Controller: create templated downcastAndTakeOwnership method

mixxxdj · Feb 17, 2021 · 4efdeb5 · 4efdeb5
1 parent fd670fe
commit 4efdeb5
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Showing 4 changed files with 20 additions and 24 deletions.
diff --git a/src/controllers/bulk/bulkcontroller.cpp b/src/controllers/bulk/bulkcontroller.cpp
@@ -99,14 +99,7 @@ QString BulkController::mappingExtension() {
 }
 
 void BulkController::setMapping(std::shared_ptr<LegacyControllerMapping> pMapping) {
-    VERIFY_OR_DEBUG_ASSERT(pMapping.use_count() == 1) {
-        return;
-    }
-    auto pDowncastedMapping = std::dynamic_pointer_cast<LegacyHidControllerMapping>(pMapping);
-    VERIFY_OR_DEBUG_ASSERT(pDowncastedMapping) {
-        return;
-    }
-    m_pMapping = pDowncastedMapping;
+    m_pMapping = downcastAndTakeOwnership<LegacyHidControllerMapping>(std::move(pMapping));
 }
 
 std::shared_ptr<LegacyControllerMapping> BulkController::cloneMapping() {

diff --git a/src/controllers/controller.h b/src/controllers/controller.h
@@ -79,6 +79,23 @@ class Controller : public QObject {
     void stopLearning();
 
   protected:
+    template<typename SpecificMappingType>
+    std::shared_ptr<SpecificMappingType> downcastAndTakeOwnership(
+            std::shared_ptr<LegacyControllerMapping>&& pMapping) {
+        // Controller cannot take ownership if pMapping is referenced elsewhere because
+        // the controller polling thread needs exclusive accesses to the non-thread safe
+        // LegacyControllerMapping.
+        // Trying to cast a std::shared_ptr to a std::unique_ptr is not worth the trouble.
+        VERIFY_OR_DEBUG_ASSERT(pMapping.use_count() == 1) {
+            return nullptr;
+        }
+        auto pDowncastedMapping = std::dynamic_pointer_cast<SpecificMappingType>(pMapping);
+        VERIFY_OR_DEBUG_ASSERT(pDowncastedMapping) {
+            return nullptr;
+        }
+        return pDowncastedMapping;
+    }
+
     // The length parameter is here for backwards compatibility for when scripts
     // were required to specify it.
     virtual void send(const QList<int>& data, unsigned int length = 0);

diff --git a/src/controllers/hid/hidcontroller.cpp b/src/controllers/hid/hidcontroller.cpp
@@ -39,14 +39,7 @@ QString HidController::mappingExtension() {
 }
 
 void HidController::setMapping(std::shared_ptr<LegacyControllerMapping> pMapping) {
-    VERIFY_OR_DEBUG_ASSERT(pMapping.use_count() == 1) {
-        return;
-    }
-    auto pDowncastedMapping = std::dynamic_pointer_cast<LegacyHidControllerMapping>(pMapping);
-    VERIFY_OR_DEBUG_ASSERT(pDowncastedMapping) {
-        return;
-    }
-    m_pMapping = pDowncastedMapping;
+    m_pMapping = downcastAndTakeOwnership<LegacyHidControllerMapping>(std::move(pMapping));
 }
 
 std::shared_ptr<LegacyControllerMapping> HidController::cloneMapping() {

diff --git a/src/controllers/midi/midicontroller.cpp b/src/controllers/midi/midicontroller.cpp
@@ -31,14 +31,7 @@ QString MidiController::mappingExtension() {
 }
 
 void MidiController::setMapping(std::shared_ptr<LegacyControllerMapping> pMapping) {
-    VERIFY_OR_DEBUG_ASSERT(pMapping.use_count() == 1) {
-        return;
-    }
-    auto pDowncastedMapping = std::dynamic_pointer_cast<LegacyMidiControllerMapping>(pMapping);
-    VERIFY_OR_DEBUG_ASSERT(pDowncastedMapping) {
-        return;
-    }
-    m_pMapping = pDowncastedMapping;
+    m_pMapping = downcastAndTakeOwnership<LegacyMidiControllerMapping>(std::move(pMapping));
 }
 
 std::shared_ptr<LegacyControllerMapping> MidiController::cloneMapping() {