Verification and Correction of Renderer Logs

Summary

Implemented diagnostic logs at the start of `render_frame()` to verify that it runs correctly, verified and corrected logging system configuration, verified that output redirection captures all logs (stdout and stderr), and added log condition checks. The logs now appear correctly in the generated log files, confirming that the renderer is running and that the framebuffer-display matching logs from Step 0343 are also working correctly.

Hardware Concept

Logging System in Python:Python's logging system allows you to log events during the execution of a program. The `logging` module provides different log levels (DEBUG, INFO, WARNING, ERROR, CRITICAL) and different handlers (StreamHandler, FileHandler, etc.) to direct the logs to different destinations (console, file, etc.).

Output Redirection:On Unix/Linux systems, it is possible to redirect standard output (stdout) and error output (stderr) to files or other processes. The `2>&1` command redirects stderr to stdout, and `tee` duplicates the output to both a file and the console. This is useful for capturing all logs (both from `logger` and `print()`) to a file while still displaying them in the console.

Logger Configuration:A logger can inherit its configuration from the root logger or have its own configuration. If a logger does not have a configured level (NOTSET), it inherits the level of the parent logger. If it does not have handlers, the logs are propagated to the parent logger. To ensure that logs appear, it is important to explicitly configure the level and add handlers if necessary.

Implementation

Four main improvements were implemented to the renderer logging system:

1. Diagnostic Logs at Startup of render_frame()

Added logs immediately at the start of `render_frame()` that verify that the method is executed correctly. Logs use both `logger.info()` and `print()` to ensure they appear even if there are problems with the logger configuration. They are also sent to stderr as an additional fallback.

# --- Step 0346: Diagnostic Logs at Startup of render_frame() ---
if not hasattr(self, '_render_frame_entry_debug_count'):
    self._render_frame_entry_debug_count = 0

self._render_frame_entry_debug_count += 1

debug_msg = (f"[Renderer-Frame-Entry] Frame {self._render_frame_entry_debug_count} | "
            f"render_frame() executed | framebuffer_data is None: {framebuffer_data is None}")

logger.info(debug_msg)
print(debug_msg)
print(debug_msg, file=sys.stderr)
# -------------------------------------------

2. Logger Verification and Configuration

Added code to the start of the `renderer.py` module that verifies that the logger is configured correctly. If the logger does not have a level configured (NOTSET), it is explicitly set to INFO. If you don't have handlers, a basic StreamHandler is added.

# --- Step 0346: Logger Verification and Configuration ---
if logger.level == logging.NOTSET:
    logger.setLevel(logging.INFO)

if not logger.handlers:
    handler = logging.StreamHandler()
    handler.setLevel(logging.INFO)
    formatter = logging.Formatter('%(message)s')
    handler.setFormatter(formatter)
    logger.addHandler(handler)
# -------------------------------------------

3. Output Redirection Verification

Added test logs to the start of `run()` in `viboy.py` that verify that output redirection is working correctly. Logs are sent to both stdout and stderr to ensure that both streams are captured.

# --- Step 0346: Output Redirection Verification ---
test_msg = "[Viboy-Output-Test] Verifying output redirection"
logger.info(test_msg)
print(test_msg)
print(test_msg, file=sys.stderr)
# -------------------------------------------

4. Verification of Log Conditions

Added checks after getting `frame_indices` that verify the variable is available before using it in diagnostic blocks. This helps identify if the logs are not appearing because the conditions are not met.

# --- Step 0346: Verification of Log Conditions ---
if 'frame_indices' not in locals():
    logger.warning("[Renderer-Conditions] frame_indices is not defined")
elif frame_indices is None:
    logger.warning("[Renderer-Conditions] frame_indices is None")
elif len(frame_indices) == 0:
    logger.warning(f"[Renderer-Conditions] frame_indices is empty (length=0)")
else:
    logger.info(f"[Renderer-Conditions] available frame_indices: length={len(frame_indices)}")
# -------------------------------------------

Design Decisions

• Multiple logging methods:Both `logger.info()` and `print()` are used to ensure that logs appear even if there are problems with the logger configuration. This is especially important for critical diagnostic logs.
• Logs to stderr:Logs are also sent to stderr as an additional fallback, since some systems may redirect stdout and stderr differently.
• Explicit logger configuration:You explicitly configure the logger in the module to ensure that it works correctly regardless of how the root logger is configured.
• Condition verification:Conditions are checked before running diagnostic blocks to identify problems early.

Affected Files

• src/gpu/renderer.py- Added diagnostic logs to the start of `render_frame()`, logger verification and configuration, and log condition verification
• src/viboy.py- Added output redirection check logs to the start of `run()`
• logs/test_tetris_step0346_quick.log- Log file generated during testing

Tests and Verification

A quick test (30 seconds) was run with Tetris to verify that the logs appear correctly:

• Command executed: timeout 30 python3 main.py roms/tetris.gb 2>&1 | tee logs/test_tetris_step0346_quick.log
• Result:All logs appear correctly in the log file
• Verified logs:
  • ✅ [Renderer-Logger-Config]- Appears at the beginning of the program
  • ✅ [Viboy-Output-Test]- Appears at the beginning of the program
  • ✅ [Renderer-Frame-Entry]- Appears in every frame
  • ✅ [Renderer-Conditions]- Appears when frame_indices is available
  • ✅ [Renderer-Framebuffer-Size]- Appears in the first frames
  • ✅ [Renderer-Pixel-Order-Verification]- Appears in the first frames
  • ✅ [Renderer-Framebuffer-Visualization-Correspondence]- Appears in the first frames (from Step 0343)

Compiled C++ module validation:The logs confirm that the renderer is running correctly and that the framebuffer is the correct size (23040 pixels = 160x144).

Sources consulted

• Python Documentation:logging — Logging facility for Python
• Python Documentation:sys.stdout, sys.stderr

Educational Integrity

Next Steps

• [ ] Analyze the generated framebuffer-display correspondence logs to identify display problems
• [ ] If problems are identified, implement corrections based on the findings
• [ ] Verify that the display matches the framebuffer on different ROMs