Introduce a simple timer API....
One can use add_timer or schedule_timer to add a timer. After
the timeout time has been reached the callback will be called.
One can call add_time/schedule_timer and del_timer from within
the callback.
diff --git a/src/Makefile.am b/src/Makefile.am
index bf55f26..6209906 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -4,7 +4,7 @@
sbin_PROGRAMS = bsc_hack db_test
bsc_hack_SOURCES = bsc_hack.c misdn.c abis_rsl.c abis_nm.c gsm_04_08.c gsm_data.c \
- gsm_subscriber.c msgb.c select.c chan_alloc.c
+ gsm_subscriber.c msgb.c select.c chan_alloc.c timer.c
db_test_SOURCES = db_test.c db.c
db_test_LDADD = -ldl -ldbi
diff --git a/src/select.c b/src/select.c
index 4af1670..b5d22c5 100644
--- a/src/select.c
+++ b/src/select.c
@@ -21,6 +21,7 @@
#include <fcntl.h>
#include <openbsc/select.h>
#include <openbsc/linuxlist.h>
+#include <openbsc/timer.h>
static int maxfd = 0;
static LLIST_HEAD(bsc_fds);
@@ -74,24 +75,29 @@
FD_SET(ufd->fd, &exceptset);
}
- i = select(maxfd+1, &readset, &writeset, &exceptset, NULL);
- if (i > 0) {
- /* call registered callback functions */
- llist_for_each_entry(ufd, &bsc_fds, list) {
- int flags = 0;
+ prepare_timers();
+ i = select(maxfd+1, &readset, &writeset, &exceptset, nearest_timer());
+ if (i < 0)
+ return i;
- if (FD_ISSET(ufd->fd, &readset))
- flags |= BSC_FD_READ;
+ /* fire timers */
+ update_timers();
- if (FD_ISSET(ufd->fd, &writeset))
- flags |= BSC_FD_WRITE;
+ /* call registered callback functions */
+ llist_for_each_entry(ufd, &bsc_fds, list) {
+ int flags = 0;
- if (FD_ISSET(ufd->fd, &exceptset))
- flags |= BSC_FD_EXCEPT;
+ if (FD_ISSET(ufd->fd, &readset))
+ flags |= BSC_FD_READ;
- if (flags)
- ufd->cb(ufd, flags);
- }
+ if (FD_ISSET(ufd->fd, &writeset))
+ flags |= BSC_FD_WRITE;
+
+ if (FD_ISSET(ufd->fd, &exceptset))
+ flags |= BSC_FD_EXCEPT;
+
+ if (flags)
+ ufd->cb(ufd, flags);
}
return i;
}
diff --git a/src/timer.c b/src/timer.c
new file mode 100644
index 0000000..158ee76
--- /dev/null
+++ b/src/timer.c
@@ -0,0 +1,168 @@
+/*
+ * (C) 2008 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <assert.h>
+#include <string.h>
+#include <openbsc/timer.h>
+
+static LLIST_HEAD(timer_list);
+static struct timeval s_nearest_time;
+static struct timeval s_select_time;
+
+#define MICRO_SECONDS 1000000LL
+
+#define TIME_SMALLER(left, right) \
+ (left.tv_sec*MICRO_SECONDS+left.tv_usec) <= (right.tv_sec*MICRO_SECONDS+right.tv_usec)
+
+void add_timer(struct timer_list *timer)
+{
+ struct timer_list *list_timer;
+
+ /* TODO: Optimize and remember the closest item... */
+ timer->active = 1;
+
+ /* this might be called from within update_timers */
+ llist_for_each_entry(list_timer, &timer_list, entry)
+ if (timer == list_timer)
+ return;
+
+ llist_add(&timer->entry, &timer_list);
+}
+
+void schedule_timer(struct timer_list *timer, int seconds, int microseconds)
+{
+ struct timeval current_time;
+
+ gettimeofday(¤t_time, NULL);
+ unsigned long long currentTime = current_time.tv_sec * MICRO_SECONDS + current_time.tv_usec;
+ currentTime += seconds * MICRO_SECONDS + microseconds;
+ timer->timeout.tv_sec = currentTime / MICRO_SECONDS;
+ timer->timeout.tv_usec = currentTime % MICRO_SECONDS;
+ add_timer(timer);
+}
+
+void del_timer(struct timer_list *timer)
+{
+ if (timer_pending(timer)) {
+ timer->active = 0;
+ llist_del(&timer->entry);
+ }
+}
+
+int timer_pending(struct timer_list *timer)
+{
+ return timer->active;
+}
+
+/*
+ * if we have a nearest time return the delta between the current
+ * time and the time of the nearest timer.
