Merge pull request ARMmbed#1656 from ARMmbed/IOTTHD-2441

FHSS: Added random timeout before polling TX queue after channel change

Author: Jarkko Paso

source/Service_Libs/fhss/fhss_ws.c

@@ -25,6 +25,8 @@
 #include "fhss_ws.h"
 #include "nsdynmemLIB.h"
 #include "common_functions.h"
+#include "eventOS_callback_timer.h"
+#include "randLIB.h"
 #include "ns_trace.h"
 #include <string.h>
 
@@ -48,6 +50,7 @@ struct ws_ie_t {
 
 static void fhss_ws_update_uc_channel_callback(fhss_structure_t *fhss_structure);
 static void fhss_unicast_handler(const fhss_api_t *fhss_api, uint16_t delay);
+static void fhss_ws_start_tx_poll_timer(fhss_structure_t *fhss_structure, uint16_t queue_size, uint8_t channel_dwell_interval);
 
 fhss_structure_t *fhss_ws_enable(fhss_api_t *fhss_api, const fhss_ws_configuration_t *fhss_configuration, const fhss_timer_t *fhss_timer)
 {
@@ -124,10 +127,8 @@ static void fhss_broadcast_handler(const fhss_api_t *fhss_api, uint16_t delay)
 #endif /*FHSS_CHANNEL_DEBUG*/
     }
     fhss_structure->callbacks.change_channel(fhss_structure->fhss_api, next_channel);
-    if (fhss_structure->callbacks.read_tx_queue_size(fhss_structure->fhss_api, true)) {
-        // TODO: Randomize polling TX queue when on broadcast channel
-        fhss_structure->callbacks.tx_poll(fhss_structure->fhss_api);
-    }
+    fhss_ws_start_tx_poll_timer(fhss_structure, fhss_structure->callbacks.read_tx_queue_size(fhss_structure->fhss_api, true),
+            fhss_structure->ws->fhss_configuration.fhss_bc_dwell_interval);
 }
 
 static int own_floor(float value)
@@ -454,9 +455,24 @@ static void fhss_unicast_handler(const fhss_api_t *fhss_api, uint16_t delay)
     timeout = fhss_ws_get_sf_timeout_callback(fhss_structure);
     fhss_start_timer(fhss_structure, timeout - (delay * fhss_structure->platform_functions.fhss_resolution_divider), fhss_unicast_handler);
     fhss_ws_update_uc_channel_callback(fhss_structure);
-    if (fhss_structure->callbacks.read_tx_queue_size(fhss_structure->fhss_api, false)) {
-        fhss_structure->callbacks.tx_poll(fhss_structure->fhss_api);
+    fhss_ws_start_tx_poll_timer(fhss_structure, fhss_structure->callbacks.read_tx_queue_size(fhss_structure->fhss_api, false),
+            fhss_structure->ws->fhss_configuration.fhss_uc_dwell_interval);
+}
+
+static void fhss_ws_start_tx_poll_timer(fhss_structure_t *fhss_structure, uint16_t queue_size, uint8_t channel_dwell_interval)
+{
+    if (!queue_size) {
+        return;
     }
+    /* Start timer with random timeout to trigger TX queue poll event.
+     * Min random is 1/50 of the channel dwell interval.
+     * Max random is 1/10 of the channel dwell interval.
+     * Event timer resolution is 50us.
+     * Divide random with TX queue size to transmit faster when TX queue is growing
+     */
+    uint16_t min_random = ((((uint32_t)channel_dwell_interval * 1000) / 50) / 50) / queue_size;
+    uint16_t max_random = ((((uint32_t)channel_dwell_interval * 1000) / 10) / 50) / queue_size;
+    eventOS_callback_timer_start(fhss_structure->fhss_event_timer, randLIB_get_random_in_range(min_random, max_random));
 }
 
 int fhss_ws_set_callbacks(fhss_structure_t *fhss_structure)

test/nanostack/unittest/service_libs/fhss_ws/Makefile

@@ -16,6 +16,9 @@ TEST_SRC_FILES = \
         ../../stub/ns_list_stub.c \
         ../../stub/channel_list_stub.c \
         ../../stub/channel_functions_stub.c \
+        ../../stub/ns_timer_stub.c \
+        ../../stub/randLIB_stub.c \
+        ../../stub/event_stub.c \
         ../../stub/fhss_stub.c \
         ../../stub/fhss_common_stub.c \
         ../../stub/fhss_callbacks_stub.c \