513 lines
14 KiB
Markdown
513 lines
14 KiB
Markdown
# lixenwraith/log Quick Reference Guide
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This guide details the `lixenwraith/log` package, a high-performance, buffered, rotating file logger for Go with built-in disk management, operational monitoring, and framework compatibility adapters.
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## Quick Start: Recommended Usage
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The recommended pattern uses the **Builder** with type-safe configuration. This provides compile-time safety and eliminates runtime errors.
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```go
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package main
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import (
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"fmt"
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"time"
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"github.com/lixenwraith/log"
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)
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func main() {
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// 1. Use the builder pattern for configuration (recommended).
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logger, err := log.NewBuilder().
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Directory("/var/log/myapp"). // Log directory path
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LevelString("info"). // Minimum log level
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Format("json"). // Output format
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BufferSize(2048). // Channel buffer size
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MaxSizeMB(10). // Max file size before rotation
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HeartbeatLevel(1). // Enable operational monitoring
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HeartbeatIntervalS(300). // Every 5 minutes
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Build() // Build the logger instance
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if err != nil {
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panic(fmt.Errorf("logger build failed: %w", err))
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}
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defer logger.Shutdown(5 * time.Second)
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// 2. Start the logger (required before logging).
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if err := logger.Start(); err != nil {
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panic(fmt.Errorf("logger start failed: %w", err))
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}
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// 3. Begin logging with structured key-value pairs.
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logger.Info("Application started", "version", "1.0.0", "pid", os.Getpid())
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logger.Debug("Debug information", "user_id", 12345)
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logger.Warn("High memory usage", "used_mb", 1800, "limit_mb", 2048)
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logger.Error("Connection failed", "host", "db.example.com", "error", err)
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}
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```
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## Alternative Initialization Methods
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### Using ApplyConfigString (Quick Configuration)
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```go
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logger := log.NewLogger()
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err := logger.ApplyConfigString(
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"directory=/var/log/app",
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"format=json",
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"level=debug",
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"max_size_kb=5000",
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)
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if err != nil {
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return fmt.Errorf("config failed: %w", err)
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}
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defer logger.Shutdown()
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logger.Start()
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```
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### Using ApplyConfig (Full Control)
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```go
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logger := log.NewLogger()
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cfg := log.DefaultConfig()
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cfg.Directory = "/var/log/app"
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cfg.Format = "json"
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cfg.Level = log.LevelDebug
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cfg.MaxSizeKB = 5000
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cfg.HeartbeatLevel = 2 // Process + disk stats
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err := logger.ApplyConfig(cfg)
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if err != nil {
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return fmt.Errorf("config failed: %w", err)
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}
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defer logger.Shutdown()
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logger.Start()
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```
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## Builder Pattern
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The `Builder` is the primary way to construct a `Logger` instance with compile-time safety.
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```go
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// NewBuilder creates a new logger builder.
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func NewBuilder() *Builder
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// Build finalizes configuration and creates the logger.
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func (b *Builder) Build() (*Logger, error)
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```
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### Builder Methods
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All builder methods return `*Builder` for chaining.
