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.

10 files changed, 172 insertions, 192 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;
+}
diff --git a/common/meson.build b/common/meson.build
index 44a29508..224a9c3f 100644
--- a/common/meson.build
+++ b/common/meson.build
@@ -5,6 +5,7 @@ lib_sway_common = static_library(
 		'cairo.c',
 		'ipc-client.c',
 		'log.c',
+		'loop.c',
 		'list.c',
 		'pango.c',
 		'readline.c',
diff --git a/include/loop.h b/include/loop.h
new file mode 100644
index 00000000..7c151785
--- /dev/null
+++ b/include/loop.h
@@ -0,0 +1,47 @@
+#ifndef _SWAY_LOOP_H
+#define _SWAY_LOOP_H
+#include <stdbool.h>
+
+/**
+ * This is an event loop system designed for sway clients, not sway itself.
+ *
+ * It uses pollfds to block on multiple file descriptors at once, and provides
+ * an easy way to set timers. Typically the Wayland display's fd will be one of
+ * the fds in the loop.
+ */
+
+struct loop;
+
+/**
+ * Create an event loop.
+ */
+struct loop *loop_create(void);
+
+/**
+ * Destroy the event loop (eg. on program termination).
+ */
+void loop_destroy(struct loop *loop);
+
+/**
+ * Poll the event loop. This will block until one of the fds has data.
+ */
+void loop_poll(struct loop *loop);
+
+/**
+ * Add an fd to the loop.
+ */
+struct loop_event *loop_add_fd(struct loop *loop, int fd, short mask,
+		void (*func)(int fd, short mask, void *data), void *data);
+
+/**
+ * Add a timer to the loop.
+ */
+struct loop_event *loop_add_timer(struct loop *loop, int ms,
+		void (*callback)(int fd, short mask, void *data), void *data);
+
+/**
+ * Remove an event from the loop.
+ */
+bool loop_remove_event(struct loop *loop, struct loop_event *event);
+
+#endif
diff --git a/include/swaybar/bar.h b/include/swaybar/bar.h
index 9ff3fe7b..d61da5dc 100644
--- a/include/swaybar/bar.h
+++ b/include/swaybar/bar.h
@@ -8,6 +8,8 @@
 struct swaybar_config;
 struct swaybar_output;
 struct swaybar_workspace;
+struct loop;
+struct loop_event;
 
 struct swaybar_pointer {
 	struct wl_pointer *pointer;
@@ -66,6 +68,9 @@ struct swaybar {
 	struct swaybar_pointer pointer;
 	struct status_line *status;
 
+	struct loop *eventloop;
+	struct loop_event *status_event;
+
 	int ipc_event_socketfd;
 	int ipc_socketfd;
 
diff --git a/include/swaybar/event_loop.h b/include/swaybar/event_loop.h
deleted file mode 100644
index 47be5b79..00000000
--- a/include/swaybar/event_loop.h
+++ /dev/null
@@ -1,26 +0,0 @@
-#ifndef _SWAYBAR_EVENT_LOOP_H
-#define _SWAYBAR_EVENT_LOOP_H
-#include <stdbool.h>
-#include <time.h>
-
-void add_event(int fd, short mask,
-		void(*cb)(int fd, short mask, void *data),
-		void *data);
-
-// Not guaranteed to notify cb immediately
-void add_timer(timer_t timer,
-		void(*cb)(timer_t timer, void *data),
-		void *data);
-
-// Returns false if nothing exists, true otherwise
-bool remove_event(int fd);
-
-// Returns false if nothing exists, true otherwise
-bool remove_timer(timer_t timer);
-
-// Blocks and returns after sending callbacks
-void event_loop_poll(void);
-
-void init_event_loop(void);
-
-#endif
diff --git a/include/swaybar/status_line.h b/include/swaybar/status_line.h
index 5e7e8771..957a808e 100644
--- a/include/swaybar/status_line.h
+++ b/include/swaybar/status_line.h
@@ -14,6 +14,8 @@ enum status_protocol {
 };
 
