Add clear scan duplicate filter cache method + clear on start.

This allows for clearing the duplicate filter cache when required and will also clear it
automatically when starting a scan.

This is useful when unexpectedly disconnected from a device and attempting to reconnect.
Previously the scan filter would not report advertisements from a device if it was multi-connectable
and advertising while connected. The result was long delays until the device would be scanned again.
This resolves it by clearing the filter cache on each scan start/clearResults call
and adding a method to NimBLEScan for manually clearing the cache on demand.

src/NimBLEScan.cpp

@@ -316,6 +316,8 @@ bool NimBLEScan::start(uint32_t duration, void (*scanCompleteCB)(NimBLEScanResul
             break;
 
         case BLE_HS_EALREADY:
+            // Clear the cache if already scanning in case an advertiser was missed.
+            clearDuplicateCache();
             break;
 
         case BLE_HS_EBUSY:
@@ -398,6 +400,14 @@ bool NimBLEScan::stop() {
 } // stop
 
 
+/**
+ * @brief Clears the duplicate scan filter cache.
+ */
+void NimBLEScan::clearDuplicateCache() {
+    esp_ble_scan_dupilcate_list_flush();
+}
+
+
 /**
  * @brief Delete peer device from the scan results vector.
  * @param [in] address The address of the device to delete from the results.
@@ -453,6 +463,7 @@ void NimBLEScan::clearResults() {
         delete it;
     }
     m_scanResults.m_advertisedDevicesVector.clear();
+    clearDuplicateCache();
 }
 
 

src/NimBLEScan.h

@@ -70,6 +70,7 @@ public:
     void                setDuplicateFilter(bool enabled);
     void                setLimitedOnly(bool enabled);
     void                setFilterPolicy(uint8_t filter);
+    void                clearDuplicateCache();
     bool                stop();
     void                clearResults();
     NimBLEScanResults   getResults();