From e1b1daf5e3a7ecaa2352813d394ab50a845214b4 Mon Sep 17 00:00:00 2001
From: Joachim Nilsson <troglobit@gmail.com>
Date: Sun, 21 Jul 2013 08:31:29 +0200
Subject: [PATCH] Simplify linked list of I/O watchers and its garbage collect
 mechanism.

Simplifed uev_io_t by removing uev_io_rem_t completely.  A refactor that
would not have been possible without the BSD queue.h API.  This makes
the code readable and thus maintainable and less error prone.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
---
 libuev.c | 35 +++++++++++++++++------------------
 libuev.h | 13 +++----------
 2 files changed, 20 insertions(+), 28 deletions(-)

diff --git a/libuev.c b/libuev.c
index 29466cb..2a47e85 100644
--- a/libuev.c
+++ b/libuev.c
@@ -46,7 +46,6 @@ uev_io_t *uev_io_create(uev_t *ctx, int fd, uev_dir_t dir, uev_io_cb_t handler,
 	if (!w)
 		return NULL;
 
-	w->rem.ent = w;
 	w->fd      = fd;
 	w->dir     = dir;
 	w->handler = (void *)handler;
@@ -60,22 +59,23 @@ uev_io_t *uev_io_create(uev_t *ctx, int fd, uev_dir_t dir, uev_io_cb_t handler,
 
 int uev_io_delete(uev_t *ctx, uev_io_t *w)
 {
-	uev_io_rem_t *ent;
+	uev_io_t *tmp;
 
 	if (!ctx || !w) {
 		errno = EINVAL;
 		return -1;
 	}
 
-	TAILQ_FOREACH(ent, &ctx->io_delist, link) {
-		if (ent->ent == w) {
+	/* Check if already removed */
+	TAILQ_FOREACH(tmp, &ctx->io_delist, gc) {
+		if (tmp == w) {
 			errno = EALREADY;
-			return -1;	/* Already removed */
+			return -1;
 		}
 	}
 
 	w->handler = NULL;
-	TAILQ_INSERT_TAIL(&ctx->io_delist, &w->rem, link);
+	TAILQ_INSERT_TAIL(&ctx->io_delist, w, gc);
 
 	return 0;
 }
@@ -150,10 +150,11 @@ int uev_timer_delete(uev_t *ctx, uev_timer_t *w)
 		return -1;
 	}
 
+	/* Check if already removed */
 	TAILQ_FOREACH(tmp, &ctx->timer_delist, link) {
 		if (tmp == w) {
 			errno = EALREADY;
-			return -1;	/* Already removed */
+			return -1;
 		}
 	}
 
@@ -191,7 +192,7 @@ static int do_run_pending(uev_t *ctx, int immediate)
                         diff = TIME_DIFF_MSEC(now, ctx->base_time);
 		}
 
-                /* Reap timer zombies */
+                /* Garbage collect */
                 TAILQ_FOREACH_SAFE(timer, &ctx->timer_delist, link, tmp) {
                         TAILQ_REMOVE(&ctx->timer_delist, timer, link);
                         free(timer);
@@ -248,13 +249,12 @@ static int do_run_pending(uev_t *ctx, int immediate)
 			}
 		}
 
+                /* Garbage collect */
 		if (!TAILQ_EMPTY(&ctx->io_delist)) {
-			uev_io_rem_t *tmp;
-
-			TAILQ_FOREACH(tmp, &ctx->io_delist, link) {
-				TAILQ_REMOVE(&ctx->io_delist, tmp, link);
-				TAILQ_REMOVE(&ctx->io_list, tmp->ent, link);
-				free(tmp->ent);
+			TAILQ_FOREACH(w, &ctx->io_delist, gc) {
+				TAILQ_REMOVE(&ctx->io_delist, w, gc);
+				TAILQ_REMOVE(&ctx->io_list, w, link);
+				free(w);
 			}
 		}
 	} else if (diff > 0) {
@@ -286,10 +286,9 @@ void uev_run(uev_t *ctx)
 /**
  * Drive the timeouts ourself (from now on until an increment of -1)
  * This is intended for use in testing frameworks
- * Caveat emptor: Currently, interactions with the scheduler (agent) API is undefined.
- *                Not for use in uevs that use the agent scheduler
- * @param ctx UEVlication context object
- * @param msec Ms to advance. Use -1 to return to realtime
+ *
+ * @param ctx  libuev context object
+ * @param msec Milliseconds to advance the timer. Use -1 to return to realtime
  */
 void uev_run_tick(uev_t *ctx, int msec)
 {
diff --git a/libuev.h b/libuev.h
index 4f4fdc9..c62fdb2 100644
--- a/libuev.h
+++ b/libuev.h
@@ -33,10 +33,8 @@
 	( (now - then) / clock_tick  * 1000 +			\
 	 ((now - then) % clock_tick) * 1000 / clock_tick )
 
-/* Forward declarations due to dependencys, don't try this at home. */
+/* Forward declare due to dependencys, don't try this at home. */
 struct uev;
-struct uev_io;
-struct uev_timer;
 
 /* I/O direction */
 typedef enum {
@@ -45,14 +43,9 @@ typedef enum {
 } uev_dir_t;
 
 /* I/O event watcher */
-typedef struct uev_io_rem {
-	TAILQ_ENTRY(uev_io_rem) link;
-	struct uev_io *ent;
-} uev_io_rem_t;
-
 typedef struct uev_io {
 	TAILQ_ENTRY(uev_io) link;
-	uev_io_rem_t   rem;             ///< For postponed removal
+	TAILQ_ENTRY(uev_io) gc;
 
 	int            fd;              ///< File descriptor
 	uev_dir_t      dir;             ///< Direction: in or out
@@ -77,7 +70,7 @@ typedef struct {
 	TAILQ_HEAD(, uev_io)     io_list;      ///< File handlers
 	TAILQ_HEAD(, uev_timer)  timer_list;   ///< Timer handlers
 
-	TAILQ_HEAD(, uev_io_rem) io_delist;    ///< List of file handles to be garbage collected
+	TAILQ_HEAD(, uev_io)     io_delist;    ///< List of file handles to be garbage collected
 	TAILQ_HEAD(, uev_timer)  timer_delist; ///< List of timer handles to be garbage collected
 
 	clock_t           base_time;    ///< Time at last timer tick