From 1e1de177e7da8075b016b703168f3473f58e0568 Mon Sep 17 00:00:00 2001
From: dimitri staessens <dimitri.staessens@ugent.be>
Date: Wed, 20 Sep 2017 21:28:56 +0200
Subject: ipcpd: Handle DHT SDUs in different thread

The DHT will now spawn a thread when receiving SDUs to avoid
starvation of sdu scheduler threads.

Also fixes some locking issues.
---
 src/ipcpd/normal/dht.c | 73 +++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 58 insertions(+), 15 deletions(-)

diff --git a/src/ipcpd/normal/dht.c b/src/ipcpd/normal/dht.c
index e7ba4bf3..996b122a 100644
--- a/src/ipcpd/normal/dht.c
+++ b/src/ipcpd/normal/dht.c
@@ -227,6 +227,11 @@ struct join_info {
         uint64_t     addr;
 };
 
+struct sdu_info {
+        struct dht *         dht;
+        struct shm_du_buff * sdb;
+};
+
 static uint8_t * dht_dup_key(const uint8_t * key,
                              size_t          len)
 {
@@ -1665,11 +1670,16 @@ static int kad_join(struct dht * dht,
         msg.has_t_refresh   = true;
         msg.has_t_replicate = true;
         msg.alpha           = KAD_ALPHA;
-        msg.b               = dht->b;
         msg.k               = KAD_K;
         msg.t_refresh       = KAD_T_REFR;
         msg.t_replicate     = KAD_T_REPL;
 
+        pthread_rwlock_rdlock(&dht->lock);
+
+        msg.b               = dht->b;
+
+        pthread_rwlock_unlock(&dht->lock);
+
         if (send_msg(dht, &msg, addr))
                 return -1;
 
@@ -1798,12 +1808,16 @@ static ssize_t dht_get_contacts(struct dht *          dht,
         pthread_rwlock_rdlock(&dht->lock);
 
         len = dht_contact_list(dht, &l, key);
-        if (len == 0)
+        if (len == 0) {
+                pthread_rwlock_unlock(&dht->lock);
                 return 0;
+        }
 
         *msgs = malloc(len * sizeof(**msgs));
-        if (*msgs == NULL)
+        if (*msgs == NULL) {
+                pthread_rwlock_unlock(&dht->lock);
                 return 0;
+        }
 
         list_for_each_safe(p, h, &l) {
                 struct contact * c = list_entry(p, struct contact, next);
@@ -1976,8 +1990,6 @@ static int kad_handle_join_resp(struct dht *     dht,
                 return -1;
         }
 
-        dht->state = DHT_RUNNING;
-
         kad_req_respond(req);
 
         dht_update_bucket(dht, msg->s_id.data, msg->s_addr);
@@ -2201,10 +2213,10 @@ uint64_t dht_query(struct dht *    dht,
         return 0;
 }
 
-void dht_post_sdu(void *               ae,
-                  struct shm_du_buff * sdb)
+static void * dht_handle_sdu(void * o)
 {
         struct dht *         dht;
+        struct shm_du_buff * sdb;
         kad_msg_t *          msg;
         kad_contact_msg_t ** cmsgs;
         kad_msg_t            resp_msg = KAD_MSG__INIT;
@@ -2212,12 +2224,15 @@ void dht_post_sdu(void *               ae,
         buffer_t             buf;
         size_t               i;
 
-        assert(ae);
-        assert(sdb);
+        assert(o);
 
         memset(&buf, 0, sizeof(buf));
 
-        dht = (struct dht *) ae;
+        dht = ((struct sdu_info *) o)->dht;
+        sdb = ((struct sdu_info *) o)->sdb;
+
+        assert(dht);
+        assert(sdb);
 
         msg = kad_msg__unpack(NULL,
                               shm_du_buff_tail(sdb) - shm_du_buff_head(sdb),
@@ -2225,27 +2240,29 @@ void dht_post_sdu(void *               ae,
 
         ipcp_sdb_release(sdb);
 
+        free((struct sdu_info *) o);
+
         if (msg == NULL) {
                 log_err("Failed to unpack message.");
-                return;
+                return (void *) -1;
         }
 
         if (msg->has_key && msg->key.len != dht->b) {
                 kad_msg__free_unpacked(msg, NULL);
                 log_warn("Bad key in message.");
-                return;
+                return (void *) -1;
         }
 
         if (msg->has_s_id && !msg->has_b && msg->s_id.len != dht->b) {
                 kad_msg__free_unpacked(msg, NULL);
                 log_warn("Bad source ID in message of type %d.", msg->code);
-                return;
+                return (void *) -1;
         }
 
         if (msg->code != KAD_RESPONSE && dht_wait_running(dht)) {
                 kad_msg__free_unpacked(msg, NULL);
                 log_dbg("Got a request message when not running.");
-                return;
+                return (void *) -1;
         }
 
         addr = msg->s_addr;
@@ -2341,11 +2358,34 @@ void dht_post_sdu(void *               ae,
                 free(resp_msg.addrs);
 
         if (resp_msg.n_contacts == 0)
-                return;
+                return (void *) -1;
 
         for (i = 0; i < resp_msg.n_contacts; ++i)
                 kad_contact_msg__free_unpacked(resp_msg.contacts[i], NULL);
         free(resp_msg.contacts);
+
+        return (void *) 0;
+}
+
+static void dht_post_sdu(void *               comp,
+                         struct shm_du_buff * sdb)
+{
+        pthread_t         thr;
+        struct sdu_info * info;
+
+        info = malloc(sizeof(*info));
+        if (info == NULL)
+                return;
+
+        info->dht = (struct dht *) comp;
+        info->sdb = sdb;
+
+        if (pthread_create(&thr, NULL, dht_handle_sdu, info)) {
+                free(info);
+                return;
+        }
+
+        pthread_detach(thr);
 }
 
 void dht_destroy(struct dht * dht)
@@ -2421,6 +2461,8 @@ static void * join_thr(void * o)
                 sleep(KAD_JOIN_INTV);
         }
 
+        dht_set_state(info->dht, DHT_RUNNING);
+
         lu = kad_lookup(info->dht, info->dht->id, KAD_FIND_NODE);
         if (lu != NULL)
                 lookup_destroy(lu);
@@ -2509,6 +2551,7 @@ struct dht * dht_create(uint64_t addr)
         notifier_reg(handle_event, dht);
 #else
         (void) handle_event;
+        (void) dht_post_sdu;
 #endif
         dht->state = DHT_INIT;
 
-- 
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