Merge branch 'async-master' into 'master'

Draft: render,types/wlr_shm: Offload slow cleanup ops

See merge request wlroots/wlroots!4755

util/cleanup.c

@@ -0,0 +1,86 @@
+#include "util/cleanup.h"
+
+#include <pthread.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/eventfd.h>
+#include <unistd.h>
+
+#define MAX_TASKS 16
+struct work_queue {
+	struct wlr_task list[MAX_TASKS];
+	int size;
+	bool running;
+
+	pthread_mutex_t lock;
+	pthread_t thread;
+	int efd;
+};
+
+static struct work_queue queue;
+
+static void *cleanup_thread(void *unused)
+{
+	struct wlr_task work[MAX_TASKS];
+	eventfd_t v;
+	do {
+		eventfd_read(queue.efd, &v);
+
+		pthread_mutex_lock(&queue.lock);
+		for (int i = 0; i < (int)v; i++) {
+			work[i] = queue.list[i];
+		}
+		for (int i = (int)v; i < queue.size; i++) {
+			queue.list[i - v] = queue.list[i];
+		}
+		queue.size -= (int)v;
+		pthread_mutex_unlock(&queue.lock);
+
+		for (int i = 0; i < (int)v; i++) {
+			work[i].task(work[i].data);
+		}
+	} while (queue.running);
+
+	return NULL;
+}
+
+extern void wlr_cleanup_defer(struct wlr_task t)
+{
+	wlr_cleanup_queue_init();
+
+	pthread_mutex_lock(&queue.lock);
+	if (queue.size < MAX_TASKS) {
+		queue.list[queue.size] = t;
+		queue.size++;
+	} else {
+		// In case too much work is queue, apply backpressure.
+		pthread_mutex_unlock(&queue.lock);
+		return t.task(t.data);
+	}
+	pthread_mutex_unlock(&queue.lock);
+	eventfd_write(queue.efd, 1);
+}
+
+extern void wlr_cleanup_queue_init(void)
+{
+	if (!queue.running) {
+		queue = (struct work_queue){0};
+		queue.running = true;
+		queue.efd = eventfd(0, 0);
+		pthread_mutex_init(&queue.lock, NULL);
+		pthread_create(&queue.thread, NULL, cleanup_thread, NULL);
+	}
+}
+
+static void done(void *unused) { queue.running = false; }
+
+extern void wlr_cleanup_queue_finish(void)
+{
+	if (queue.running) {
+		// Notify the cleanup thread that it's done.
+		wlr_cleanup_defer((struct wlr_task){&done, NULL});
+		pthread_join(queue.thread, NULL);
+		close(queue.efd);
+		queue = (struct work_queue){0};
+	}
+}

util/meson.build

@@ -15,4 +15,5 @@ wlr_files += files(
 	'token.c',
 	'transform.c',
 	'utf8.c',
+	'cleanup.c',
 )