From 42a6c76e281b8028e8ec0eddbf68ee633463a1ae Mon Sep 17 00:00:00 2001
From: David Herrmann <dh.herrmann@googlemail.com>
Date: Sat, 3 Dec 2011 12:04:29 +0100
Subject: [PATCH] Eloop: Add idle-event support

Idle events are dispatched everytime kmscon_eloop_dispatch() is called. To allow
the callbacks to add/remove/modify all current idle events (including themself),
we need to keep a pointer to the currently dispatched event.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
---
 src/eloop.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/eloop.h |  14 ++++++
 2 files changed, 154 insertions(+)

diff --git a/src/eloop.c b/src/eloop.c
index be3b0c7..1b6168c 100644
--- a/src/eloop.c
+++ b/src/eloop.c
@@ -47,10 +47,23 @@ struct kmscon_eloop {
 	int efd;
 	unsigned long ref;
 
+	struct kmscon_idle *idle_list;
+	struct kmscon_idle *cur_idle;
+
 	struct epoll_event *cur_fds;
 	size_t cur_fds_cnt;
 };
 
+struct kmscon_idle {
+	unsigned long ref;
+	struct kmscon_eloop *loop;
+	struct kmscon_idle *next;
+	struct kmscon_idle *prev;
+
+	kmscon_idle_cb cb;
+	void *data;
+};
+
 struct kmscon_fd {
 	unsigned long ref;
 	struct kmscon_eloop *loop;
@@ -68,6 +81,124 @@ struct kmscon_signal {
 	void *data;
 };
 
+int kmscon_idle_new(struct kmscon_idle **out)
+{
+	struct kmscon_idle *idle;
+
+	if (!out)
+		return -EINVAL;
+
+	idle = malloc(sizeof(*idle));
+	if (!idle)
+		return -ENOMEM;
+
+	memset(idle, 0, sizeof(*idle));
+	idle->ref = 1;
+
+	*out = idle;
+	return 0;
+}
+
+void kmscon_idle_ref(struct kmscon_idle *idle)
+{
+	if (!idle)
+		return;
+
+	++idle->ref;
+}
+
+void kmscon_idle_unref(struct kmscon_idle *idle)
+{
+	if (!idle || !idle->ref)
+		return;
+
+	if (--idle->ref)
+		return;
+
+	free(idle);
+}
+
+int kmscon_eloop_new_idle(struct kmscon_eloop *loop, struct kmscon_idle **out,
+						kmscon_idle_cb cb, void *data)
+{
+	struct kmscon_idle *idle;
+	int ret;
+
+	if (!out)
+		return -EINVAL;
+
+	ret = kmscon_idle_new(&idle);
+	if (ret)
+		return ret;
+
+	ret = kmscon_eloop_add_idle(loop, idle, cb, data);
+	if (ret) {
+		kmscon_idle_unref(idle);
+		return ret;
+	}
+
+	kmscon_idle_unref(idle);
+	*out = idle;
+	return 0;
+}
+
+int kmscon_eloop_add_idle(struct kmscon_eloop *loop, struct kmscon_idle *idle,
+						kmscon_idle_cb cb, void *data)
+{
+	if (!loop || !idle || !cb)
+		return -EINVAL;
+
+	if (idle->next || idle->prev || idle->loop)
+		return -EALREADY;
+
+	idle->next = loop->idle_list;
+	if (idle->next)
+		idle->next->prev = idle;
+	loop->idle_list = idle;
+
+	idle->loop = loop;
+	idle->cb = cb;
+	idle->data = data;
+
+	kmscon_idle_ref(idle);
+	kmscon_eloop_ref(loop);
+
+	return 0;
+}
+
+void kmsocn_eloop_rm_idle(struct kmscon_idle *idle)
+{
+	struct kmscon_eloop *loop;
+
+	if (!idle || !idle->loop)
+		return;
+
+	loop = idle->loop;
+
+	/*
+	 * If the loop is currently dispatching, we need to check whether we are
+	 * the current element and correctly set it to the next element.
+	 */
+	if (loop->cur_idle == idle)
+		loop->cur_idle = idle->next;
+
+	if (idle->prev)
+		idle->prev->next = idle->next;
+	if (idle->next)
+		idle->next->prev = idle->prev;
+	if (loop->idle_list == idle)
+		loop->idle_list = idle->next;
+
+	idle->next = NULL;
+	idle->prev = NULL;
+	idle->loop = NULL;
+	idle->cb = NULL;
+	idle->data = NULL;
+
+	kmscon_idle_unref(idle);
+	kmscon_eloop_unref(loop);
+}
+
 int kmscon_fd_new(struct kmscon_fd **out)
 {
 	struct kmscon_fd *fd;
@@ -401,6 +532,15 @@ int kmscon_eloop_dispatch(struct kmscon_eloop *loop, int timeout)
 	if (!loop)
 		return -EINVAL;
 
+	/* dispatch idle events */
+	loop->cur_idle = loop->idle_list;
+	while (loop->cur_idle) {
+		loop->cur_idle->cb(loop->cur_idle, loop->cur_idle->data);
+		if (loop->cur_idle)
+			loop->cur_idle = loop->cur_idle->next;
+	}
+
+	/* dispatch fd events */
 	count = epoll_wait(loop->efd, ep, 32, timeout);
 	if (count < 0)
 		return -errno;
diff --git a/src/eloop.h b/src/eloop.h
index 5372a13..c10db1c 100644
--- a/src/eloop.h
+++ b/src/eloop.h
@@ -37,9 +37,11 @@
 #include <stdlib.h>
 
 struct kmscon_eloop;
+struct kmscon_idle;
 struct kmscon_fd;
 struct kmscon_signal;
 
+typedef void (*kmscon_idle_cb) (struct kmscon_idle *idle, void *data);
 typedef void (*kmscon_fd_cb) (struct kmscon_fd *fd, void *data);
 typedef void (*kmscon_signal_cb)
 			(struct kmscon_signal *sig, int signum, void *data);
@@ -57,6 +59,18 @@ void kmscon_eloop_unref(struct kmscon_eloop *loop);
 int kmscon_eloop_get_fd(struct kmscon_eloop *loop);
 int kmscon_eloop_dispatch(struct kmscon_eloop *loop, int timeout);
 
+/* idle sources */
+
+int kmscon_idle_new(struct kmscon_idle **out);
+void kmscon_idle_ref(struct kmscon_idle *idle);
+void kmscon_idle_unref(struct kmscon_idle *idle);
+
+int kmscon_eloop_new_idle(struct kmscon_eloop *loop, struct kmscon_idle **out,
+						kmscon_idle_cb cb, void *data);
+int kmscon_eloop_add_idle(struct kmscon_eloop *loop, struct kmscon_idle *idle,
+						kmscon_idle_cb cb, void *data);
+void kmsocn_eloop_rm_idle(struct kmscon_idle *idle);
+
 /* fd sources */
 
 int kmscon_fd_new(struct kmscon_fd **out);