arehbein has uploaded this change for review.

View Change

write_queue: Enable updating max_length field

Dequeue and free any excess messages, in case the new queue length
is shorter than the old.

Related: OS#5774
Change-Id: Ibfe51a2faf29f8ae160a9c330c9af0d09b5a9002
---
M include/osmocom/core/write_queue.h
M src/core/libosmocore.map
M src/core/write_queue.c
M tests/write_queue/wqueue_test.c
4 files changed, 56 insertions(+), 0 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/44/34444/1

diff --git a/include/osmocom/core/write_queue.h b/include/osmocom/core/write_queue.h
index 6cb0a6b..0d658af 100644
--- a/include/osmocom/core/write_queue.h
+++ b/include/osmocom/core/write_queue.h
@@ -50,6 +50,7 @@
 void osmo_wqueue_clear(struct osmo_wqueue *queue);
 int osmo_wqueue_enqueue(struct osmo_wqueue *queue, struct msgb *data);
 int osmo_wqueue_enqueue_quiet(struct osmo_wqueue *queue, struct msgb *data);
+size_t osmo_wqueue_update_maxlen(struct osmo_wqueue *queue, size_t len);
 int osmo_wqueue_bfd_cb(struct osmo_fd *fd, unsigned int what);
 
 /*! @} */
diff --git a/src/core/libosmocore.map b/src/core/libosmocore.map
index c0e164b..4a9d7bc 100644
--- a/src/core/libosmocore.map
+++ b/src/core/libosmocore.map
@@ -565,6 +565,7 @@
 osmo_wqueue_clear;
 osmo_wqueue_enqueue;
 osmo_wqueue_enqueue_quiet;
+osmo_wqueue_update_maxlen;
 osmo_wqueue_init;
 rate_ctr_add;
 rate_ctr_difference;
diff --git a/src/core/write_queue.c b/src/core/write_queue.c
index 884cebd..7557c7b 100644
--- a/src/core/write_queue.c
+++ b/src/core/write_queue.c
@@ -147,4 +147,22 @@
 	queue->bfd.when &= ~OSMO_FD_WRITE;
 }
 
+/* Update write queue length & drop excess messages.
+ * \param[in] queue linked list header of message queue
+ * \param[in] len new max. wqueue length
+ * \returns Number of messages dropped.
+ *
+ * Messages beyond the new maximum message queue size will be dropped.
+ */
+size_t osmo_wqueue_update_maxlen(struct osmo_wqueue *queue, size_t len)
+{
+	size_t dropped_msgs;
+	struct llist_head *q = &queue->msg_queue;
+	int diff = queue->max_length - len;
+	queue->max_length = len;
+	for (dropped_msgs = 0; dropped_msgs < diff && !llist_empty(q); dropped_msgs++)
+		msgb_free(msgb_dequeue(q));
+	return dropped_msgs;
+}
+
 /*! @} */
diff --git a/tests/write_queue/wqueue_test.c b/tests/write_queue/wqueue_test.c
index 3823ef5..f82a34a 100644
--- a/tests/write_queue/wqueue_test.c
+++ b/tests/write_queue/wqueue_test.c
@@ -15,6 +15,7 @@
 	struct msgb *msg;
 	struct osmo_wqueue wqueue;
 	int rc;
+	size_t dropped_msgs;
 
 	osmo_wqueue_init(&wqueue, 0);
 	OSMO_ASSERT(wqueue.max_length == 0);
@@ -63,6 +64,28 @@
 	OSMO_ASSERT(wqueue.current_length == 2);
 	msgb_free(msg);
 	osmo_wqueue_clear(&wqueue);
+
+	/* Update limit */
+	OSMO_ASSERT(osmo_wqueue_update_maxlen(&wqueue, 5) == 0);
+	OSMO_ASSERT(osmo_wqueue_update_maxlen(&wqueue, 1) == 0);
+	OSMO_ASSERT(osmo_wqueue_update_maxlen(&wqueue, 4) == 0);
+
+	/* Add three, update limit to 1 */
+	OSMO_ASSERT(wqueue.max_length == 4);
+	msg = msgb_alloc(4096, "msg6");
+	rc = osmo_wqueue_enqueue(&wqueue, msg);
+	OSMO_ASSERT(rc == 0);
+	OSMO_ASSERT(wqueue.current_length == 1);
+	msg = msgb_alloc(4096, "msg7");
+	rc = osmo_wqueue_enqueue(&wqueue, msg);
+	OSMO_ASSERT(rc == 0);
+	OSMO_ASSERT(wqueue.current_length == 2);
+	msg = msgb_alloc(4096, "msg8");
+	rc = osmo_wqueue_enqueue(&wqueue, msg);
+	OSMO_ASSERT(wqueue.current_length == 3);
+	dropped_msgs = osmo_wqueue_update_maxlen(&wqueue, 1);
+	OSMO_ASSERT(dropped_msgs = 2);
+	osmo_wqueue_clear(&wqueue);
 }
 
 int main(int argc, char **argv)

To view, visit change 34444. To unsubscribe, or for help writing mail filters, visit settings.