log_buffer.h

Go to the documentation of this file.

#ifndef SENSESP_SRC_SENSESP_SYSTEM_LOG_BUFFER_H_
#define SENSESP_SRC_SENSESP_SYSTEM_LOG_BUFFER_H_
 
#include <freertos/FreeRTOS.h>
#include <freertos/queue.h>
#include <freertos/semphr.h>
#include <freertos/task.h>
 
#include <cstdarg>
#include <cstdint>
#include <deque>
#include <string>
#include <vector>
 
namespace sensesp {
 
struct LogRecord {
  uint32_t seq;
  uint32_t timestamp_ms;
  std::string text;
};
 
inline constexpr size_t kLogCaptureLineMax = 256;
inline constexpr size_t kLogCaptureQueueDepth = 8;
inline constexpr uint32_t kLogCaptureTaskStackSize = 3072;
inline constexpr UBaseType_t kLogCaptureTaskPriority = 1;
inline constexpr size_t kLogCaptureMinHeadroomBytes = 8192;
 
struct LogQueueItem {
  uint32_t timestamp_ms;
  uint16_t length;
  char text[kLogCaptureLineMax];
};
 
struct LogSnapshot {
  uint32_t session_id;
  uint32_t next;
  bool gap;
  std::vector<std::string> lines;
};
 
class LogBuffer {
 public:
  // max_line_length defaults to kLogCaptureLineMax to match the capture buffer
  // in vprintf_trampoline(); a larger value cannot recover more than that
  // buffer already captured.
  explicit LogBuffer(size_t max_lines = 100, uint32_t max_age_ms = 2000,
                     size_t max_line_length = kLogCaptureLineMax,
                     size_t min_headroom_bytes = kLogCaptureMinHeadroomBytes);
 
  void install();
 
  void push_line(const char* text, size_t length, uint32_t now_ms);
 
  LogSnapshot snapshot_since(uint32_t since, bool has_since, uint32_t now_ms);
  LogSnapshot snapshot_since(uint32_t since, bool has_since);
 
  uint32_t session_id() const { return session_id_; }
 
  size_t size();
 
  static LogBuffer* instance() { return instance_; }
 
 private:
  static int vprintf_trampoline(const char* format, va_list args);
 
  static void capture_task(void* arg);
 
  void enqueue_capture(LogQueueItem& item, int n);
 
  void prune_locked(uint32_t now_ms);
 
  size_t max_lines_;
  uint32_t max_age_ms_;
  size_t max_line_length_;
  size_t min_headroom_bytes_;
 
  std::deque<LogRecord> records_;
  uint32_t next_seq_ = 0;
  uint32_t session_id_;
 
  int (*previous_vprintf_)(const char*, va_list) = nullptr;
 
  // The capture task is created once in install() and runs for the process
  // lifetime (never torn down), so its handle is not retained.
  QueueHandle_t capture_queue_ = nullptr;
 
  SemaphoreHandle_t mutex_;
  StaticSemaphore_t mutex_buffer_;
 
  static LogBuffer* instance_;
};
 
}  // namespace sensesp
 
#endif  // SENSESP_SRC_SENSESP_SYSTEM_LOG_BUFFER_H_