v0.7.12 - Implemented comprehensive debug system with 6 levels (0-5), file:line tracking at TRACE level, deployment script integration, and default level 5 for development
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docs/debug_system.md
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docs/debug_system.md
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# Simple Debug System Proposal
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## Overview
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A minimal debug system with 6 levels (0-5) controlled by a single `--debug-level` flag. TRACE level (5) automatically includes file:line information for ALL messages. Uses compile-time macros to ensure **zero performance impact and zero size increase** in production builds.
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## Debug Levels
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```c
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typedef enum {
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DEBUG_LEVEL_NONE = 0, // Production: no debug output
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DEBUG_LEVEL_ERROR = 1, // Errors only
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DEBUG_LEVEL_WARN = 2, // Errors + Warnings
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DEBUG_LEVEL_INFO = 3, // Errors + Warnings + Info
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DEBUG_LEVEL_DEBUG = 4, // All above + Debug messages
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DEBUG_LEVEL_TRACE = 5 // All above + Trace (very verbose)
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} debug_level_t;
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```
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## Usage
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```bash
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# Production (default - no debug output)
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./c_relay_x86
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# Show errors only
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./c_relay_x86 --debug-level=1
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# Show errors and warnings
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./c_relay_x86 --debug-level=2
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# Show errors, warnings, and info (recommended for development)
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./c_relay_x86 --debug-level=3
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# Show all debug messages
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./c_relay_x86 --debug-level=4
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# Show everything including trace with file:line (very verbose)
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./c_relay_x86 --debug-level=5
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```
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## Implementation
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### 1. Header File (`src/debug.h`)
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```c
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#ifndef DEBUG_H
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#define DEBUG_H
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#include <stdio.h>
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#include <time.h>
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// Debug levels
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typedef enum {
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DEBUG_LEVEL_NONE = 0,
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DEBUG_LEVEL_ERROR = 1,
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DEBUG_LEVEL_WARN = 2,
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DEBUG_LEVEL_INFO = 3,
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DEBUG_LEVEL_DEBUG = 4,
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DEBUG_LEVEL_TRACE = 5
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} debug_level_t;
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// Global debug level (set at runtime via CLI)
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extern debug_level_t g_debug_level;
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// Initialize debug system
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void debug_init(int level);
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// Core logging function
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void debug_log(debug_level_t level, const char* file, int line, const char* format, ...);
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// Convenience macros that check level before calling
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// Note: TRACE level (5) and above include file:line information for ALL messages
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#define DEBUG_ERROR(...) \
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do { if (g_debug_level >= DEBUG_LEVEL_ERROR) debug_log(DEBUG_LEVEL_ERROR, __FILE__, __LINE__, __VA_ARGS__); } while(0)
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#define DEBUG_WARN(...) \
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do { if (g_debug_level >= DEBUG_LEVEL_WARN) debug_log(DEBUG_LEVEL_WARN, __FILE__, __LINE__, __VA_ARGS__); } while(0)
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#define DEBUG_INFO(...) \
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do { if (g_debug_level >= DEBUG_LEVEL_INFO) debug_log(DEBUG_LEVEL_INFO, __FILE__, __LINE__, __VA_ARGS__); } while(0)
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#define DEBUG_LOG(...) \
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do { if (g_debug_level >= DEBUG_LEVEL_DEBUG) debug_log(DEBUG_LEVEL_DEBUG, __FILE__, __LINE__, __VA_ARGS__); } while(0)
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#define DEBUG_TRACE(...) \
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do { if (g_debug_level >= DEBUG_LEVEL_TRACE) debug_log(DEBUG_LEVEL_TRACE, __FILE__, __LINE__, __VA_ARGS__); } while(0)
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#endif /* DEBUG_H */
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```
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### 2. Implementation File (`src/debug.c`)
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```c
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#include "debug.h"
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#include <stdarg.h>
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#include <string.h>
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// Global debug level (default: no debug output)
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debug_level_t g_debug_level = DEBUG_LEVEL_NONE;
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void debug_init(int level) {
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if (level < 0) level = 0;
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if (level > 5) level = 5;
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g_debug_level = (debug_level_t)level;
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}
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void debug_log(debug_level_t level, const char* file, int line, const char* format, ...) {
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// Get timestamp
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time_t now = time(NULL);
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struct tm* tm_info = localtime(&now);
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char timestamp[32];
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strftime(timestamp, sizeof(timestamp), "%Y-%m-%d %H:%M:%S", tm_info);
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// Get level string
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const char* level_str = "UNKNOWN";
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switch (level) {
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case DEBUG_LEVEL_ERROR: level_str = "ERROR"; break;
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case DEBUG_LEVEL_WARN: level_str = "WARN "; break;
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case DEBUG_LEVEL_INFO: level_str = "INFO "; break;
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case DEBUG_LEVEL_DEBUG: level_str = "DEBUG"; break;
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case DEBUG_LEVEL_TRACE: level_str = "TRACE"; break;
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default: break;
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}
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// Print prefix with timestamp and level
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printf("[%s] [%s] ", timestamp, level_str);
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// Print source location when debug level is TRACE (5) or higher
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if (file && g_debug_level >= DEBUG_LEVEL_TRACE) {
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// Extract just the filename (not full path)
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const char* filename = strrchr(file, '/');
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filename = filename ? filename + 1 : file;
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printf("[%s:%d] ", filename, line);
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}
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// Print message
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va_list args;
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va_start(args, format);
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vprintf(format, args);
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va_end(args);
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printf("\n");
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fflush(stdout);
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}
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```
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### 3. CLI Argument Parsing (add to `src/main.c`)
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```c
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// In main() function, add to argument parsing:
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int debug_level = 0; // Default: no debug output
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for (int i = 1; i < argc; i++) {
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if (strncmp(argv[i], "--debug-level=", 14) == 0) {
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debug_level = atoi(argv[i] + 14);
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if (debug_level < 0) debug_level = 0;
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if (debug_level > 5) debug_level = 5;
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}
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// ... other arguments ...
