Replace semaphores with task notifications. (#9)

* Replace all semaphores with task notifications.

* use critical sections to prevent concurrent data access.

* Ensure scan stop has been called before connecting.

* Optimize and cleanup

* Add template casting to NimBLERemoteDescriptor::readValue()

* Removed storage of the descriptor value read as it did not serve any purpose.

src/NimBLEScan.cpp

@@ -18,7 +18,6 @@
 #if defined(CONFIG_BT_NIMBLE_ROLE_OBSERVER)
 
 #include "NimBLEScan.h"
-#include "NimBLEUtils.h"
 #include "NimBLEDevice.h"
 #include "NimBLELog.h"
 
@@ -70,6 +69,7 @@ NimBLEScan::NimBLEScan() {
     m_pAdvertisedDeviceCallbacks     = nullptr;
     m_stopped                        = true;
     m_wantDuplicates                 = false;
+    m_pTaskData                      = nullptr;
 }
 
 
@@ -101,14 +101,6 @@ NimBLEScan::NimBLEScan() {
 
             NimBLEAddress advertisedAddress(event->disc.addr);
 
-            // Print advertisement data
-    //        print_adv_fields(&fields);
-
-            // If we are not scanning, nothing to do with the extra results.
-            if (pScan->m_stopped) {
-                return 0;
-            }
-
             // Examine our list of ignored addresses and stop processing if we don't want to see it or are already connected
             if(NimBLEDevice::isIgnored(advertisedAddress)) {
                 NIMBLE_LOGI(LOG_TAG, "Ignoring device: address: %s", advertisedAddress.toString().c_str());
@@ -131,7 +123,6 @@ NimBLEScan::NimBLEScan() {
                 advertisedDevice = new NimBLEAdvertisedDevice();
                 advertisedDevice->setAddressType(event->disc.addr.type);
                 advertisedDevice->setAddress(advertisedAddress);
-                //NIMBLE_LOGE(LOG_TAG, "advertisement type: %d, %s",event->disc.event_type, NimBLEUtils::advTypeToString(event->disc.event_type));
                 advertisedDevice->setAdvType(event->disc.event_type);
                 pScan->m_scanResults.m_advertisedDevicesVector.push_back(advertisedDevice);
                 NIMBLE_LOGI(LOG_TAG, "NEW DEVICE FOUND: %s", advertisedAddress.toString().c_str());
@@ -153,7 +144,6 @@ NimBLEScan::NimBLEScan() {
                 } else if (event->disc.event_type == BLE_HCI_ADV_RPT_EVTYPE_SCAN_RSP) {
                     pScan->m_pAdvertisedDeviceCallbacks->onResult(advertisedDevice);
                 }
-                //m_pAdvertisedDeviceCallbacks->onResult(*advertisedDevice);
             }
 
             return 0;
@@ -167,7 +157,11 @@ NimBLEScan::NimBLEScan() {
             }
 
             pScan->m_stopped = true;
-            pScan->m_semaphoreScanEnd.give();
+            if(pScan->m_pTaskData != nullptr) {
+                pScan->m_pTaskData->rc = event->disc_complete.reason;
+                xTaskNotifyGive(pScan->m_pTaskData->task);
+            }
+
             return 0;
         }
 
@@ -249,7 +243,6 @@ bool NimBLEScan::start(uint32_t duration, void (*scanCompleteCB)(NimBLEScanResul
     }
 
     m_stopped = false;
-    m_semaphoreScanEnd.take("start");
 
     // Save the callback to be invoked when the scan completes.
     m_scanCompleteCB = scanCompleteCB;
@@ -275,7 +268,7 @@ bool NimBLEScan::start(uint32_t duration, void (*scanCompleteCB)(NimBLEScanResul
         rc = ble_gap_disc(m_own_addr_type, duration, &m_scan_params,
                                     NimBLEScan::handleGapEvent, this);
         if(rc == BLE_HS_EBUSY) {
-            vTaskDelay(2);
+            vTaskDelay(1 / portTICK_PERIOD_MS);
         }
     } while(rc == BLE_HS_EBUSY);
 
@@ -283,7 +276,6 @@ bool NimBLEScan::start(uint32_t duration, void (*scanCompleteCB)(NimBLEScanResul
         NIMBLE_LOGE(LOG_TAG, "Error initiating GAP discovery procedure; rc=%d, %s",
                                         rc, NimBLEUtils::returnCodeToString(rc));
         m_stopped = true;
-        m_semaphoreScanEnd.give();
         return false;
     }
 
@@ -298,9 +290,18 @@ bool NimBLEScan::start(uint32_t duration, void (*scanCompleteCB)(NimBLEScanResul
  * @return The BLEScanResults.
  */
 NimBLEScanResults NimBLEScan::start(uint32_t duration, bool is_continue) {
-    if(start(duration, nullptr, is_continue)) {
-        m_semaphoreScanEnd.wait("start");   // Wait for the semaphore to release.
+    if(duration == 0) {
+        NIMBLE_LOGW(LOG_TAG, "Blocking scan called with duration = forever");
     }
+
+    ble_task_data_t taskData = {nullptr, xTaskGetCurrentTaskHandle(),0, nullptr};
+    m_pTaskData = &taskData;
+
+    if(start(duration, nullptr, is_continue)) {
+        ulTaskNotifyTake(pdTRUE, portMAX_DELAY);
+    }
+
+    m_pTaskData = nullptr;
     return m_scanResults;
 } // start
 
@@ -309,13 +310,13 @@ NimBLEScanResults NimBLEScan::start(uint32_t duration, bool is_continue) {
  * @brief Stop an in progress scan.
  * @return N/A.
  */
-void NimBLEScan::stop() {
+bool NimBLEScan::stop() {
     NIMBLE_LOGD(LOG_TAG, ">> stop()");
 
     int rc = ble_gap_disc_cancel();
     if (rc != 0 && rc != BLE_HS_EALREADY) {
         NIMBLE_LOGE(LOG_TAG, "Failed to cancel scan; rc=%d\n", rc);
-        return;
+        return false;
     }
 
     m_stopped = true;
@@ -324,9 +325,12 @@ void NimBLEScan::stop() {
         m_scanCompleteCB(m_scanResults);
     }
 
-    m_semaphoreScanEnd.give();
+    if(m_pTaskData != nullptr) {
+        xTaskNotifyGive(m_pTaskData->task);
+    }
 
     NIMBLE_LOGD(LOG_TAG, "<< stop()");
+    return true;
 } // stop
 
 
@@ -350,7 +354,6 @@ void NimBLEScan::erase(const NimBLEAddress &address) {
  */
 void NimBLEScan::onHostReset() {
     m_stopped = true;
-    m_semaphoreScanEnd.give();
 }