391 lines
7.5 KiB
Markdown
391 lines
7.5 KiB
Markdown
# API Reference
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Complete API documentation for the lixenwraith/log package.
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## Logger Creation
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### NewLogger
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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 instance with default configuration parameters registered internally.
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**Example:**
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```go
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logger := log.NewLogger()
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```
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## Initialization Methods
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### ApplyConfig
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```go
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func (l *Logger) ApplyConfig(cfg *Config) error
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```
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Applies a validated configuration to the logger. This is the recommended method for applications that need full control over configuration.
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**Parameters:**
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- `cfg`: A `*Config` struct with desired settings
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**Returns:**
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- `error`: Configuration error if invalid
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**Example:**
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```go
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logger := log.NewLogger()
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cfg := log.GetConfig()
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cfg.Level = log.LevelDebug
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cfg.Directory = "/var/log/app"
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err := logger.ApplyConfig(cfg)
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```
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### ApplyConfigString
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```go
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func (l *Logger) ApplyConfigString(overrides ...string) error
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```
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Applies key-value overrides to the logger. Convenient interface for minor changes.
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**Parameters:**
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- `overrides`: Variadic overrides in the format "key=value"
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**Returns:**
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- `error`: Configuration error if invalid
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**Example:**
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```go
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logger := log.NewLogger()
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err := logger.ApplyConfigString("directory=/var/log/app", "name=app")
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```
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## Logging Methods
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All logging methods accept variadic arguments, typically used as key-value pairs for structured logging.
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### Debug
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```go
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func (l *Logger) Debug(args ...any)
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```
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Logs a message at debug level (-4).
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**Example:**
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```go
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logger.Debug("Processing started", "items", 100, "mode", "batch")
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```
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### Info
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```go
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func (l *Logger) Info(args ...any)
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```
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Logs a message at info level (0).
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**Example:**
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```go
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logger.Info("Server started", "port", 8080, "tls", true)
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```
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### Warn
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```go
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func (l *Logger) Warn(args ...any)
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```
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Logs a message at warning level (4).
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**Example:**
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```go
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logger.Warn("High memory usage", "used_mb", 1800, "limit_mb", 2048)
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```
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### Error
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```go
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func (l *Logger) Error(args ...any)
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```
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Logs a message at error level (8).
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**Example:**
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```go
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logger.Error("Database connection failed", "host", "db.example.com", "error", err)
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```
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### LogStructured
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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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```
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Logs a message with structured fields as proper JSON (when format="json").
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**Example:**
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```go
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logger.LogStructured(log.LevelInfo, "User action", map[string]any{
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"user_id": 42,
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"action": "login",
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"metadata": map[string]any{"ip": "192.168.1.1"},
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})
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```
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### Write
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```go
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func (l *Logger) Write(args ...any)
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```
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Outputs raw, unformatted data regardless of configured format. Bypasses all formatting (timestamps, levels, JSON structure) and writes args as space-separated strings without a trailing newline.
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**Example:**
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```go
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logger.Write("METRIC", "cpu_usage", 85.5, "timestamp", 1234567890)
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// Output: METRIC cpu_usage 85.5 timestamp 1234567890
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```
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## Trace Logging Methods
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These methods include function call traces in the log output.
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### DebugTrace
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```go
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func (l *Logger) DebugTrace(depth int, args ...any)
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```
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Logs at debug level with function call trace.
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**Parameters:**
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- `depth`: Number of stack frames to include (0-10)
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- `args`: Log message and fields
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**Example:**
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```go
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logger.DebugTrace(3, "Entering critical section", "mutex", "db_lock")
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```
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### InfoTrace
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```go
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func (l *Logger) InfoTrace(depth int, args ...any)
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```
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Logs at info level with function call trace.
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### WarnTrace
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```go
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func (l *Logger) WarnTrace(depth int, args ...any)
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```
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Logs at warning level with function call trace.
