6 files changed, 43 insertions, 0 deletions
diff --git a/src/vnet/session/application.h b/src/vnet/session/application.h
index 81be238094e..24c6fc3eeaf 100644
--- a/src/vnet/session/application.h
+++ b/src/vnet/session/application.h
@@ -255,6 +255,8 @@ int app_worker_transport_closed_notify (app_worker_t * app_wrk,
 int app_worker_reset_notify (app_worker_t * app_wrk, session_t * s);
 int app_worker_cleanup_notify (app_worker_t * app_wrk, session_t * s,
 			       session_cleanup_ntf_t ntf);
+int app_worker_migrate_notify (app_worker_t * app_wrk, session_t * s,
+			       session_handle_t new_sh);
 int app_worker_builtin_rx (app_worker_t * app_wrk, session_t * s);
 int app_worker_builtin_tx (app_worker_t * app_wrk, session_t * s);
 segment_manager_t *app_worker_get_listen_segment_manager (app_worker_t *,
diff --git a/src/vnet/session/application_interface.h b/src/vnet/session/application_interface.h
index 3a1c9b55738..6cc1af4d78b 100644
--- a/src/vnet/session/application_interface.h
+++ b/src/vnet/session/application_interface.h
@@ -48,6 +48,9 @@ typedef struct _stream_session_cb_vft
   /** Notify app that session was reset */
   void (*session_reset_callback) (session_t * s);
 
+  /** Notify app that session pool migration happened */
+  void (*session_migrate_callback) (session_t * s, session_handle_t new_sh);
+
   /** Direct RX callback for built-in application */
   int (*builtin_app_rx_callback) (session_t * session);
 
diff --git a/src/vnet/session/application_worker.c b/src/vnet/session/application_worker.c
index 0be1a2e85f7..28793681afb 100644
--- a/src/vnet/session/application_worker.c
+++ b/src/vnet/session/application_worker.c
@@ -373,6 +373,15 @@ app_worker_builtin_tx (app_worker_t * app_wrk, session_t * s)
 }
 
 int
+app_worker_migrate_notify (app_worker_t * app_wrk, session_t * s,
+			   session_handle_t new_sh)
+{
+  application_t *app = application_get (app_wrk->app_index);
+  app->cb_fns.session_migrate_callback (s, new_sh);
+  return 0;
+}
+
+int
 app_worker_own_session (app_worker_t * app_wrk, session_t * s)
 {
   segment_manager_t *sm;
diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
index 318e01dbf54..3d22cc27ef4 100644
--- a/src/vnet/session/session.c
+++ b/src/vnet/session/session.c
@@ -715,17 +715,32 @@ typedef struct _session_switch_pool_args
   u32 new_session_index;
 } session_switch_pool_args_t;
 
+/**
+ * Notify old thread of the session pool switch
+ */
 static void
 session_switch_pool (void *cb_args)
 {
   session_switch_pool_args_t *args = (session_switch_pool_args_t *) cb_args;
+  app_worker_t *app_wrk;
   session_t *s;
+
   ASSERT (args->thread_index == vlib_get_thread_index ());
   s = session_get (args->session_index, args->thread_index);
   s->tx_fifo->master_session_index = args->new_session_index;
   s->tx_fifo->master_thread_index = args->new_thread_index;
   transport_cleanup (session_get_transport_proto (s), s->connection_index,
 		     s->thread_index);
+
+  app_wrk = app_worker_get_if_valid (s->app_wrk_index);
+  if (app_wrk)
+    {
+      session_handle_t new_sh;
+      new_sh = session_make_handle (args->new_session_index,
+				    args->new_thread_index);
+      app_worker_migrate_notify (app_wrk, s, new_sh);
+    }
+
   session_free (s);
   clib_mem_free (cb_args);
 }
diff --git a/src/vnet/session/session_api.c b/src/vnet/session/session_api.c
index 479c5d1ca83..e3e3bb3c596 100755
--- a/src/vnet/session/session_api.c
+++ b/src/vnet/session/session_api.c
@@ -438,11 +438,19 @@ done:
   return 0;
 }
 
+static void
+mq_send_session_migrate_cb (session_t * s, session_handle_t new_sh)
+{
+  clib_warning ("not supported");
+}
+
+
 static session_cb_vft_t session_mq_cb_vft = {
   .session_accept_callback = mq_send_session_accepted_cb,
   .session_disconnect_callback = mq_send_session_disconnected_cb,
   .session_connected_callback = mq_send_session_connected_cb,
   .session_reset_callback = mq_send_session_reset_cb,
+  .session_migrate_callback = mq_send_session_migrate_cb,
   .add_segment_callback = send_add_segment_callback,
   .del_segment_callback = send_del_segment_callback,
 };
diff --git a/src/vnet/session/session_types.h b/src/vnet/session/session_types.h
index 9a5bc768808..f9472ba3828 100644
--- a/src/vnet/session/session_types.h
+++ b/src/vnet/session/session_types.h
@@ -275,6 +275,12 @@ session_parse_handle (session_handle_t handle, u32 * index,
   *thread_index = session_thread_from_handle (handle);
 }
 
+static inline session_handle_t
+session_make_handle (u32 session_index, u32 thread_index)
+{
+  return (((u64) thread_index << 32) | (u64) session_index);
+}
+
 typedef enum
 {
   SESSION_IO_EVT_RX,