Config API

The Config struct controls the behavior of the logger, including all enterprise features like thread pools, schedulers, compression, and async logging through centralized configuration.

Fields

Core Settings

level: Level

Minimum log level to output. Default: .info.

global_color_display: bool

Enable colored output globally. Default: true.

global_console_display: bool

Enable console output globally. Default: true.

global_file_storage: bool

Enable file output globally. Default: true.

json: bool

Output logs in JSON format. Default: false.

pretty_json: bool

Pretty print JSON output. Default: false.

color: bool

Enable ANSI colors. Default: true.

check_for_updates: bool

Check GitHub for the latest Logly release on startup. Runs in a background thread and prints a highlighted notice when a newer version is available. Default: true.

emit_system_diagnostics_on_init: bool

Emit a single system diagnostics log (OS, arch, CPU, cores, memory) when the logger initializes. Default: false.

include_drive_diagnostics: bool

When emitting diagnostics, include per-drive totals and free space. Applies to startup diagnostics and manual logSystemDiagnostics calls. Default: true.

log_compact: bool

Use compact log format. Default: false.

use_arena_allocator: bool

Enable arena allocator for the main logger instance. When enabled, the logger uses an arena allocator for temporary record/format allocations, which can improve performance by reducing allocation overhead. Default: false.

var config = logly.Config.default();
config.use_arena_allocator = true;
config.arena_reset_threshold = 64 * 1024;

Equivalent builder aliases:

var config = logly.Config.default().withArenaAllocation();
// or
config = config.withArenaAllocator();
// or
config = config.withArena();

All three builder names are behavior-equivalent and set use_arena_allocator = true.

Difference from direct field assignment:

• config.use_arena_allocator = true mutates an existing config value.
• config = config.withArenaAllocator() (or aliases) returns a modified copy and requires reassignment.

You can also use your own application/request arena backed by GPA independently of Logly's internal scratch arena:

const std = @import("std");

var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer _ = gpa.deinit();

var request_arena = std.heap.ArenaAllocator.init(gpa.allocator());
defer request_arena.deinit();

const tmp_alloc = request_arena.allocator();
const buf = try tmp_alloc.alloc(u8, 512);
_ = buf;
_ = request_arena.reset(.retain_capacity);

arena_reset_threshold: usize

Arena reset threshold in bytes. When approximate temporary arena usage reaches this value, the logger resets the arena before processing the next record. Default: 64 * 1024.

logs_root_path: ?[]const u8

Optional global root path for all log files. If set, file sinks will be stored relative to this path. Default: null.

diagnostics_output_path: ?[]const u8

If set, system diagnostics will be stored at this path. Default: null.

auto_flush: bool

Automatically flush sinks after every log operation. Creates immediate output but significantly impacts performance in high-throughput applications. Default: false (for performance). Set to true only when immediate output visibility is critical.

Distributed Logging

distributed: DistributedConfig

Configuration for distributed tracing and service identification. Contains:

• enabled: bool: Enable distributed context features.
• service_name: ?[]const u8: Name of the service (e.g. "auth-service").
• service_version: ?[]const u8: Version of the service.
• environment: ?[]const u8: Environment (e.g. "production", "staging").
• datacenter: ?[]const u8: Datacenter identifier.
• region: ?[]const u8: Cloud region (e.g. "us-east-1").
• instance_id: ?[]const u8: Unique instance identifier.
• trace_header: []const u8: HTTP header for Trace ID (default: Constants.ConfigDefaults.distributed_trace_header).
• span_header: []const u8: HTTP header for Span ID (default: Constants.ConfigDefaults.distributed_span_header).
• parent_header: []const u8: HTTP header for Parent Span ID (default: Constants.ConfigDefaults.distributed_parent_header).
• baggage_header: []const u8: HTTP header for Baggage/Correlation Context (default: Constants.ConfigDefaults.distributed_baggage_header).
• trace_sampling_rate: f64: Sampling rate for distributed tracing 0.0 to 1.0 (default: 1.0).

Defaults for distributed headers are centralized in Constants.ConfigDefaults to prevent string-literal drift.

Telemetry

telemetry: TelemetryConfig

OpenTelemetry integration configuration for trace and metric export. This section controls OTLP/Jaeger/Zipkin/Datadog/Azure/Google providers and local file exporters.

