HO: move penalty timers to own file as proper API

Separate penalty timers API from specific struct members and move to own .h/.c
file, so that future code may re-use the API arbitrarily.

Change-Id: Ife975a1c7c17a500b1693be620475a8bea72f86f

6 files changed, 171 insertions, 18 deletions

diff --git a/include/osmocom/bsc/Makefile.am b/include/osmocom/bsc/Makefile.am
index b99607042..924711999 100644
--- a/include/osmocom/bsc/Makefile.am
+++ b/include/osmocom/bsc/Makefile.am
@@ -49,4 +49,5 @@ noinst_HEADERS = \
 	ussd.h \
 	vty.h \
 	bsc_api.h \
+	penalty_timers.h \
 	$(NULL)
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 3da4fff6f..b8f8f81f8 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -79,13 +79,6 @@ struct gsm_classmark {
 	uint8_t classmark3[14]; /* if cm3 gets extended by spec, it will be truncated */
 };
 
-/* penalty timers for handover */
-struct ho_penalty_timer {
-	struct llist_head entry;
-	uint8_t bts;
-	time_t timeout;
-};
-
 /* active radio connection of a mobile subscriber */
 struct gsm_subscriber_connection {
 	/* global linked list of subscriber_connections */
@@ -117,8 +110,7 @@ struct gsm_subscriber_connection {
 	struct llist_head ho_dtap_cache;
 	unsigned int ho_dtap_cache_len;
 
-	/* penalty timers for handover */
-	struct llist_head ho_penalty_timers;
+	struct penalty_timers *ho_penalty_timers;
 };
 
 
diff --git a/include/osmocom/bsc/penalty_timers.h b/include/osmocom/bsc/penalty_timers.h
new file mode 100644
index 000000000..4b1dcce55
--- /dev/null
+++ b/include/osmocom/bsc/penalty_timers.h
@@ -0,0 +1,36 @@
+/* Manage a list of penalty timers per BTS;
+ * initially used by handover algorithm 2 to keep per-BTS timers for each subscriber connection. */
+#pragma once
+
+/* Opaque struct to manage penalty timers */
+struct penalty_timers;
+
+/* Initialize a list of penalty timers.
+ * param ctx: talloc context to allocate in.
+ * returns an empty struct penalty_timers.  */
+struct penalty_timers *penalty_timers_init(void *ctx);
+
+/* Add a penalty timer for a BTS.
+ * param pt: penalty timers list as from penalty_timers_init().
+ * param for_object: arbitrary pointer reference to store a penalty timer for (passing NULL is possible,
+ *         but note that penalty_timers_clear() will clear all timers if given for_object=NULL).
+ * param timeout: penalty time in seconds. */
+void penalty_timers_add(struct penalty_timers *pt, void *for_object, int timeout);
+
+/* Return the amount of penalty time remaining for a BTS.
+ * param pt: penalty timers list as from penalty_timers_init().
+ * param for_object: arbitrary pointer reference to query penalty timers for.
+ * returns seconds remaining until all penalty time has expired. */
+unsigned int penalty_timers_remaining(struct penalty_timers *pt, void *for_object);
+
+/* Clear penalty timers for one or all BTS.
+ * param pt: penalty timers list as from penalty_timers_init().
+ * param for_object: arbitrary pointer reference to clear penalty time for,
+ *                   or NULL to clear all timers. */
+void penalty_timers_clear(struct penalty_timers *pt, void *for_object);
+
+/* Free a struct as returned from penalty_timers_init().
+ * Clear all timers from the list, deallocate the list and set the pointer to NULL.
+ * param pt: pointer-to-pointer which references a struct penalty_timers as returned by
+ *            penalty_timers_init(); *pt_p will be set to NULL. */
+void penalty_timers_free(struct penalty_timers **pt_p);
diff --git a/src/libbsc/Makefile.am b/src/libbsc/Makefile.am
index e8e69c7a4..81b7a662f 100644
--- a/src/libbsc/Makefile.am
+++ b/src/libbsc/Makefile.am
@@ -59,5 +59,6 @@ libbsc_a_SOURCES = \
 	bts_ipaccess_nanobts_omlattr.c \
 	handover_vty.c \
 	handover_cfg.c \
+	penalty_timers.c \
 	$(NULL)
 
diff --git a/src/libbsc/bsc_api.c b/src/libbsc/bsc_api.c
index d81bf0db0..2cb5b1032 100644
--- a/src/libbsc/bsc_api.c
+++ b/src/libbsc/bsc_api.c
@@ -31,6 +31,7 @@
 #include <osmocom/bsc/debug.h>
 #include <osmocom/bsc/gsm_04_08_utils.h>
 #include <osmocom/bsc/bsc_subscriber.h>
+#include <osmocom/bsc/penalty_timers.h>
 