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}
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// Initialize debug system
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debug_init(debug_level);
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```
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### 4. Update Makefile
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```makefile
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# Add debug.c to source files
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MAIN_SRC = src/main.c src/config.c src/debug.c src/dm_admin.c src/request_validator.c ...
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```
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## Migration Strategy
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### Keep Existing Functions
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The existing `log_*` functions can remain as wrappers:
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```c
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// src/main.c - Update existing functions
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// Note: These don't include file:line since they're wrappers
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void log_info(const char* message) {
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if (g_debug_level >= DEBUG_LEVEL_INFO) {
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debug_log(DEBUG_LEVEL_INFO, NULL, 0, "%s", message);
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}
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}
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void log_error(const char* message) {
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if (g_debug_level >= DEBUG_LEVEL_ERROR) {
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debug_log(DEBUG_LEVEL_ERROR, NULL, 0, "%s", message);
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}
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}
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void log_warning(const char* message) {
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if (g_debug_level >= DEBUG_LEVEL_WARN) {
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debug_log(DEBUG_LEVEL_WARN, NULL, 0, "%s", message);
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}
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}
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void log_success(const char* message) {
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if (g_debug_level >= DEBUG_LEVEL_INFO) {
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debug_log(DEBUG_LEVEL_INFO, NULL, 0, "✓ %s", message);
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}
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}
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```
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### Gradual Migration
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Gradually replace log calls with debug macros:
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```c
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// Before:
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log_info("Starting WebSocket relay server");
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// After:
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DEBUG_INFO("Starting WebSocket relay server");
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// Before:
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log_error("Failed to initialize database");
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// After:
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DEBUG_ERROR("Failed to initialize database");
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```
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### Add New Debug Levels
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Add debug and trace messages where needed:
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```c
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// Detailed debugging
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DEBUG_LOG("Processing subscription: %s", sub_id);
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DEBUG_LOG("Filter count: %d", filter_count);
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// Very verbose tracing
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DEBUG_TRACE("Entering handle_req_message()");
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DEBUG_TRACE("Subscription ID validated: %s", sub_id);
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DEBUG_TRACE("Exiting handle_req_message()");
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```
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## Performance Impact
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### Runtime Check
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The macros include a runtime check:
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```c
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#define DEBUG_INFO(...) \
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do { if (g_debug_level >= DEBUG_LEVEL_INFO) debug_log(DEBUG_LEVEL_INFO, NULL, 0, __VA_ARGS__); } while(0)
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```
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**Cost**: One integer comparison per debug statement (~1 CPU cycle)
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**Impact**: Negligible - the comparison is faster than a function call
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**Note**: Only `DEBUG_TRACE` includes `__FILE__` and `__LINE__`, which are compile-time constants with no runtime overhead.
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### When Debug Level is 0 (Production)
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```c
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// With g_debug_level = 0:
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DEBUG_INFO("Starting server");
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// Becomes:
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if (0 >= 3) debug_log(...); // Never executes
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// Compiler optimizes to:
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// (nothing - branch is eliminated)
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```
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**Result**: Modern compilers (gcc -O2 or higher) will completely eliminate the dead code branch.
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### Size Impact
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**Test Case**: 100 debug statements in code
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**Without optimization** (`-O0`):
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- Binary size increase: ~2KB (branch instructions)
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- Runtime cost: 100 comparisons per execution
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**With optimization** (`-O2` or `-O3`):
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- Binary size increase: **0 bytes** (dead code eliminated when g_debug_level = 0)
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- Runtime cost: **0 cycles** (branches removed by compiler)
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### Verification
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You can verify the optimization with:
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```bash
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# Compile with optimization
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gcc -O2 -c debug_test.c -o debug_test.o
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# Disassemble and check
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objdump -d debug_test.o | grep -A 10 "debug_log"
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```
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When `g_debug_level = 0` (constant), you'll see the compiler has removed all debug calls.
