Imported my own pairing-heap timer queue implementation

include/time.h

@@ -1,4 +1,21 @@
 #ifndef KARLOS_TIME_H
 #define KARLOS_TIME_H
 
+#include <stdint.h>
+
+typedef struct Timer Timer;
+typedef void (*TimerFunc)(Timer *timer);
+
+struct Timer {
+	Timer    *parent;
+	Timer    *prev;
+	Timer    *next;
+	Timer    *first;
+	uint64_t       time;
+	TimerFunc func;
+};
+
+void timer_insert(Timer **queue, Timer *timer, uint64_t time, TimerFunc func);
+void timer_delete(Timer **queue, Timer *timer);
+
 #endif

src/time.c

@@ -1,3 +1,99 @@
+#include <stddef.h>
+
 #include <time.h>
 
+static Timer *
+timer_meld(Timer *heap1, Timer *heap2)
+{
+	if (!heap1) {
+		return heap2;
+	}
+	if (!heap2) {
+		return heap1;
+	}
+	if (heap1->time <= heap2->time) {
+		heap2->parent = heap1;
+		heap2->prev   = NULL;
+		heap2->next   = heap1->first;
+		heap1->parent = NULL;
+		heap1->prev   = NULL;
+		heap1->next   = NULL;
+		heap1->first  = heap2;
+		return heap1;
+	} else {
+		heap1->parent = heap2;
+		heap1->prev   = NULL;
+		heap1->next   = heap2->first;
+		heap2->parent = NULL;
+		heap2->prev   = NULL;
+		heap2->next   = NULL;
+		heap2->first  = heap1;
+		return heap2;
+	}
+}
+
+static Timer *
+timer_pair(Timer *list)
+{
+	Timer *root = NULL, *black = list, *white, *gray;
+	while (black) {
+		white = black->next;
+		if (white) {
+			gray = timer_meld(black, white);
+			root = timer_meld(root, gray);
+			black = white->next;
+		} else {
+			root = timer_meld(root, black);
+			break;
+		}
+	}
+	return root;
+}
+
+void
+timer_insert(Timer **queue, Timer *timer, uint64_t time, TimerFunc func)
+{
+	timer->time   = time;
+	timer->func   = func;
+	timer->parent = NULL;
+	timer->prev   = NULL;
+	timer->next   = NULL;
+	timer->first  = NULL;
+	*queue = timer_meld(*queue, timer);
+}
+
+void
+timer_delete(Timer **queue, Timer *timer)
+{
+	Timer *root = *queue;
+
+	if (root == timer) {
+		root = NULL;
+	}
+	if (timer->parent && timer->parent->first == timer) {
+		timer->parent->first = timer->next;
+	}
+	if (timer->prev) {
+		timer->prev->next = timer->next;
+	}
+	if (timer->next) {
+		timer->next->prev = timer->prev;
+	}
+	if (timer->first) {
+		Timer *list = timer->first;
+		if (root) {
+			root->next = list;
+			list->prev = root;
+			list = root;
+		}
+		root = timer_pair(list);
+	}
+
+	timer->parent = NULL;
+	timer->prev   = NULL;
+	timer->next   = NULL;
+	timer->first  = NULL;
+
+	*queue = root;
+}