 #include <osmocom/gsm/protocol/gsm_08_08.h>
 #include <osmocom/gsm/gsm48.h>
@@ -276,7 +277,7 @@ struct gsm_subscriber_connection *bsc_subscr_con_allocate(struct gsm_lchan *lcha
 	conn->lchan = lchan;
 	lchan->conn = conn;
 	INIT_LLIST_HEAD(&conn->ho_dtap_cache);
-	INIT_LLIST_HEAD(&conn->ho_penalty_timers);
+	conn->ho_penalty_timers = penalty_timers_init(conn);
 	llist_add_tail(&conn->entry, &net->subscr_conns);
 	return conn;
 }
@@ -326,8 +327,6 @@ static void ho_dtap_cache_flush(struct gsm_subscriber_connection *conn, int send
 
 void bsc_subscr_con_free(struct gsm_subscriber_connection *conn)
 {
-	struct ho_penalty_timer *penalty;
-
 	if (!conn)
 		return;
 
@@ -352,12 +351,7 @@ void bsc_subscr_con_free(struct gsm_subscriber_connection *conn)
 	/* drop pending messages */
 	ho_dtap_cache_flush(conn, 0);
 
-	/* flush handover penalty timers */
-	while ((penalty = llist_first_entry_or_null(&conn->ho_penalty_timers,
-						    struct ho_penalty_timer, entry))) {
-		llist_del(&penalty->entry);
-		talloc_free(penalty);
-	}
+	penalty_timers_free(&conn->ho_penalty_timers);
 
 	llist_del(&conn->entry);
 	talloc_free(conn);
diff --git a/src/libbsc/penalty_timers.c b/src/libbsc/penalty_timers.c
new file mode 100644
index 000000000..b80fec946
--- /dev/null
+++ b/src/libbsc/penalty_timers.c
@@ -0,0 +1,129 @@
+/* (C) 2018 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * Author: Neels Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <talloc.h>
+#include <time.h>
+#include <stdint.h>
+
+#include <osmocom/core/linuxlist.h>
+
+#include <osmocom/bsc/penalty_timers.h>
+#include <osmocom/bsc/gsm_data.h>
+
+struct penalty_timers {
+	struct llist_head timers;
+};
+
+struct penalty_timer {
+	struct llist_head entry;
+	void *for_object;
+	unsigned int timeout;
+};
+
+static unsigned int time_now(void)
+{
+	time_t now;
+	time(&now);
+	/* FIXME: use monotonic clock */
+	return (unsigned int)now;
+}
+
+struct penalty_timers *penalty_timers_init(void *ctx)
+{
+	struct penalty_timers *pt = talloc_zero(ctx, struct penalty_timers);
+	if (!pt)
+		return NULL;
+	INIT_LLIST_HEAD(&pt->timers);
+	return pt;
+}
+
+void penalty_timers_add(struct penalty_timers *pt, void *for_object, int timeout)
+{
+	struct penalty_timer *timer;
+	unsigned int now;
+	unsigned int then;
+	now = time_now();
+
+	if (timeout <= 0)
+		return;
+
+	then = now + timeout;
+
+	/* timer already running for that BTS? */
+	llist_for_each_entry(timer, &pt->timers, entry) {
+		if (timer->for_object != for_object)
+			continue;
+		/* raise, if running timer will timeout earlier or has timed
+		 * out already, otherwise keep later timeout */
+		if (timer->timeout < then)
+			timer->timeout = then;
+		return;
+	}
+
+	/* add new timer */
+	timer = talloc_zero(pt, struct penalty_timer);
+	if (!timer)
+		return;
+
+	timer->for_object = for_object;
+	timer->timeout = then;
+
+	llist_add_tail(&timer->entry, &pt->timers);
+}
+
+unsigned int penalty_timers_remaining(struct penalty_timers *pt, void *for_object)
+{
+	struct penalty_timer *timer;
+	unsigned int now = time_now();
+	unsigned int max_remaining = 0;
+	llist_for_each_entry(timer, &pt->timers, entry) {
+		unsigned int remaining;
+		if (timer->for_object != for_object)
+			continue;
+		if (now >= timer->timeout)
+			continue;
+		remaining = timer->timeout - now;
+		if (remaining > max_remaining)
+			max_remaining = remaining;
+	}
+	return max_remaining;
+}
+
+void penalty_timers_clear(struct penalty_timers *pt, void *for_object)
+{
+	struct penalty_timer *timer, *timer2;
+	llist_for_each_entry_safe(timer, timer2, &pt->timers, entry) {
+		if (for_object && timer->for_object != for_object)
+			continue;
+		llist_del(&timer->entry);
+		talloc_free(timer);
+	}
+}
+
+void penalty_timers_free(struct penalty_timers **pt_p)
+{
+	struct penalty_timers *pt = *pt_p;
+	if (!pt)
+		return;
+	penalty_timers_clear(pt, NULL);
+	talloc_free(pt);
+	*pt_p = NULL;
+}