e1.2.0 Heartbeat feature added.

README.md

@@ -1,133 +1,84 @@
 # Log
 
-A high-performance, buffered, rotating file logger for Go applications, configured via the [LixenWraith/config](https://github.com/LixenWraith/config) package. Designed for production-grade reliability with features like disk management, log retention, and lock-free asynchronous processing using atomic operations and channels.
+A high-performance, buffered, rotating file logger for Go applications, configured via
+the [LixenWraith/config](https://github.com/LixenWraith/config) package or simple overrides. Designed for
+production-grade reliability with features like disk management, log retention, and lock-free asynchronous processing
+using atomic operations and channels.
+
+**Note:** This logger requires creating an instance using `NewLogger()` and calling methods on that instance (e.g.,
+`l.Info(...)`). It does not use package-level logging functions.
 
 ## Features
 
--   **Lock-free Asynchronous Logging:** Non-blocking log operations with minimal application impact. Logs are sent via a buffered channel, processed by a dedicated background goroutine. Uses atomic operations for state management, avoiding mutexes in the hot path.
+- **Instance-Based API:** Create logger instances via `NewLogger()` and use methods like `l.Info()`, `l.Warn()`, etc.
--   **External Configuration:** Fully configured using `github.com/LixenWraith/config`, supporting both TOML files and CLI overrides with centralized management.
+- **Lock-free Asynchronous Logging:** Non-blocking log operations with minimal application impact. Logs are sent via a
--   **Automatic File Rotation:** Seamlessly rotates log files when they reach configurable size limits (`max_size_mb`), generating timestamped filenames.
+  buffered channel, processed by a dedicated background goroutine. Uses atomic operations for state management, avoiding
+  mutexes in the hot path.
+- **External Configuration:** Fully configured using `github.com/LixenWraith/config`, supporting both TOML files and CLI
+  overrides with centralized management. Also supports simple initialization with defaults and string overrides via
+  `InitWithDefaults`.
+- **Automatic File Rotation:** Seamlessly rotates log files when they reach configurable size limits (`max_size_mb`),
+  generating timestamped filenames.
 - **Comprehensive Disk Management:**
     - Monitors total log directory size against configured limits (`max_total_size_mb`)
     - Enforces minimum free disk space requirements (`min_disk_free_mb`)
     - Automatically prunes oldest log files to maintain space constraints
     - Implements recovery behavior when disk space is exhausted
--   **Adaptive Resource Monitoring:** Dynamically adjusts disk check frequency based on logging volume (`enable_adaptive_interval`, `min_check_interval_ms`, `max_check_interval_ms`), optimizing performance under varying loads.
+- **Adaptive Resource Monitoring:** Dynamically adjusts disk check frequency based on logging volume (
--   **Reliable Buffer Management:** Periodic buffer flushing with configurable intervals (`flush_interval_ms`). Detects and reports dropped logs during high-volume scenarios.
+  `enable_adaptive_interval`, `min_check_interval_ms`, `max_check_interval_ms`), optimizing performance under varying
--   **Automated Log Retention:** Time-based log file cleanup with configurable retention periods (`retention_period_hrs`, `retention_check_mins`).
+  loads.
--   **Structured Logging:** Support for both human-readable text (`txt`) and machine-parseable (`json`) output formats with consistent field handling.
+- **Operational Heartbeats:** Multi-level periodic statistics messages (process, disk, system) that bypass level
--   **Comprehensive Log Levels:** Standard severity levels (Debug, Info, Warn, Error) with numeric values compatible with other logging systems.
+  filtering to ensure operational monitoring even with higher log levels.
--   **Function Call Tracing:** Optional function call stack traces with configurable depth (`trace_depth`) for debugging complex execution flows.
+- **Reliable Buffer Management:** Periodic buffer flushing with configurable intervals (`flush_interval_ms`). Detects
--   **Clean API Design:** Straightforward logging methods that don't require `context.Context` parameters.
+  and reports dropped logs during high-volume scenarios.
--   **Graceful Shutdown:** Managed termination with best-effort flushing to minimize log data loss during application shutdown.
+- **Automated Log Retention:** Time-based log file cleanup with configurable retention periods (`retention_period_hrs`,
+  `retention_check_mins`).
+- **Structured Logging:** Support for both human-readable text (`txt`) and machine-parseable (`json`) output formats
+  with consistent field handling.
+- **Comprehensive Log Levels:** Standard severity levels (Debug, Info, Warn, Error) with numeric values compatible with
+  other logging systems.
+- **Function Call Tracing:** Optional function call stack traces with configurable depth (`trace_depth`) for debugging
+  complex execution flows.
+- **Clean API Design:** Straightforward logging methods on the logger instance that don't require `context.Context`
+  parameters.
+- **Graceful Shutdown:** Managed termination with best-effort flushing to minimize log data loss during application
+  shutdown.
 
 ## Installation
 
 ```bash
 go get github.com/LixenWraith/log
-go get github.com/LixenWraith/config
+# If using full TOML/CLI config:
+# go get github.com/LixenWraith/config
 ```
 
 ## Basic Usage
 
+This example shows minimal initialization using defaults with a single override, logging one message, and shutting down.
+
 ```go
 package main
 
 import (
-	"fmt"
+    "github.com/LixenWraith/log"
-	"os"
-	"sync"
-	"time"
-
-	"github.com/LixenWraith/config" // External config package
-	"github.com/LixenWraith/log"    // This logger package
 )
 
-const configFile = "app_config.toml"
-const logConfigPath = "logging" // Base path for logger settings in TOML/config
-
-// Example app_config.toml content:
-/*
-[logging]
-  level = 0 # Info Level (0)
-  directory = "./app_logs"
-  format = "json"
-  extension = "log"
-  max_size_mb = 50
-  flush_interval_ms = 100
-  disk_check_interval_ms = 5000 # Check disk every 5s
-  enable_adaptive_interval = true
-  # Other settings will use defaults registered by log.Init
-*/
-
 func main() {
-	// 1. Initialize the main config manager
+    logger := log.NewLogger()
-	cfg := config.New()
+    _ = logger.InitWithDefaults("directory=/var/log/myapp")
-
+    logger.Info("Application starting", "pid", 12345)
-	// Optional: Create a dummy config file if it doesn't exist
+    _ = logger.Shutdown()
-	if _, err := os.Stat(configFile); os.IsNotExist(err) {
-		content := fmt.Sprintf("[%s]\n  level = 0\n  directory = \"./app_logs\"\n", logConfigPath)
-		os.WriteFile(configFile, []byte(content), 0644)
-	}
-
-	// 2. Load configuration (e.g., from file and/or CLI)
-	_, err := cfg.Load(configFile, os.Args[1:])
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Warning: Failed to load config file '%s': %v. Using defaults.\n", configFile, err)
-	}
-
-	// 3. Initialize the logger, passing the config instance and base path.
-	// log.Init registers necessary keys (e.g., "logging.level") with cfg.
-	err = log.Init(cfg, logConfigPath)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Fatal: Failed to initialize logger: %v\n", err)
-		os.Exit(1)
-	}
-	fmt.Println("Logger initialized.")
-
-	// 4. Optionally save the merged config (defaults + file/CLI overrides)
-	err = cfg.Save(configFile) // Save back to the file
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Warning: Failed to save config: %v\n", err)
-	}
-
-	// 5. Use the logger
-	log.Info("Application started", "pid", os.Getpid())
-	log.Debug("Debugging info", "value", 42) // Might be filtered by level
-
-	// Example concurrent logging
-	var wg sync.WaitGroup
-	for i := 0; i < 3; i++ {
-		wg.Add(1)
-		go func(id int) {
-			defer wg.Done()
-			log.Info("Goroutine task started", "goroutine_id", id)
-			time.Sleep(time.Duration(id*10) * time.Millisecond)
-			log.InfoTrace(1, "Goroutine task finished", "goroutine_id", id)
-		}(i)
-	}
-	wg.Wait()
-
-	// ... application logic ...
-
-	// 6. Shutdown the logger gracefully before exit
-	fmt.Println("Shutting down...")
-	// Shutdown timeout is used internally for a brief wait, not a hard deadline for flushing.
-	shutdownTimeout := 2 * time.Second
-	err = log.Shutdown(shutdownTimeout) // Pass timeout (used for internal sleep)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Logger shutdown error: %v\n", err)
-	}
-	fmt.Println("Shutdown complete.")
 }
 ```
 
 ## Configuration
 
-The `log` package is configured via keys registered with the `config.Config` instance passed to `log.Init`. `log.Init` expects these keys relative to the `basePath` argument.
+The `log` package is configured via keys registered with the `config.Config` instance passed to `(l *Logger) Init`, or
+via string overrides passed to `(l *Logger) InitWithDefaults`. `Init` expects these keys relative to the `basePath`
+argument.
 
 | Key (`basePath` + Key)     | Type      | Description                                                               | Default Value |
-|:---------------------------| :-------- |:-----------------------------------------------------------------|:--------------|
+|:---------------------------|:----------|:--------------------------------------------------------------------------|:--------------|
 | `level`                    | `int64`   | Minimum log level (-4=Debug, 0=Info, 4=Warn, 8=Error)                     | `0` (Info)    |
 | `name`                     | `string`  | Base name for log files                                                   | `"log"`       |
 | `directory`                | `string`  | Directory to store log files                                              | `"./logs"`    |
@@ -145,130 +96,156 @@ The `log` package is configured via keys registered with the `config.Config` ins
 | `retention_check_mins`     | `float64` | Minutes between retention checks via timer (if enabled)                   | `60.0`        |
 | `disk_check_interval_ms`   | `int64`   | Base interval (ms) for periodic disk space checks via timer               | `5000`        |
 | `enable_adaptive_interval` | `bool`    | Adjust disk check interval based on load (within min/max bounds)          | `true`        |
-| `enable_periodic_sync`     | `bool`    | Periodic sync with disk based on flush interval                  | `false`       |
+| `enable_periodic_sync`     | `bool`    | Periodic sync with disk based on flush interval                           | `true`        |
 | `min_check_interval_ms`    | `int64`   | Minimum interval (ms) for adaptive disk checks                            | `100`         |
 | `max_check_interval_ms`    | `int64`   | Maximum interval (ms) for adaptive disk checks                            | `60000`       |
+| `heartbeat_level`          | `int64`   | Heartbeat detail level (0=disabled, 1=proc, 2=proc+disk, 3=proc+disk+sys) | `0`           |
+| `heartbeat_interval_s`     | `int64`   | Interval (s) between heartbeat messages                                   | `60`          |
 
