Simplify BpfLogger::init

Make BpfLogger::init(bpf) log using the default logger. Add
BpfLoger::init_with_logger(bpf, logger) for logging using a custom
logger instance.

README.md

@@ -33,21 +33,22 @@ to log eBPF messages to the terminal.
 ### User space code
 
 ```rust
-use aya_log::BpfLogger;
 use simplelog::{ColorChoice, ConfigBuilder, LevelFilter, TermLogger, TerminalMode};
+use aya_log::BpfLogger;
 
-BpfLogger::init(
+TermLogger::init(
-    &mut bpf,
+    LevelFilter::Debug,
-    TermLogger::new(
-        LevelFilter::Trace,
     ConfigBuilder::new()
         .set_target_level(LevelFilter::Error)
         .set_location_level(LevelFilter::Error)
         .build(),
     TerminalMode::Mixed,
     ColorChoice::Auto,
-    ),
+)
-).unwrap();
+.unwrap();
+
+// Will log using the default logger, which is TermLogger in this case
+BpfLogger::init(&mut bpf).unwrap();
 ```
 
 ### eBPF code

aya-log/src/lib.rs

@@ -13,21 +13,23 @@
 //!
 //! ```no_run
 //! # let mut bpf = aya::Bpf::load(&[], None)?;
-//! use aya_log::BpfLogger;
 //! use simplelog::{ColorChoice, ConfigBuilder, LevelFilter, TermLogger, TerminalMode};
+//! use aya_log::BpfLogger;
 //!
-//! BpfLogger::init(
+//! // initialize simplelog::TermLogger as the default logger
-//!     &mut bpf,
+//! TermLogger::init(
-//!     TermLogger::new(
+//!     LevelFilter::Debug,
-//!         LevelFilter::Trace,
 //!     ConfigBuilder::new()
 //!         .set_target_level(LevelFilter::Error)
 //!         .set_location_level(LevelFilter::Error)
 //!         .build(),
 //!     TerminalMode::Mixed,
 //!     ColorChoice::Auto,
-//!     ),
+//! )
-//! ).unwrap();
+//! .unwrap();
+//!
+//! // start reading aya-log records and log them using the default logger
+//! BpfLogger::init(&mut bpf).unwrap();
 //! ```
 //!
 //! With the following eBPF code:
@@ -61,7 +63,7 @@ use std::{convert::TryInto, io, mem, ptr, sync::Arc};
 
 use aya_log_common::{RecordField, LOG_BUF_CAPACITY, LOG_FIELDS};
 use bytes::BytesMut;
-use log::{Level, Log, Record};
+use log::{logger, Level, Log, Record};
 use thiserror::Error;
 
 use aya::{
@@ -79,9 +81,18 @@ use aya::{
 pub struct BpfLogger;
 
 impl BpfLogger {
+    /// Starts reading log records created with `aya-log-ebpf` and logs them
+    /// with the default logger. See [log::logger].
+    pub fn init(bpf: &mut Bpf) -> Result<BpfLogger, Error> {
+        BpfLogger::init_with_logger(bpf, DefaultLogger {})
+    }
+
     /// Starts reading log records created with `aya-log-ebpf` and logs them
     /// with the given logger.
-    pub fn init<T: Log + 'static>(bpf: &mut Bpf, logger: T) -> Result<BpfLogger, Error> {
+    pub fn init_with_logger<T: Log + 'static>(
+        bpf: &mut Bpf,
+        logger: T,
+    ) -> Result<BpfLogger, Error> {
         let logger = Arc::new(logger);
         let mut logs: AsyncPerfEventArray<_> = bpf.map_mut("AYA_LOGS")?.try_into()?;
 
@@ -110,6 +121,23 @@ impl BpfLogger {
     }
 }
 
+#[derive(Copy, Clone, Debug)]
+struct DefaultLogger;
+
+impl Log for DefaultLogger {
+    fn enabled(&self, metadata: &log::Metadata) -> bool {
+        log::logger().enabled(metadata)
+    }
+
+    fn log(&self, record: &Record) {
+        log::logger().log(record)
+    }
+
+    fn flush(&self) {
+        log::logger().flush()
+    }
+}
+
 #[derive(Error, Debug)]
 pub enum Error {
     #[error("error opening log event array")]