 struct status_line {
+	struct swaybar *bar;
+
 	pid_t pid;
 	int read_fd, write_fd;
 	FILE *read, *write;
diff --git a/swaybar/bar.c b/swaybar/bar.c
index 9f72c94c..8e89c9a8 100644
--- a/swaybar/bar.c
+++ b/swaybar/bar.c
@@ -18,7 +18,6 @@
 #endif
 #include "swaybar/bar.h"
 #include "swaybar/config.h"
-#include "swaybar/event_loop.h"
 #include "swaybar/i3bar.h"
 #include "swaybar/ipc.h"
 #include "swaybar/status_line.h"
@@ -26,6 +25,7 @@
 #include "ipc-client.h"
 #include "list.h"
 #include "log.h"
+#include "loop.h"
 #include "pool-buffer.h"
 #include "wlr-layer-shell-unstable-v1-client-protocol.h"
 #include "xdg-output-unstable-v1-client-protocol.h"
@@ -573,7 +573,7 @@ static void set_bar_dirty(struct swaybar *bar) {
 
 bool bar_setup(struct swaybar *bar, const char *socket_path) {
 	bar_init(bar);
-	init_event_loop();
+	bar->eventloop = loop_create();
 
 	bar->ipc_socketfd = ipc_open_socket(socket_path);
 	bar->ipc_event_socketfd = ipc_open_socket(socket_path);
@@ -582,6 +582,7 @@ bool bar_setup(struct swaybar *bar, const char *socket_path) {
 	}
 	if (bar->config->status_command) {
 		bar->status = status_line_init(bar->config->status_command);
+		bar->status->bar = bar;
 	}
 
 	bar->display = wl_display_connect(NULL);
@@ -646,21 +647,23 @@ static void status_in(int fd, short mask, void *data) {
 	if (mask & (POLLHUP | POLLERR)) {
 		status_error(bar->status, "[error reading from status command]");
 		set_bar_dirty(bar);
-		remove_event(fd);
+		loop_remove_event(bar->eventloop, bar->status_event);
 	} else if (status_handle_readable(bar->status)) {
 		set_bar_dirty(bar);
 	}
 }
 
 void bar_run(struct swaybar *bar) {
-	add_event(wl_display_get_fd(bar->display), POLLIN, display_in, bar);
-	add_event(bar->ipc_event_socketfd, POLLIN, ipc_in, bar);
+	loop_add_fd(bar->eventloop, wl_display_get_fd(bar->display), POLLIN,
+			display_in, bar);
+	loop_add_fd(bar->eventloop, bar->ipc_event_socketfd, POLLIN, ipc_in, bar);
 	if (bar->status) {
-		add_event(bar->status->read_fd, POLLIN, status_in, bar);
+		bar->status_event = loop_add_fd(
+				bar->eventloop, bar->status->read_fd, POLLIN, status_in, bar);
 	}
 	while (1) {
 		wl_display_flush(bar->display);
-		event_loop_poll();
+		loop_poll(bar->eventloop);
 	}
 }
 
