Crate reovim_driver_log 

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

Structs

LogConfig

Configuration for the logging driver.

TracingLogger

Logger implementation that forwards to tracing.

Enums

Level

Log level for kernel messages.

LogError

Error type for logging initialization.

LogFormat

Log message format.

LogOutput

Log output destination.

RotationPolicy

Log file rotation policy.

Traits

Logger

Logger trait - the kernel mechanism for logging.

Functions

from_tracing_level

Convert tracing Level to kernel Level.

init_logging

Initialize logging with the given configuration.

set_logger

Sets the global logger.

to_tracing_level

Convert kernel Level to tracing Level.