Key fields:

• enabled: bool — Enable OpenTelemetry integration (default: false).
• provider: Provider — Provider enum (.none, .jaeger, .zipkin, .datadog, .google_cloud, .google_analytics, .google_tag_manager, .aws_xray, .azure, .generic, .file, .custom).
• exporter_endpoint: ?[]const u8 — Exporter endpoint URL for HTTP/gRPC exporters (e.g., "http://localhost:4317").
• api_key: ?[]const u8 — API key for providers that require authentication.
• connection_string: ?[]const u8 — Connection string for Azure Application Insights.
• exporter_file_path: ?[]const u8 — File path for JSONL file exporter.
• batch_size: usize = Constants.TelemetryDefaults.batch_size — Batch span export size (default: 256).
• batch_timeout_ms: u64 = Constants.TelemetryDefaults.batch_timeout_ms — Batch export timeout in ms (default: 5000).
• sampling_strategy: SamplingStrategy — Sampling strategy (.always_on, .always_off, .trace_id_ratio, .parent_based).
• sampling_rate: f64 = Constants.TelemetryDefaults.sampling_rate — Sampling rate used when trace_id_ratio is selected.
• service_name, service_version, environment, datacenter — Resource identification fields.
• span_processor_type: SpanProcessorType = .simple — Span processor: .simple keeps completed spans pending until an explicit exportSpans() or flush() call; .batch will automatically export spans when the configured batch size or timeout is reached.
• metric_format: MetricFormat — Format for metrics export (e.g., .otlp, .prometheus, .json).
• compress_exports: bool — Whether to compress span export payloads.
• custom_exporter_fn: ?*const fn () anyerror!void — Optional custom exporter callback for user-defined exporters.
• on_span_start, on_span_end, on_metric_recorded, on_error — Lifecycle callbacks for telemetry events.
• auto_context_propagation: bool — Automatically propagate trace/context headers (default: true).
• trace_header: []const u8 = Constants.TelemetryDefaults.trace_header — Trace header name (default: "traceparent").
• baggage_header: []const u8 = Constants.TelemetryDefaults.baggage_header — Baggage header name (default: "baggage").

Presets and factory helpers:

• TelemetryConfig.jaeger(), TelemetryConfig.zipkin(), TelemetryConfig.datadog(api_key), TelemetryConfig.googleCloud(project_id, api_key), TelemetryConfig.googleAnalytics(id, secret), TelemetryConfig.googleTagManager(url, key), TelemetryConfig.awsXray(region), TelemetryConfig.azure(connection_string), TelemetryConfig.otelCollector(endpoint), TelemetryConfig.file(path), TelemetryConfig.custom(exporter_fn), TelemetryConfig.highThroughput(), TelemetryConfig.development().

Notes:

• Use .simple when you prefer explicit export control (call exportSpans() at safe points in your application). Use .batch for automatic behavior when you want the library to flush spans based on batch size or timeout.
• Defaults are centralized in Constants.TelemetryDefaults (batch size, timeout, header defaults, etc.).
• v0.1.6 includes a small OTLP exporter fix: a compile-time issue in the OTLP span writer (writeOtlpSpan) was resolved so the telemetry feature builds cleanly across targets.

Display Options

show_time: bool

Show timestamp in logs. Default: true.

show_module: bool

Show module name. Default: true.

show_function: bool

Show function name. Default: false.

show_filename: bool

Show filename. Default: false.

show_lineno: bool

Show line number. Default: false.

show_thread_id: bool

Show thread ID. Default: false.

show_process_id: bool

Show process ID. Default: false.

include_hostname: bool

Include hostname in logs (for distributed systems). Default: false.

include_pid: bool

Include process ID in logs. Default: false.

capture_stack_trace: bool

Capture stack traces for Error and Critical log levels. If false, stack traces will not be collected or displayed. Default: false.

symbolize_stack_trace: bool

Resolve memory addresses in stack traces to function names and file locations. This provides human-readable stack traces but has a performance cost. Default: false.