-**Example TOML Configuration (`app_config.toml`)**
+**Example TOML Configuration** (Used with `(l *Logger) Init` and the `config` package)
+
+# Assuming basePath = "logging" passed to Init
 
 ```toml
-# Main application settings
-app_name = "My Service"
-
-# Logger settings under the 'logging' base path
 [logging]
-  level = -4 # Debug
+level = -4 # Debug
-  directory = "/var/log/my_service"
+directory = "/var/log/my_service"
-  format = "json"
+format = "json"
-  extension = "log"
+max_size_mb = 100
-  max_size_mb = 100
+retention_period_hrs = 168.0 # 7 days
-  max_total_size_mb = 1024 # 1 GB total
+heartbeat_level = 2 # Process + disk statistics
-  min_disk_free_mb = 512 # 512 MB free required
-  flush_interval_ms = 100
-  trace_depth = 2
-  retention_period_hrs = 168.0 # 7 days (7 * 24)
-  retention_check_mins = 60.0
-  disk_check_interval_ms = 10000 # Check disk every 10 seconds
-  enable_adaptive_interval = false # Disable adaptive checks
-
-# Other application settings
-[database]
-  host = "db.example.com"
 ```
 
 ## API Reference
 
+**Note:** All logging and control functions are methods on a `*Logger` instance obtained via `NewLogger()`.
+
+### Creation
+
+- **`NewLogger() *Logger`**
+  Creates a new, uninitialized logger instance with default configuration parameters registered internally.
+
 ### Initialization
 
--   **`Init(cfg *config.Config, basePath string) error`**
+- **`(l *Logger) Init(cfg *config.Config, basePath string) error`**
-    Initializes or reconfigures the logger using settings from the provided `config.Config` instance under `basePath`. Registers required keys with defaults if not present. Thread-safe.
+  Initializes the logger instance `l` using settings from the provided `config.Config` instance under `basePath`. Starts
--   **`InitWithDefaults(overrides ...string) error`**
+  the background processing goroutine.
-    Initializes the logger using built-in defaults, applying optional overrides provided as "key=value" strings. Thread-safe.
+- **`(l *Logger) InitWithDefaults(overrides ...string) error`**
+  Initializes the logger instance `l` using built-in defaults, applying optional overrides provided as "key=value"
+  strings (e.g., `"directory=/tmp/logs"`). Starts the background processing goroutine.
 
 ### Logging Functions
 
-These methods accept `...any` arguments, typically used as key-value pairs for structured logging (e.g., `"user_id", 123, "status", "active"`). All logging functions are non-blocking and use atomic operations for state checks.
+These methods accept `...any` arguments, typically used as key-value pairs for structured logging. They are called on an
+initialized `*Logger` instance (e.g., `l.Info(...)`).
 
--   **`Debug(args ...any)`**: Logs at Debug level (-4).
+- **`(l *Logger) Debug(args ...any)`**: Logs at Debug level (-4).
--   **`Info(args ...any)`**: Logs at Info level (0).
+- **`(l *Logger) Info(args ...any)`**: Logs at Info level (0).
--   **`Warn(args ...any)`**: Logs at Warn level (4).
+- **`(l *Logger) Warn(args ...any)`**: Logs at Warn level (4).
--   **`Error(args ...any)`**: Logs at Error level (8).
+- **`(l *Logger) Error(args ...any)`**: Logs at Error level (8).
 
 ### Trace Logging Functions
 
-Temporarily enable function call tracing for a single log entry, regardless of the configured `trace_depth`.
+Temporarily enable function call tracing for a single log entry on an initialized `*Logger` instance.
 
--   **`DebugTrace(depth int, args ...any)`**: Logs Debug with trace.
+- **`(l *Logger) DebugTrace(depth int, args ...any)`**: Logs Debug with trace.
--   **`InfoTrace(depth int, args ...any)`**: Logs Info with trace.
+- **`(l *Logger) InfoTrace(depth int, args ...any)`**: Logs Info with trace.
--   **`WarnTrace(depth int, args ...any)`**: Logs Warn with trace.
+- **`(l *Logger) WarnTrace(depth int, args ...any)`**: Logs Warn with trace.
--   **`ErrorTrace(depth int, args ...any)`**: Logs Error with trace.
+- **`(l *Logger) ErrorTrace(depth int, args ...any)`**: Logs Error with trace.
   (`depth` specifies the number of stack frames, 0-10).
 
 ### Other Logging Variants
 
--   **`Log(args ...any)`**: Logs with timestamp only, no level (uses Info internally).
+Called on an initialized `*Logger` instance.
--   **`Message(args ...any)`**: Logs raw message without timestamp or level.
+
--   **`LogTrace(depth int, args ...any)`**: Logs with timestamp and trace, no level.
+- **`(l *Logger) Log(args ...any)`**: Logs with timestamp only, no level (uses Info internally).
+- **`(l *Logger) Message(args ...any)`**: Logs raw message without timestamp or level.
+- **`(l *Logger) LogTrace(depth int, args ...any)`**: Logs with timestamp and trace, no level.
 
 ### Shutdown and Control
 
--   **`Shutdown(timeout time.Duration) error`**
+Called on an initialized `*Logger` instance.
-    Gracefully shuts down the logger. Signals the processor to stop, waits briefly for pending logs to flush, then closes file handles. Returns error details if closing operations fail.
 
--   **`Flush(timeout time.Duration) error`**
+- **`(l *Logger) Shutdown(timeout time.Duration) error`**
-    Explicitly triggers a sync of the current log file buffer to disk and waits for completion or timeout.
+  Gracefully shuts down the logger instance `l`. Signals the processor to stop, waits briefly for pending logs to flush,
+  then closes file handles.
+
+- **`(l *Logger) Flush(timeout time.Duration) error`**
+  Explicitly triggers a sync of the current log file buffer to disk for instance `l` and waits for completion or
+  timeout.
 
 ### Constants
 
--   **`LevelDebug (-4)`, `LevelInfo (0)`, `LevelWarn (4)`, `LevelError (8)` (`int64`)**: Log level constants.
+- **`LevelDebug (-4)`, `LevelInfo (0)`, `LevelWarn (4)`, `LevelError (8)` (`int64`)**: Standard log level constants.
+- **`LevelProc (12)`, `LevelDisk (16)`, `LevelSys (20)` (`int64`)**: Heartbeat log level constants. These levels bypass
+  the configured `level` filter.
 - **`FlagShowTimestamp`, `FlagShowLevel`, `FlagDefault`**: Record flag constants controlling output format.
 
 ## Implementation Details
 
--   **Lock-Free Hot Path:** Log methods (`Info`, `Debug`, etc.) operate without locks, using atomic operations to check logger state and non-blocking channel sends. Only initialization, reconfiguration, and shutdown use a mutex.
+- **Lock-Free Hot Path:** Logging methods (`l.Info`, `l.Debug`, etc.) operate without locks, using atomic operations to
+  check logger state and non-blocking channel sends. Only initialization, reconfiguration, and shutdown use a mutex
+  internally.
 
--   **Channel-Based Architecture:** Log records flow through a buffered channel from producer methods to a single consumer goroutine, preventing contention and serializing file I/O operations.
+- **Channel-Based Architecture:** Log records flow through a buffered channel from producer methods to a single consumer
+  goroutine per logger instance, preventing contention and serializing file I/O operations.
 
 - **Adaptive Resource Management:**
-    - Disk checks run periodically via timer and reactively when write volume thresholds are crossed
+    - Disk checks run periodically via timer and reactively when write volume thresholds are crossed.
-    - Check frequency automatically adjusts based on logging rate when `enable_adaptive_interval` is enabled
+    - Check frequency automatically adjusts based on logging rate when `enable_adaptive_interval` is enabled.
-    - Intelligently backs off during low activity and increases responsiveness during high volume
+
+- **Heartbeat Messages:**
+    - Periodic operational statistics that bypass log level filtering.
+    - Three levels of detail (`heartbeat_level`):
+        - Level 1 (PROC): Logger metrics (uptime, processed/dropped logs)
+        - Level 2 (DISK): Adds disk metrics (rotations, deletions, file counts, sizes)
+        - Level 3 (SYS): Adds system metrics (memory usage, goroutine count, GC stats)
+    - Ensures monitoring data is available regardless of the configured `level`.
 
 - **File Management:**
-    - Log files are rotated when `max_size_mb` is exceeded, with new files named using timestamps
+    - Log files are rotated when `max_size_mb` is exceeded.
-    - Oldest files (by modification time) are automatically pruned when space limits are approached
+    - Oldest files are automatically pruned when space limits (`max_total_size_mb`, `min_disk_free_mb`) are approached.
-    - Files older than `retention_period_hrs` are periodically removed
+    - Files older than `retention_period_hrs` are periodically removed.
 
--   **Recovery Behavior:** When disk issues occur, the logger temporarily pauses new logs and attempts recovery on subsequent operations, logging one disk warning message to prevent error spam.
+- **Recovery Behavior:** When disk issues occur, the logger temporarily pauses new logs and attempts recovery on
+  subsequent operations, logging one disk warning message to prevent error spam.
 
 - **Graceful Shutdown Flow:**
-    1. Sets atomic flags to prevent new logs
+    1. Sets atomic flags to prevent new logs on the specific instance.
-    2. Closes the active log channel to signal processor shutdown
+    2. Closes the active log channel to signal processor shutdown for that instance.
-    3. Waits briefly for processor to finish pending records
+    3. Waits briefly for the processor to finish pending records.
-    4. Performs final sync and closes the file handle
+    4. Performs final sync and closes the file handle.
 
 ## Performance Considerations
 
--   **Non-blocking Design:** The logger is designed to have minimal impact on application performance, with non-blocking log operations and buffered processing.
+- **Non-blocking Design:** The logger is designed to have minimal impact on application performance, with non-blocking
+  log operations and buffered processing.
 
--   **Memory Efficiency:** Uses a reusable buffer for serialization, avoiding unnecessary allocations when formatting log entries.
+- **Memory Efficiency:** Uses a reusable buffer (`serializer`) per instance for serialization, avoiding unnecessary
+  allocations when formatting log entries.
 
--   **Disk I/O Management:** Batches writes and intelligently schedules disk operations to minimize I/O overhead while maintaining data safety.
+- **Disk I/O Management:** Batches writes and intelligently schedules disk operations to minimize I/O overhead while
+  maintaining data safety.
 
--   **Concurrent Safety:** Thread-safe through careful use of atomic operations, minimizing mutex usage to initialization and shutdown paths only.
+- **Concurrent Safety:** Thread-safe through careful use of atomic operations and channel-based processing, minimizing
+  mutex usage to initialization and shutdown paths only. Multiple `*Logger` instances operate independently.
 
