firesse/index.h

#pragma once

#include "stream.h"

namespace firesse {

// Track live streams
// O(1) for Add(), Remove(), and Freshen()
// Manages this by only supporting insertion of the freshest element,
// and by requiring an iterator for removal.
// Avoids allocation and folds in iterators by using an intrusive list
// inside Stream.
class Index {
  public:
	void Add(Stream* stream);
	void Remove(Stream* stream);
	void Freshen(Stream* stream);

	// Returns time to sleep until next stalest, or min_stale if none
	// Only calls callback if stalest is at least min_stale
	// Handles all locking and marks Stream as fresh after callback
	std::chrono::nanoseconds WithStalest(std::function<void(Stream*)> callback, const std::chrono::nanoseconds& min_stale);

  private:
	std::recursive_mutex mu_;
	Stream* freshest_ = nullptr;
	Stream* stalest_ = nullptr;
};

} // namespace firesse