From aae4baa99b8ea38388a39c110ebb01300b5d3479 Mon Sep 17 00:00:00 2001
From: Roman Dmitrienko <roman@dmitrienko.com>
Date: Tue, 6 Aug 2024 18:06:01 +0300
Subject: [PATCH] Implement daily log file rotation.

---
 src/logger.rs | 76 +++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 55 insertions(+), 21 deletions(-)

diff --git a/src/logger.rs b/src/logger.rs
index 5f8627e07..bd4a6ed8c 100644
--- a/src/logger.rs
+++ b/src/logger.rs
@@ -9,17 +9,16 @@ use chrono::Utc;
 use std::fs;
 #[cfg(not(target_os = "windows"))]
 use std::os::unix::fs::symlink;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 pub(crate) struct FilesystemLogger {
-	file_path: String,
+	log_dir: String,
 	level: Level,
 }
 
 impl FilesystemLogger {
 	pub(crate) fn new(log_dir: String, level: Level) -> Result<Self, ()> {
-		let log_file_name =
-			format!("ldk_node_{}.log", chrono::offset::Local::now().format("%Y_%m_%d"));
+		let log_file_name = FilesystemLogger::make_log_file_name();
 		let log_file_path = format!("{}/{}", log_dir, log_file_name);
 
 		if let Some(parent_dir) = Path::new(&log_file_path).parent() {
@@ -32,21 +31,59 @@ impl FilesystemLogger {
 				.open(log_file_path.clone())
 				.map_err(|e| eprintln!("ERROR: Failed to open log file: {}", e))?;
 
-			#[cfg(not(target_os = "windows"))]
-			{
-				// Create a symlink to the current log file, with prior cleanup
-				let log_file_symlink = parent_dir.join("ldk_node_latest.log");
-				if log_file_symlink.as_path().is_symlink() {
-					fs::remove_file(&log_file_symlink).map_err(|e| {
-						eprintln!("ERROR: Failed to remove log file symlink: {}", e)
-					})?;
-				}
-				symlink(&log_file_name, &log_file_symlink)
-					.map_err(|e| eprintln!("ERROR: Failed to create log file symlink: {}", e))?;
+			FilesystemLogger::make_log_file_symlink(&parent_dir, &log_file_name)?;
+		}
+
+		Ok(Self { log_dir, level })
+	}
+
+	fn make_log_file_name() -> String {
+		format!("ldk_node_{}.log", chrono::offset::Local::now().format("%Y_%m_%d"))
+	}
+
+	fn make_log_file_symlink<D: AsRef<Path>, F: AsRef<Path>>(
+		log_dir: D, log_file_name: F,
+	) -> Result<(), ()> {
+		#[cfg(not(target_os = "windows"))]
+		{
+			// Create a symlink to the current log file, with prior cleanup
+			let log_file_symlink = log_dir.as_ref().join("ldk_node_latest.log");
+			if log_file_symlink.as_path().is_symlink() {
+				fs::remove_file(&log_file_symlink)
+					.map_err(|e| eprintln!("ERROR: Failed to remove log file symlink: {}", e))?;
 			}
+			symlink(&log_file_name, &log_file_symlink)
+				.map_err(|e| eprintln!("ERROR: Failed to create log file symlink: {}", e))?;
+		}
+
+		Ok(())
+	}
+
+	fn log_file_path(&self) -> PathBuf {
+		PathBuf::from(format!("{}/{}", self.log_dir, FilesystemLogger::make_log_file_name()))
+	}
+
+	fn open_log_file(&self) -> Result<fs::File, ()> {
+		let log_path = self.log_file_path();
+		let is_new_file = log_path.try_exists().and_then(|e| Ok(!e)).unwrap_or(false);
+
+		let ret = fs::OpenOptions::new()
+			.create(true)
+			.append(true)
+			.open(&log_path)
+			.map_err(|e| eprintln!("ERROR: Failed to open log file: {}", e))?;
+
+		if is_new_file {
+			// Do not check for errors; in concurrent scenarios, this is not
+			// unlikely to fail. The concurrent thread should be able to finish
+			// the operation.
+			let _ = FilesystemLogger::make_log_file_symlink(
+				&self.log_dir,
+				log_path.file_name().unwrap(),
+			);
 		}
 
-		Ok(Self { file_path: log_file_path, level })
+		Ok(ret)
 	}
 }
 impl Logger for FilesystemLogger {
@@ -63,12 +100,9 @@ impl Logger for FilesystemLogger {
 			record.line,
 			raw_log
 		);
-		fs::OpenOptions::new()
-			.create(true)
-			.append(true)
-			.open(self.file_path.clone())
+		self.open_log_file()
 			.expect("Failed to open log file")
 			.write_all(log.as_bytes())
-			.expect("Failed to write to log file")
+			.expect("Failed to write to log file");
 	}
 }