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### ErrorTrace
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```go
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func (l *Logger) ErrorTrace(depth int, args ...any)
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```
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Logs at error level with function call trace.
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## Special Logging Methods
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### Log
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```go
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func (l *Logger) Log(args ...any)
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```
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Logs with timestamp only, no level information (uses Info level internally).
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**Example:**
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```go
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logger.Log("Checkpoint reached", "step", 5)
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```
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### Message
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```go
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func (l *Logger) Message(args ...any)
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```
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Logs raw message without timestamp or level.
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**Example:**
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```go
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logger.Message("Raw output for special formatting")
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```
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### LogTrace
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```go
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func (l *Logger) LogTrace(depth int, args ...any)
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```
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Logs with timestamp and trace, but no level information.
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**Example:**
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```go
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logger.LogTrace(2, "Function boundary", "entering", true)
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```
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## Control Methods
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### Shutdown
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```go
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func (l *Logger) Shutdown(timeout ...time.Duration) error
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```
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Gracefully shuts down the logger, attempting to flush pending logs.
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**Parameters:**
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- `timeout`: Optional timeout duration (defaults to 2x flush interval)
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**Returns:**
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- `error`: Shutdown error if flush fails or timeout exceeded
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**Example:**
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```go
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err := logger.Shutdown(5 * time.Second)
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if err != nil {
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fmt.Printf("Shutdown error: %v\n", err)
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}
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```
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### Flush
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```go
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func (l *Logger) Flush(timeout time.Duration) error
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```
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Explicitly triggers a sync of the current log file buffer to disk.
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**Parameters:**
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- `timeout`: Maximum time to wait for flush completion
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**Returns:**
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- `error`: Flush error if timeout exceeded
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**Example:**
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```go
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err := logger.Flush(1 * time.Second)
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```
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## Constants
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### Log Levels
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```go
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const (
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LevelDebug int64 = -4
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LevelInfo int64 = 0
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LevelWarn int64 = 4
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LevelError int64 = 8
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)
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```
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Standard log levels for filtering output.
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### Heartbeat Levels
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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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Special levels for heartbeat monitoring that bypass level filtering.
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### Level Helper Function
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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.
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**Parameters:**
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- `levelStr`: Level name ("debug", "info", "warn", "error", "proc", "disk", "sys")
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**Returns:**
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- `int64`: Numeric level value
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- `error`: Conversion error for invalid strings
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**Example:**
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```go
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level, err := log.Level("debug") // Returns -4
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```
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## Error Types
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The logger returns errors prefixed with "log: " for easy identification:
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```go
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// Configuration errors
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"log: invalid format: 'xml' (use txt, json, or raw)"
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"log: buffer_size must be positive: 0"
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// Initialization errors
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"log: failed to create log directory '/var/log/app': permission denied"
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"log: logger previously failed to initialize and is disabled"
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// Runtime errors
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"log: logger not initialized or already shut down"
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"log: timeout waiting for flush confirmation (1s)"
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```
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## Thread Safety
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All public methods are thread-safe and can be called concurrently from multiple goroutines. The logger uses atomic operations and channels to ensure safe concurrent access without locks in the critical path.
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### Usage Pattern Example
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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 := log.NewLogger()
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err := logger.ApplyConfigString(
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"directory=/var/log/service",
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"format=json",
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"buffer_size=2048",
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"heartbeat_level=1")
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if err != nil {
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return nil, fmt.Errorf("logger init: %w", 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) ProcessRequest(id string) error {
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s.logger.InfoTrace(1, "Processing request", "id", id)
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if err := s.doWork(id); err != nil {
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s.logger.Error("Request failed", "id", id, "error", err)
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return err
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}
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s.logger.Info("Request completed", "id", id)
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return nil
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}
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func (s *Service) Shutdown() error {
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return s.logger.Shutdown(5 * time.Second)
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}
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```
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---
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[← Configuration Builder](config-builder.md) | [← Back to README](../README.md) | [Logging Guide →](logging-guide.md) |