform_real(double min, double max) override;
+  double exponential(double lambda) override;
+  double normal(double mean, double sd) override;
+};
+
+/**
+ * @brief Tells xbt/random to use the ad-hoc distribution implementation.
+ */
+void set_implem_xbt();
+
+/**
+ * @brief Tells xbt/random to use the standard library distribution implementation.
+ */
+void set_implem_std();
+
+/**
+ * @brief Sets the seed of the Mersenne-Twister RNG
+ */
+void set_mersenne_seed(int);
+
+/**
+ * @brief Read the state of the Mersenne-Twister RNG from a file.
+ */
+bool read_mersenne_state(const std::string& filename);
+
+/**
+ * @brief Write the state of the Mersenne-Twister RNG to a file.
+ */
+bool write_mersenne_state(const std::string& filename);
+
+/**
+ * @brief Draws an integer number uniformly in range [min, max] (min and max included)
+ *
+ * @param min Minimum value
+ * @param max Maximum value
+ */
+int uniform_int(int min, int max);
+
+/**
+ * @brief Draws a real number uniformly in range [min, max) (min included, and max excluded)
+ *
+ * @param min Minimum value
+ * @param max Maximum value
+ */
+double uniform_real(double min, double max);
+
+/**
+ * @brief Draws a real number according to the given exponential distribution
+ *
+ * @param lambda Parameter of the exponential law
+ */
+double exponential(double lambda);
+
+/**
+ * @brief Draws a real number according to the given normal distribution
+ *
+ * @param mean Mean of the normal distribution
+ * @param sd Standard deviation of the normal distribution
+ */
+double normal(double mean, double sd);
 } // namespace random
 } // namespace xbt
 } // namespace simgrid