 ## Caveats & Limitations
 
 - **Log Loss Scenarios:**
-    -   **Buffer Saturation:** Under extreme load, logs may be dropped if the internal buffer fills faster than records can be processed. A summary message will be logged once capacity is available again.
+    - **Buffer Saturation:** Under extreme load, logs may be dropped if the internal buffer fills faster than records
-    -   **Shutdown Race:** The `Shutdown` function provides a best-effort attempt to process remaining logs, but cannot guarantee all buffered logs will be written if the application terminates quickly.
+      can be processed by the background goroutine. A summary message will be logged once capacity is available again.
-    -   **Persistent Disk Issues:** If disk space cannot be reclaimed through cleanup, logs will be dropped until the condition is resolved.
+    - **Shutdown Race:** The `Shutdown` function provides a best-effort attempt to process remaining logs, but cannot
+      guarantee all buffered logs will be written if the application terminates abruptly or the timeout is too short.
+    - **Persistent Disk Issues:** If disk space cannot be reclaimed through cleanup, logs will be dropped until the
+      condition is resolved.
 
--   **Configuration Dependencies:** Requires the `github.com/LixenWraith/config` package for advanced configuration management.
+- **Configuration Dependencies:** Requires the `github.com/LixenWraith/config` package for advanced configuration
+  management via TOML/CLI using the `Init` method. `InitWithDefaults` provides simpler initialization without this
+  dependency.
 
--   **Retention Accuracy:** Log retention relies on file modification times, which could be affected by external file system operations.
+- **Retention Accuracy:** Log retention relies on file modification times, which could potentially be affected by
-
+  external file system operations.
--   **Reconfiguration Impact:** Changing buffer size during runtime requires restarting the background processor, which may cause a brief period where logs could be dropped.
 
 ## License
 

cmd/heartbeat/main.go

@@ -0,0 +1,80 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/LixenWraith/log"
+)
+
+func main() {
+	// Create test log directory if it doesn't exist
+	if err := os.MkdirAll("./logs", 0755); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to create test logs directory: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Test cycle: disable -> PROC -> PROC+DISK -> PROC+DISK+SYS -> PROC+DISK -> PROC -> disable
+	levels := []struct {
+		level       int64
+		description string
+	}{
+		{0, "Heartbeats disabled"},
+		{1, "PROC heartbeats only"},
+		{2, "PROC+DISK heartbeats"},
+		{3, "PROC+DISK+SYS heartbeats"},
+		{2, "PROC+DISK heartbeats (reducing from 3)"},
+		{1, "PROC heartbeats only (reducing from 2)"},
+		{0, "Heartbeats disabled (final)"},
+	}
+
+	// Create a single logger instance that we'll reconfigure
+	logger := log.NewLogger()
+
+	for _, levelConfig := range levels {
+		// Set up configuration overrides
+		overrides := []string{
+			"directory=./logs",
+			"level=-4",               // Debug level to see everything
+			"format=txt",             // Use text format for easier reading
+			"heartbeat_interval_s=5", // Short interval for testing
+			fmt.Sprintf("heartbeat_level=%d", levelConfig.level),
+		}
+
+		// Initialize logger with the new configuration
+		// Note: InitWithDefaults handles reconfiguration of an existing logger
+		if err := logger.InitWithDefaults(overrides...); err != nil {
+			fmt.Fprintf(os.Stderr, "Failed to initialize logger: %v\n", err)
+			os.Exit(1)
+		}
+
+		// Log the current test state
+		fmt.Printf("\n--- Testing heartbeat level %d: %s ---\n", levelConfig.level, levelConfig.description)
+		logger.Info("Heartbeat test started", "level", levelConfig.level, "description", levelConfig.description)
+
+		// Generate some logs to trigger heartbeat counters
+		for j := 0; j < 10; j++ {
+			logger.Debug("Debug test log", "iteration", j, "level_test", levelConfig.level)
+			logger.Info("Info test log", "iteration", j, "level_test", levelConfig.level)
+			logger.Warn("Warning test log", "iteration", j, "level_test", levelConfig.level)
+			logger.Error("Error test log", "iteration", j, "level_test", levelConfig.level)
+			time.Sleep(100 * time.Millisecond)
+		}
+
+		// Wait for heartbeats to generate (slightly longer than the interval)
+		waitTime := 6 * time.Second
+		fmt.Printf("Waiting %v for heartbeats to generate...\n", waitTime)
+		time.Sleep(waitTime)
+
+		logger.Info("Heartbeat test completed for level", "level", levelConfig.level)
+	}
+
+	// Final shutdown
+	if err := logger.Shutdown(2 * time.Second); err != nil {
+		fmt.Fprintf(os.Stderr, "Warning: Failed to shut down logger: %v\n", err)
+	}
+
+	fmt.Println("\nHeartbeat test program completed successfully")
+	fmt.Println("Check logs directory for generated log files")
+}

cmd/simple/main.go

@@ -18,7 +18,7 @@ var tomlContent = `
 # Example simple_config.toml
 [logging]
   level = -4 # Debug
-  directory = "./simple_logs"
+  directory = "./logs"
   format = "txt"
   extension = "log"
   show_timestamp = true
@@ -113,5 +113,5 @@ func main() {
 
 	// NO time.Sleep needed here - log.Shutdown waits.
 	fmt.Println("--- Example Finished ---")
-	fmt.Printf("Check log files in './simple_logs' and the saved config '%s'.\n", configFile)
+	fmt.Printf("Check log files in './logs' and the saved config '%s'.\n", configFile)
 }

cmd/stress/main.go

@@ -31,7 +31,7 @@ var tomlContent = `
 [logstress]
   level = -4 # Debug
   name = "stress_test"
-  directory = "./stress_logs" # Log package will create this
+  directory = "./logs" # Log package will create this
   format = "txt"
   extension = "log"
   show_timestamp = true
@@ -115,7 +115,7 @@ func main() {
 		os.Exit(1)
 	}
 	fmt.Printf("Created dummy config file: %s\n", configFile)
-	logsDir := "./stress_logs" // Match config
+	logsDir := "./logs"       // Match config
 	_ = os.RemoveAll(logsDir) // Clean previous run's LOGS directory before starting
 	// defer os.Remove(configFile) // Remove to keep the saved config file
 	// defer os.RemoveAll(logsDir) // Remove to keep the log directory

config.go

@@ -36,6 +36,10 @@ type Config struct {
 	EnablePeriodicSync     bool  `toml:"enable_periodic_sync"`     // Periodic sync with disk
 	MinCheckIntervalMs     int64 `toml:"min_check_interval_ms"`    // Minimum adaptive interval
 	MaxCheckIntervalMs     int64 `toml:"max_check_interval_ms"`    // Maximum adaptive interval
+
+	// Heartbeat configuration
+	HeartbeatLevel     int64 `toml:"heartbeat_level"`      // 0=disabled, 1=proc only, 2=proc+disk, 3=proc+disk+sys
+	HeartbeatIntervalS int64 `toml:"heartbeat_interval_s"` // Interval seconds for heartbeat
 }
 
 // defaultConfig is the single source of truth for all default values
@@ -66,9 +70,13 @@ var defaultConfig = Config{
 	// Disk check settings
 	DiskCheckIntervalMs:    5000,
 	EnableAdaptiveInterval: true,
-	EnablePeriodicSync:     false,
+	EnablePeriodicSync:     true,
 	MinCheckIntervalMs:     100,
 	MaxCheckIntervalMs:     60000,
+
+	// Heartbeat settings
+	HeartbeatLevel:     0,  // Disabled by default
+	HeartbeatIntervalS: 60, // Default to 60 seconds if enabled
 }
 
 // DefaultConfig returns a copy of the default configuration
@@ -123,7 +131,13 @@ func (c *Config) validate() error {
 		return fmtErrorf("retention_period_hrs cannot be negative: %f", c.RetentionPeriodHrs)
 	}
 	if c.RetentionCheckMins < 0 {
-		// Allow 0 check interval (disables periodic check but not initial)
+		return fmtErrorf("retention_check_mins cannot be negative: %f", c.RetentionCheckMins)
+	}
+	if c.HeartbeatLevel < 0 || c.HeartbeatLevel > 3 {
+		return fmtErrorf("heartbeat_level must be between 0 and 3: %d", c.HeartbeatLevel)
+	}
+	if c.HeartbeatLevel > 0 && c.HeartbeatIntervalS <= 0 {
+		return fmtErrorf("heartbeat_interval_s must be positive when heartbeat is enabled: %d", c.HeartbeatIntervalS)
 	}
 	return nil
 }

format.go

@@ -232,7 +232,7 @@ func (s *serializer) writeJSONValue(v any) {
 	}
 }
 
-// levelToString converts numeric levels to string representation.
+// Update the levelToString function to include the new heartbeat levels
 func levelToString(level int64) string {
 	switch level {
 	case LevelDebug:
@@ -243,6 +243,12 @@ func levelToString(level int64) string {
 		return "WARN"
 	case LevelError:
 		return "ERROR"
+	case LevelProc:
+		return "PROC"
+	case LevelDisk:
+		return "DISK"
+	case LevelSys:
+		return "SYS"
 	default:
 		return fmt.Sprintf("LEVEL(%d)", level)
 	}

go.mod

@@ -2,7 +2,7 @@ module github.com/LixenWraith/log
 
 go 1.24.2
 
-require github.com/LixenWraith/config v0.0.0-20250423043415-925ccb5f1748
+require github.com/LixenWraith/config v0.0.0-20250423082047-b106c94c2c8b
 
 require (
 	github.com/LixenWraith/tinytoml v0.0.0-20250422065624-8aa28720f04a // indirect

go.sum

@@ -1,5 +1,5 @@
-github.com/LixenWraith/config v0.0.0-20250423043415-925ccb5f1748 h1:d5Kq0OSqsJM8eSwA4xvoAOAWwniKBgZOy3h4e4fjiPo=
+github.com/LixenWraith/config v0.0.0-20250423082047-b106c94c2c8b h1:IYhbozsDOhT1fiogABpomRq9IEonNmQs54ROPn3Xy4g=
-github.com/LixenWraith/config v0.0.0-20250423043415-925ccb5f1748/go.mod h1:LWz2FXeYAN1IxmPFAmbMZLhL/5LbHzJgnj4m7l5jGvc=
+github.com/LixenWraith/config v0.0.0-20250423082047-b106c94c2c8b/go.mod h1:LWz2FXeYAN1IxmPFAmbMZLhL/5LbHzJgnj4m7l5jGvc=
 github.com/LixenWraith/tinytoml v0.0.0-20250422065624-8aa28720f04a h1:m+lhpIexwlJa5m1QuEveRmaGIE+wp87T97PyX1IWbMw=
 github.com/LixenWraith/tinytoml v0.0.0-20250422065624-8aa28720f04a/go.mod h1:Vax79K0I//Klsa8POjua/XHbsMUiIdjJHr59VFbc0/8=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=

interface.go

@@ -13,6 +13,13 @@ const (
 	LevelError int64 = 8
 )
 