Format Settings

log_format: ?[]const u8

Custom format string for log messages. Available placeholders:

• {time} - Timestamp
• {level} - Log level
• {message} - Log message
• {module} - Module name
• {function} - Function name
• {file} - Filename
• {line} - Line number
• {thread_id} - Thread ID
• {pid} - Process ID
• {host} - Hostname

time_format: []const u8

Time format string. Supported formats:

• "YYYY-MM-DD HH:mm:ss.SSS" - Default human-readable format with milliseconds
• "default" - Alias that resolves to the default human-readable pattern
• "ISO8601" - ISO 8601 format (e.g., 2025-12-04T06:39:53.091Z)
• "RFC3339" - RFC 3339 format (e.g., 2025-12-04T06:39:53+00:00)
• "YYYY-MM-DD" - Date only
• "HH:mm:ss" - Time only
• "HH:mm:ss.SSS" - Time with milliseconds
• "unix" - Unix timestamp in seconds
• "unix_ms" - Unix timestamp in milliseconds
• Custom timezone placeholders are also supported in pattern formats:
  • ZZZ => +HH:MM (e.g. +01:00)
  • ZZ => +HHMM (e.g. +0100)

For production code, prefer centralized constants over raw string literals:

config.time_format = logly.Config.TimeFormat.iso8601;
config.time_format = logly.Config.TimeFormat.default_pattern;

ZZZ and ZZ are important when using custom patterns in distributed systems because they preserve explicit timezone context for parsing, correlation, and incident timelines.

Default: "YYYY-MM-DD HH:mm:ss.SSS".

timezone: Timezone

Timezone for timestamps. Options: .local, .utc. Default: .local.

Behavior details:

• .utc: ISO8601 ends with Z, RFC3339 uses +00:00.
• .local: uses process/system local timezone when available and emits +/-HH:MM offsets for ISO8601/RFC3339.

format_structure: FormatStructureConfig

Custom format structure configuration.

• message_prefix: Prefix to add before each log message.
• message_suffix: Suffix to add after each log message.
• field_separator: Separator between log fields/components.
• enable_nesting: Enable nested/hierarchical formatting for structured logs.
• nesting_indent: Indentation for nested fields.
• field_order: Custom field order.
• include_empty_fields: Whether to include empty/null fields in output.
• placeholder_open: Custom placeholder prefix.
• placeholder_close: Custom placeholder suffix.

level_colors: LevelColorConfig

Level-specific color customization with theme presets (v0.1.5).

• theme_preset: Theme preset for base colors (.default, .bright, .dim, .minimal, .neon, .pastel, .dark, .light, .none).
• trace_color, debug_color, info_color, notice_color, success_color, warning_color, error_color, fail_color, critical_color, fatal_color: Individual color overrides (take precedence over theme).
• use_rgb: Use RGB color mode.
• support_background: Background color support.
• reset_code: Reset code at end of each log.
• getColorForLevel(level): Returns the effective color (override or theme-based).

highlighters: HighlighterConfig

Highlighter patterns and alert configuration.

• enabled: Enable highlighter system.
• patterns: Pattern-based highlighters.
• alert_on_match: Alert callbacks for matched patterns.
• alert_min_severity: Severity level that triggers alerts.
• alert_callback: Custom callback function name for alerts.
• max_matches_per_message: Maximum number of highlighter matches to track per message.
• log_matches: Whether to log highlighter matches as separate records.

Feature Toggles

auto_sink: bool

Automatically add a console sink on init. Default: true.

enable_callbacks: bool

Enable callback invocation for log events. Default: false (for performance). Enable only when using log callbacks.

enable_exception_handling: bool

Enable exception/error handling within the logger. Default: true.

enable_version_check: bool

Enable version checking (for update notifications). Default: false.

debug_mode: bool

Debug mode for internal logger diagnostics. Default: false.

debug_log_file: ?[]const u8

Path for internal debug log file. Default: null.

enable_tracing: bool

Enable distributed tracing support. Default: false.

trace_header: []const u8

Trace ID header name for distributed tracing. Default: X-Trace-ID.

enable_metrics: bool

Enable metrics collection. Default: false.

Enterprise Features

sampling: SamplingConfig

Sampling configuration for high-throughput scenarios.

• enabled: Enable sampling.
• strategy: Sampling strategy (.none, .probability, .rate_limit, .every_n, .adaptive).

rate_limit: RateLimitConfig

Rate limiting configuration to prevent log flooding.

• enabled: Enable rate limiting.
• max_per_second: Maximum records per second.
• burst_size: Burst size.
• per_level: Apply rate limiting per log level.

redaction: RedactionConfig

Redaction settings for sensitive data.

