Introduce the timed events

src/test.cpp

@@ -3,6 +3,7 @@
  */
 
 #include <xmpp/xmpp_component.hpp>
+#include <utils/timed_events.hpp>
 #include <xmpp/xmpp_parser.hpp>
 #include <utils/encoding.hpp>
 #include <logger/logger.hpp>
@@ -16,6 +17,7 @@
 #include <string.h>
 
 #include <iostream>
+#include <thread>
 #include <vector>
 
 #include <assert.h>
@@ -25,6 +27,28 @@ static const std::string reset("");
 
 int main()
 {
+  /**
+   * Timed events
+   */
+  std::cout << color << "Testing timed events…" << reset << std::endl;
+  TimedEventsManager te_manager;
+  // No event.
+  assert(te_manager.get_timeout() == utils::no_timeout);
+  assert(te_manager.execute_expired_events() == 0);
+
+  // Add a single event
+  te_manager.add_event(TimedEvent(std::chrono::steady_clock::now() + 50ms, [](){ std::cout << "Timeout expired" << std::endl; }));
+  // The event should not yet be expired
+  assert(te_manager.get_timeout() > 0ms);
+  assert(te_manager.execute_expired_events() == 0);
+  std::chrono::milliseconds timoute = te_manager.get_timeout();
+  std::cout << "Sleeping for " << timoute.count() << "ms" << std::endl;
+  std::this_thread::sleep_for(timoute);
+
+  // Event is now expired
+  assert(te_manager.execute_expired_events() == 1);
+  assert(te_manager.get_timeout() == utils::no_timeout);
+
   /**
    * Encoding
    */

src/utils/timed_events.cpp

+#include <utils/timed_events.hpp>
+
+TimedEvent::TimedEvent(std::chrono::steady_clock::time_point&& time_point,
+                       std::function<void()> callback):
+  time_point(std::move(time_point)),
+  callback(callback),
+  repeat(false),
+  repeat_delay(0)
+{
+}
+
+TimedEvent::TimedEvent(std::chrono::milliseconds&& duration,
+                       std::function<void()> callback):
+  time_point(std::chrono::steady_clock::now() + duration),
+  callback(callback),
+  repeat(true),
+  repeat_delay(std::move(duration))
+{
+}
+
+TimedEvent::TimedEvent(TimedEvent&& other):
+  time_point(std::move(other.time_point)),
+  callback(std::move(other.callback)),
+  repeat(other.repeat),
+  repeat_delay(std::move(other.repeat_delay))
+{
+}
+
+TimedEvent::~TimedEvent()
+{
+}
+
+bool TimedEvent::is_after(const TimedEvent& other) const
+{
+  return this->is_after(other.time_point);
+}
+
+bool TimedEvent::is_after(const std::chrono::steady_clock::time_point& time_point) const
+{
+  return this->time_point >= time_point;
+}
+
+std::chrono::milliseconds TimedEvent::get_timeout() const
+{
+  auto now = std::chrono::steady_clock::now();
+  if (now > this->time_point)
+    return std::chrono::milliseconds(0);
+  return std::chrono::duration_cast<std::chrono::milliseconds>(this->time_point - now);
+}
+
+void TimedEvent::execute()
+{
+  this->callback();
+}