+// Heartbeat log levels
+const (
+	LevelProc int64 = 12 // Process/Logger Stats
+	LevelDisk int64 = 16 // Disk/File Stats
+	LevelSys  int64 = 20 // System/Runtime Stats
+)
+
 // Record flags for controlling output structure
 const (
 	FlagShowTimestamp int64 = 0b01

logger.go

@@ -13,10 +13,10 @@ import (
 
 // Logger is the core struct that encapsulates all logger functionality
 type Logger struct {
-	config     *config.Config // Config management
+	config     *config.Config
 	state      State
-	initMu     sync.Mutex  // Only mutex we need to keep
+	initMu     sync.Mutex
-	serializer *serializer // Encapsulated serializer instance
+	serializer *serializer
 }
 
 // NewLogger creates a new Logger instance with default settings
@@ -39,6 +39,13 @@ func NewLogger() *Logger {
 	l.state.CurrentSize.Store(0)
 	l.state.EarliestFileTime.Store(time.Time{})
 
+	// Initialize heartbeat counters
+	l.state.HeartbeatSequence.Store(0)
+	l.state.LoggerStartTime.Store(time.Now())
+	l.state.TotalLogsProcessed.Store(0)
+	l.state.TotalRotations.Store(0)
+	l.state.TotalDeletions.Store(0)
+
 	// Create a closed channel initially to prevent nil pointer issues
 	initialChan := make(chan logRecord)
 	close(initialChan)
@@ -245,6 +252,8 @@ func (l *Logger) loadCurrentConfig() *Config {
 	cfg.MinCheckIntervalMs, _ = l.config.Int64("log.min_check_interval_ms")
 	cfg.MaxCheckIntervalMs, _ = l.config.Int64("log.max_check_interval_ms")
 	cfg.EnablePeriodicSync, _ = l.config.Bool("log.enable_periodic_sync")
+	cfg.HeartbeatLevel, _ = l.config.Int64("log.heartbeat_level")
+	cfg.HeartbeatIntervalS, _ = l.config.Int64("log.heartbeat_interval_s")
 	return cfg
 }
 

processor.go

@@ -4,10 +4,7 @@ package log
 import (
 	"fmt"
 	"os"
-	"path/filepath"
+	"runtime"
-	"sort"
-	"strings"
-	"syscall"
 	"time"
 )
 
@@ -24,30 +21,148 @@ func (l *Logger) processLogs(ch <-chan logRecord) {
 	l.state.ProcessorExited.Store(false)      // Mark processor as running
 	defer l.state.ProcessorExited.Store(true) // Ensure flag is set on exit
 
-	// Get configuration values for setup
+	// Set up timers and state variables
+	timers := l.setupProcessingTimers()
+	defer l.closeProcessingTimers(timers)
+
+	// Perform an initial disk check on startup
+	l.performDiskCheck(true) // Force check and update status
+
+	// Send initial heartbeats immediately instead of waiting for first tick
+	heartbeatLevel, _ := l.config.Int64("log.heartbeat_level")
+	if heartbeatLevel > 0 {
+		if heartbeatLevel >= 1 {
+			l.logProcHeartbeat()
+		}
+		if heartbeatLevel >= 2 {
+			l.logDiskHeartbeat()
+		}
+		if heartbeatLevel >= 3 {
+			l.logSysHeartbeat()
+		}
+	}
+
+	// State variables for adaptive disk checks
+	var bytesSinceLastCheck int64 = 0
+	var lastCheckTime time.Time = time.Now()
+	var logsSinceLastCheck int64 = 0
+
+	// --- Main Loop ---
+	for {
+		select {
+		case record, ok := <-ch:
+			if !ok {
+				// Channel closed: Perform final sync and exit
+				l.performSync()
+				return
+			}
+
+			// Process the received log record
+			bytesWritten := l.processLogRecord(record)
+			if bytesWritten > 0 {
+				// Update adaptive check counters
+				bytesSinceLastCheck += bytesWritten
+				logsSinceLastCheck++
+
+				// Reactive Check Trigger
+				if bytesSinceLastCheck > reactiveCheckThresholdBytes {
+					if l.performDiskCheck(false) { // Check without forcing cleanup yet
+						bytesSinceLastCheck = 0 // Reset if check OK
+						logsSinceLastCheck = 0
+						lastCheckTime = time.Now()
+					}
+				}
+			}
+
+		case <-timers.flushTicker.C:
+			l.handleFlushTick()
+
+		case <-timers.diskCheckTicker.C:
+			// Periodic disk check
+			if l.performDiskCheck(true) { // Periodic check, force cleanup if needed
+				l.adjustDiskCheckInterval(timers, lastCheckTime, logsSinceLastCheck)
+				// Reset counters after successful periodic check
+				bytesSinceLastCheck = 0
+				logsSinceLastCheck = 0
+				lastCheckTime = time.Now()
+			}
+
+		case confirmChan := <-l.state.flushRequestChan:
+			l.handleFlushRequest(confirmChan)
+
+		case <-timers.retentionChan:
+			l.handleRetentionCheck()
+
+		case <-timers.heartbeatChan:
+			l.handleHeartbeat()
+		}
+	}
+}
+
+// TimerSet holds all timers used in processLogs
+type TimerSet struct {
+	flushTicker     *time.Ticker
+	diskCheckTicker *time.Ticker
+	retentionTicker *time.Ticker
+	heartbeatTicker *time.Ticker
+	retentionChan   <-chan time.Time
+	heartbeatChan   <-chan time.Time
+}
+
+// setupProcessingTimers creates and configures all necessary timers for the processor
+func (l *Logger) setupProcessingTimers() *TimerSet {
+	timers := &TimerSet{}
+
+	// Set up flush timer
 	flushInterval, _ := l.config.Int64("log.flush_interval_ms")
 	if flushInterval <= 0 {
 		flushInterval = 100
 	}
-	flushTicker := time.NewTicker(time.Duration(flushInterval) * time.Millisecond)
+	timers.flushTicker = time.NewTicker(time.Duration(flushInterval) * time.Millisecond)
-	defer flushTicker.Stop()
 
-	// Retention Timer
+	// Set up retention timer if enabled
-	var retentionTicker *time.Ticker
+	timers.retentionChan = l.setupRetentionTimer(timers)
-	var retentionChan <-chan time.Time = nil
+
+	// Set up disk check timer
+	timers.diskCheckTicker = l.setupDiskCheckTimer()
+
+	// Set up heartbeat timer
+	timers.heartbeatChan = l.setupHeartbeatTimer(timers)
+
+	return timers
+}
+
+// closeProcessingTimers stops all active timers
+func (l *Logger) closeProcessingTimers(timers *TimerSet) {
+	timers.flushTicker.Stop()
+	if timers.diskCheckTicker != nil {
+		timers.diskCheckTicker.Stop()
+	}
+	if timers.retentionTicker != nil {
+		timers.retentionTicker.Stop()
+	}
+	if timers.heartbeatTicker != nil {
+		timers.heartbeatTicker.Stop()
+	}
+}
+
+// setupRetentionTimer configures the retention check timer if retention is enabled
+func (l *Logger) setupRetentionTimer(timers *TimerSet) <-chan time.Time {
 	retentionPeriodHrs, _ := l.config.Float64("log.retention_period_hrs")
 	retentionCheckMins, _ := l.config.Float64("log.retention_check_mins")
 	retentionDur := time.Duration(retentionPeriodHrs * float64(time.Hour))
 	retentionCheckInterval := time.Duration(retentionCheckMins * float64(time.Minute))
 
 	if retentionDur > 0 && retentionCheckInterval > 0 {
-		retentionTicker = time.NewTicker(retentionCheckInterval)
+		timers.retentionTicker = time.NewTicker(retentionCheckInterval)
-		defer retentionTicker.Stop()
-		retentionChan = retentionTicker.C
 		l.updateEarliestFileTime() // Initial check
+		return timers.retentionTicker.C
 	}
+	return nil
+}
 
-	// Disk Check Timer
+// setupDiskCheckTimer configures the disk check timer
+func (l *Logger) setupDiskCheckTimer() *time.Ticker {
 	diskCheckIntervalMs, _ := l.config.Int64("log.disk_check_interval_ms")
 	if diskCheckIntervalMs <= 0 {
 		diskCheckIntervalMs = 5000
@@ -67,31 +182,31 @@ func (l *Logger) processLogs(ch <-chan logRecord) {
 		currentDiskCheckInterval = maxCheckInterval
 	}
 
-	diskCheckTicker := time.NewTicker(currentDiskCheckInterval)
+	return time.NewTicker(currentDiskCheckInterval)
-	defer diskCheckTicker.Stop()
+}
 
-	// --- State Variables ---
+// setupHeartbeatTimer configures the heartbeat timer if heartbeats are enabled
-	var bytesSinceLastCheck int64 = 0
+func (l *Logger) setupHeartbeatTimer(timers *TimerSet) <-chan time.Time {
-	var lastCheckTime time.Time = time.Now()
+	heartbeatLevel, _ := l.config.Int64("log.heartbeat_level")
-	var logsSinceLastCheck int64 = 0
+	if heartbeatLevel > 0 {
-
+		intervalS, _ := l.config.Int64("log.heartbeat_interval_s")
-	// Perform an initial disk check on startup
+		// Make sure interval is positive
-	l.performDiskCheck(true) // Force check and update status
+		if intervalS <= 0 {
-
+			intervalS = 60 // Default to 60 seconds
-	// --- Main Loop ---
-	for {
-		select {
-		case record, ok := <-ch:
-			if !ok {
-				// Channel closed: Perform final sync and exit
-				l.performSync()
-				return
 		}
+		// Create a new ticker that's offset slightly to avoid skipping the first tick
+		// by creating it and then waiting until exactly the next interval time
+		timers.heartbeatTicker = time.NewTicker(time.Duration(intervalS) * time.Second)
+		return timers.heartbeatTicker.C
+	}
+	return nil
+}
 