• enabled: Enable redaction.
• fields: Fields to redact.
• patterns: Regex patterns to redact.
• replacement: Replacement string.

error_handling: ErrorHandling

Error handling behavior. Options: .silent, .log_and_continue, .fail_fast, .callback. Default: .log_and_continue.

max_message_length: ?usize

Maximum message length (truncate if exceeded). Default: null.

structured: bool

Enable structured logging with automatic context propagation. Default: false.

default_fields: ?[]const DefaultField

Default context fields to include with every log.

app_name: ?[]const u8

Application name for identification in distributed systems.

app_version: ?[]const u8

Application version for tracing.

environment: ?[]const u8

Environment identifier (e.g., "production", "staging", "development").

stack_size: usize

Stack size for capturing stack traces. Default: 1MB.

Advanced Configuration

buffer_config: BufferConfig

Buffer configuration for async operations.

• size: Buffer size.
• flush_interval_ms: Flush interval.
• max_pending: Max pending records.
• overflow_strategy: Overflow strategy (.drop_oldest, .drop_newest, .block).

async_config: AsyncConfig

Async logging configuration.

• enabled: Enable async logging.
• buffer_size: Buffer size for async queue.
• batch_size: Batch size for flushing.
• flush_interval_ms: Flush interval.
• min_flush_interval_ms: Minimum time between flushes.
• max_latency_ms: Maximum latency before forcing a flush.
• overflow_policy: Overflow policy (.drop_oldest, .drop_newest, .block).
• background_worker: Auto-start worker thread.
• use_arena: Enable arena allocator for batch processing. Default: false.

rules: RulesConfig

Rules system configuration. The rules system respects global switches (global_console_display, global_file_storage, global_color_display).

• enabled: Master switch for rules system. Default: false.
• client_rules_enabled: Enable client-defined rules. Default: true.
• builtin_rules_enabled: Enable built-in rules (reserved). Default: true.
• use_unicode: Use Unicode symbols (set false for ASCII). Default: false.
• enable_colors: ANSI colors in output. Default: true.
• show_rule_id: Show rule IDs in output. Default: false.
• include_rule_id_prefix: Include "R0001:" prefix. Default: false.
• rule_id_format: Custom rule ID format. Default: "R{d}".
• indent: Message indent. Default: " ".
• message_prefix: Prefix character (deprecated, use symbols). Default: "↳".
• symbols: Custom symbols for message categories. See RuleSymbols.
• console_output: Output to console (AND'd with global_console_display). Default: true.
• file_output: Output to files (AND'd with global_file_storage). Default: true.
• include_in_json: Include in JSON output. Default: true.
• verbose: Full context output. Default: false.
• max_rules: Maximum rules allowed. Default: 1000.
• max_messages_per_rule: Max messages to show per match. Default: 10.
• sort_by_severity: Order by severity. Default: false.

Presets:

• RulesConfig.development(): Full debugging with colors and Unicode.
• RulesConfig.production(): Minimal output, no colors, no verbose.
• RulesConfig.ascii(): ASCII-only for terminals without Unicode.
• RulesConfig.disabled(): Zero overhead.
• RulesConfig.silent(): Rules evaluate but don't output.
• RulesConfig.consoleOnly(): No file output.
• RulesConfig.fileOnly(): No console output.

RuleSymbols

Customizable symbols for rule message categories. Defaults are ASCII-compatible.

• error_analysis: Default ">> [ERROR]"
• solution_suggestion: Default ">> [FIX]"
• performance_hint: Default ">> [PERF]"
• security_alert: Default ">> [SEC]"
• deprecation_warning: Default ">> [DEP]"
• best_practice: Default ">> [HINT]"
• accessibility: Default ">> [A11Y]"
• documentation: Default ">> [DOC]"
• action_required: Default ">> [ACTION]"
• bug_report: Default ">> [BUG]"
• general_information: Default ">> [INFO]"
• warning_explanation: Default ">> [WARN]"
• default: Default ">>"

thread_pool: ThreadPoolConfig

Thread pool configuration.

• enabled: Enable thread pool.
• thread_count: Number of worker threads.
• queue_size: Maximum queue size.
• stack_size: Stack size per thread.
• work_stealing: Enable work stealing.
• enable_arena: Enable per-worker arena allocator.
• thread_name_prefix: Thread naming prefix.
• keep_alive_ms: Keep alive time for idle threads.
• thread_affinity: Enable thread affinity.

scheduler: SchedulerConfig

Scheduler configuration.

• enabled: Enable scheduler.
• cleanup_max_age_days: Default cleanup max age.
• max_files: Default max files to keep.
• compress_before_cleanup: Enable compression before cleanup.
• file_pattern: Default file pattern for cleanup.

compression: CompressionConfig

Compression configuration.

