Logging driver for reovim.

This driver implements the kernel's Logger trait using the tracing ecosystem. It bridges kernel pr_*! macros to tracing subscribers.

Architecture

Following Linux kernel design (mechanism vs policy):

• Kernel provides mechanism: Logger trait, Level, Record, pr_*! macros
• This driver provides policy: Where logs go, formatting, filtering

┌─────────────────────────────────────────────────────────────────┐
│                         User Code                                │
│   pr_info!("buffer {} opened", id);                              │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                     Kernel (printk/)                             │
│   Level │ Record │ Logger trait │ Global OnceLock                │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                 Driver (drivers/log/)                            │
│   TracingLogger │ LogConfig │ init_logging()                     │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                     tracing ecosystem                            │
│   tracing │ tracing-subscriber │ tracing-appender                │
└─────────────────────────────────────────────────────────────────┘

Usage

use reovim_driver_log::{TracingLogger, init_logging, LogConfig};
use reovim_kernel::api::v1::set_logger;

// Step 1: Initialize tracing subscriber
let config = LogConfig::default();
init_logging(&config)?;

// Step 2: Set TracingLogger as global kernel logger
static LOGGER: TracingLogger = TracingLogger;
set_logger(&LOGGER)?;

// Step 3: Now pr_*! macros route to tracing
pr_info!("editor started");
pr_debug!("buffer count: {}", 5);

Environment Variable

Set REOVIM_LOG to control log level (overrides LogConfig.level):

REOVIM_LOG=debug reovim myfile.txt
REOVIM_LOG=trace reovim --log=- myfile.txt
REOVIM_LOG=reovim_kernel=trace,warn reovim myfile.txt  # Fine-grained control

Output Formats

• Plain: 2024-01-15T10:30:00Z INFO file.rs:42 message
• JSON: {"timestamp":"...","level":"INFO","target":"...","message":"..."}
• Pretty: Colorized output for terminal (development)

File Rotation

When using LogOutput::File, log files can be rotated:

• RotationPolicy::Never - Single file
• RotationPolicy::Daily - Rotate at midnight UTC
• RotationPolicy::Hourly - Rotate every hour