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**Basic Configuration:**
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- `Level(level int64)`: Set numeric log level (-4 to 8)
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- `LevelString(level string)`: Set level by name ("debug", "info", "warn", "error")
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- `Directory(dir string)`: Set log directory path
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- `Name(name string)`: Set base filename (default: "log")
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- `Format(format string)`: Set format ("txt", "json", "raw")
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- `Extension(ext string)`: Set file extension (default: ".log")
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**Buffer and Performance:**
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- `BufferSize(size int64)`: Channel buffer size (default: 1024)
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- `FlushIntervalMs(ms int64)`: Buffer flush interval (default: 100ms)
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- `TraceDepth(depth int64)`: Default function trace depth 0-10 (default: 0)
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**File Management:**
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- `MaxSizeKB(size int64)` / `MaxSizeMB(size int64)`: Max file size before rotation
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- `MaxTotalSizeKB(size int64)` / `MaxTotalSizeMB(size int64)`: Max total directory size
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- `MinDiskFreeKB(size int64)` / `MinDiskFreeMB(size int64)`: Required free disk space
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- `RetentionPeriodHrs(hours float64)`: Hours to keep logs (0=disabled)
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- `RetentionCheckMins(mins float64)`: Retention check interval
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**Output Control:**
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- `EnableConsole(enable bool)`: Enable stdout/stderr output
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- `EnableFile(enable bool)`: Enable file output
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- `ConsoleTarget(target string)`: "stdout", "stderr", or "split"
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**Formatting:**
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- `ShowTimestamp(show bool)`: Add timestamps
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- `ShowLevel(show bool)`: Add level labels
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- `TimestampFormat(format string)`: Go time format string
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**Monitoring:**
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- `HeartbeatLevel(level int64)`: 0=off, 1=proc, 2=+disk, 3=+sys
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- `HeartbeatIntervalS(seconds int64)`: Heartbeat interval
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**Disk Monitoring:**
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- `DiskCheckIntervalMs(ms int64)`: Base disk check interval
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- `EnableAdaptiveInterval(enable bool)`: Adjust interval based on load
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- `MinCheckIntervalMs(ms int64)`: Minimum adaptive interval
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- `MaxCheckIntervalMs(ms int64)`: Maximum adaptive interval
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- `EnablePeriodicSync(enable bool)`: Periodic disk sync
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**Error Handling:**
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- `InternalErrorsToStderr(enable bool)`: Send internal errors to stderr
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## API Reference
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### Logger Creation
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```go
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func NewLogger() *Logger
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```
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Creates a new uninitialized logger with default configuration.
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### Configuration Methods
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```go
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func (l *Logger) ApplyConfig(cfg *Config) error
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func (l *Logger) ApplyConfigString(overrides ...string) error
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func (l *Logger) GetConfig() *Config
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```
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### Lifecycle Methods
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```go
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func (l *Logger) Start() error // Start log processing
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func (l *Logger) Stop(timeout ...time.Duration) error // Stop (can restart)
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func (l *Logger) Shutdown(timeout ...time.Duration) error // Terminal shutdown
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func (l *Logger) Flush(timeout time.Duration) error // Force buffer flush
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```
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### Standard Logging Methods
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```go
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func (l *Logger) Debug(args ...any) // Level -4
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func (l *Logger) Info(args ...any) // Level 0
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func (l *Logger) Warn(args ...any) // Level 4
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func (l *Logger) Error(args ...any) // Level 8
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```
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### Trace Logging Methods
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Include function call traces (depth 0-10):
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```go
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func (l *Logger) DebugTrace(depth int, args ...any)
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func (l *Logger) InfoTrace(depth int, args ...any)
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func (l *Logger) WarnTrace(depth int, args ...any)
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func (l *Logger) ErrorTrace(depth int, args ...any)
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```
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### Special Logging Methods
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```go
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func (l *Logger) LogStructured(level int64, message string, fields map[string]any)
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func (l *Logger) Write(args ...any) // Raw output, no formatting
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func (l *Logger) Log(args ...any) // Timestamp only, no level
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func (l *Logger) Message(args ...any) // No timestamp or level
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func (l *Logger) LogTrace(depth int, args ...any) // Timestamp + trace, no level
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```
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## Constants and Levels
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### Standard Log Levels
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```go
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const (
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LevelDebug int64 = -4 // Verbose debugging
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LevelInfo int64 = 0 // Informational messages
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LevelWarn int64 = 4 // Warning conditions
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LevelError int64 = 8 // Error conditions
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)
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```
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### Heartbeat Monitoring Levels
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Special levels that bypass filtering:
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```go
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const (
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LevelProc int64 = 12 // Process statistics
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LevelDisk int64 = 16 // Disk usage statistics
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LevelSys int64 = 20 // System statistics
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)
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```
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### Level Helper
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```go
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func Level(levelStr string) (int64, error)
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```
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Converts level string to numeric constant: "debug", "info", "warn", "error", "proc", "disk", "sys".