• enabled: Enable compression.
• algorithm: Compression algorithm (.none, .deflate, .zlib, .raw_deflate, .gzip, .zstd, .lzma, .lzma2, .xz, .zip, .tar_gz, .lz4).
• level: Compression level (.none, .fastest, .fast, .default, .best).
• on_rotation: Compress on rotation.
• keep_original: Keep original file after compression.
• mode: Compression mode (.disabled, .on_rotation, .on_size_threshold, .scheduled, .streaming).
• size_threshold: Size threshold for on_size_threshold mode.
• buffer_size: Buffer size for streaming compression.
• strategy: Compression strategy.
• extension: File extension for compressed files.
• delete_after: Delete files older than this after compression.
• checksum: Enable checksum validation.
• streaming: Enable streaming compression.
• background: Use background thread for compression.
• dictionary: Dictionary for compression.
• parallel: Enable multi-threaded compression.
• memory_limit: Memory limit for compression.

Presets

Logly provides several configuration presets for common scenarios.

Config.default()

Returns the default configuration.

• Level: .info
• Colors: Enabled
• Output: Console and File enabled

Config.production()

Optimized for production environments.

• Level: .info
• Colors: Disabled (for cleaner logs)
• JSON: Enabled (for parsing)
• Async: Enabled (for performance)
• Metrics: Enabled
• Structured: Enabled
• Compression: Enabled (on rotation)
• Scheduler: Enabled (cleanup old logs)

Config.development()

Optimized for development environments.

• Level: .debug
• Colors: Enabled
• Source Info: Function, File, Line enabled
• Debug Mode: Enabled

Config.highThroughput()

Optimized for high-volume logging.

• Level: .warning
• Sampling: Adaptive (target 1000/sec)
• Rate Limit: 10000/sec
• Buffer: 64KB
• Thread Pool: Enabled (auto-detect threads)
• Async: Enabled (aggressive batching)

Config.secure()

Compliant with security standards.

• Redaction: Enabled
• Structured: Enabled
• Hostname/PID: Disabled (minimize info leakage)

Builder Methods

Helper methods to modify configuration fluently.

withAsync(config: AsyncConfig) Config

Enables async logging with the provided configuration.

withCompression(config: CompressionConfig) Config

Enables compression with the provided configuration.

withCompressionEnabled() Config

Enables compression with default settings.

withImplicitCompression() Config

Enables automatic compression on rotation.

withExplicitCompression() Config

Enables manual compression control.

withFastCompression() Config

Enables fast compression (speed priority).

withBestCompression() Config

Enables best compression (ratio priority).

withBackgroundCompression() Config

Enables background thread compression.

withLogCompression() Config

Enables log-optimized compression (text strategy).

withProductionCompression() Config

Enables production-ready compression (balanced, checksums, background).

Zstd Compression Methods (v0.1.5+)

withZstdCompression() Config

Enables default zstd compression (level 6). Uses .zst extension.

withZstdFastCompression() Config

Enables fast zstd compression (level 1). Prioritizes speed over ratio.

withZstdBestCompression() Config

Enables best zstd compression (level 19). Prioritizes ratio over speed.

withZstdProductionCompression() Config

Enables production zstd compression with background processing and checksums.

withThreadPool(config: ThreadPoolConfig) Config

Enables thread pool with the provided configuration.

withScheduler(config: SchedulerConfig) Config

Enables scheduler with the provided configuration.

withArenaAllocation() Config

Enables arena allocator for internal temporary allocations to improve performance.

Aliases: withArenaAllocator(), withArena().

merge(other: Config) Config

Merges another configuration into the current one. Non-default values from other override the current values.

enable_callbacks: bool

Enable log callbacks. Default: false. Set to true only when using log callbacks.

enable_exception_handling: bool

Enable exception handling within the logger. Default: true.