-			// --- Process the received record ---
+// processLogRecord handles individual log records, returning bytes written
+func (l *Logger) processLogRecord(record logRecord) int64 {
 	if !l.state.DiskStatusOK.Load() {
 		l.state.DroppedLogs.Add(1)
-				continue // Skip processing if disk known to be unavailable
+		return 0 // Skip processing if disk known to be unavailable
 	}
 
 	// Serialize the record
@@ -115,8 +230,6 @@ func (l *Logger) processLogs(ch <-chan logRecord) {
 		if err := l.rotateLogFile(); err != nil {
 			fmtFprintf(os.Stderr, "log: failed to rotate log file: %v\n", err)
 		}
-				bytesSinceLastCheck = 0 // Reset counters after rotation
-				logsSinceLastCheck = 0
 	}
 
 	// Write to the current log file
@@ -127,76 +240,34 @@ func (l *Logger) processLogs(ch <-chan logRecord) {
 			fmtFprintf(os.Stderr, "log: failed to write to log file: %v\n", err)
 			l.state.DroppedLogs.Add(1)
 			l.performDiskCheck(true) // Force check if write fails
+			return 0
 		} else {
 			l.state.CurrentSize.Add(int64(n))
-					bytesSinceLastCheck += int64(n)
+			l.state.TotalLogsProcessed.Add(1)
-					logsSinceLastCheck++
+			return int64(n)
-
-					// Reactive Check Trigger
-					if bytesSinceLastCheck > reactiveCheckThresholdBytes {
-						if l.performDiskCheck(false) { // Check without forcing cleanup yet
-							bytesSinceLastCheck = 0 // Reset if check OK
-							logsSinceLastCheck = 0
-							lastCheckTime = time.Now()
-						}
-					}
 		}
 	} else {
 		l.state.DroppedLogs.Add(1) // File pointer somehow nil
+		return 0
 	}
+}
 
-		case <-flushTicker.C:
+// handleFlushTick handles the periodic flush timer tick
+func (l *Logger) handleFlushTick() {
 	enableSync, _ := l.config.Bool("log.enable_periodic_sync")
 	if enableSync {
 		l.performSync()
 	}
+}
 
-		case <-diskCheckTicker.C:
+// handleFlushRequest handles an explicit flush request
-			// Periodic disk check
+func (l *Logger) handleFlushRequest(confirmChan chan struct{}) {
-			if l.performDiskCheck(true) { // Periodic check, force cleanup if needed
-				enableAdaptive, _ := l.config.Bool("log.enable_adaptive_interval")
-				if enableAdaptive {
-					elapsed := time.Since(lastCheckTime)
-					if elapsed < 10*time.Millisecond {
-						elapsed = 10 * time.Millisecond
-					}
-
-					logsPerSecond := float64(logsSinceLastCheck) / elapsed.Seconds()
-					targetLogsPerSecond := float64(100) // Baseline
-
-					if logsPerSecond < targetLogsPerSecond/2 { // Load low -> increase interval
-						currentDiskCheckInterval = time.Duration(float64(currentDiskCheckInterval) * adaptiveIntervalFactor)
-					} else if logsPerSecond > targetLogsPerSecond*2 { // Load high -> decrease interval
-						currentDiskCheckInterval = time.Duration(float64(currentDiskCheckInterval) * adaptiveSpeedUpFactor)
-					}
-
-					// Clamp interval using current config
-					minCheckIntervalMs, _ := l.config.Int64("log.min_check_interval_ms")
-					maxCheckIntervalMs, _ := l.config.Int64("log.max_check_interval_ms")
-					minCheckInterval := time.Duration(minCheckIntervalMs) * time.Millisecond
-					maxCheckInterval := time.Duration(maxCheckIntervalMs) * time.Millisecond
-
-					if currentDiskCheckInterval < minCheckInterval {
-						currentDiskCheckInterval = minCheckInterval
-					}
-					if currentDiskCheckInterval > maxCheckInterval {
-						currentDiskCheckInterval = maxCheckInterval
-					}
-
-					diskCheckTicker.Reset(currentDiskCheckInterval)
-				}
-				// Reset counters after successful periodic check
-				bytesSinceLastCheck = 0
-				logsSinceLastCheck = 0
-				lastCheckTime = time.Now()
-			}
-
-		case confirmChan := <-l.state.flushRequestChan:
 	l.performSync()
 	close(confirmChan) // Signal completion back to the Flush caller
+}
 
-		case <-retentionChan:
+// handleRetentionCheck performs file retention check and cleanup
-			// Check file retention
+func (l *Logger) handleRetentionCheck() {
 	retentionPeriodHrs, _ := l.config.Float64("log.retention_period_hrs")
 	retentionDur := time.Duration(retentionPeriodHrs * float64(time.Hour))
 
@@ -214,375 +285,217 @@ func (l *Logger) processLogs(ch <-chan logRecord) {
 			l.updateEarliestFileTime()
 		}
 	}
-		}
-	}
 }
 
-// performSync syncs the current log file
+// adjustDiskCheckInterval modifies the disk check interval based on logging activity
-func (l *Logger) performSync() {
+func (l *Logger) adjustDiskCheckInterval(timers *TimerSet, lastCheckTime time.Time, logsSinceLastCheck int64) {
-	cfPtr := l.state.CurrentFile.Load()
+	enableAdaptive, _ := l.config.Bool("log.enable_adaptive_interval")
-	if cfPtr != nil {
+	if !enableAdaptive {
-		if currentLogFile, isFile := cfPtr.(*os.File); isFile && currentLogFile != nil {
-			if err := currentLogFile.Sync(); err != nil {
-				// Log sync error
-				syncErrRecord := logRecord{
-					Flags:     FlagDefault,
-					TimeStamp: time.Now(),
-					Level:     LevelWarn,
-					Args:      []any{"Log file sync failed", "file", currentLogFile.Name(), "error", err.Error()},
-				}
-				l.sendLogRecord(syncErrRecord)
-			}
-		}
-	}
-}
-
-// performDiskCheck checks disk space, triggers cleanup if needed, and updates status
-// Returns true if disk is OK, false otherwise
-func (l *Logger) performDiskCheck(forceCleanup bool) bool {
-	dir, _ := l.config.String("log.directory")
-	ext, _ := l.config.String("log.extension")
-	maxTotalMB, _ := l.config.Int64("log.max_total_size_mb")
-	minDiskFreeMB, _ := l.config.Int64("log.min_disk_free_mb")
-	maxTotal := maxTotalMB * 1024 * 1024
-	minFreeRequired := minDiskFreeMB * 1024 * 1024
-
-	if maxTotal <= 0 && minFreeRequired <= 0 {
-		if !l.state.DiskStatusOK.Load() {
-			l.state.DiskStatusOK.Store(true)
-			l.state.DiskFullLogged.Store(false)
-		}
-		return true
-	}
-
-	freeSpace, err := l.getDiskFreeSpace(dir)
-	if err != nil {
-		fmtFprintf(os.Stderr, "log: warning - failed to check free disk space for '%s': %v\n", dir, err)
-		if l.state.DiskStatusOK.Load() {
-			l.state.DiskStatusOK.Store(false)
-		}
-		return false
-	}
-
-	needsCleanupCheck := false
-	spaceToFree := int64(0)
-	if minFreeRequired > 0 && freeSpace < minFreeRequired {
-		needsCleanupCheck = true
-		spaceToFree = minFreeRequired - freeSpace
-	}
-
-	if maxTotal > 0 {
-		dirSize, err := l.getLogDirSize(dir, ext)
-		if err != nil {
-			fmtFprintf(os.Stderr, "log: warning - failed to check log directory size for '%s': %v\n", dir, err)
-			if l.state.DiskStatusOK.Load() {
-				l.state.DiskStatusOK.Store(false)
-			}
-			return false
-		}
-		if dirSize > maxTotal {
-			needsCleanupCheck = true
-			amountOver := dirSize - maxTotal
-			if amountOver > spaceToFree {
-				spaceToFree = amountOver
-			}
-		}
-	}
-
-	if needsCleanupCheck && forceCleanup {
-		if err := l.cleanOldLogs(spaceToFree); err != nil {
-			if !l.state.DiskFullLogged.Swap(true) {
-				diskFullRecord := logRecord{
-					Flags: FlagDefault, TimeStamp: time.Now(), Level: LevelError,
-					Args: []any{"Log directory full or disk space low, cleanup failed", "error", err.Error()},
-				}
-				l.sendLogRecord(diskFullRecord)
-			}
-			if l.state.DiskStatusOK.Load() {
-				l.state.DiskStatusOK.Store(false)
-			}
-			return false
-		}
-		// Cleanup succeeded
-		l.state.DiskFullLogged.Store(false)
-		l.state.DiskStatusOK.Store(true)
-		l.updateEarliestFileTime()
-		return true
-	} else if needsCleanupCheck {
-		// Limits exceeded, but not forcing cleanup now
-		if l.state.DiskStatusOK.Load() {
-			l.state.DiskStatusOK.Store(false)
-		}
-		return false
-	} else {
-		// Limits OK
-		if !l.state.DiskStatusOK.Load() {
-			l.state.DiskStatusOK.Store(true)
-			l.state.DiskFullLogged.Store(false)
-		}
-		return true
-	}
-}
-
-// getDiskFreeSpace retrieves available disk space for the given path
-func (l *Logger) getDiskFreeSpace(path string) (int64, error) {
-	var stat syscall.Statfs_t
-	info, err := os.Stat(path)
-	if err != nil {
-		if os.IsNotExist(err) {
-			return 0, fmtErrorf("log directory '%s' does not exist for disk check: %w", path, err)
-		}
-		return 0, fmtErrorf("failed to stat log directory '%s': %w", path, err)
-	}
-	if !info.IsDir() {
-		path = filepath.Dir(path)
-	}
-
-	if err := syscall.Statfs(path, &stat); err != nil {
-		return 0, fmtErrorf("failed to get disk stats for '%s': %w", path, err)
-	}
-	availableBytes := int64(stat.Bavail) * int64(stat.Bsize)
-	return availableBytes, nil
-}
-
-// getLogDirSize calculates total size of log files matching the current extension
-func (l *Logger) getLogDirSize(dir, fileExt string) (int64, error) {
-	var size int64
-	entries, err := os.ReadDir(dir)
-	if err != nil {
-		if os.IsNotExist(err) {
-			return 0, nil
-		}
-		return 0, fmtErrorf("failed to read log directory '%s': %w", dir, err)
-	}
-
-	targetExt := "." + fileExt
-	for _, entry := range entries {
-		if entry.IsDir() {
-			continue
-		}
-		if filepath.Ext(entry.Name()) == targetExt {
-			info, errInfo := entry.Info()
-			if errInfo != nil {
-				continue
-			}
-			size += info.Size()
-		}
-	}
-	return size, nil
-}
-
-// cleanOldLogs removes oldest log files until required space is freed
-func (l *Logger) cleanOldLogs(required int64) error {
-	dir, _ := l.config.String("log.directory")
-	fileExt, _ := l.config.String("log.extension")
-
-	entries, err := os.ReadDir(dir)
-	if err != nil {
-		return fmtErrorf("failed to read log directory '%s' for cleanup: %w", dir, err)
-	}
-
-	currentLogFileName := ""
-	cfPtr := l.state.CurrentFile.Load()
-	if cfPtr != nil {
-		if clf, ok := cfPtr.(*os.File); ok && clf != nil {
-			currentLogFileName = filepath.Base(clf.Name())
-		}
-	}
-
-	type logFileMeta struct {
-		name    string
-		modTime time.Time
-		size    int64
-	}
-	var logs []logFileMeta
-	targetExt := "." + fileExt
-	for _, entry := range entries {
-		if entry.IsDir() || filepath.Ext(entry.Name()) != targetExt || entry.Name() == currentLogFileName {
-			continue
-		}
-		info, errInfo := entry.Info()
-		if errInfo != nil {
-			continue
-		}
-		logs = append(logs, logFileMeta{name: entry.Name(), modTime: info.ModTime(), size: info.Size()})
-	}
-
-	if len(logs) == 0 {
-		if required > 0 {
-			return fmtErrorf("no old logs available to delete in '%s', needed %d bytes", dir, required)
-		}
-		return nil
-	}
-
-	sort.Slice(logs, func(i, j int) bool { return logs[i].modTime.Before(logs[j].modTime) })
-
-	var freedSpace int64
-	for _, log := range logs {
-		if required > 0 && freedSpace >= required {
-			break
-		}
-		filePath := filepath.Join(dir, log.name)
-		if err := os.Remove(filePath); err != nil {
-			fmtFprintf(os.Stderr, "log: failed to remove old log file '%s': %v\n", filePath, err)
-			continue
-		}
-		freedSpace += log.size
-	}
-
-	if required > 0 && freedSpace < required {
-		return fmtErrorf("could not free enough space in '%s': freed %d bytes, needed %d bytes", dir, freedSpace, required)
-	}
-	return nil
-}
-
-// updateEarliestFileTime scans the log directory for the oldest log file
-func (l *Logger) updateEarliestFileTime() {
-	dir, _ := l.config.String("log.directory")
-	fileExt, _ := l.config.String("log.extension")
-	baseName, _ := l.config.String("log.name")
-
-	entries, err := os.ReadDir(dir)
-	if err != nil {
-		l.state.EarliestFileTime.Store(time.Time{})
 		return
 	}
 