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## Configuration Structure
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```go
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type Config struct {
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// Output Settings
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EnableConsole bool // Enable stdout/stderr output
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ConsoleTarget string // "stdout", "stderr", or "split"
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EnableFile bool // Enable file output
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// Basic Settings
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Level int64 // Minimum log level
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Name string // Base filename (default: "log")
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Directory string // Log directory path
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Format string // "txt", "json", or "raw"
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Extension string // File extension (default: ".log")
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// Formatting
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ShowTimestamp bool // Add timestamps
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ShowLevel bool // Add level labels
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TimestampFormat string // Go time format
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// Buffer and Performance
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BufferSize int64 // Channel buffer size
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FlushIntervalMs int64 // Buffer flush interval
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TraceDepth int64 // Default trace depth (0-10)
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// File Management
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MaxSizeKB int64 // Max file size (KB)
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MaxTotalSizeKB int64 // Max total directory size (KB)
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MinDiskFreeKB int64 // Required free disk space (KB)
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RetentionPeriodHrs float64 // Hours to keep logs
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RetentionCheckMins float64 // Retention check interval
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// Disk Monitoring
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DiskCheckIntervalMs int64 // Base check interval
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EnableAdaptiveInterval bool // Adjust based on load
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MinCheckIntervalMs int64 // Minimum interval
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MaxCheckIntervalMs int64 // Maximum interval
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EnablePeriodicSync bool // Periodic disk sync
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// Heartbeat
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HeartbeatLevel int64 // 0=off, 1=proc, 2=+disk, 3=+sys
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HeartbeatIntervalS int64 // Heartbeat interval
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// Error Handling
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InternalErrorsToStderr bool // Write internal errors to stderr
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}
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```
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### Default Configuration
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```go
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func DefaultConfig() *Config
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```
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Returns default configuration with sensible values:
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- Console output enabled to stdout
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- File output enabled
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- Info level logging
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- 1MB max file size
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- 5MB max total size
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- 100ms flush interval
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## Output Formats
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### Text Format (default)
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Human-readable format with optional timestamps and levels:
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```
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2024-01-15T10:30:00.123456Z INFO Application started version="1.0.0" pid=1234
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2024-01-15T10:30:01.456789Z ERROR Connection failed host="db.example.com" error="timeout"
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```
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### JSON Format
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Structured JSON output for log aggregation:
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```json
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{"time":"2024-01-15T10:30:00.123456Z","level":"INFO","fields":["Application started","version","1.0.0","pid",1234]}
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{"time":"2024-01-15T10:30:01.456789Z","level":"ERROR","fields":["Connection failed","host","db.example.com","error","timeout"]}
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```
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### Raw Format
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Minimal format without timestamps or levels:
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```
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Application started version="1.0.0" pid=1234
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Connection failed host="db.example.com" error="timeout"
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```
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## Framework Adapters (compat package)
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### gnet v2 Adapter
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```go
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import (
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"github.com/lixenwraith/log"
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"github.com/lixenwraith/log/compat"
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"github.com/panjf2000/gnet/v2"
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)
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// Create adapter
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adapter := compat.NewGnetAdapter(logger)
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// Use with gnet
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gnet.Run(handler, "tcp://127.0.0.1:9000", gnet.WithLogger(adapter))
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```
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### fasthttp Adapter
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```go
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import (
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"github.com/lixenwraith/log"
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"github.com/lixenwraith/log/compat"
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"github.com/valyala/fasthttp"
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)
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// Create adapter
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adapter := compat.NewFastHTTPAdapter(logger)
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// Use with fasthttp
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server := &fasthttp.Server{
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Handler: requestHandler,
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Logger: adapter,
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}
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```
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### Adapter Builder Pattern
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```go
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// Share logger across adapters
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builder := compat.NewBuilder().WithLogger(logger)
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gnetAdapter, err := builder.BuildGnet()
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fasthttpAdapter, err := builder.BuildFastHTTP()
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// Or create structured adapters
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structuredGnet, err := builder.BuildStructuredGnet()
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```
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## Common Patterns
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### Service with Shared Logger
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```go
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type Service struct {
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logger *log.Logger
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}
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func NewService() (*Service, error) {
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logger, err := log.NewBuilder().