Sampling Configuration

sampling: SamplingConfig

Sampling configuration for high-throughput scenarios.

pub const SamplingConfig = struct {
    enabled: bool = false,
    rate: f64 = 1.0,
    strategy: SamplingStrategy = .probability,

    pub const SamplingStrategy = enum {
        probability,
        rate_limit,
        adaptive,
        every_n,
    };
};

Rate Limiting Configuration

rate_limit: RateLimitConfig

Rate limiting configuration to prevent log flooding.

pub const RateLimitConfig = struct {
    enabled: bool = false,
    max_per_second: u32 = 1000,
    burst_size: u32 = 100,
    per_level: bool = false,
};

Redaction Configuration

redaction: RedactionConfig

Sensitive data redaction configuration.

pub const RedactionConfig = struct {
    enabled: bool = false,
    fields: ?[]const []const u8 = null,
    patterns: ?[]const []const u8 = null,
    replacement: []const u8 = "[REDACTED]",
};

Buffer Configuration

buffer_config: BufferConfig

Buffer configuration for async writing.

pub const BufferConfig = struct {
    size: usize = 8192,
    flush_interval_ms: u64 = 1000,
    max_pending: usize = 10000,
    overflow_strategy: OverflowStrategy = .drop_oldest,

    pub const OverflowStrategy = enum {
        drop_oldest,
        drop_newest,
        block,
    };
};

Thread Pool Configuration

thread_pool: ThreadPoolConfig

Centralized thread pool configuration for parallel processing.

pub const ThreadPoolConfig = struct {
    /// Enable thread pool for parallel processing.
    enabled: bool = false,
    /// Number of worker threads (0 = auto-detect based on CPU cores).
    thread_count: usize = 0,
    /// Maximum queue size for pending tasks.
    queue_size: usize = 10000,
    /// Stack size per thread in bytes.
    stack_size: usize = 1024 * 1024,
    /// Enable work stealing between threads.
    work_stealing: bool = true,
    /// Enable per-worker arena allocator for efficient memory usage.
    enable_arena: bool = false,
};

Scheduler Configuration

scheduler: SchedulerConfig

Centralized scheduler configuration for automated log maintenance.

pub const SchedulerConfig = struct {
    /// Enable the scheduler.
    enabled: bool = false,
    /// Default cleanup max age in days.
    cleanup_max_age_days: u64 = 7,
    /// Default max files to keep.
    max_files: ?usize = null,
    /// Enable compression before cleanup.
    compress_before_cleanup: bool = false,
    /// Default file pattern for cleanup.
    file_pattern: []const u8 = "*.log",
};

Compression Configuration

compression: CompressionConfig

Centralized compression configuration.

pub const CompressionConfig = struct {
    /// Enable compression.
    enabled: bool = false,
    /// Compression algorithm.
    algorithm: CompressionAlgorithm = .deflate,
    /// Compression level.
    level: CompressionLevel = .default,
    /// Custom zstd level (1-22). If set, overrides the level enum for zstd.
    custom_zstd_level: ?i32 = null,
    /// Compress on rotation.
    on_rotation: bool = true,
    /// Keep original file after compression.
    keep_original: bool = false,
    /// Compression mode.
    mode: Mode = .on_rotation,
    /// Size threshold in bytes for on_size_threshold mode.
    size_threshold: u64 = 10 * 1024 * 1024,
    /// Buffer size for streaming compression.
    buffer_size: usize = 32 * 1024,
    /// Compression strategy.
    strategy: Strategy = .default,
    /// File extension for compressed files.
    extension: []const u8 = ".gz",
    /// Delete files older than this after compression (in seconds, 0 = never).
    delete_after: u64 = 0,
    /// Enable checksum validation.
    checksum: bool = true,
    /// Enable streaming compression (compress while writing).
    streaming: bool = false,
    /// Use background thread for compression.
    background: bool = false,
    /// Dictionary for compression (pre-trained patterns).
    dictionary: ?[]const u8 = null,
    /// Enable multi-threaded compression (for large files).
    parallel: bool = false,
    /// Memory limit for compression (bytes, 0 = unlimited).
    memory_limit: usize = 0,
    /// Custom prefix for compressed file names
    file_prefix: ?[]const u8 = null,
    /// Custom suffix before extension
    file_suffix: ?[]const u8 = null,
    /// Root directory for all compressed files
    archive_root_dir: ?[]const u8 = null,
    /// Create date-based subdirectories in archive root
    create_date_subdirs: bool = false,
    /// Preserve original directory structure when archiving to root dir.
    preserve_dir_structure: bool = true,
    /// Custom naming pattern for compressed files.
    naming_pattern: ?[]const u8 = null,

    pub const CompressionAlgorithm = enum {
        none,
        deflate,
        zlib,
        raw_deflate,
        gzip,
        zstd,
        lzma,
        lzma2,
        xz,
        tar_gz,
        zip,
        lz4,
    };

    pub const CompressionLevel = enum {
        none,
        fastest,
        fast,
        default,
        best,

