From 05080abad4a93404863f7ee243d78d0c884ff1b4 Mon Sep 17 00:00:00 2001
From: h2zero <powellperalta@gmail.com>
Date: Wed, 31 Mar 2021 20:24:57 -0600
Subject: [PATCH] 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 | 11 +++++++++++
 src/NimBLEScan.h   |  1 +
 2 files changed, 12 insertions(+)

diff --git a/src/NimBLEScan.cpp b/src/NimBLEScan.cpp
index 00aeab0..bc08896 100644
--- a/src/NimBLEScan.cpp
+++ b/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();
 }
 
 
diff --git a/src/NimBLEScan.h b/src/NimBLEScan.h
index 57e7430..49d67c8 100644
--- a/src/NimBLEScan.h
+++ b/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();