Allow defining own infix formatter

examples/rotate_custom_format.rs

@@ -0,0 +1,43 @@
+use flexi_logger::{
+    sort_by_creation_date, Age, Cleanup, Criterion, CustomFormatter, Duplicate, FileSorter,
+    FileSpec, FlexiLoggerError, LevelFilter, Logger, Naming,
+};
+use std::{thread::sleep, time::Duration};
+
+fn format_infix(o_last_infix: Option<String>) -> String {
+    let id = match o_last_infix {
+        Some(infix) => {
+            let id: usize = infix.parse().unwrap();
+            id + 1
+        }
+        None => 0,
+    };
+    id.to_string()
+}
+
+fn main() -> Result<(), FlexiLoggerError> {
+    Logger::with(LevelFilter::Info)
+        .rotate(
+            Criterion::Age(Age::Second),
+            Naming::CustomFormat(CustomFormatter::new(format_infix)),
+            Cleanup::KeepLogFiles(4),
+        )
+        .log_to_file(
+            FileSpec::default()
+                .directory(std::env::current_dir().unwrap().join("log_files"))
+                .basename("app-log")
+                .suffix("txt")
+                .file_sorter(FileSorter::new(sort_by_creation_date)),
+        )
+        .duplicate_to_stdout(Duplicate::All)
+        .start()?;
+
+    log::info!("start");
+    for step in 0..30 {
+        log::info!("step {}", step);
+        sleep(Duration::from_millis(250));
+    }
+    log::info!("done");
+
+    Ok(())
+}

src/lib.rs

@@ -72,7 +72,10 @@ pub use crate::{
     log_specification::{LogSpecBuilder, LogSpecification, ModuleFilter},
     logger::{Duplicate, ErrorChannel, Logger},
     logger_handle::{LogfileSelector, LoggerHandle},
-    parameters::{Age, Cleanup, Criterion, FileSpec, Naming},
+    parameters::{
+        sort_by_creation_date, sort_by_default, Age, Cleanup, Criterion, CustomFormatter,
+        FileSorter, FileSpec, Naming,
+    },
     write_mode::{WriteMode, DEFAULT_BUFFER_CAPACITY, DEFAULT_FLUSH_INTERVAL},
 };
 

src/parameters.rs

@@ -7,5 +7,7 @@ mod naming;
 pub use age::Age;
 pub use cleanup::Cleanup;
 pub use criterion::Criterion;
-pub use file_spec::FileSpec;
+pub use file_spec::{sort_by_creation_date, sort_by_default};
+pub use file_spec::{FileSorter, FileSpec};
+pub use naming::CustomFormatter;
 pub use naming::Naming;

src/parameters/file_spec.rs

@@ -1,5 +1,6 @@
 use crate::writers::file_log_writer::InfixFilter;
 use crate::{DeferredNow, FlexiLoggerError};
+use std::fs;
 use std::{
     ffi::{OsStr, OsString},
     ops::Add,
@@ -51,6 +52,7 @@ pub struct FileSpec {
     timestamp_cfg: TimestampCfg,
     o_suffix: Option<String>,
     pub(crate) use_utc: bool,
+    file_sorter: FileSorter,
 }
 impl Default for FileSpec {
     /// Describes a file in the current folder,
@@ -65,6 +67,7 @@ impl Default for FileSpec {
             timestamp_cfg: TimestampCfg::Default,
             o_suffix: Some(String::from("log")),
             use_utc: false,
+            file_sorter: FileSorter::default(),
         }
     }
 }
@@ -108,6 +111,7 @@ impl FileSpec {
                 o_suffix: p.extension().map(|s| s.to_string_lossy().to_string()),
                 timestamp_cfg: TimestampCfg::No,
                 use_utc: false,
+                file_sorter: FileSorter::default(),
             })
         }
     }
@@ -136,6 +140,11 @@ impl FileSpec {
         self
     }
 
