SLF4A - Asynchronous Logging

SLF4A is the logging standard in otavia, referencing the design of SLF4J. It provides an asynchronous logging framework that integrates with the Actor system.

Getting a Logger

In Actors

StateActor and ChannelsActor already have a built-in logger property:

class MyActor extends StateActor[MyCall] {
  override protected def resumeNotice(stack: NoticeStack[MyNotice]): StackYield = {
    logger.info("Received notice: {}", stack.notice)
    stack.return()
  }
}

Outside Actors

val logger = Logger.getLogger(getClass, system)

Design

SLF4A references SLF4J's design with the following components:

• Logger: The logging interface providing trace, debug, info, warn, error methods
• LoggerFactory: Creates Logger instances
• Logging backend: Pluggable backend implementations

The key difference from SLF4J is that logging operations in the Actor context are asynchronous — log messages are sent through the Actor's mailbox system rather than executing synchronously, preventing logging from blocking the Actor's message processing.

Log Levels

SLF4A supports the standard log levels:

• TRACE — Fine-grained debug information
• DEBUG — Debug information
• INFO — Informational messages
• WARN — Warning conditions
• ERROR — Error conditions

Usage Pattern

class MyServiceActor extends StateActor[ServiceCall] {
  override protected def afterMount(): Unit = {
    logger.info("MyServiceActor mounted with id {}", context.actorId)
  }

  override protected def resumeAsk(stack: AskStack[ServiceRequest]): StackYield = {
    logger.debug("Processing request: {}", stack.call)
    // ... process ...
    logger.info("Request completed successfully")
    stack.return(ServiceReply(result))
  }
}