Improve combination of append with Criterion::Age. Fixes #122.

CHANGELOG.md

@@ -7,8 +7,12 @@ project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [0.24.0] - unpublished
 
-Revert back to using `chrono`, since `chrono` is now fortunately maintained again and the timezone
-handling is fixed (largely reverting the changes done for [0.19.6]).
+Revert back to using `chrono`, since `chrono` is now fortunately maintained again and its timezone
+handling is fixed meanwhile (largely reverting the changes done for [0.19.6];
+version bump since this affects the API, e.g. in `DeferredNow`).
+
+Improve the logic that handles the issue described again in
+[issue-122](https://github.com/emabee/flexi_logger/issues/122).
 
 ## [0.23.3] - 2022-09-11
 

src/parameters.rs

@@ -23,8 +23,9 @@ pub enum Criterion {
     /// for different reasons.
     ///
     /// To minimize the impact on age-based file-rotation,
-    /// `flexi_logger` uses on Windows and unix its initialization time
-    /// rather than the real file property
+    /// `flexi_logger` uses on Windows, and on all other platforms where the creation date
+    /// of a file is not available (like on Unix), the last modification date
+    /// (or, if this is also not available, the current time stamp)
     /// as the created_at-info of an rCURRENT file that already exists, and the
     /// current timestamp when file rotation happens during further execution.
     /// Consequently, a left-over rCURRENT file from a previous program run will look newer
@@ -42,11 +43,6 @@ pub enum Criterion {
     ///
     /// <a name="ref-1">\[1\]</a> [https://superuser.com/questions/966490/windows-7-what-is-date-created-file-property-referring-to](https://superuser.com/questions/966490/windows-7-what-is-date-created-file-property-referring-to).
     ///
-    /// #### Issue on unix
-    ///
-    /// `std::fs::metadata.created()` returns `Err`, because unix does not maintain a
-    /// created-at-timestamp.
-    ///
     Age(Age),
     /// Rotate the file when it has either become older than the specified age, or when it has
     /// exceeded the specified size in bytes.

src/writers/file_log_writer/state.rs

@@ -736,26 +736,28 @@ fn rotate_output_file_to_idx(
 // See documentation of Criterion::Age.
 fn get_creation_date(path: &Path) -> DateTime<Local> {
     // On windows, we know that try_get_creation_date() returns a result, but it is wrong.
-    // On unix, we know that try_get_creation_date() returns an error.
-    if cfg!(any(target_os = "windows", target_family = "unix")) {
-        get_fake_creation_date()
+    if cfg!(target_os = "windows") {
+        try_get_modification_date(path).unwrap_or_else(|_| get_current_date())
     } else {
         // On all others of the many platforms, we give the real creation date a try,
-        // and fall back to the fake if it is not available.
-        match try_get_creation_date(path) {
-            Ok(d) => d,
-            Err(_e) => get_fake_creation_date(),
-        }
+        // and fall back if it is not available.
+        try_get_creation_date(path)
+            .or_else(|_| try_get_modification_date(path))
+            .unwrap_or_else(|_| get_current_date())
     }
 }
 
-fn get_fake_creation_date() -> DateTime<Local> {
-    Local::now()
-}
-
 fn try_get_creation_date(path: &Path) -> Result<DateTime<Local>, FlexiLoggerError> {
     Ok(std::fs::metadata(path)?.created()?.into())
 }
+fn try_get_modification_date(path: &Path) -> Result<DateTime<Local>, FlexiLoggerError> {
+    let md = std::fs::metadata(path)?;
+    let d = md.created().or_else(|_| md.modified())?;
+    Ok(d.into())
+}
+fn get_current_date() -> DateTime<Local> {
+    Local::now()
+}
 
 mod platform {
     #[cfg(target_family = "unix")]