From 9ab9c80183edcb23297a644d0e63f7c1f28cd968 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alessandro=C2=A0Decina?= <alessandro.d@gmail.com>
Date: Fri, 15 Oct 2021 09:03:12 +0000
Subject: [PATCH] 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.
---
 aya-log/README.md          | 27 +++++++++---------
 aya-log/aya-log/src/lib.rs | 58 ++++++++++++++++++++++++++++----------
 2 files changed, 57 insertions(+), 28 deletions(-)

diff --git a/aya-log/README.md b/aya-log/README.md
index 0cb3b167..5e1245ca 100644
--- a/aya-log/README.md
+++ b/aya-log/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(
-    &mut bpf,
-    TermLogger::new(
-        LevelFilter::Trace,
-        ConfigBuilder::new()
-            .set_target_level(LevelFilter::Error)
-            .set_location_level(LevelFilter::Error)
-            .build(),
-        TerminalMode::Mixed,
-        ColorChoice::Auto,
-    ),
-).unwrap();
+TermLogger::init(
+    LevelFilter::Debug,
+    ConfigBuilder::new()
+        .set_target_level(LevelFilter::Error)
+        .set_location_level(LevelFilter::Error)
+        .build(),
+    TerminalMode::Mixed,
+    ColorChoice::Auto,
+)
+.unwrap();
+
+// Will log using the default logger, which is TermLogger in this case
+BpfLogger::init(&mut bpf).unwrap();
 ```
 
 ### eBPF code
diff --git a/aya-log/aya-log/src/lib.rs b/aya-log/aya-log/src/lib.rs
index 838fe5a5..d50fd860 100644
--- a/aya-log/aya-log/src/lib.rs
+++ b/aya-log/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(
-//!     &mut bpf,
-//!     TermLogger::new(
-//!         LevelFilter::Trace,
-//!         ConfigBuilder::new()
-//!             .set_target_level(LevelFilter::Error)
-//!             .set_location_level(LevelFilter::Error)
-//!             .build(),
-//!         TerminalMode::Mixed,
-//!         ColorChoice::Auto,
-//!     ),
-//! ).unwrap();
+//! // initialize simplelog::TermLogger as the default logger
+//! TermLogger::init(
+//!     LevelFilter::Debug,
+//!     ConfigBuilder::new()
+//!         .set_target_level(LevelFilter::Error)
+//!         .set_location_level(LevelFilter::Error)
+//!         .build(),
+//!     TerminalMode::Mixed,
+//!     ColorChoice::Auto,
+//! )
+//! .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")]