Resolve adapter lifecycle issue: Have Add/remove callbacks in dedicated thread, drop DBTAdapter::close() call; Fix DBTManager.java COW adapters usage

Resolve adapter lifecycle issue: No use after free:

- Perform add/remove callbacks in dedicated thread
  Have remove also being called from a dedicated thread in DBTManager (like add),
  hence calling down into the MgmtEventCallbacks + User callbacks from here on sequentially.

- drop erratic DBTAdapter::close() call
  DBTAdapter shall not react itself to its removal, since user will

- DBTAdapter dtor and close() shall just return if !isValid

Fix DBTManager.java COW adapters usage:

- Benefit from all locked-COW [write-]operation
  via removeIf, forEach

- Otherwise use iterators, which operate on the snapshot

1 files changed, 13 insertions, 9 deletions

diff --git a/examples/direct_bt_scanner10/dbt_scanner10.cpp b/examples/direct_bt_scanner10/dbt_scanner10.cpp
index 4c95f823..30bd3e81 100644
--- a/examples/direct_bt_scanner10/dbt_scanner10.cpp
+++ b/examples/direct_bt_scanner10/dbt_scanner10.cpp
@@ -565,22 +565,21 @@ static std::shared_ptr<DBTAdapter> getAdapter(const uint16_t dev_id) {
         return *it;
     }
 }
-static int removeAdapter(const uint16_t dev_id) {
+static std::shared_ptr<DBTAdapter> removeAdapter(const uint16_t dev_id) {
+    std::shared_ptr<DBTAdapter> res = nullptr;
     const std::lock_guard<std::recursive_mutex> lock(adapterList.get_write_mutex());
     std::shared_ptr<std::vector<std::shared_ptr<DBTAdapter>>> store = adapterList.copy_store();
-    int count = 0;
     for(auto it = store->begin(); it != store->end(); ) {
         if ( (*it)->dev_id == dev_id ) {
+            res = *it;
             it = store->erase(it);
-            count++;
+            adapterList.set_store(std::move(store));
+            return res;
         } else {
             ++it;
         }
     }
-    if( 0 < count ) {
-        adapterList.set_store(std::move(store));
-    }
-    return count;
+    return nullptr;
 }
 
 static bool myChangedAdapterSetFunc(const bool added, const AdapterInfo& adapterInfo) {
@@ -600,8 +599,13 @@ static bool myChangedAdapterSetFunc(const bool added, const AdapterInfo& adapter
             }
         }
     } else {
-        const int count = removeAdapter(adapterInfo.dev_id);
-        fprintf(stderr, "****** Adapter REMOVED: count %d, %s\n", count, adapterInfo.toString().c_str());
+        std::shared_ptr<DBTAdapter> removed = removeAdapter(adapterInfo.dev_id);
+        if( nullptr != removed ) {
+            fprintf(stderr, "****** Adapter REMOVED: %s\n", removed->toString().c_str());
+            removed->close();
+        } else {
+            fprintf(stderr, "****** Adapter REMOVED: Not found %s\n", adapterInfo.toString().c_str());
+        }
     }
     return true;
 }