src/utils/timed_events.hpp

+#ifndef TIMED_EVENTS_HPP
+# define TIMED_EVENTS_HPP
+
+#include <functional>
+#include <chrono>
+#include <list>
+
+using namespace std::literals::chrono_literals;
+
+namespace utils {
+static constexpr std::chrono::milliseconds no_timeout = std::chrono::milliseconds(-1);
+}
+
+class TimedEventsManager;
+
+/**
+ * A callback with an associated date.
+ */
+
+class TimedEvent
+{
+  friend class TimedEventsManager;
+public:
+  /**
+   * An event the occurs only once, at the given time_point
+   */
+  explicit TimedEvent(std::chrono::steady_clock::time_point&& time_point,
+                      std::function<void()> callback);
+  explicit TimedEvent(std::chrono::milliseconds&& duration,
+                      std::function<void()> callback);
+
+  explicit TimedEvent(TimedEvent&&);
+  ~TimedEvent();
+  /**
+   * Whether or not this event happens after the other one.
+   */
+  bool is_after(const TimedEvent& other) const;
+  bool is_after(const std::chrono::steady_clock::time_point& time_point) const;
+  /**
+   * Return the duration difference between now and the event time point.
+   * If the difference would be negative (i.e. the event is expired), the
+   * returned value is 0 instead. The value cannot then be negative.
+   */
+  std::chrono::milliseconds get_timeout() const;
+  void execute();
+
+private:
+  /**
+   * The next time point at which the event is executed.
+   */
+  std::chrono::steady_clock::time_point time_point;
+  /**
+   * The function to execute.
+   */
+  const std::function<void()> callback;
+  /**
+   * Whether or not this events repeats itself until it is destroyed.
+   */
+  const bool repeat;
+  /**
+   * This value is added to the time_point each time the event is executed,
+   * if repeat is true. Otherwise it is ignored.
+   */
+  const std::chrono::milliseconds repeat_delay;
+
+  TimedEvent(const TimedEvent&) = delete;
+  TimedEvent& operator=(const TimedEvent&) = delete;
+  TimedEvent& operator=(TimedEvent&&) = delete;
+};
+
+/**
+ * A class managing a list of TimedEvents.
+ * They are sorted, new events can be added, removed, fetch, etc.
+ */
+
+class TimedEventsManager
+{
+public:
+  explicit TimedEventsManager();
+  ~TimedEventsManager();
+  /**
+   * Add an event to the list of managed events. The list is sorted after
+   * this call.
+   */
+  void add_event(TimedEvent&& event);
+  /**
+   * Returns the duration, in milliseconds, between now and the next
+   * available event. If the event is already expired (the duration is
+   * negative), 0 is returned instead (as in “it's not too late, execute it
+   * now”)
+   * Returns a negative value if no event is available.
+   */
+  std::chrono::milliseconds get_timeout() const;
+  /**
+   * Execute all the expired events (if their expiration time is exactly
+   * now, or before now). The event is then removed from the list. If the
+   * event does repeat, its expiration time is updated and it is reinserted
+   * in the list at the correct position.
+   * Returns the number of executed events.
+   */
+  std::size_t execute_expired_events();
+
+private:
+  std::list<TimedEvent> events;
+  TimedEventsManager(const TimedEventsManager&) = delete;
+  TimedEventsManager(TimedEventsManager&&) = delete;
+  TimedEventsManager& operator=(const TimedEventsManager&) = delete;
+  TimedEventsManager& operator=(TimedEventsManager&&) = delete;
+};
+
+#endif // TIMED_EVENTS_HPP

src/utils/timed_events_manager.cpp

+#include <utils/timed_events.hpp>
+
+TimedEventsManager::TimedEventsManager()
+{
+}
+
+TimedEventsManager::~TimedEventsManager()
+{
+}
+
+void TimedEventsManager::add_event(TimedEvent&& event)
+{
+  for (auto it = this->events.begin(); it != this->events.end(); ++it)
+    {
+      if (it->is_after(event))
+        {
+          this->events.emplace(it, std::move(event));
+          return;
+        }
+    }
+  this->events.emplace_back(std::move(event));
+}
+
+std::chrono::milliseconds TimedEventsManager::get_timeout() const
+{
+  if (this->events.empty())
+    return utils::no_timeout;
+  return this->events.front().get_timeout() + std::chrono::milliseconds(1);
+}
+
+std::size_t TimedEventsManager::execute_expired_events()
+{
+  std::size_t count = 0;
+  const auto now = std::chrono::steady_clock::now();
+  for (auto it = this->events.begin(); it != this->events.end();)
+    {
+      if (!it->is_after(now))
+        {
+          TimedEvent copy(std::move(*it));
+          it = this->events.erase(it);
+          ++count;
+          copy.execute();
+          if (copy.repeat)
+            {
+              copy.time_point += copy.repeat_delay;
+              this->add_event(std::move(copy));
+            }
+          continue;
+        }
+      else
+        break;
+    }
+  return count;
+}
+