Separate Index class to track streams via intrusive list

index.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "stream.h"
+
+namespace firesse {
+
+// Track live streams
+class Index {
+  public:
+	void Add(Stream* stream);
+	void Remove(Stream* stream);
+
+  private:
+	std::mutex mu_;
+	Stream* freshest_ = nullptr;
+	Stream* stalest_ = nullptr;
+};
+
+} // namespace firesse