libos: Move timer handling to a separate class and use POSIX timers

libos/CMakeLists.txt

@@ -19,6 +19,7 @@ set(SOURCES
     src/LocalClient.cpp
     src/IPC.cpp
     src/SharedMemory.cpp
+    src/Timer.cpp
 )
 
 add_library(os ${SOURCES})

libos/include/os/EventLoop.h

@@ -3,15 +3,15 @@
  * @author apio (cloudapio.eu)
  * @brief Base class for event-driven applications.
  *
- * @copyright Copyright (c) 2023, the Luna authors.
+ * @copyright Copyright (c) 2023-2024, the Luna authors.
  *
  */
 
 #pragma once
 #include <luna/HashMap.h>
-#include <luna/LinkedList.h>
 #include <luna/Vector.h>
 #include <os/Action.h>
+#include <os/Timer.h>
 #include <sys/poll.h>
 
 namespace os
@@ -61,15 +61,6 @@ namespace os
          */
         Result<void> register_signal_handler(int sig, void (*handler)(int));
 
-        /**
-         * @brief Register a function to be called in a certain amount of time.
-         *
-         * @param milliseconds The number of milliseconds to wait before invoking the function.
-         * @param callback The function to call when the time is up.
-         * @return Result<void> Whether the operation succeeded.
-         */
-        Result<void> register_timer(long milliseconds, Action&& callback);
-
         /**
          * @brief Run the event loop until it is asked to quit.
          *
@@ -98,12 +89,8 @@ namespace os
 
         int m_signal_pipe[2];
 
-        struct Timer final : public LinkedListNode<Timer>
-        {
-            long target;
-            Action action;
-        };
+        LinkedList<Timer> m_timer_list;
 
-        LinkedList<Timer> m_timer_queue;
+        friend class Timer;
     };
 }

libos/include/os/Timer.h

@@ -0,0 +1,39 @@
+/**
+ * @file Timer.h
+ * @author apio (cloudapio.eu)
+ * @brief Millisecond-precision timer.
+ *
+ * @copyright Copyright (c) 2024, the Luna authors.
+ *
+ */
+
+#pragma once
+#include <luna/LinkedList.h>
+#include <luna/OwnedPtr.h>
+#include <os/Action.h>
+#include <time.h>
+
+namespace os
+{
+    class EventLoop;
+    class Timer : LinkedListNode<Timer>
+    {
+      public:
+        static Result<OwnedPtr<Timer>> create_singleshot(unsigned int milliseconds, Action&& action);
+        static Result<OwnedPtr<Timer>> create_repeating(unsigned int milliseconds, Action&& action);
+
+        ~Timer();
+
+      private:
+        timer_t m_timerid { -1 };
+        bool m_repeating;
+        struct timespec m_interval;
+        Action m_action;
+
+        void check_if_should_invoke_action();
+
+        Timer() = default;
+
+        friend class EventLoop;
+    };
+}

libos/src/EventLoop.cpp

@@ -3,7 +3,7 @@
  * @author apio (cloudapio.eu)
  * @brief Base class for event-driven applications.
  *
- * @copyright Copyright (c) 2023, the Luna authors.
+ * @copyright Copyright (c) 2023-2024, the Luna authors.
  *
  */
 
@@ -18,21 +18,6 @@
 
 static os::EventLoop* s_the = nullptr;
 
-static void alarm_milliseconds(long target)
-{
-    struct itimerval itimer;
-    memset(&itimer.it_interval, 0, sizeof(itimer.it_interval));
-    itimer.it_value = { .tv_sec = target / 1000, .tv_usec = (target % 1000) * 1000 };
-    setitimer(ITIMER_REAL, &itimer, nullptr);
-}
-
-static long get_monotonic_time_in_milliseconds()
-{
-    struct timespec time;
-    clock_gettime(CLOCK_MONOTONIC, &time);
-    return time.tv_sec * 1000 + time.tv_nsec / 1'000'000;
-}
-
 namespace os
 {
     EventLoop::EventLoop()
@@ -78,40 +63,6 @@ namespace os
         return {};
     }
 
