[ntcore] Unify listeners (#4536)

This combines all 4 NT listener APIs (topic, value, connection, and
logging) into a single unified listener API.

ntcore/src/main/native/cpp/LoggerImpl.h

@@ -4,34 +4,29 @@
 
 #pragma once
 
-#include <utility>
+#include <atomic>
 #include <vector>
 
-#include <wpi/SafeThread.h>
-#include <wpi/Synchronization.h>
 #include <wpi/mutex.h>
 
-#include "Handle.h"
-#include "HandleMap.h"
+#include "IListenerStorage.h"
 #include "ntcore_c.h"
 #include "ntcore_cpp.h"
 
 namespace nt {
 
+class IListenerStorage;
+
 class LoggerImpl {
  public:
-  explicit LoggerImpl(int inst);
+  explicit LoggerImpl(IListenerStorage& listenerStorage);
+  LoggerImpl(const LoggerImpl&) = delete;
+  LoggerImpl& operator=(const LoggerImpl&) = delete;
   ~LoggerImpl();
 
-  NT_Logger Add(std::function<void(const LogMessage& msg)> callback,
-                unsigned int minLevel, unsigned int maxLevel);
-
-  NT_LoggerPoller CreatePoller();
-  void DestroyPoller(NT_LoggerPoller pollerHandle);
-  NT_Logger AddPolled(NT_LoggerPoller pollerHandle, unsigned int minLevel,
-                      unsigned int maxLevel);
-  std::vector<LogMessage> ReadQueue(NT_LoggerPoller pollerHandle);
-  void Remove(NT_Logger listenerHandle);
+  void AddListener(NT_Listener listener, unsigned int minLevel,
+                   unsigned int maxLevel);
+  void RemoveListener(NT_Listener listener);
 
   unsigned int GetMinLevel();
 
@@ -39,38 +34,20 @@ class LoggerImpl {
            const char* msg);
 
  private:
-  int m_inst;
-  mutable wpi::mutex m_mutex;
+  IListenerStorage& m_listenerStorage;
+  std::atomic_int m_listenerCount{0};
+  wpi::mutex m_mutex;
 
-  struct PollerData {
-    static constexpr auto kType = Handle::kLoggerPoller;
+  struct ListenerLevels {
+    ListenerLevels(NT_Listener listener, unsigned int minLevel,
+                   unsigned int maxLevel)
+        : listener{listener}, minLevel{minLevel}, maxLevel{maxLevel} {}
 
-    explicit PollerData(NT_LoggerPoller handle) : handle{handle} {}
-
-    wpi::SignalObject<NT_LoggerPoller> handle;
-    std::vector<LogMessage> queue;
-  };
-  HandleMap<PollerData, 8> m_pollers;
-
-  struct ListenerData {
-    static constexpr auto kType = Handle::kLogger;
-
-    ListenerData(NT_Logger handle, PollerData* poller, unsigned int minLevel,
-                 unsigned int maxLevel)
-        : handle{handle},
-          poller{poller},
-          minLevel{minLevel},
-          maxLevel{maxLevel} {}
-
-    wpi::SignalObject<NT_Logger> handle;
-    PollerData* poller;
+    NT_Listener listener;
     unsigned int minLevel;
     unsigned int maxLevel;
   };
-  HandleMap<ListenerData, 8> m_listeners;
-
-  class Thread;
-  wpi::SafeThreadOwner<Thread> m_thread;
+  std::vector<ListenerLevels> m_listenerLevels;
 };
 
 }  // namespace nt