[PATCH 2/2] graph: add callback in dispatch mode

[Christophe Fontaine <cfontain@redhat.com>]

In dispatch mode, the assumption is that the graphs will be
polled continuously: there is no way to know when packets are transferred
from one graph to another.

Introduce a callback to be notified when packets are enqueue in the work
queue: this can be useful if we want to wake up a thread.
This sleep/wake up mechanism is deferred to the application.

Signed-off-by: Christophe Fontaine <cfontain@redhat.com>
---
 lib/graph/graph.c                          | 10 +++++++---
 lib/graph/rte_graph.h                      | 14 ++++++++++++++
 lib/graph/rte_graph_model_mcore_dispatch.c |  2 ++
 lib/graph/rte_graph_worker_common.h        |  2 ++
 4 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/lib/graph/graph.c b/lib/graph/graph.c
index 146d0a12b4..61159edc72 100644
--- a/lib/graph/graph.c
+++ b/lib/graph/graph.c
@@ -600,9 +600,13 @@ graph_clone(struct graph *parent_graph, const char *name, struct rte_graph_param
 	graph->graph->model = parent_graph->graph->model;
 
 	/* Create the graph schedule work queue */
-	if (rte_graph_worker_model_get(graph->graph) == RTE_GRAPH_MODEL_MCORE_DISPATCH &&
-	    graph_sched_wq_create(graph, parent_graph, prm))
-		goto graph_mem_destroy;
+	if (rte_graph_worker_model_get(graph->graph) == RTE_GRAPH_MODEL_MCORE_DISPATCH) {
+		if (graph_sched_wq_create(graph, parent_graph, prm))
+			goto graph_mem_destroy;
+
+		graph->graph->dispatch.notify_cb = prm->dispatch.notify_cb;
+		graph->graph->dispatch.cb_priv = prm->dispatch.cb_priv;
+	}
 
 	/* Call init() of the all the nodes in the graph */
 	if (graph_node_init(graph))
diff --git a/lib/graph/rte_graph.h b/lib/graph/rte_graph.h
index 097d0dc9d5..16b1dbac3f 100644
--- a/lib/graph/rte_graph.h
+++ b/lib/graph/rte_graph.h
@@ -150,6 +150,18 @@ typedef void (*rte_node_fini_t)(const struct rte_graph *graph,
 typedef int (*rte_graph_cluster_stats_cb_t)(bool is_first, bool is_last,
 	     void *cookie, const struct rte_graph_cluster_node_stats *stats);
 
+
+/**
+ * Graph dispatch enqueue notification callback.
+ *
+ * @param graph
+ *   Current graph
+ * @param cb_priv
+ *   Opaque argument given to the callback.
+ *
+ */
+typedef void (*packets_enqueued_cb)(struct rte_graph *graph, uint64_t priv);
+
 /**
  * Structure to hold configuration parameters for creating the graph.
  *
@@ -172,6 +184,8 @@ struct rte_graph_param {
 		struct {
 			uint32_t wq_size_max; /**< Maximum size of workqueue for dispatch model. */
 			uint32_t mp_capacity; /**< Capacity of memory pool for dispatch model. */
+			packets_enqueued_cb notify_cb;
+			uint64_t cb_priv;
 		} dispatch;
 	};
 };
diff --git a/lib/graph/rte_graph_model_mcore_dispatch.c b/lib/graph/rte_graph_model_mcore_dispatch.c
index 70f0069bc1..706b5469f0 100644
--- a/lib/graph/rte_graph_model_mcore_dispatch.c
+++ b/lib/graph/rte_graph_model_mcore_dispatch.c
@@ -102,6 +102,8 @@ __graph_sched_node_enqueue(struct rte_node *node, struct rte_graph *graph)
 	if (node->idx > 0)
 		goto submit_again;
 
+	if (graph->dispatch.notify_cb)
+		graph->dispatch.notify_cb(graph, graph->dispatch.cb_priv);
 	return true;
 
 fallback:
diff --git a/lib/graph/rte_graph_worker_common.h b/lib/graph/rte_graph_worker_common.h
index aef0f65673..221deceaee 100644
--- a/lib/graph/rte_graph_worker_common.h
+++ b/lib/graph/rte_graph_worker_common.h
@@ -68,6 +68,8 @@ struct __rte_cache_aligned rte_graph {
 			unsigned int lcore_id;  /**< The graph running Lcore. */
 			struct rte_ring *wq;    /**< The work-queue for pending streams. */
 			struct rte_mempool *mp; /**< The mempool for scheduling streams. */
+			packets_enqueued_cb notify_cb; /**< callback when a packet crosses lcores */
+			uint64_t cb_priv; /**< Opaque parameter for notify_cb */
 		} dispatch; /** Only used by dispatch model */
 	};
 	SLIST_ENTRY(rte_graph) next;   /* The next for rte_graph list */
-- 
2.43.5