signalk_delta_queue.h

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#ifndef SENSESP_SIGNALK_DELTA_QUEUE_H_
#define SENSESP_SIGNALK_DELTA_QUEUE_H_
 
#include <ArduinoJson.h>
#include <list>
 
namespace sensesp {
 
class SKDeltaQueue {
 public:
  SKDeltaQueue(unsigned int max_buffer_size = 20);
  void append(const String& val);
  bool data_available();
  void get_delta(String& output);
 
  void connect_emitters();
 
  void reset_meta_send() {
    take_semaphore();
    this->meta_sent_ = false;
    release_semaphore();
  }
 
  bool take_semaphore(uint64_t timeout_ms = 0);
  void release_semaphore();
 
 private:
  unsigned int max_buffer_size;
  std::list<String> buffer{};
  bool meta_sent_;
 
  unsigned int get_doc_size_estimate();
  unsigned int get_metadata_size_estimate();
 
  std::size_t get_buffer_size() {
    std::size_t size;
    take_semaphore();
    size = buffer.size();
    release_semaphore();
    return size;
  }
 
  // Adds Signal K meta data to the specified document
  void add_metadata(JsonArray updates);
 
  SemaphoreHandle_t semaphore_ = NULL;
};
 
}  // namespace sensesp
 
#endif