-	var earliest time.Time
+	elapsed := time.Since(lastCheckTime)
-	currentLogFileName := ""
+	if elapsed < 10*time.Millisecond { // Min arbitrary reasonable value
-	cfPtr := l.state.CurrentFile.Load()
+		elapsed = 10 * time.Millisecond
-	if cfPtr != nil {
-		if clf, ok := cfPtr.(*os.File); ok && clf != nil {
-			currentLogFileName = filepath.Base(clf.Name())
-		}
 	}
 
-	targetExt := "." + fileExt
+	logsPerSecond := float64(logsSinceLastCheck) / elapsed.Seconds()
-	prefix := baseName + "_"
+	targetLogsPerSecond := float64(100) // Baseline
-	for _, entry := range entries {
-		if entry.IsDir() {
-			continue
-		}
-		fname := entry.Name()
-		if !strings.HasPrefix(fname, prefix) || filepath.Ext(fname) != targetExt || fname == currentLogFileName {
-			continue
-		}
-		info, errInfo := entry.Info()
-		if errInfo != nil {
-			continue
-		}
-		if earliest.IsZero() || info.ModTime().Before(earliest) {
-			earliest = info.ModTime()
-		}
-	}
-	l.state.EarliestFileTime.Store(earliest)
-}
 
-// cleanExpiredLogs removes log files older than the retention period
+	// Get current disk check interval from config
-func (l *Logger) cleanExpiredLogs(oldest time.Time) error {
+	diskCheckIntervalMs, _ := l.config.Int64("log.disk_check_interval_ms")
-	dir, _ := l.config.String("log.directory")
+	currentDiskCheckInterval := time.Duration(diskCheckIntervalMs) * time.Millisecond
-	fileExt, _ := l.config.String("log.extension")
-	retentionPeriodHrs, _ := l.config.Float64("log.retention_period_hrs")
-	rpDuration := time.Duration(retentionPeriodHrs * float64(time.Hour))
 
-	if rpDuration <= 0 {
+	// Calculate the new interval
-		return nil
+	var newInterval time.Duration
-	}
+	if logsPerSecond < targetLogsPerSecond/2 { // Load low -> increase interval
-	cutoffTime := time.Now().Add(-rpDuration)
+		newInterval = time.Duration(float64(currentDiskCheckInterval) * adaptiveIntervalFactor)
-	if oldest.IsZero() || !oldest.Before(cutoffTime) {
+	} else if logsPerSecond > targetLogsPerSecond*2 { // Load high -> decrease interval
-		return nil
+		newInterval = time.Duration(float64(currentDiskCheckInterval) * adaptiveSpeedUpFactor)
-	}
-
-	entries, err := os.ReadDir(dir)
-	if err != nil {
-		return fmtErrorf("failed to read log directory '%s' for retention cleanup: %w", dir, err)
-	}
-
-	currentLogFileName := ""
-	cfPtr := l.state.CurrentFile.Load()
-	if cfPtr != nil {
-		if clf, ok := cfPtr.(*os.File); ok && clf != nil {
-			currentLogFileName = filepath.Base(clf.Name())
-		}
-	}
-
-	targetExt := "." + fileExt
-	var deletedCount int
-	for _, entry := range entries {
-		if entry.IsDir() || filepath.Ext(entry.Name()) != targetExt || entry.Name() == currentLogFileName {
-			continue
-		}
-		info, errInfo := entry.Info()
-		if errInfo != nil {
-			continue
-		}
-		if info.ModTime().Before(cutoffTime) {
-			filePath := filepath.Join(dir, entry.Name())
-			if err := os.Remove(filePath); err != nil {
-				fmtFprintf(os.Stderr, "log: failed to remove expired log file '%s': %v\n", filePath, err)
 	} else {
-				deletedCount++
+		// No change needed if within normal range
-			}
+		return
-		}
 	}
 
-	if deletedCount == 0 && err != nil {
+	// Clamp interval using current config
-		return err
+	minCheckIntervalMs, _ := l.config.Int64("log.min_check_interval_ms")
+	maxCheckIntervalMs, _ := l.config.Int64("log.max_check_interval_ms")
+	minCheckInterval := time.Duration(minCheckIntervalMs) * time.Millisecond
+	maxCheckInterval := time.Duration(maxCheckIntervalMs) * time.Millisecond
+
+	if newInterval < minCheckInterval {
+		newInterval = minCheckInterval
 	}
-	return nil
+	if newInterval > maxCheckInterval {
+		newInterval = maxCheckInterval
+	}
+
+	// Reset the ticker with the new interval
+	timers.diskCheckTicker.Reset(newInterval)
 }
 
-// generateLogFileName creates a unique log filename using a timestamp
+// handleHeartbeat processes a heartbeat timer tick
-func (l *Logger) generateLogFileName(timestamp time.Time) string {
+func (l *Logger) handleHeartbeat() {
-	name, _ := l.config.String("log.name")
+	heartbeatLevel, _ := l.config.Int64("log.heartbeat_level")
-	ext, _ := l.config.String("log.extension")
+
-	tsFormat := timestamp.Format("060102_150405")
+	// Process heartbeat based on configured level
-	nano := timestamp.Nanosecond()
+	if heartbeatLevel >= 1 {
-	return fmt.Sprintf("%s_%s_%d.%s", name, tsFormat, nano, ext)
+		l.logProcHeartbeat()
+	}
+
+	if heartbeatLevel >= 2 {
+		l.logDiskHeartbeat()
+	}
+
+	if heartbeatLevel >= 3 {
+		l.logSysHeartbeat()
+	}
 }
 
-// createNewLogFile generates a unique name and opens a new log file
+// logProcHeartbeat logs process/logger statistics heartbeat
-func (l *Logger) createNewLogFile() (*os.File, error) {
+func (l *Logger) logProcHeartbeat() {
+	// 1. Gather process/logger stats
+	processed := l.state.TotalLogsProcessed.Load()
+	dropped := l.state.DroppedLogs.Load()
+	sequence := l.state.HeartbeatSequence.Add(1) // Increment and get sequence number
+
+	// Calculate uptime
+	startTimeVal := l.state.LoggerStartTime.Load()
+	var uptimeHours float64 = 0
+	if startTime, ok := startTimeVal.(time.Time); ok && !startTime.IsZero() {
+		uptime := time.Since(startTime)
+		uptimeHours = uptime.Hours()
+	}
+
+	// 2. Format Args
+	procArgs := []any{
+		"type", "proc",
+		"sequence", sequence,
+		"uptime_hours", fmt.Sprintf("%.2f", uptimeHours),
+		"processed_logs", processed,
+		"dropped_logs", dropped,
+	}
+
+	// 3. Write the heartbeat record
+	l.writeHeartbeatRecord(LevelProc, procArgs)
+}
+
+// logDiskHeartbeat logs disk/file statistics heartbeat
+func (l *Logger) logDiskHeartbeat() {
+	sequence := l.state.HeartbeatSequence.Load()
+	rotations := l.state.TotalRotations.Load()
+	deletions := l.state.TotalDeletions.Load()
+
+	// Get file system stats
 	dir, _ := l.config.String("log.directory")
-	filename := l.generateLogFileName(time.Now())
+	ext, _ := l.config.String("log.extension")
-	fullPath := filepath.Join(dir, filename)
+	currentSizeMB := float64(l.state.CurrentSize.Load()) / (1024 * 1024) // Current file size
+	totalSizeMB := float64(-1.0)                                         // Default error value
+	fileCount := -1                                                      // Default error value
 
