TCPClient.hpp

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#ifndef DAQ_TCP_CLIENT_HPP
#define DAQ_TCP_CLIENT_HPP
 
#include <fcntl.h>
#include <sys/socket.h>
#include <unistd.h>
 
#include <cstdint>
#include <memory>
#include <mutex>
#include <string>
#include <vector>
 
namespace daq_comms {
namespace transport {
 
/**
 * @brief Simple TCP client for Elodin database connection
 *
 * Standalone implementation without FSW dependencies.
 */
class TCPClient {
public:
    TCPClient();
    ~TCPClient();
 
    /**
     * @brief Connect to TCP server
     * @param host Server hostname or IP address
     * @param port Server port
     * @return true if connection successful, false otherwise
     */
    bool connect(const std::string& host, uint16_t port);
 
    /**
     * @brief Disconnect from server
     */
    void disconnect();
 
    /**
     * @brief Check if connected
     */
    bool is_connected() const;
 
    /**
     * @brief Write data directly (for VTable registration)
     * @param data Data to write
     * @param len Length of data
     * @return true if successful
     */
    bool write_all(const void* data, size_t len);
 
    /**
     * @brief Write data with buffering (for data publishing)
     * @param data Data to write
     * @param len Length of data
     * @return true if successful
     */
    bool write_buffered(const void* data, size_t len);
 
    /**
     * @brief Flush buffered data
     */
    void flush();
 
    /**
     * @brief Read data from socket (non-blocking)
     * @param buffer Buffer to read into
     * @param max_len Maximum bytes to read
     * @return Number of bytes read, 0 if no data available, -1 on error
     */
    ssize_t read(void* buffer, size_t max_len);
 
    /**
     * @brief Read exactly len bytes (blocking)
     * @param buffer Buffer to read into
     * @param len Exact number of bytes to read
     * @return true if successful, false on error
     */
    bool read_exact(void* buffer, size_t len);
 
    /**
     * @brief Get last error message
     */
    std::string last_error() const;
 
    /**
     * @brief Set socket receive timeout (0 = blocking)
     * @param timeout_ms Receive timeout in milliseconds
     */
    void set_recv_timeout_ms(int timeout_ms);
 
private:
    int socket_fd_;
    bool connected_;
    std::string last_error_;
 
    // Buffering for efficient writes
    static constexpr size_t BUFFER_SIZE = 8192;
    std::vector<uint8_t> write_buffer_;
    size_t buffer_pos_;
    std::mutex write_mutex_;
 
    bool _write_all(const void* data, size_t len);
    void _flush_buffer();
};
 
}  // namespace transport
}  // namespace daq_comms
 
#endif  // DAQ_TCP_CLIENT_HPP