DBTAdapter: startDiscovery(..) also might need to change 'keepDiscoveringAlive' even if still in discovery

Hence adding locking mtx_discovery in mgmtEvDeviceDiscoveringMgmt due to multiple state changes
and updating keepDiscoveringAlive even if not initiating discovery (still running).

Further all calls to startDiscovery(..) (C++ and Java) shall clear the list of discovered devices
to end up in the same state, regardless of an alread running discovery or not.
Note: We might have to observe this behavior in more detail, but as we usually utilize the
status listener model, this list is of less interest.

The Java implementation simply always calls down to native code,
ensuring same 'keepAlive' behavior.
It hence also always clears the list of discovered devices.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/direct_bt/DBTAdapter.cpp b/src/direct_bt/DBTAdapter.cpp
index e972f277..8707a1f7 100644
--- a/src/direct_bt/DBTAdapter.cpp
+++ b/src/direct_bt/DBTAdapter.cpp
@@ -342,14 +342,21 @@ bool DBTAdapter::startDiscovery(const bool keepAlive, const HCILEOwnAddressType
     checkValid();
     const std::lock_guard<std::recursive_mutex> lock(mtx_discovery); // RAII-style acquire and relinquish via destructor
     if( ScanType::SCAN_TYPE_NONE != currentScanType ) {
+        removeDiscoveredDevices();
+        if( keepDiscoveringAlive == keepAlive ) {
+            DBG_PRINT("DBTAdapter::startDiscovery: Already discovering, unchanged keepAlive %d -> %d ...", keepDiscoveringAlive.load(), keepAlive);
+        } else {
+            DBG_PRINT("DBTAdapter::startDiscovery: Already discovering, changed keepAlive %d -> %d ...", keepDiscoveringAlive.load(), keepAlive);
+            keepDiscoveringAlive = keepAlive;
+        }
         return true;
     }
     (void)own_mac_type;
     (void)le_scan_interval;
     (void)le_scan_window;
 
-    DBG_PRINT("DBTAdapter::startDiscovery: keepAlive %d ...", keepAlive);
     removeDiscoveredDevices();
+    DBG_PRINT("DBTAdapter::startDiscovery: Initiating discovery, keepAlive %d -> %d ...", keepDiscoveringAlive.load(), keepAlive);
     keepDiscoveringAlive = keepAlive;
     currentScanType = mgmt.startDiscovery(dev_id);
     return ScanType::SCAN_TYPE_NONE != currentScanType;
@@ -465,6 +472,7 @@ std::string DBTAdapter::toString() const {
 // *************************************************
 
 bool DBTAdapter::mgmtEvDeviceDiscoveringMgmt(std::shared_ptr<MgmtEvent> e) {
+    const std::lock_guard<std::recursive_mutex> lock(mtx_discovery); // RAII-style acquire and relinquish via destructor
     DBG_PRINT("DBTAdapter::EventCB:DeviceDiscovering(dev_id %d, keepDiscoveringAlive %d): %s",
         dev_id, keepDiscoveringAlive.load(), e->toString().c_str());
     const MgmtEvtDiscovering &event = *static_cast<const MgmtEvtDiscovering *>(e.get());