-	// Retry logic for potential collisions (rare)
+	dirSize, err := l.getLogDirSize(dir, ext)
-	for i := 0; i < 5; i++ {
+	if err == nil {
-		if _, err := os.Stat(fullPath); os.IsNotExist(err) {
+		totalSizeMB = float64(dirSize) / (1024 * 1024)
-			break
+	} else {
-		}
+		fmtFprintf(os.Stderr, "log: warning - heartbeat failed to get dir size: %v\n", err)
-		time.Sleep(1 * time.Millisecond)
-		filename := l.generateLogFileName(time.Now())
-		fullPath = filepath.Join(dir, filename)
 	}
 
-	file, err := os.OpenFile(fullPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	count, err := l.getLogFileCount(dir, ext)
-	if err != nil {
+	if err == nil {
-		return nil, fmtErrorf("failed to open/create log file '%s': %w", fullPath, err)
+		fileCount = count
+	} else {
+		fmtFprintf(os.Stderr, "log: warning - heartbeat failed to get file count: %v\n", err)
 	}
-	return file, nil
+
+	// Format Args
+	diskArgs := []any{
+		"type", "disk",
+		"sequence", sequence,
+		"rotated_files", rotations,
+		"deleted_files", deletions,
+		"total_log_size_mb", fmt.Sprintf("%.2f", totalSizeMB),
+		"log_file_count", fileCount,
+		"current_file_size_mb", fmt.Sprintf("%.2f", currentSizeMB),
+		"disk_status_ok", l.state.DiskStatusOK.Load(),
+	}
+
+	// Add disk free space if we can get it
+	freeSpace, err := l.getDiskFreeSpace(dir)
+	if err == nil {
+		freeSpaceMB := float64(freeSpace) / (1024 * 1024)
+		diskArgs = append(diskArgs, "disk_free_mb", fmt.Sprintf("%.2f", freeSpaceMB))
+	}
+
+	// Write the heartbeat record
+	l.writeHeartbeatRecord(LevelDisk, diskArgs)
 }
 
-// rotateLogFile handles closing the current log file and opening a new one
+// logSysHeartbeat logs system/runtime statistics heartbeat
-func (l *Logger) rotateLogFile() error {
+func (l *Logger) logSysHeartbeat() {
-	newFile, err := l.createNewLogFile()
+	sequence := l.state.HeartbeatSequence.Load()
-	if err != nil {
+
-		return fmtErrorf("failed to create new log file for rotation: %w", err)
+	// Get memory stats
+	var memStats runtime.MemStats
+	runtime.ReadMemStats(&memStats)
+
+	// Format Args
+	sysArgs := []any{
+		"type", "sys",
+		"sequence", sequence,
+		"alloc_mb", fmt.Sprintf("%.2f", float64(memStats.Alloc)/(1024*1024)),
+		"sys_mb", fmt.Sprintf("%.2f", float64(memStats.Sys)/(1024*1024)),
+		"num_gc", memStats.NumGC,
+		"num_goroutine", runtime.NumGoroutine(),
 	}
 
-	oldFilePtr := l.state.CurrentFile.Swap(newFile)
+	// Write the heartbeat record
-	l.state.CurrentSize.Store(0) // Reset size for the new file
+	l.writeHeartbeatRecord(LevelSys, sysArgs)
-
+}
-	if oldFilePtr != nil {
+
-		if oldFile, ok := oldFilePtr.(*os.File); ok && oldFile != nil {
+// writeHeartbeatRecord handles the common logic for writing a heartbeat record
-			if err := oldFile.Close(); err != nil {
+func (l *Logger) writeHeartbeatRecord(level int64, args []any) {
-				fmtFprintf(os.Stderr, "log: failed to close old log file '%s': %v\n", oldFile.Name(), err)
+	// Skip if logger disabled or shutting down
-				// Continue with new file anyway
+	if l.state.LoggerDisabled.Load() || l.state.ShutdownCalled.Load() {
-			}
+		return
-		}
+	}
-	}
+
-
+	// Skip if disk known to be unavailable
-	l.updateEarliestFileTime() // Update earliest time after rotation
+	if !l.state.DiskStatusOK.Load() {
-	return nil
+		return
+	}
+
+	// 1. Serialize the record
+	format, _ := l.config.String("log.format")
+	// Use FlagDefault | FlagShowLevel so Level appears in the output
+	hbData := l.serializer.serialize(format, FlagDefault|FlagShowLevel, time.Now(), level, "", args)
+
+	// 2. Write the record
+	cfPtr := l.state.CurrentFile.Load()
+	if cfPtr == nil {
+		fmtFprintf(os.Stderr, "log: error - current file handle is nil during heartbeat\n")
+		return
+	}
+
+	currentLogFile, isFile := cfPtr.(*os.File)
+	if !isFile || currentLogFile == nil {
+		fmtFprintf(os.Stderr, "log: error - invalid file handle type during heartbeat\n")
+		return
+	}
+
+	// Write with a single retry attempt
+	n, err := currentLogFile.Write(hbData)
+	if err != nil {
+		fmtFprintf(os.Stderr, "log: failed to write heartbeat: %v\n", err)
+		l.performDiskCheck(true) // Force disk check on write failure
+
+		// One retry after disk check
+		n, err = currentLogFile.Write(hbData)
+		if err != nil {
+			fmtFprintf(os.Stderr, "log: failed to write heartbeat on retry: %v\n", err)
+		} else {
+			l.state.CurrentSize.Add(int64(n))
+		}
+	} else {
+		l.state.CurrentSize.Add(int64(n))
+	}
 }

state.go

@@ -31,6 +31,13 @@ type State struct {
 	LoggedDrops      atomic.Uint64 // Counter for dropped logs message already logged
 
 	ActiveLogChannel atomic.Value // stores chan logRecord
+
+	// Heartbeat statistics
+	HeartbeatSequence  atomic.Uint64 // Counter for heartbeat sequence numbers
+	LoggerStartTime    atomic.Value  // Stores time.Time for uptime calculation
+	TotalLogsProcessed atomic.Uint64 // Counter for non-heartbeat logs successfully processed
+	TotalRotations     atomic.Uint64 // Counter for successful log rotations
+	TotalDeletions     atomic.Uint64 // Counter for successful log deletions (cleanup/retention)
 }
 
 // Init initializes or reconfigures the logger using the provided config.Config instance
@@ -124,7 +131,9 @@ func (l *Logger) InitWithDefaults(overrides ...string) error {
 }
 
 // Shutdown gracefully closes the logger, attempting to flush pending records
-func (l *Logger) Shutdown(timeout time.Duration) error {
+// If no timeout is provided, uses a default of 2x flush interval
+func (l *Logger) Shutdown(timeout ...time.Duration) error {
+
 	// Ensure shutdown runs only once
 	if !l.state.ShutdownCalled.CompareAndSwap(false, true) {
 		return nil
@@ -153,10 +162,12 @@ func (l *Logger) Shutdown(timeout time.Duration) error {
 	}
 	l.initMu.Unlock()
 
-	// Determine the maximum time to wait for the processor to finish
+	// Determine the effective timeout, if timeout is zero or negative, use a default based on flush interval
-	effectiveTimeout := timeout
+	var effectiveTimeout time.Duration
-	if effectiveTimeout <= 0 {
+	if len(timeout) > 0 {
-		// Use the configured flush interval as the default timeout if none provided
+		effectiveTimeout = timeout[0]
+	} else {
+		// Default to 2x flush interval
 		flushMs, _ := l.config.Int64("log.flush_interval_ms")
 		effectiveTimeout = 2 * time.Duration(flushMs) * time.Millisecond
 	}

