lib/waiter: Add timeout waiters

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

2 files changed, 146 insertions, 34 deletions

diff --git a/lib/waiter/waiter.c b/lib/waiter/waiter.c
index 78ba045..513ab60 100644
--- a/lib/waiter/waiter.c
+++ b/lib/waiter/waiter.c
@@ -3,15 +3,21 @@
 #include <stdbool.h>
 #include <string.h>
 #include <assert.h>
+#include <sys/time.h>
 
 #include <talloc/talloc.h>
 
 #include "waiter.h"
 
 struct waiter {
+	enum {
+		WAITER_IO,
+		WAITER_TIME,
+	}		type;
 	struct waitset	*set;
 	int		fd;
 	int		events;
+	struct timeval	timeout;
 	waiter_cb	callback;
 	void		*arg;
 };
@@ -21,12 +27,17 @@ struct waitset {
 	int		n_waiters;
 	bool		waiters_changed;
 
+	struct timeval	next_timeout;
+
 	/* These are kept consistent over each call to waiter_poll, as
 	 * set->waiters may be updated (by waiters' callbacks calling
 	 * waiter_register or waiter_remove) during iteration. */
 	struct pollfd	*pollfds;
-	struct waiter	**cur_waiters;
-	int		cur_n_waiters;
+	int		n_pollfds;
+	struct waiter	**io_waiters;
+	int		n_io_waiters;
+	struct waiter	**time_waiters;
+	int		n_time_waiters;
 };
 
 struct waitset *waitset_create(void *ctx)
@@ -40,8 +51,7 @@ void waitset_destroy(struct waitset *set)
 	talloc_free(set);
 }
 
-struct waiter *waiter_register(struct waitset *set, int fd, int events,
-		waiter_cb callback, void *arg)
+static struct waiter *waiter_new(struct waitset *set)
 {
 	struct waiter **waiters, *waiter;
 
@@ -62,7 +72,15 @@ struct waiter *waiter_register(struct waitset *set, int fd, int events,
 	set->n_waiters++;
 
 	set->waiters[set->n_waiters - 1] = waiter;
+	return waiter;
+}
+
+struct waiter *waiter_register_io(struct waitset *set, int fd, int events,
+		waiter_cb callback, void *arg)
+{
+	struct waiter *waiter = waiter_new(set);
 
+	waiter->type = WAITER_IO;
 	waiter->set = set;
 	waiter->fd = fd;
 	waiter->events = events;
@@ -72,6 +90,27 @@ struct waiter *waiter_register(struct waitset *set, int fd, int events,
 	return waiter;
 }
 
+struct waiter *waiter_register_timeout(struct waitset *set, int delay_ms,
+		waiter_cb callback, void *arg)
+{
+	struct waiter *waiter = waiter_new(set);
+	struct timeval now, delay;
+
+	delay.tv_sec = delay_ms / 1000;
+	delay.tv_usec = 1000 * (delay_ms % 1000);
+
+	gettimeofday(&now, NULL);
+
+	timeradd(&now, &delay, &waiter->timeout);
+
+	waiter->type = WAITER_TIME;
+	waiter->set = set;
+	waiter->callback = callback;
+	waiter->arg = arg;
+
+	return waiter;
+}
+
 void waiter_remove(struct waiter *waiter)
 {
 	struct waitset *set = waiter->set;
@@ -94,47 +133,117 @@ void waiter_remove(struct waiter *waiter)
 	talloc_free(waiter);
 }
 