diff --git a/swaybar/event_loop.c b/swaybar/event_loop.c
deleted file mode 100644
index 686b9962..00000000
--- a/swaybar/event_loop.c
+++ /dev/null
@@ -1,156 +0,0 @@
-#define _XOPEN_SOURCE 700
-#include <stdlib.h>
-#include <stdbool.h>
-#include <string.h>
-#include <strings.h>
-#include <poll.h>
-#include <time.h>
-#include "swaybar/event_loop.h"
-#include "list.h"
-
-struct event_item {
-	void (*cb)(int fd, short mask, void *data);
-	void *data;
-};
-
-struct timer_item {
-	timer_t timer;
-	void (*cb)(timer_t timer, void *data);
-	void *data;
-};
-
-static struct {
-	// The order of each must be kept consistent
-	struct {   /* pollfd array */
-		struct pollfd *items;
-		int capacity;
-		int length;
-	} fds;
-	list_t *items; /* event_item list */
-
-	// Timer list
-	list_t *timers;
-} event_loop;
-
-void add_timer(timer_t timer,
-		void(*cb)(timer_t timer, void *data),
-		void *data) {
-
-	struct timer_item *item = malloc(sizeof(struct timer_item));
-	item->timer = timer;
-	item->cb = cb;
-	item->data = data;
-
-	list_add(event_loop.timers, item);
-}
-
-void add_event(int fd, short mask,
-		void(*cb)(int fd, short mask, void *data), void *data) {
-
-	struct pollfd pollfd = {
-		fd,
-		mask,
-		0,
-	};
-
-	// Resize
-	if (event_loop.fds.length == event_loop.fds.capacity) {
-		event_loop.fds.capacity += 10;
-		event_loop.fds.items = realloc(event_loop.fds.items,
-			sizeof(struct pollfd) * event_loop.fds.capacity);
-	}
-
-	event_loop.fds.items[event_loop.fds.length++] = pollfd;
-
-	struct event_item *item = malloc(sizeof(struct event_item));
-	item->cb = cb;
-	item->data = data;
-
-	list_add(event_loop.items, item);
-
-	return;
-}
-
-bool remove_event(int fd) {
-	/*
-	 * Instead of removing events immediately, we mark them for deletion
-	 * and clean them up later. This is so we can call remove_event inside
-	 * an event callback safely.
-	 */
-	for (int i = 0; i < event_loop.fds.length; ++i) {
-		if (event_loop.fds.items[i].fd == fd) {
-			event_loop.fds.items[i].fd = -1;
-			return true;
-		}
-	}
-	return false;
-}
-
-static int timer_item_timer_cmp(const void *_timer_item, const void *_timer) {
-	const struct timer_item *timer_item = _timer_item;
-	const timer_t *timer = _timer;
-	if (timer_item->timer == *timer) {
-		return 0;
-	} else {
-		return -1;
-	}
-}
-bool remove_timer(timer_t timer) {
-	int index = list_seq_find(event_loop.timers, timer_item_timer_cmp, &timer);
-	if (index != -1) {
-		free(event_loop.timers->items[index]);
-		list_del(event_loop.timers, index);
-		return true;
-	}
-	return false;
-}
-
-void event_loop_poll(void) {
-	poll(event_loop.fds.items, event_loop.fds.length, -1);
-
-	for (int i = 0; i < event_loop.fds.length; ++i) {
-		struct pollfd pfd = event_loop.fds.items[i];
-		struct event_item *item = (struct event_item *)event_loop.items->items[i];
-
-		// Always send these events
-		unsigned events = pfd.events | POLLHUP | POLLERR;
-
-		if (pfd.revents & events) {
-			item->cb(pfd.fd, pfd.revents, item->data);
-		}
-	}
-
-	// Cleanup removed events
-	int end = 0;
-	int length = event_loop.fds.length;
-	for (int i = 0; i < length; ++i) {
-		if (event_loop.fds.items[i].fd == -1) {
-			free(event_loop.items->items[i]);
-			list_del(event_loop.items, i);
-			--event_loop.fds.length;
-		} else if (end != i) {
-			event_loop.fds.items[end++] = event_loop.fds.items[i];
-		} else {
-			end = i + 1;
-		}
-	}
-
-	// check timers
-	// not tested, but seems to work
-	for (int i = 0; i < event_loop.timers->length; ++i) {
-		struct timer_item *item = event_loop.timers->items[i];
-		int overrun = timer_getoverrun(item->timer);
-		if (overrun && overrun != -1) {
-			item->cb(item->timer, item->data);
-		}
-	}
-}
-
-void init_event_loop(void) {
-	event_loop.fds.length = 0;
-	event_loop.fds.capacity = 10;
-	event_loop.fds.items = malloc(
-			event_loop.fds.capacity * sizeof(struct pollfd));
-	event_loop.items = create_list();
-	event_loop.timers = create_list();
-}
diff --git a/swaybar/meson.build b/swaybar/meson.build
index 7a02a33f..0c116172 100644
--- a/swaybar/meson.build
+++ b/swaybar/meson.build
@@ -2,7 +2,6 @@ executable(
 	'swaybar', [
 		'bar.c',
 		'config.c',
-		'event_loop.c',
 		'i3bar.c',
 		'ipc.c',
 		'main.c',
diff --git a/swaybar/status_line.c b/swaybar/status_line.c
index 000609ce..3f7a386f 100644
--- a/swaybar/status_line.c
+++ b/swaybar/status_line.c
@@ -7,16 +7,16 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <wlr/util/log.h>
+#include "loop.h"
 #include "swaybar/bar.h"
 #include "swaybar/config.h"
 #include "swaybar/i3bar.h"
-#include "swaybar/event_loop.h"
 #include "swaybar/status_line.h"
 #include "readline.h"
 
 static void status_line_close_fds(struct status_line *status) {
 	if (status->read_fd != -1) {
-		remove_event(status->read_fd);
+		loop_remove_event(status->bar->eventloop, status->bar->status_event);
 		close(status->read_fd);
 		status->read_fd = -1;
 	}