Add extra layer of queuing above the Flounder UMP one.

[barrelfish] / usr / proc_mgmt / spawnd_state.c

diff --git a/usr/proc_mgmt/spawnd_state.c b/usr/proc_mgmt/spawnd_state.c
index 75f3022..219a000 100644 (file)
--- a/usr/proc_mgmt/spawnd_state.c
+++ b/usr/proc_mgmt/spawnd_state.c
@@ -25,6 +25,8 @@ errval_t spawnd_state_alloc(coreid_t core_id, struct spawn_binding *b)
 
     spawnds[core_id]->b = b;
     spawnds[core_id]->core_id = core_id;
+    spawnds[core_id]->queue.head = NULL;
+    spawnds[core_id]->queue.tail = NULL;
 
     return SYS_ERR_OK;
 }
@@ -45,3 +47,112 @@ inline struct spawnd_state *spawnd_state_get(coreid_t core_id)
 {
     return spawnds[core_id];
 }
+
+/**
+ * \brief Enqueue on a waitset queue.
+ *
+ * \param q    Pointer to queue to enqueue on
+ * \param m    Pointer to element to enqueue
+ *
+ * \return true if queue was empty, false if not.
+ */
+static bool enqueue_send(struct msg_queue *q, struct msg_queue_elem *m)
+{
+    assert(m->next == NULL);
+
+    // Enqueue on the queue
+    if(q->tail != NULL) {
+        q->tail->next = m;
+    } else {
+        assert(q->head == NULL);
+        q->head = m;
+    }
+    q->tail = m;
+
+    return q->head == q->tail ? true : false;
+}
+
+/**
+ * \brief Dequeues from a waitset queue.
+ *
+ * \param q    Pointer to queue to dequeue from
+ *
+ * \return the newly dequeued element.
+ */
+static struct msg_queue_elem *dequeue_send(struct msg_queue *q)
+{
+    // Queue should have at least one element
+    assert(q->head != NULL && q->tail != NULL);
+
+    struct msg_queue_elem *e = q->head;
+    q->head = e->next;
+    if(q->head == NULL) {
+        q->tail = NULL;
+    }
+
+    return e;
+}
+
+/**
+ * \brief Enqueue an element on a waitset queue IN FRONT.
+ *
+ * \param q    Pointer to queue to enqueue on
+ * \param m    Pointer to element to enqueue
+ *
+ * \return true if queue was empty, false if not.
+ */
+static bool enqueue_send_at_front(struct msg_queue *q, struct msg_queue_elem *m)
+{
+    assert(m->next == NULL);
+    if(q->tail == NULL) {
+        assert(q->head == NULL);
+        q->head = m;
+        q->tail = m;
+    } else {
+        m->next = q->head;
+        q->head = m;
+    }
+    return q->head == q->tail ? true : false;
+}
+
+static void spawnd_send_handler(void *arg)
+{
+    struct spawnd_state *spawnd = (struct spawnd_state*) arg;
+    struct msg_queue *q = &spawnd->queue;
+
+    // Dequeue next element from the queue
+    struct msg_queue_elem *m = (struct msg_queue_elem*) dequeue_send(q);
+
+    assert(m->cont != NULL);
+    if (!m->cont(m)) {
+        // Flounder TX busy, need to re-enqueue message.
+        // TODO(razvan): Re-enqueuing at the front of the queue, to preserve
+        // original message order. Could a different strategy be preferrable?
+        enqueue_send_at_front(q, m);
+    }
+
+    if (q->head != NULL) {
+        // Queue is non-empty, therefore re-register.
+        errval_t err = spawnd->b->register_send(spawnd->b, spawnd->b->waitset,
+                                                MKCONT(spawnd_send_handler,
+                                                       arg));
+        if (err_is_fail(err)) {
+            DEBUG_ERR(err, "regitering for spawnd send");
+            return;
+        }
+    }
+}
+
+errval_t spawnd_state_enqueue_send(struct spawnd_state *spawnd,
+                                   struct msg_queue_elem *msg)
+{
+    msg->next = NULL;
+
+    // If queue was empty, enqueue on waitset
+    if(enqueue_send(&spawnd->queue, msg)) {
+        return spawnd->b->register_send(spawnd->b, spawnd->b->waitset,
+                                        MKCONT(spawnd_send_handler, spawnd));
+    } else {
+        return SYS_ERR_OK;
+    }
+}
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