storage.go

@@ -0,0 +1,407 @@
+package log
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// performSync syncs the current log file
+func (l *Logger) performSync() {
+	cfPtr := l.state.CurrentFile.Load()
+	if cfPtr != nil {
+		if currentLogFile, isFile := cfPtr.(*os.File); isFile && currentLogFile != nil {
+			if err := currentLogFile.Sync(); err != nil {
+				// Log sync error
+				syncErrRecord := logRecord{
+					Flags:     FlagDefault,
+					TimeStamp: time.Now(),
+					Level:     LevelWarn,
+					Args:      []any{"Log file sync failed", "file", currentLogFile.Name(), "error", err.Error()},
+				}
+				l.sendLogRecord(syncErrRecord)
+			}
+		}
+	}
+}
+
+// performDiskCheck checks disk space, triggers cleanup if needed, and updates status
+// Returns true if disk is OK, false otherwise
+func (l *Logger) performDiskCheck(forceCleanup bool) bool {
+	dir, _ := l.config.String("log.directory")
+	ext, _ := l.config.String("log.extension")
+	maxTotalMB, _ := l.config.Int64("log.max_total_size_mb")
+	minDiskFreeMB, _ := l.config.Int64("log.min_disk_free_mb")
+	maxTotal := maxTotalMB * 1024 * 1024
+	minFreeRequired := minDiskFreeMB * 1024 * 1024
+
+	if maxTotal <= 0 && minFreeRequired <= 0 {
+		if !l.state.DiskStatusOK.Load() {
+			l.state.DiskStatusOK.Store(true)
+			l.state.DiskFullLogged.Store(false)
+		}
+		return true
+	}
+
+	freeSpace, err := l.getDiskFreeSpace(dir)
+	if err != nil {
+		fmtFprintf(os.Stderr, "log: warning - failed to check free disk space for '%s': %v\n", dir, err)
+		if l.state.DiskStatusOK.Load() {
+			l.state.DiskStatusOK.Store(false)
+		}
+		return false
+	}
+
+	needsCleanupCheck := false
+	spaceToFree := int64(0)
+	if minFreeRequired > 0 && freeSpace < minFreeRequired {
+		needsCleanupCheck = true
+		spaceToFree = minFreeRequired - freeSpace
+	}
+
+	if maxTotal > 0 {
+		dirSize, err := l.getLogDirSize(dir, ext)
+		if err != nil {
+			fmtFprintf(os.Stderr, "log: warning - failed to check log directory size for '%s': %v\n", dir, err)
+			if l.state.DiskStatusOK.Load() {
+				l.state.DiskStatusOK.Store(false)
+			}
+			return false
+		}
+		if dirSize > maxTotal {
+			needsCleanupCheck = true
+			amountOver := dirSize - maxTotal
+			if amountOver > spaceToFree {
+				spaceToFree = amountOver
+			}
+		}
+	}
+
+	if needsCleanupCheck && forceCleanup {
+		if err := l.cleanOldLogs(spaceToFree); err != nil {
+			if !l.state.DiskFullLogged.Swap(true) {
+				diskFullRecord := logRecord{
+					Flags: FlagDefault, TimeStamp: time.Now(), Level: LevelError,
+					Args: []any{"Log directory full or disk space low, cleanup failed", "error", err.Error()},
+				}
+				l.sendLogRecord(diskFullRecord)
+			}
+			if l.state.DiskStatusOK.Load() {
+				l.state.DiskStatusOK.Store(false)
+			}
+			return false
+		}
+		// Cleanup succeeded
+		l.state.DiskFullLogged.Store(false)
+		l.state.DiskStatusOK.Store(true)
+		l.updateEarliestFileTime()
+		return true
+	} else if needsCleanupCheck {
+		// Limits exceeded, but not forcing cleanup now
+		if l.state.DiskStatusOK.Load() {
+			l.state.DiskStatusOK.Store(false)
+		}
+		return false
+	} else {
+		// Limits OK
+		if !l.state.DiskStatusOK.Load() {
+			l.state.DiskStatusOK.Store(true)
+			l.state.DiskFullLogged.Store(false)
+		}
+		return true
+	}
+}
+
+// getDiskFreeSpace retrieves available disk space for the given path
+func (l *Logger) getDiskFreeSpace(path string) (int64, error) {
+	var stat syscall.Statfs_t
+	info, err := os.Stat(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return 0, fmtErrorf("log directory '%s' does not exist for disk check: %w", path, err)
+		}
+		return 0, fmtErrorf("failed to stat log directory '%s': %w", path, err)
+	}
+	if !info.IsDir() {
+		path = filepath.Dir(path)
+	}
+
+	if err := syscall.Statfs(path, &stat); err != nil {
+		return 0, fmtErrorf("failed to get disk stats for '%s': %w", path, err)
+	}
+	availableBytes := int64(stat.Bavail) * int64(stat.Bsize)
+	return availableBytes, nil
+}
+
+// getLogDirSize calculates total size of log files matching the current extension
+func (l *Logger) getLogDirSize(dir, fileExt string) (int64, error) {
+	var size int64
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return 0, nil
+		}
+		return 0, fmtErrorf("failed to read log directory '%s': %w", dir, err)
+	}
+
+	targetExt := "." + fileExt
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		if filepath.Ext(entry.Name()) == targetExt {
+			info, errInfo := entry.Info()
+			if errInfo != nil {
+				continue
+			}
+			size += info.Size()
+		}
+	}
+	return size, nil
+}
+
+// cleanOldLogs removes oldest log files until required space is freed
+func (l *Logger) cleanOldLogs(required int64) error {
+	dir, _ := l.config.String("log.directory")
+	fileExt, _ := l.config.String("log.extension")
+
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return fmtErrorf("failed to read log directory '%s' for cleanup: %w", dir, err)
+	}
+
+	currentLogFileName := ""
+	cfPtr := l.state.CurrentFile.Load()
+	if cfPtr != nil {
+		if clf, ok := cfPtr.(*os.File); ok && clf != nil {
+			currentLogFileName = filepath.Base(clf.Name())
+		}
+	}
+
+	type logFileMeta struct {
+		name    string
+		modTime time.Time
+		size    int64
+	}
+	var logs []logFileMeta
+	targetExt := "." + fileExt
+	for _, entry := range entries {
+		if entry.IsDir() || filepath.Ext(entry.Name()) != targetExt || entry.Name() == currentLogFileName {
+			continue
+		}
+		info, errInfo := entry.Info()
+		if errInfo != nil {
+			continue
+		}
+		logs = append(logs, logFileMeta{name: entry.Name(), modTime: info.ModTime(), size: info.Size()})
+	}
+
+	if len(logs) == 0 {
+		if required > 0 {
+			return fmtErrorf("no old logs available to delete in '%s', needed %d bytes", dir, required)
+		}
+		return nil
+	}
+
+	sort.Slice(logs, func(i, j int) bool { return logs[i].modTime.Before(logs[j].modTime) })
+
+	var freedSpace int64
+	for _, log := range logs {
+		if required > 0 && freedSpace >= required {
+			break
+		}
+		filePath := filepath.Join(dir, log.name)
+		if err := os.Remove(filePath); err != nil {
+			fmtFprintf(os.Stderr, "log: failed to remove old log file '%s': %v\n", filePath, err)
+			continue
+		}
+		freedSpace += log.size
+		l.state.TotalDeletions.Add(1)
+	}
+
+	if required > 0 && freedSpace < required {
+		return fmtErrorf("could not free enough space in '%s': freed %d bytes, needed %d bytes", dir, freedSpace, required)
+	}
+	return nil
+}
+
+// updateEarliestFileTime scans the log directory for the oldest log file
+func (l *Logger) updateEarliestFileTime() {
+	dir, _ := l.config.String("log.directory")
+	fileExt, _ := l.config.String("log.extension")
+	baseName, _ := l.config.String("log.name")
+
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		l.state.EarliestFileTime.Store(time.Time{})
+		return
+	}
+
+	var earliest time.Time
+	currentLogFileName := ""
+	cfPtr := l.state.CurrentFile.Load()
+	if cfPtr != nil {
+		if clf, ok := cfPtr.(*os.File); ok && clf != nil {
+			currentLogFileName = filepath.Base(clf.Name())
+		}
+	}
+
+	targetExt := "." + fileExt
+	prefix := baseName + "_"
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		fname := entry.Name()
+		if !strings.HasPrefix(fname, prefix) || filepath.Ext(fname) != targetExt || fname == currentLogFileName {
+			continue
+		}
+		info, errInfo := entry.Info()
+		if errInfo != nil {
+			continue
+		}
+		if earliest.IsZero() || info.ModTime().Before(earliest) {
+			earliest = info.ModTime()
+		}
+	}
+	l.state.EarliestFileTime.Store(earliest)
+}
+
+// cleanExpiredLogs removes log files older than the retention period
+func (l *Logger) cleanExpiredLogs(oldest time.Time) error {
+	dir, _ := l.config.String("log.directory")
+	fileExt, _ := l.config.String("log.extension")
+	retentionPeriodHrs, _ := l.config.Float64("log.retention_period_hrs")
+	rpDuration := time.Duration(retentionPeriodHrs * float64(time.Hour))
+
+	if rpDuration <= 0 {
+		return nil
+	}
+	cutoffTime := time.Now().Add(-rpDuration)
+	if oldest.IsZero() || !oldest.Before(cutoffTime) {
+		return nil
+	}
+
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return fmtErrorf("failed to read log directory '%s' for retention cleanup: %w", dir, err)
+	}
+
+	currentLogFileName := ""
+	cfPtr := l.state.CurrentFile.Load()
+	if cfPtr != nil {
+		if clf, ok := cfPtr.(*os.File); ok && clf != nil {
+			currentLogFileName = filepath.Base(clf.Name())
+		}
+	}
+
+	targetExt := "." + fileExt
+	var deletedCount int
+	for _, entry := range entries {
+		if entry.IsDir() || filepath.Ext(entry.Name()) != targetExt || entry.Name() == currentLogFileName {
+			continue
+		}
+		info, errInfo := entry.Info()
+		if errInfo != nil {
+			continue
+		}
+		if info.ModTime().Before(cutoffTime) {
+			filePath := filepath.Join(dir, entry.Name())
+			if err := os.Remove(filePath); err != nil {
+				fmtFprintf(os.Stderr, "log: failed to remove expired log file '%s': %v\n", filePath, err)
+			} else {
+				deletedCount++
+				l.state.TotalDeletions.Add(1)
+			}
+		}
+	}
+
+	if deletedCount == 0 && err != nil {
+		return err
+	}
+	return nil
+}
+
+// generateLogFileName creates a unique log filename using a timestamp
+func (l *Logger) generateLogFileName(timestamp time.Time) string {
+	name, _ := l.config.String("log.name")
+	ext, _ := l.config.String("log.extension")
+	tsFormat := timestamp.Format("060102_150405")
+	nano := timestamp.Nanosecond()
+	return fmt.Sprintf("%s_%s_%d.%s", name, tsFormat, nano, ext)
+}
+
+// createNewLogFile generates a unique name and opens a new log file
+func (l *Logger) createNewLogFile() (*os.File, error) {
+	dir, _ := l.config.String("log.directory")
+	filename := l.generateLogFileName(time.Now())
+	fullPath := filepath.Join(dir, filename)
+
+	// Retry logic for potential collisions (rare)
+	for i := 0; i < 5; i++ {
+		if _, err := os.Stat(fullPath); os.IsNotExist(err) {
+			break
+		}
+		time.Sleep(1 * time.Millisecond)
+		filename := l.generateLogFileName(time.Now())
+		fullPath = filepath.Join(dir, filename)
+	}
+
+	file, err := os.OpenFile(fullPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return nil, fmtErrorf("failed to open/create log file '%s': %w", fullPath, err)
+	}
+	return file, nil
+}
+
+// rotateLogFile handles closing the current log file and opening a new one
+func (l *Logger) rotateLogFile() error {
+	newFile, err := l.createNewLogFile()
+	if err != nil {
+		return fmtErrorf("failed to create new log file for rotation: %w", err)
+	}
+
+	oldFilePtr := l.state.CurrentFile.Swap(newFile)
+	l.state.CurrentSize.Store(0) // Reset size for the new file
+
+	if oldFilePtr != nil {
+		if oldFile, ok := oldFilePtr.(*os.File); ok && oldFile != nil {
+			if err := oldFile.Close(); err != nil {
+				fmtFprintf(os.Stderr, "log: failed to close old log file '%s': %v\n", oldFile.Name(), err)
+				// Continue with new file anyway
+			}
+		}
+	}
+
+	l.updateEarliestFileTime()
+	l.state.TotalRotations.Add(1)
+	return nil
+}
+
+// getLogFileCount calculates the number of log files matching the current extension
+func (l *Logger) getLogFileCount(dir, fileExt string) (int, error) {
+	count := 0
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return 0, nil
+		}
+		return -1, fmtErrorf("failed to read log directory '%s': %w", dir, err)
+	}
+
+	targetExt := "." + fileExt
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		// Count all files matching the extension, including the current one if present
+		if filepath.Ext(entry.Name()) == targetExt {
+			count++
+		}
+	}
+	return count, nil
+}

utility.go

@@ -153,7 +153,13 @@ func Level(levelStr string) (int64, error) {
 		return LevelWarn, nil
 	case "error":
 		return LevelError, nil
+	case "proc":
+		return LevelProc, nil
+	case "disk":
+		return LevelDisk, nil
+	case "sys":
+		return LevelSys, nil
 	default:
-		return 0, fmtErrorf("invalid level string: '%s' (use debug, info, warn, error)", levelStr)
+		return 0, fmtErrorf("invalid level string: '%s' (use debug, info, warn, error, proc, disk, sys)", levelStr)
 	}
 }