Move swaybar's event loop to common directory and refactor

* The loop functions are now prefixed with `loop_`.
* It is now easy to add timers to the loop.
* Timers are implemented using pollfd and timerfd, rather than manually
checking them when any other event happens to arrive.

1 files changed, 105 insertions, 0 deletions

diff --git a/common/loop.c b/common/loop.c
new file mode 100644
index 00000000..bfbfd5a6
--- /dev/null
+++ b/common/loop.c
@@ -0,0 +1,105 @@
+#include <string.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <poll.h>
+#include <sys/timerfd.h>
+#include <unistd.h>
+#include "list.h"
+#include "log.h"
+#include "loop.h"
+
+struct loop_event {
+        void (*callback)(int fd, short mask, void *data);
+        void *data;
+};
+
+struct loop {
+        struct pollfd *fds;
+        int fd_length;
+        int fd_capacity;
+
+        list_t *events; // struct loop_event
+};
+
+struct loop *loop_create(void) {
+        struct loop *loop = calloc(1, sizeof(struct loop));
+        if (!loop) {
+                wlr_log(WLR_ERROR, "Unable to allocate memory for loop");
+                return NULL;
+        }
+        loop->fd_capacity = 10;
+        loop->fds = malloc(sizeof(struct pollfd) * loop->fd_capacity);
+        loop->events = create_list();
+        return loop;
+}
+
+void loop_destroy(struct loop *loop) {
+        list_foreach(loop->events, free);
+        list_free(loop->events);
+        free(loop);
+}
+
+void loop_poll(struct loop *loop) {
+        poll(loop->fds, loop->fd_length, -1);
+
+        for (int i = 0; i < loop->fd_length; ++i) {
+                struct pollfd pfd = loop->fds[i];
+                struct loop_event *event = loop->events->items[i];
+
+                // Always send these events
+                unsigned events = pfd.events | POLLHUP | POLLERR;
+
+                if (pfd.revents & events) {
+                        event->callback(pfd.fd, pfd.revents, event->data);
+                }
+        }
+}
+
+struct loop_event *loop_add_fd(struct loop *loop, int fd, short mask,
+                void (*callback)(int fd, short mask, void *data), void *data) {
+        struct pollfd pfd = {fd, mask, 0};
+
+        if (loop->fd_length == loop->fd_capacity) {
+                loop->fd_capacity += 10;
+                loop->fds = realloc(loop->fds, sizeof(struct pollfd) * loop->fd_capacity);
+        }
+
+        loop->fds[loop->fd_length++] = pfd;
+
+        struct loop_event *event = calloc(1, sizeof(struct loop_event));
+        event->callback = callback;
+        event->data = data;
+
+        list_add(loop->events, event);
+
+        return event;
+}
+
+struct loop_event *loop_add_timer(struct loop *loop, int ms,
+                void (*callback)(int fd, short mask, void *data), void *data) {
+        int fd = timerfd_create(CLOCK_MONOTONIC, 0);
+        struct itimerspec its;
+        its.it_interval.tv_sec = 0;
+        its.it_interval.tv_nsec = 0;
+        its.it_value.tv_sec = ms / 1000000000;
+        its.it_value.tv_nsec = (ms * 1000000) % 1000000000;
+        timerfd_settime(fd, 0, &its, NULL);
+
+        return loop_add_fd(loop, fd, POLLIN, callback, data);
+}
+
+bool loop_remove_event(struct loop *loop, struct loop_event *event) {
+        for (int i = 0; i < loop->events->length; ++i) {
+                if (loop->events->items[i] == event) {
+                        list_del(loop->events, i);
+
+                        loop->fd_length--;
+                        memmove(&loop->fds[i], &loop->fds[i + 1], sizeof(void*) * (loop->fd_length - i));
+
+                        free(event);
+                        return true;
+                }
+        }
+        return false;
+}