Wayfinder/lidar_reader_V2.py

# lidar_reader.py (Modified Again)

import time
import subprocess
import signal
from logger import get_logger
import math # Import math for float('nan') if preferred

logger = get_logger("lidar_reader")

# Define a constant for invalid/filtered readings
INVALID_READING_VALUE = -1.0 # Or use float('nan') if your processing logic handles it

class LidarReader:
    def __init__(self, device='/dev/lidar', baud='256000'):
        logger.info(f"Initializing LIDAR on device {device} with baud rate {baud}")
        # Note: self.scan is now primarily managed within get_scan
        self.proc = None
        self.running = True

        try:
            self.proc = subprocess.Popen(
                [
                    '/home/poebot/RPLidar/libs/rplidar_sdk/output/Linux/Release/ultra_simple',
                    '--channel', '--serial', device, baud
                ],
                stdout=subprocess.PIPE,
                stderr=subprocess.STDOUT, # Consider PIPE stderr too for logging errors
                universal_newlines=True,
                bufsize=1 # Line buffering
            )
            logger.info("✅ LIDAR subprocess started successfully.")
        except Exception as e:
            logger.error(f"❌ Failed to start LIDAR subprocess: {e}")
            self.running = False # Ensure running flag is false if Popen fails
            raise

        # Give the LIDAR process a moment to start up fully
        logger.debug("🌀 Letting LIDAR warm up for 1 second...")
        time.sleep(1.0) # Keep the warmup delay

    def get_scan(self, timeout=2.0):
        """
        Attempts to read a full 360-degree scan from the LIDAR subprocess.

        Args:
            timeout (float): Maximum time in seconds to wait for a full scan.

        Returns:
            tuple: (list[float], list[int]) containing the scan data and angles (0-359)
                   if a full scan is received within the timeout. Returns (None, None)
                   if a timeout occurs or the process stops.
            list[float]: Scan data where each index corresponds to the angle.
                         INVALID_READING_VALUE indicates a filtered or missing reading.
            list[int]: List of angles [0, 1, ..., 359].
        """
        if not self.running or self.proc is None or self.proc.poll() is not None:
            logger.warning("⚠️ Attempted to get scan but LIDAR process is not running.")
            return None, None

        # Initialize scan list with the invalid value placeholder for this attempt
        current_scan = [INVALID_READING_VALUE] * 360
        angles_received_this_scan = set()
        start_time = time.time()

        while time.time() - start_time < timeout:
            # Check if the process terminated unexpectedly
            if self.proc.poll() is not None:
                logger.error("❌ LIDAR subprocess terminated unexpectedly.")
                self.running = False
                return None, None

            line = self.proc.stdout.readline()
            if not line:
                # No output ready, small sleep to prevent busy-waiting 100% CPU
                # Adjust sleep time based on expected data rate vs CPU usage.
                time.sleep(0.001)
                continue

            line = line.strip()
            if ',' not in line:
                # logger.debug(f"Skipping line without comma: {line}") # Optional debug
                continue

            try:
                angle_str, distance_str = line.split(',')
                angle = float(angle_str)
                distance = float(distance_str)

                # Convert angle to integer index (0-359)
                # Consider rounding instead of truncating if angles are slightly off
                i = int(round(angle)) % 360 # Use round() and modulo for robustness

                # Apply distance filter
                if 100 < distance < 6000:
                    current_scan[i] = distance # Store as float for consistency
                else:
                    # Already initialized to INVALID_READING_VALUE, but explicit is fine
                    current_scan[i] = INVALID_READING_VALUE

                angles_received_this_scan.add(i)

                # Check if we have potentially received a full scan
                # --- THIS IS THE MODIFIED LINE ---
                # Changed >= 360 to >= 359
                if len(angles_received_this_scan) >= 359:
                    # logger.debug(f"✅ Scan received ({len(angles_received_this_scan)} angles) in {time.time() - start_time:.3f}s") # Optional debug
                    return current_scan, list(range(360))

            except ValueError:
                # logger.debug(f"Skipping malformed line (ValueError): {line}") # Optional debug
                continue
            except Exception as e:
                 logger.error(f"Unexpected error processing line '{line}': {e}")
                 continue


        # --- Timeout occurred ---
        logger.warning(f"⏳ Scan timeout after {timeout:.1f}s, received {len(angles_received_this_scan)}/360 angles.")
        # Return None to indicate failure to get a full scan
        return None, None

    def stop(self):
        logger.info("🛑 Stopping LIDAR...")
        self.running = False # Signal get_scan loop to stop trying

        if self.proc and self.proc.poll() is None: # Check if process exists and is running
            try:
                # Try interrupting gracefully first
                self.proc.send_signal(signal.SIGINT)
                self.proc.wait(timeout=3.0) # Wait 3 seconds
                logger.info("✅ LIDAR subprocess terminated successfully.")
            except subprocess.TimeoutExpired:
                logger.warning("⚠️ LIDAR subprocess did not exit via SIGINT, killing...")
                self.proc.kill() # Force kill if it didn't respond
                try:
                    # Wait a moment after kill to ensure it's gone
                    self.proc.wait(timeout=1.0)
                except subprocess.TimeoutExpired:
                    logger.error("❌ Failed to confirm LIDAR subprocess killed.")
                logger.warning("⚠️ LIDAR subprocess killed due to timeout.")
            except Exception as e:
                 logger.error(f"Error during LIDAR stop: {e}")
        else:
            logger.info("✅ LIDAR subprocess already stopped or never started.")
        logger.info("✅ LIDAR stopped.")