Module debug 

Unified debug logging system Unified Debug Logging System for Azul

This module provides a thread-safe debug logging infrastructure that can be passed through function arguments to collect debug messages during execution.

Design Philosophy

1. No global state for logging - All logging goes through explicit parameters
2. Zero-cost when disabled - Option<&mut DebugLogger> is None in production
3. Structured messages - Each message has level, category, and location
4. Thread-safe collection - Can collect messages from multiple threads

Usage Pattern

Functions that need debug logging accept debug_log: &mut Option<DebugLogger>:

fn do_layout(
    dom: &Dom,
    // ... other params ...
    debug_log: &mut Option<DebugLogger>,
) {
    log_debug!(debug_log, Layout, "Starting layout for {} nodes", dom.len());
    // ... do work ...
}

Integration with HTTP Debug Server

When AZUL_DEBUG is set, the debug server creates a DebugLogger for each incoming request, which collects all messages until the frame is rendered, then returns them in the HTTP response.

Structs

DebugLogger

Debug logger that collects messages during execution.

LogMessage

A structured log message for the debug logger

Enums

DebugCategory

Categories for debug messages to enable filtering

DebugLevel

Debug message severity level

Functions

debug_log

Helper function to conditionally log (when logger is Some)

get_debug_port

Get the debug server port from environment variable

is_debug_enabled

Check if debug mode is enabled via environment variable

Type Aliases

DebugLog

Type alias for the debug logger parameter pattern used throughout the codebase