cscore: Change impl to only one singleton (#1398)

This avoids a number of shutdown use-after-free races by controlling the
destruction order.  It also is a prerequisite to making the internal
interfaces mockable for unit testing.

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

@@ -0,0 +1,75 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#ifndef CSCORE_INSTANCE_H_
+#define CSCORE_INSTANCE_H_
+
+#include <memory>
+#include <utility>
+
+#include <wpi/EventLoopRunner.h>
+#include <wpi/Logger.h>
+
+#include "Log.h"
+#include "NetworkListener.h"
+#include "Notifier.h"
+#include "SinkImpl.h"
+#include "SourceImpl.h"
+#include "Telemetry.h"
+#include "UnlimitedHandleResource.h"
+
+namespace cs {
+
+struct SourceData {
+  SourceData(CS_SourceKind kind_, std::shared_ptr<SourceImpl> source_)
+      : kind{kind_}, refCount{0}, source{source_} {}
+
+  CS_SourceKind kind;
+  std::atomic_int refCount;
+  std::shared_ptr<SourceImpl> source;
+};
+
+struct SinkData {
+  explicit SinkData(CS_SinkKind kind_, std::shared_ptr<SinkImpl> sink_)
+      : kind{kind_}, refCount{0}, sourceHandle{0}, sink{sink_} {}
+
+  CS_SinkKind kind;
+  std::atomic_int refCount;
+  std::atomic<CS_Source> sourceHandle;
+  std::shared_ptr<SinkImpl> sink;
+};
+
+class Instance {
+ public:
+  Instance(const Instance&) = delete;
+  Instance& operator=(const Instance&) = delete;
+  ~Instance();
+
+  static Instance& GetInstance();
+
+  UnlimitedHandleResource<Handle, SourceData, Handle::kSource> sources;
+  UnlimitedHandleResource<Handle, SinkData, Handle::kSink> sinks;
+
+  wpi::Logger logger;
+  Notifier notifier;
+  Telemetry telemetry;
+  NetworkListener network_listener;
+  wpi::EventLoopRunner event_loop;
+
+  std::pair<CS_Sink, std::shared_ptr<SinkData>> FindSink(const SinkImpl& sink);
+  std::pair<CS_Source, std::shared_ptr<SourceData>> FindSource(
+      const SourceImpl& source);
+
+  void SetDefaultLogger();
+
+ private:
+  Instance();
+};
+
+}  // namespace cs
+
+#endif  // CSCORE_INSTANCE_H_