cscore: Add Shutdown() function

This allows ordered shutdown / destruction of sources and sinks prior to
global singleton destruction.

cscore/src/main/native/cpp/Instance.cpp

@@ -45,8 +45,17 @@ Instance::Instance() : telemetry(notifier), networkListener(logger, notifier) {
 Instance::~Instance() {}
 
 Instance& Instance::GetInstance() {
-  static Instance inst;
-  return inst;
+  static Instance* inst = new Instance;
+  return *inst;
+}
+
+void Instance::Shutdown() {
+  eventLoop.Stop();
+  m_sinks.FreeAll();
+  m_sources.FreeAll();
+  networkListener.Stop();
+  telemetry.Stop();
+  notifier.Stop();
 }
 
 void Instance::SetDefaultLogger() { logger.SetLogger(def_log_func); }

cscore/src/main/native/cpp/Instance.h

@@ -51,6 +51,8 @@ class Instance {
 
   static Instance& GetInstance();
 
+  void Shutdown();
+
   wpi::Logger logger;
   Notifier notifier;
   Telemetry telemetry;

cscore/src/main/native/cpp/cscore_c.cpp

@@ -348,6 +348,8 @@ void CS_SetDefaultLogger(unsigned int min_level) {
   cs::SetDefaultLogger(min_level);
 }
 
+void CS_Shutdown(void) { cs::Shutdown(); }
+
 CS_Source* CS_EnumerateSources(int* count, CS_Status* status) {
   wpi::SmallVector<CS_Source, 32> buf;
   auto handles = cs::EnumerateSourceHandles(buf, status);

cscore/src/main/native/cpp/cscore_cpp.cpp

@@ -665,6 +665,11 @@ void SetDefaultLogger(unsigned int min_level) {
   inst.logger.set_min_level(min_level);
 }
 
+//
+// Shutdown Function
+//
+void Shutdown() { Instance::GetInstance().Shutdown(); }
+
 //
 // Utility Functions
 //

cscore/src/main/native/cpp/jni/CameraServerJNI.cpp

@@ -87,6 +87,8 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved) {
 }
 
 JNIEXPORT void JNICALL JNI_OnUnload(JavaVM* vm, void* reserved) {
+  cs::Shutdown();
+
   JNIEnv* env;
   if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK)
     return;

cscore/src/main/native/include/cscore_c.h

@@ -440,6 +440,13 @@ void CS_SetLogger(CS_LogFunc func, unsigned int min_level);
 void CS_SetDefaultLogger(unsigned int min_level);
 /** @} */
 
+/**
+ * @defgroup cscore_shutdown_cfunc Library Shutdown Function
+ * @{
+ */
+void CS_Shutdown(void);
+/** @} */
+
 /**
  * @defgroup cscore_utility_cfunc Utility Functions
  * @{

cscore/src/main/native/include/cscore_cpp.h

@@ -377,6 +377,13 @@ void SetLogger(LogFunc func, unsigned int min_level);
 void SetDefaultLogger(unsigned int min_level);
 /** @} */
 
+/**
+ * @defgroup cscore_shutdown_func Library Shutdown Function
+ * @{
+ */
+void Shutdown();
+/** @} */
+
 /**
  * @defgroup cscore_utility_func Utility Functions
  * @{