X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/6b0684975782916e6257c792879e1c0f3963411b..84402e8e2ee2a2d0bef25fdceb0a263ed8b471f6:/examples/s4u/engine-filtering/s4u-engine-filtering.cpp

diff --git a/examples/s4u/engine-filtering/s4u-engine-filtering.cpp b/examples/s4u/engine-filtering/s4u-engine-filtering.cpp
index 76065d8c8c..639e1edc88 100644
--- a/examples/s4u/engine-filtering/s4u-engine-filtering.cpp
+++ b/examples/s4u/engine-filtering/s4u-engine-filtering.cpp
@@ -1,19 +1,46 @@
-/* Copyright (c) 2017-2018. The SimGrid Team. All rights reserved.          */
+/* Copyright (c) 2017-2020. 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. */
 
-#include "xbt/log.h"
 #include <simgrid/s4u.hpp>
 
+/* This example shows how to use simgrid::s4u::Engine::get_filtered_hosts() to retrieve
+ * all hosts that match a given criteria. This criteria can be specified either with:
+ *   - an inlined callback
+ *   - a boolean function, such as filter_speed_more_than_50Mf() below
+ *   - a functor (= function object), that can either be stateless such as filter::SingleCore below, or that can save
+ *     state such as filter::FrequencyChanged below
+ *
+ * This file provides examples for each of these categories. You should implement your own filters in your code.
+ */
+
 XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_engine_filtering, "Messages specific for this s4u example");
 
 namespace filter {
+/* First example of thing that we can use as a filtering criteria: a simple boolean function */
+static bool filter_speed_more_than_50Mf(const simgrid::s4u::Host* host)
+{
+  return host->get_speed() > 50E6;
+}
+
+/* Second kind of thing that we can use as a filtering criteria: a functor (=function object).
+ * This one is a bit stupid: it's a lot of boilerplate over a dummy boolean function.
+ */
+class SingleCore {
+public:
+  bool operator()(const simgrid::s4u::Host* host) { return host->get_core_count() == 1; }
+};
+
+/* This functor is a bit more complex, as it saves the current state when created.
+ * Then, it allows one to easily retrieve the hosts which frequency changed since the functor creation.
+ */
 class FrequencyChanged {
   std::map<simgrid::s4u::Host*, int> host_list;
 
 public:
-  FrequencyChanged(simgrid::s4u::Engine& e) {
+  explicit FrequencyChanged(simgrid::s4u::Engine& e)
+  {
     std::vector<simgrid::s4u::Host*> list = e.get_all_hosts();
     for (auto& host : list) {
       host_list.insert({host, host->get_pstate()});
@@ -24,57 +51,39 @@ public:
 
   double get_old_speed(simgrid::s4u::Host* host) { return host_list.at(host); }
 };
-class SingleCore {
-public:
-  bool operator()(simgrid::s4u::Host* host) { return host->get_core_count() == 1; }
-};
-
-bool filter_speed_more_than_50Mf(simgrid::s4u::Host* host);
-bool filter_speed_more_than_50Mf(simgrid::s4u::Host* host)
-{
-  return host->getSpeed() > 50E6;
-}
 }
 int main(int argc, char* argv[])
 {
   simgrid::s4u::Engine e(&argc, argv);
   e.load_platform(argv[1]);
 
-  /**
-   * Use a lambda function to filter hosts: We only want multicore hosts
-   */
+  /* Use a lambda function to filter hosts: We only want multicore hosts */
   XBT_INFO("Hosts currently registered with this engine: %zu", e.get_host_count());
   std::vector<simgrid::s4u::Host*> list =
-      e.get_filtered_hosts([](simgrid::s4u::Host* host) { return host->get_core_count() > 1; });
+      e.get_filtered_hosts([](const simgrid::s4u::Host* host) { return host->get_core_count() > 1; });
 
   for (auto& host : list)
     XBT_INFO("The following hosts have more than one core: %s", host->get_cname());
 
   xbt_assert(list.size() == 1);
 
-  /*
-   * Use a function object (functor) without memory
-   */
+  /* Use a function object (functor) without memory */
   list = e.get_filtered_hosts(filter::SingleCore());
 
   for (auto& host : list)
     XBT_INFO("The following hosts are SingleCore: %s", host->get_cname());
 
-  /**
-   * This just shows how to use a function object that uses
-   * memory to filter.
-   */
+  /* Use a function object that uses memory to filter */
   XBT_INFO("A simple example: Let's retrieve all hosts that changed their frequency");
   filter::FrequencyChanged filter(e);
   e.host_by_name("MyHost2")->set_pstate(2);
   list = e.get_filtered_hosts(filter);
 
   for (auto& host : list)
-    XBT_INFO("The following hosts changed their frequency: %s (from %.1ff to %.1ff)", host->get_cname(), host->getPstateSpeed(filter.get_old_speed(host)), host->getSpeed());
+    XBT_INFO("The following hosts changed their frequency: %s (from %.1ff to %.1ff)", host->get_cname(),
+             host->get_pstate_speed(filter.get_old_speed(host)), host->get_speed());
 
-  /*
-   * You can also just use any normal function (namespaced as well, if you want) to filter
-   */
+  /* You can also just use any regular function (namespaced on need) to filter  */
   list = e.get_filtered_hosts(filter::filter_speed_more_than_50Mf);
 
   for (auto& host : list)