-    Result<void> EventLoop::register_timer(long milliseconds, Action&& callback)
-    {
-        long target = get_monotonic_time_in_milliseconds() + milliseconds;
-
-        auto* timer = TRY(make<Timer>());
-        timer->target = target;
-        timer->action = move(callback);
-
-        Timer* next = nullptr;
-
-        for (auto* t : m_timer_queue)
-        {
-            if (target < t->target)
-            {
-                next = t;
-                break;
-            }
-        }
-
-        if (m_timer_queue.first().value_or(nullptr) == next)
-        {
-            alarm_milliseconds(milliseconds);
-            m_timer_queue.prepend(timer);
-        }
-        else if (next == nullptr) { m_timer_queue.append(timer); }
-        else
-        {
-            auto previous = m_timer_queue.previous(next).value();
-            m_timer_queue.add_after(previous, timer);
-        }
-
-        return {};
-    }
-
     int EventLoop::run()
     {
         while (!m_should_quit)
@@ -168,19 +119,7 @@ namespace os
 
     void EventLoop::handle_timer_signal(int)
     {
-        auto& queue = the().m_timer_queue;
-        if (queue.count())
-        {
-            auto timer = queue.remove(queue.expect_first());
-
-            auto first = queue.first();
-            if (first.has_value())
-            {
-                alarm((unsigned int)(first.value()->target - get_monotonic_time_in_milliseconds()));
-            }
-
-            timer->action();
-            delete timer;
-        }
+        auto& queue = the().m_timer_list;
+        queue.delayed_for_each([](Timer* t) { t->check_if_should_invoke_action(); });
     }
 }

libos/src/Timer.cpp

@@ -0,0 +1,86 @@
+/**
+ * @file Timer.cpp
+ * @author apio (cloudapio.eu)
+ * @brief Millisecond-precision timer.
+ *
+ * @copyright Copyright (c) 2024, the Luna authors.
+ *
+ */
+
+#include <errno.h>
+#include <os/EventLoop.h>
+#include <os/Timer.h>
+
+namespace os
+{
+    Result<OwnedPtr<Timer>> Timer::create_singleshot(unsigned int milliseconds, Action&& action)
+    {
+        auto timer = TRY(adopt_owned_if_nonnull(new (std::nothrow) Timer()));
+
+        int status = timer_create(CLOCK_REALTIME, nullptr, &timer->m_timerid);
+        if (status < 0) return err(errno);
+
+        struct timespec time = { .tv_sec = milliseconds / 1000, .tv_nsec = (milliseconds % 1000) * 1'000'000 };
+        struct itimerspec itimer = { .it_interval = { .tv_sec = 0, .tv_nsec = 0 }, .it_value = time };
+
+        timer_settime(timer->m_timerid, 0, &itimer, nullptr);
+
+        timer->m_repeating = false;
+        timer->m_action = move(action);
+
+        EventLoop::the().m_timer_list.append(timer.ptr());
+
+        return timer;
+    }
+
+    Result<OwnedPtr<Timer>> Timer::create_repeating(unsigned int milliseconds, Action&& action)
+    {
+        auto timer = TRY(adopt_owned_if_nonnull(new (std::nothrow) Timer()));
+
+        int status = timer_create(CLOCK_REALTIME, nullptr, &timer->m_timerid);
+        if (status < 0) return err(errno);
+
+        struct timespec time = { .tv_sec = milliseconds / 1000, .tv_nsec = (milliseconds % 1000) * 1'000'000 };
+        struct itimerspec itimer = { .it_interval = { .tv_sec = 0, .tv_nsec = 0 }, .it_value = time };
+
+        timer_settime(timer->m_timerid, 0, &itimer, nullptr);
+
+        timer->m_repeating = true;
+        timer->m_interval = time;
+        timer->m_action = move(action);
+
+        EventLoop::the().m_timer_list.append(timer.ptr());
+
+        return timer;
+    }
+
+    void Timer::check_if_should_invoke_action()
+    {
+        struct itimerspec remaining;
+        if (timer_gettime(m_timerid, &remaining) < 0) return;
+
+        if (!remaining.it_value.tv_sec && !remaining.it_value.tv_nsec)
+        {
+            // Timer expired!
+            m_action();
+
+            if (!m_repeating)
+            {
+                timer_delete(m_timerid);
+                EventLoop::the().m_timer_list.remove(this);
+                m_timerid = -1;
+            }
+            else
+            {
+                struct itimerspec itimer = { .it_interval = { .tv_sec = 0, .tv_nsec = 0 }, .it_value = m_interval };
+
+                timer_settime(m_timerid, 0, &itimer, nullptr);
+            }
+        }
+    }
+
+    Timer::~Timer()
+    {
+        if (m_timerid >= 0) timer_delete(m_timerid);
+    }
+}