task_log_buffer_host.h

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#pragma once
 
#ifdef USE_HOST
 
#include "esphome/core/defines.h"
#include "esphome/core/helpers.h"
 
#ifdef USE_ESPHOME_TASK_LOG_BUFFER
 
#include <atomic>
#include <cstdarg>
#include <cstddef>
#include <cstring>
#include <pthread.h>
 
namespace esphome::logger {
 
class TaskLogBuffer {
 public:
  // Structure for a log message (fixed size for lock-free operation)
  struct LogMessage {
    // Size constants
    static constexpr size_t MAX_THREAD_NAME_SIZE = 32;
    static constexpr size_t MAX_TEXT_SIZE = 512;
 
    const char *tag;                         // Pointer to static tag string
    char thread_name[MAX_THREAD_NAME_SIZE];  // Thread name (copied)
    char text[MAX_TEXT_SIZE + 1];            // Message text with null terminator
    uint16_t text_length;                    // Actual length of text
    uint16_t line;                           // Source line number
    uint8_t level;                           // Log level
    std::atomic<bool> ready;                 // Message is ready to be consumed
 
    LogMessage() : tag(nullptr), text_length(0), line(0), level(0), ready(false) {
      thread_name[0] = '\0';
      text[0] = '\0';
    }
    inline char *text_data() { return this->text; }
  };
 
  TaskLogBuffer() = default;
 
  // NOT thread-safe - get next message from buffer, only call from main loop
  // Returns true if a message was retrieved, false if buffer is empty
  bool borrow_message_main_loop(LogMessage *&message, uint16_t &text_length);
 
  // NOT thread-safe - release the message after processing, only call from main loop
  void release_message_main_loop();
 
  // Thread-safe - send a message to the buffer from any thread
  // Returns true if message was queued, false if buffer is full
  bool send_message_thread_safe(uint8_t level, const char *tag, uint16_t line, const char *thread_name,
                                const char *format, va_list args);
 
  // Check if there are messages ready to be processed
  inline bool HOT has_messages() const {
    return read_index_.load(std::memory_order_acquire) != write_index_.load(std::memory_order_acquire);
  }
 
  // Get the buffer size (number of slots)
  static constexpr size_t size() { return ESPHOME_TASK_LOG_BUFFER_SIZE; }
 
 private:
  // Acquire a slot for writing (thread-safe)
  // Returns slot index or -1 if buffer is full
  int acquire_write_slot_();
 
  // Commit a slot after writing (thread-safe)
  void commit_write_slot_(int slot_index);
 
  LogMessage slots_[ESPHOME_TASK_LOG_BUFFER_SIZE];  // Embedded in Logger (no separate heap allocation)
 
  // Lock-free indices using atomics
  // - reserve_index_: Next slot to reserve (producers CAS this to claim slots)
  // - write_index_: Boundary of committed/ready slots (consumer reads up to this)
  // - read_index_: Next slot to read (only consumer modifies this)
  std::atomic<size_t> reserve_index_{0};  // Next slot to reserve for writing
  std::atomic<size_t> write_index_{0};    // Last committed slot boundary
  std::atomic<size_t> read_index_{0};     // Next slot to read from
};
 
}  // namespace esphome::logger
 
#endif  // USE_ESPHOME_TASK_LOG_BUFFER
#endif  // USE_HOST