+ * If the nearest timer timed out return NULL and then we will
+ * dispatch everything after the select
+ */
+struct timeval *nearest_timer()
+{
+ struct timeval current_time;
+
+ if (s_nearest_time.tv_sec == 0 && s_nearest_time.tv_usec == 0)
+ return NULL;
+
+ if (gettimeofday(¤t_time, NULL) == -1)
+ return NULL;
+
+ unsigned long long nearestTime = s_nearest_time.tv_sec * MICRO_SECONDS + s_nearest_time.tv_usec;
+ unsigned long long currentTime = current_time.tv_sec * MICRO_SECONDS + current_time.tv_usec;
+
+ if (nearestTime < currentTime) {
+ s_select_time.tv_sec = 0;
+ s_select_time.tv_usec = 0;
+ } else {
+ s_select_time.tv_sec = (nearestTime - currentTime) / MICRO_SECONDS;
+ s_select_time.tv_usec = (nearestTime - currentTime) % MICRO_SECONDS;
+ }
+
+ return &s_select_time;
+}
+
+/*
+ * Find the nearest time and update s_nearest_time
+ */
+void prepare_timers()
+{
+ struct timer_list *timer, *nearest_timer = NULL;
+ llist_for_each_entry(timer, &timer_list, entry) {
+ if (!nearest_timer || TIME_SMALLER(timer->timeout, nearest_timer->timeout)) {
+ nearest_timer = timer;
+ }
+ }
+
+ if (nearest_timer) {
+ s_nearest_time = nearest_timer->timeout;
+ } else {
+ memset(&s_nearest_time, 0, sizeof(struct timeval));
+ }
+}
+
+/*
+ * fire all timers... and remove them
+ */
+void update_timers()
+{
+ struct timeval current_time;
+ struct timer_list *timer, *tmp;
+
+ gettimeofday(¤t_time, NULL);
+
+ /*
+ * The callbacks might mess with our list and in this case
+ * even llist_for_each_entry_safe is not safe to use. To allow
+ * del_timer, add_timer, schedule_timer to be called from within
+ * the callback we jump through some loops.
+ *
+ * First we set the handled flag of each active timer to zero,
+ * then we iterate over the list and execute the callbacks. As the
+ * list might have been changed (specially the next) from within
+ * the callback we have to start over again. Once every callback
+ * is dispatched we will remove the non-active from the list.
+ *
+ * TODO: If this is a performance issue we can poison a global
+ * variable in add_timer and del_timer and only then restart.
+ */
+ llist_for_each_entry(timer, &timer_list, entry) {
+ timer->handled = 0;
+ }
+
+restart:
+ llist_for_each_entry(timer, &timer_list, entry) {
+ if (!timer->handled && TIME_SMALLER(timer->timeout, current_time)) {
+ timer->handled = 1;
+ timer->active = 0;
+ (*timer->cb)(timer->data);
+ goto restart;
+ }
+ }
+
+ llist_for_each_entry_safe(timer, tmp, &timer_list, entry) {
+ timer->handled = 0;
+ if (!timer->active) {
+ llist_del(&timer->entry);
+ }
+ }
+}