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Directory("/var/log/service").
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Format("json").
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BufferSize(2048).
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HeartbeatLevel(2).
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Build()
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if err != nil {
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return nil, err
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}
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if err := logger.Start(); err != nil {
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return nil, err
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}
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return &Service{logger: logger}, nil
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}
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func (s *Service) Close() error {
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return s.logger.Shutdown(5 * time.Second)
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}
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func (s *Service) ProcessRequest(id string) {
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s.logger.Info("Processing", "request_id", id)
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// ... process ...
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s.logger.Info("Completed", "request_id", id)
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}
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```
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### HTTP Middleware
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```go
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func loggingMiddleware(logger *log.Logger) func(http.Handler) http.Handler {
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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start := time.Now()
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wrapped := &responseWriter{ResponseWriter: w, status: 200}
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next.ServeHTTP(wrapped, r)
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logger.Info("HTTP request",
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"method", r.Method,
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"path", r.URL.Path,
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"status", wrapped.status,
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"duration_ms", time.Since(start).Milliseconds(),
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"remote_addr", r.RemoteAddr,
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)
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})
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}
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}
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```
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### Hot Reconfiguration
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```go
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// Initial configuration
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logger.ApplyConfigString("level=info")
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// Debugging reconfiguration
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logger.ApplyConfigString(
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"level=debug",
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"heartbeat_level=3",
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"heartbeat_interval_s=60",
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)
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// Revert to normal
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logger.ApplyConfigString(
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"level=info",
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"heartbeat_level=1",
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"heartbeat_interval_s=300",
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)
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```
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### Graceful Shutdown
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```go
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// Setup signal handling
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sigChan := make(chan os.Signal, 1)
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signal.Notify(sigChan, syscall.SIGTERM, syscall.SIGINT)
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// Shutdown sequence
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<-sigChan
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logger.Info("Shutdown initiated")
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// Flush pending logs with timeout
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if err := logger.Shutdown(5 * time.Second); err != nil {
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fmt.Fprintf(os.Stderr, "Logger shutdown error: %v\n", err)
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}
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```
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## Thread Safety
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All public methods are thread-safe. The logger uses:
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- Atomic operations for state management
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- Channels for log record passing
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- No locks in the critical logging path
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## Performance Characteristics
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- **Zero-allocation logging path**: Uses pre-allocated buffers
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- **Lock-free async design**: Non-blocking sends to buffered channel
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- **Adaptive disk checks**: Adjusts I/O based on load
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- **Batch writes**: Flushes buffer periodically, not per-record
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- **Drop tracking**: Counts dropped logs when buffer full
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## Migration Guide
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### From standard log package
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```go
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// Before: standard log
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log.Printf("User login: id=%d name=%s", id, name)
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// After: lixenwraith/log
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logger.Info("User login", "id", id, "name", name)
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```
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### From other structured loggers
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```go
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// Before: zap
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zap.Info("User login",
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zap.Int("id", id),
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zap.String("name", name))
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// After: lixenwraith/log
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logger.Info("User login", "id", id, "name", name)
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```
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## Best Practices
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1. **Use Builder pattern** for configuration - compile-time safety
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2. **Use structured logging** - consistent key-value pairs
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3. **Use appropriate levels** - filter noise in logs |