        /// Convert to zstd compression level (1-22).
        pub fn toZstdLevel(self: CompressionLevel) i32;
    };

    pub const Mode = enum {
        disabled,
        on_rotation,
        on_size_threshold,
        scheduled,
        streaming,
    };

    pub const Strategy = enum {
        default,
        text,
        binary,
        huffman_only,
        rle_only,
        adaptive,
    };

    // Preset factory methods
    pub fn enable() CompressionConfig;
    pub fn disable() CompressionConfig;
    pub fn fast() CompressionConfig;
    pub fn balanced() CompressionConfig;
    pub fn best() CompressionConfig;
    pub fn production() CompressionConfig;
    pub fn development() CompressionConfig;
    pub fn forLogs() CompressionConfig;
    pub fn archive() CompressionConfig;
    pub fn backgroundMode() CompressionConfig;
    pub fn streamingMode() CompressionConfig;
    
    // Zstd presets
    pub fn zstd() CompressionConfig;
    pub fn zstdFast() CompressionConfig;
    pub fn zstdBest() CompressionConfig;
    pub fn zstdProduction() CompressionConfig;
    pub fn zstdWithLevel(level: i32) CompressionConfig;

    // New algorithms presets
    pub fn lzma() CompressionConfig;
    pub fn lzma2() CompressionConfig;
    pub fn xz() CompressionConfig;
    pub fn tarGz() CompressionConfig;
    pub fn zip() CompressionConfig;
    pub fn lz4() CompressionConfig;
};

Rotation Configuration

rotation: RotationConfig

Global rotation and retention settings.

pub const RotationConfig = struct {
    /// Enable default rotation for file sinks.
    enabled: bool = false,

    /// Default rotation interval (e.g., "daily", "hourly").
    interval: ?[]const u8 = null,

    /// Default size limit for rotation (in bytes).
    size_limit: ?u64 = null,

    /// Maximum number of rotated files to retain.
    retention_count: ?usize = null,

    /// Maximum age of rotated files in seconds.
    max_age_seconds: ?i64 = null,

    /// Strategy for naming rotated files.
    naming_strategy: NamingStrategy = .timestamp,

    /// Optional directory to move rotated files to.
    archive_dir: ?[]const u8 = null,

    /// Whether to remove empty directories after cleanup.
    clean_empty_dirs: bool = false,

    pub const NamingStrategy = enum {
        timestamp,
        date,
        iso_datetime,
        index,
    };
};

Async Logging Configuration

async_config: AsyncConfig

Centralized async logging configuration. When async_config.enabled is true, the logger uses the AsyncLogger internally for high-performance buffered logging.

Priority Order:

1. AsyncLogger (when async_config.enabled = true) - Highest performance, buffered I/O
2. Thread Pool (when thread_pool.enabled = true) - Parallel processing for sync sinks
3. Direct Sinks - Synchronous logging to all sinks

Auto-flush Behavior:

• When using AsyncLogger, auto_flush controls whether to flush after each log operation
• When using thread pools, flushing happens in the worker threads
• When using direct sinks, auto_flush triggers immediate sink flushing

Auto-sink Integration:

• auto_sink works with all logging backends
• Sinks are automatically added to the appropriate backend (AsyncLogger, thread pool, or direct)

pub const AsyncConfig = struct {
    /// Enable async logging.
    enabled: bool = false,
    /// Buffer size for async queue.
    buffer_size: usize = 8192,
    /// Batch size for flushing.
    batch_size: usize = 100,
    /// Flush interval in milliseconds.
    flush_interval_ms: u64 = 100,
    /// Minimum time between flushes to avoid thrashing.
    min_flush_interval_ms: u64 = 0,
    /// Maximum latency before forcing a flush.
    max_latency_ms: u64 = 5000,
    /// What to do when buffer is full.
    overflow_policy: OverflowPolicy = .drop_oldest,
    /// Auto-start worker thread.
    background_worker: bool = true,
    /// Enable arena allocator for batch processing.
    use_arena: bool = false,

    pub const OverflowPolicy = enum {
        drop_oldest,
        drop_newest,
        block,
    };
};

Methods

default() Config

Returns the default configuration.

const config = logly.Config.default();

merge(other: Config) void

Merges another configuration into this one. Values from other take precedence over self.