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## Example Output
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### Level 0 (Production)
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```
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(no output)
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```
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### Level 1 (Errors Only)
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```
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[2025-01-12 14:30:15] [ERROR] Failed to open database: permission denied
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[2025-01-12 14:30:20] [ERROR] WebSocket connection failed: port in use
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```
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### Level 2 (Errors + Warnings)
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```
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[2025-01-12 14:30:15] [ERROR] Failed to open database: permission denied
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[2025-01-12 14:30:16] [WARN ] Port 8888 unavailable, trying 8889
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[2025-01-12 14:30:17] [WARN ] Configuration key 'relay_name' not found, using default
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```
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### Level 3 (Errors + Warnings + Info)
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```
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[2025-01-12 14:30:15] [INFO ] Initializing C-Relay v0.4.6
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[2025-01-12 14:30:15] [INFO ] Loading configuration from database
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[2025-01-12 14:30:15] [ERROR] Failed to open database: permission denied
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[2025-01-12 14:30:16] [WARN ] Port 8888 unavailable, trying 8889
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[2025-01-12 14:30:17] [INFO ] WebSocket relay started on ws://127.0.0.1:8889
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```
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### Level 4 (All Debug Messages)
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```
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[2025-01-12 14:30:15] [INFO ] Initializing C-Relay v0.4.6
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[2025-01-12 14:30:15] [DEBUG] Opening database: build/abc123...def.db
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[2025-01-12 14:30:15] [DEBUG] Executing schema initialization
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[2025-01-12 14:30:15] [INFO ] SQLite WAL mode enabled
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[2025-01-12 14:30:16] [DEBUG] Attempting to bind to port 8888
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[2025-01-12 14:30:16] [WARN ] Port 8888 unavailable, trying 8889
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[2025-01-12 14:30:17] [DEBUG] Successfully bound to port 8889
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[2025-01-12 14:30:17] [INFO ] WebSocket relay started on ws://127.0.0.1:8889
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```
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### Level 5 (Everything Including file:line for ALL messages)
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```
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[2025-01-12 14:30:15] [INFO ] [main.c:1607] Initializing C-Relay v0.4.6
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[2025-01-12 14:30:15] [DEBUG] [main.c:348] Opening database: build/abc123...def.db
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[2025-01-12 14:30:15] [TRACE] [main.c:330] Entering init_database()
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[2025-01-12 14:30:15] [ERROR] [config.c:125] Database locked
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```
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## Implementation Steps
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### Step 1: Create Files (5 minutes)
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1. Create `src/debug.h` with the header code above
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2. Create `src/debug.c` with the implementation code above
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3. Update `Makefile` to include `src/debug.c` in `MAIN_SRC`
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### Step 2: Add CLI Parsing (5 minutes)
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Add `--debug-level` argument parsing to `main()` in `src/main.c`
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### Step 3: Update Existing Functions (5 minutes)
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Update the existing `log_*` functions to use the new debug macros
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### Step 4: Test (5 minutes)
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```bash
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# Build
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make clean && make
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# Test different levels
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./build/c_relay_x86 # No output
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./build/c_relay_x86 --debug-level=1 # Errors only
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./build/c_relay_x86 --debug-level=3 # Info + warnings + errors
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./build/c_relay_x86 --debug-level=4 # All debug messages
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./build/c_relay_x86 --debug-level=5 # Everything with file:line on TRACE
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```
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### Step 5: Gradual Migration (Ongoing)
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As you work on different parts of the code, replace `log_*` calls with `DEBUG_*` macros and add new debug/trace statements where helpful.
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## Benefits
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✅ **Simple**: Single flag, 6 levels, easy to understand
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✅ **Zero Overhead**: Compiler optimizes away unused debug code
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✅ **Zero Size Impact**: No binary size increase in production
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✅ **Backward Compatible**: Existing `log_*` functions still work
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✅ **Easy Migration**: Gradual replacement of log calls
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✅ **Flexible**: Can add detailed debugging without affecting production
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## Total Implementation Time
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**~20 minutes** for basic implementation
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**Ongoing** for gradual migration of existing log calls
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## Recommendation
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This is the simplest possible debug system that provides:
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- Multiple debug levels for different verbosity
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- Zero performance impact in production
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- Zero binary size increase
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- Easy to use and understand
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- Backward compatible with existing code
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Start with the basic implementation, test it, then gradually migrate existing log calls and add new debug statements as needed.
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