Struct CallTraceConfig 

pub struct CallTraceConfig {
    pub enabled: bool,
    pub capture_arguments: bool,
    pub output_file: Option<String>,
    pub max_call_depth: usize,
    pub pretty_json: bool,
}

CallTrace runtime configuration

This structure holds all configuration options that control CallTrace behavior. Configuration is typically loaded from environment variables during initialization, but can be modified programmatically if needed.

Configuration Sources

1. Environment Variables (primary source, read at startup)
2. Default Values (fallback when environment variables are not set)
3. Programmatic (can be modified via unsafe access to CONFIG static)

Fields

enabled: bool

Master enable/disable switch for all tracing functionality.

• Environment: CALLTRACE_ENABLED (1/true to enable)
• Default: true
• Performance Impact: When disabled, overhead is <5ns per function call

capture_arguments: bool

Enable expensive argument capture using DWARF debugging information.

• Environment: CALLTRACE_CAPTURE_ARGS (1/true to enable)
• Default: false
• Performance Impact: 10-50x overhead when enabled, depending on argument complexity
• Requirements: Target program must be compiled with -g flag

output_file: Option<String>

Path where JSON trace output will be written.

• Environment: CALLTRACE_OUTPUT
• Default: {executable_name}.json in the same directory as the executable
• Special Values:
  • None: No output generated
  • "stderr": Output to stderr (not implemented)
  • "stdout": Output to stdout (not implemented)

max_call_depth: usize

Maximum depth of function call nesting to trace.

• Environment: CALLTRACE_MAX_DEPTH
• Default: 100
• Purpose: Prevents infinite recursion and limits memory usage
• Behavior: Calls deeper than this limit are ignored

pretty_json: bool

Whether to format JSON output with indentation and newlines.

• Environment: CALLTRACE_PRETTY_JSON (1/true to enable)
• Default: true
• Trade-off: Readable output vs. smaller file size

Examples

Reading Current Configuration

// Note: This requires unsafe access to the CONFIG static
use calltrace::CallTraceConfig;

// This is how configuration is accessed internally
// (Not recommended for external use)

Environment Variable Configuration

# Minimal configuration - basic tracing only
CALLTRACE_OUTPUT=trace.json ./your_program

# Full featured configuration
CALLTRACE_OUTPUT=full_trace.json \
CALLTRACE_CAPTURE_ARGS=1 \
CALLTRACE_MAX_DEPTH=50 \
CALLTRACE_DEBUG=1 \
CALLTRACE_PRETTY_JSON=1 \
./your_program

# Performance-optimized configuration
CALLTRACE_OUTPUT=perf_trace.json \
CALLTRACE_CAPTURE_ARGS=0 \
CALLTRACE_MAX_DEPTH=200 \
CALLTRACE_PRETTY_JSON=0 \
./your_program

Performance Guidelines

• Production: Set capture_arguments = false for minimal overhead
• Development: Enable capture_arguments = true for detailed debugging
• Deep Recursion: Increase max_call_depth if needed, but monitor memory usage
• File Size: Set pretty_json = false for smaller output files

Thread Safety

Configuration is read once during initialization and then considered immutable. All fields can be safely accessed concurrently from multiple threads.

Fields

enabled: bool

capture_arguments: bool

output_file: Option<String>

max_call_depth: usize

pretty_json: bool

Trait Implementations

impl Clone for CallTraceConfig

fn clone(&self) -> CallTraceConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CallTraceConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CallTraceConfig

fn default() -> Self

Returns the “default value” for a type.