var config = Config.default();
const overrides = Config{ .level = .debug };
config.merge(overrides);

production() Config

Returns a production-optimized configuration:

• Level: .info
• JSON format enabled
• Colors disabled
• Sampling enabled (10%)
• Metrics enabled
• Structured logging
• Compression enabled (on rotation)
• Scheduler enabled (auto cleanup, 30-day retention)

const config = logly.Config.production();

development() Config

Returns a development-friendly configuration:

• Level: .debug
• Colors enabled
• Source location shown
• Debug mode enabled

const config = logly.Config.development();

highThroughput() Config

Returns a high-throughput optimized configuration:

• Level: .warning
• Large buffers (64KB)
• Aggressive sampling (50%, adaptive)
• Rate limiting enabled (10,000/sec)
• Thread pool enabled (auto-detect cores)
• Async logging enabled (32KB buffer, 256 batch size)

const config = logly.Config.highThroughput();

secure() Config

Returns a security-focused configuration:

• Redaction enabled
• Structured logging
• No hostname/PID exposure

const config = logly.Config.secure();

withAsync(config) Config

Returns a configuration with async logging enabled.

const config = logly.Config.default().withAsync(.{
    .buffer_size = 16384,
});

withCompression(config) Config

Returns a configuration with compression enabled.

const config = logly.Config.default().withCompression(.{
    .algorithm = .deflate,
});

withThreadPool(config) Config

Returns a configuration with thread pool enabled.

const config = logly.Config.default().withThreadPool(.{
    .thread_count = 4,
});

withScheduler(config) Config

Returns a configuration with scheduler enabled.

const config = logly.Config.default().withScheduler(.{
    .cleanup_max_age_days = 7,
});

withArenaAllocation() Config

Returns a configuration with arena allocator support enabled for logger scratch allocations.

Aliases: withArenaAllocator(), withArena().

var config = logly.Config.default().withArenaAllocator();
config.arena_reset_threshold = 128 * 1024;

merge(other) Config

Merges another configuration into this one. Non-default values from other override.

const base = logly.Config.development();
const extra = logly.Config{ .json = true };
const merged = base.merge(extra);

ConfigPresets

Convenience wrapper for preset configurations:

const logly = @import("logly");

// Use presets
const prod = logly.ConfigPresets.production();
const dev = logly.ConfigPresets.development();
const high = logly.ConfigPresets.highThroughput();
const sec = logly.ConfigPresets.secure();

Re-exported Config Types

For convenience, nested config types are re-exported from the main logly module:

const logly = @import("logly");

// All available directly
const ThreadPoolConfig = logly.ThreadPoolConfig;
const SchedulerConfig = logly.SchedulerConfig;
const CompressionConfig = logly.CompressionConfig;
const AsyncConfig = logly.AsyncConfig;
const SamplingConfig = logly.SamplingConfig;
const RateLimitConfig = logly.RateLimitConfig;
const RedactionConfig = logly.RedactionConfig;
const BufferConfig = logly.BufferConfig;

Example Usage

Basic Configuration

const logly = @import("logly");

const logger = try logly.Logger.init(allocator);
defer logger.deinit();

// Configure with custom settings
var config = logly.Config.default();
config.level = .debug;
config.json = true;
config.show_filename = true;
config.time_format = "unix";

// Apply configuration
logger.configure(config);

Production with All Features

const logly = @import("logly");

// Start with production preset and enable additional features
var config = logly.Config.production();

// Enable thread pool with 4 workers
config.thread_pool = .{
    .enabled = true,
    .thread_count = 4,
    .work_stealing = true,
};

// Enable async logging
config.async_config = .{
    .enabled = true,
    .buffer_size = 16384,
    .batch_size = 128,
};

// Enable compression
config.compression = .{
    .enabled = true,
    .level = .best,
    .on_rotation = true,
};

// Enable scheduler for maintenance
config.scheduler = .{
    .enabled = true,
    .cleanup_max_age_days = 14,
    .compress_before_cleanup = true,
};

const logger = try logly.Logger.initWithConfig(allocator, config);
defer logger.deinit();

Custom Log Format

var config = logly.Config.default();

// Custom format with timestamp and level
config.log_format = "{time} | {level} | {message}";
config.time_format = "unix"; // Unix timestamp in seconds

logger.configure(config);
try logger.info("Formatted message", @src());
// Output: 1733299823 | INFO | Formatted message