+static void update_waiters(struct waitset *set)
+{
+	int n_io, n_time, i_io, i_time, i;
+
+	if (!set->waiters_changed)
+		return;
+
+	n_io = n_time = 0;
+
+	for (i = 0; i < set->n_waiters; i++) {
+		if (set->waiters[i]->type == WAITER_IO)
+			n_io++;
+		else if (set->waiters[i]->type == WAITER_TIME)
+			n_time++;
+	}
+
+	/* realloc if counts have changed */
+	if (set->n_io_waiters != n_io) {
+		set->io_waiters = talloc_realloc(set, set->io_waiters,
+				struct waiter *, n_io);
+		set->pollfds = talloc_realloc(set, set->pollfds,
+				struct pollfd, n_io);
+		set->n_io_waiters = n_io;
+	}
+	if (set->n_time_waiters != n_time) {
+		set->time_waiters = talloc_realloc(set, set->time_waiters,
+				struct waiter *, n_time);
+		set->n_time_waiters = n_time;
+	}
+
+	/* IO waiters: copy to io_waiters, populate pollfds */
+	for (i = i_io = 0; i < set->n_waiters; i++) {
+		struct waiter *waiter = set->waiters[i];
+
+		if (waiter->type != WAITER_IO)
+			continue;
+
+		set->pollfds[i_io].fd = waiter->fd;
+		set->pollfds[i_io].events = waiter->events;
+		set->io_waiters[i_io] = waiter;
+		i_io++;
+	}
+
+	/* time waiters: copy to time_waiters, calculate next expiry */
+	timerclear(&set->next_timeout);
+	for (i = i_time = 0; i < set->n_waiters; i++) {
+		struct waiter *waiter = set->waiters[i];
+
+		if (waiter->type != WAITER_TIME)
+			continue;
+
+		if (!timerisset(&set->next_timeout) ||
+				timercmp(&waiter->timeout,
+					&set->next_timeout, <))
+			set->next_timeout = waiter->timeout;
+
+		set->time_waiters[i_time] = waiter;
+		i_time++;
+	}
+}
+
 int waiter_poll(struct waitset *set)
 {
+	struct timeval now, timeout;
+	int timeout_ms;
 	int i, rc;
 
 	/* If the waiters have been updated, we need to update our
 	 * consistent copy */
-	if (set->waiters_changed) {
-
-		/* We need to reallocate if the count has changes */
-		if (set->cur_n_waiters != set->n_waiters) {
-			set->cur_waiters = talloc_realloc(set, set->cur_waiters,
-					struct waiter *, set->n_waiters);
-			set->pollfds = talloc_realloc(set, set->pollfds,
-					struct pollfd, set->n_waiters);
-			set->cur_n_waiters = set->n_waiters;
-		}
-
-		/* Populate cur_waiters and pollfds from ->waiters data */
-		for (i = 0; i < set->n_waiters; i++) {
-			set->pollfds[i].fd = set->waiters[i]->fd;
-			set->pollfds[i].events = set->waiters[i]->events;
-			set->pollfds[i].revents = 0;
-			set->cur_waiters[i] = set->waiters[i];
-		}
-
-		set->waiters_changed = false;
+	update_waiters(set);
+
+	if (timerisset(&set->next_timeout)) {
+		gettimeofday(&now, NULL);
+		timersub(&set->next_timeout, &now, &timeout);
+		timeout_ms = timeout.tv_sec * 1000 +
+				timeout.tv_usec / 1000;
+		if (timeout_ms < 0)
+			timeout_ms = 0;
+	} else {
+		timeout_ms = -1;
 	}
 
-	rc = poll(set->pollfds, set->cur_n_waiters, -1);
 
-	if (rc <= 0)
+	rc = poll(set->pollfds, set->n_io_waiters, timeout_ms);
+
+	if (rc < 0)
 		return rc;
 
-	for (i = 0; i < set->cur_n_waiters; i++) {
-		if (set->pollfds[i].revents) {
-			rc = set->cur_waiters[i]->callback(
-					set->cur_waiters[i]->arg);
+	for (i = 0; i < set->n_io_waiters; i++) {
+		struct waiter *waiter = set->io_waiters[i];
+
+		if (!set->pollfds[i].revents)
+			continue;
+		rc = waiter->callback(waiter->arg);
+
+		if (rc)
+			waiter_remove(waiter);
+	}
+
+	if (set->n_time_waiters > 0)
+		gettimeofday(&now, NULL);
+
+	for (i = 0; i < set->n_time_waiters; i++) {
+		struct waiter *waiter = set->time_waiters[i];
+
+		if (timercmp(&waiter->timeout, &now, >))
+			continue;
+
+		waiter->callback(waiter->arg);
 
-			if (rc)
-				waiter_remove(set->cur_waiters[i]);
-		}
+		waiter_remove(waiter);
 	}
 
 	return 0;
diff --git a/lib/waiter/waiter.h b/lib/waiter/waiter.h
index ed7f6bb..58ea04c 100644
--- a/lib/waiter/waiter.h
+++ b/lib/waiter/waiter.h
@@ -16,7 +16,10 @@ typedef int (*waiter_cb)(void *);
 struct waitset *waitset_create(void *ctx);
 void waitset_destroy(struct waitset *waitset);
 
-struct waiter *waiter_register(struct waitset *waitset, int fd, int events,
+struct waiter *waiter_register_io(struct waitset *waitset, int fd, int events,
+		waiter_cb callback, void *arg);
+
+struct waiter *waiter_register_timeout(struct waitset *set, int delay_ms,
 		waiter_cb callback, void *arg);
 
 void waiter_remove(struct waiter *waiter);