+    ///Basename getter
+    pub fn get_basename(&self) -> &str {
+        &self.basename
+    }
+
     /// Specifies a folder for the log files.
     ///
     /// If the specified folder does not exist, it will be created.
@@ -185,6 +194,12 @@ impl FileSpec {
         self
     }
 
+    /// Specifies file sorter
+    pub fn file_sorter(mut self, file_sorter: FileSorter) -> Self {
+        self.file_sorter = file_sorter;
+        self
+    }
+
     /// Makes the logger not include the start time into the names of the log files
     ///
     /// Equivalent to `use_timestamp(false)`.
@@ -368,8 +383,7 @@ impl FileSpec {
                 }
             })
             .collect::<Vec<PathBuf>>();
-        log_files.sort_unstable();
-        log_files.reverse();
+        self.file_sorter.sort(&mut log_files);
         log_files
     }
 
@@ -418,6 +432,45 @@ impl FileSpec {
     }
 }
 
+/// File sorter stores and exposes interface to sorting strategy
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct FileSorter {
+    sort_fn: fn(&mut [PathBuf]),
+}
+
+impl FileSorter {
+    /// Creates new FileSorter
+    pub fn new(sort_fn: fn(&mut [PathBuf])) -> Self {
+        Self { sort_fn }
+    }
+
+    fn sort(&self, files: &mut [PathBuf]) {
+        (self.sort_fn)(files)
+    }
+}
+
+impl Default for FileSorter {
+    fn default() -> Self {
+        Self::new(sort_by_default)
+    }
+}
+
+/// sorts log files by the creation date
+pub fn sort_by_creation_date(files: &mut [PathBuf]) {
+    files.sort_by_key(|path| {
+        fs::metadata(path)
+            .and_then(|metadata| metadata.created())
+            .ok()
+    });
+    files.reverse();
+}
+
+/// default sorting algorithm
+pub fn sort_by_default(files: &mut [PathBuf]) {
+    files.sort_unstable();
+    files.reverse();
+}
+
 const TS_USCORE_DASHES_USCORE_DASHES: &str = "%Y-%m-%d_%H-%M-%S";
 
 #[derive(Debug, Clone, Eq, PartialEq)]

src/parameters/naming.rs

@@ -103,7 +103,11 @@ pub enum Naming {
     ///
     /// File rotation switches over to the next file.
     NumbersDirect,
+
+    /// Allows to specify custom infix and treat each file with basename as log file
+    CustomFormat(CustomFormatter),
 }
+
 impl Naming {
     pub(crate) fn writes_direct(self) -> bool {
         matches!(
@@ -117,3 +121,21 @@ impl Naming {
         )
     }
 }
+
+/// Custom Formatter
+#[derive(Copy, Clone, Debug)]
+pub struct CustomFormatter {
+    format_fn: fn(Option<String>) -> String,
+}
+
+impl CustomFormatter {
+    /// Instantiate custom formatter
+    pub fn new(format_fn: fn(Option<String>) -> String) -> Self {
+        CustomFormatter { format_fn }
+    }
+
+    /// call custom formatter
+    pub fn call(&self, o_last_infix: Option<String>) -> String {
+        (self.format_fn)(o_last_infix)
+    }
+}

src/writers/file_log_writer/infix_filter.rs

@@ -27,7 +27,7 @@ impl InfixFilter {
             #[cfg(test)]
             InfixFilter::StartsWth(s) => infix.starts_with(s),
             InfixFilter::Equls(s) => infix.eq(s),
-            InfixFilter::None => false,
+            InfixFilter::None => true,
         }
     }
 }

src/writers/file_log_writer/state.rs

@@ -2,6 +2,7 @@ mod list_and_cleanup;
 mod numbers;
 mod timestamps;
 
+use list_and_cleanup::get_last_infix;
 pub(crate) use timestamps::timestamp_from_ts_infix;
 
 use super::{
@@ -12,7 +13,7 @@ use super::{
 use crate::util::eprint_msg;
 use crate::{
     util::{eprint_err, ErrorCode},
-    Age, Cleanup, Criterion, FlexiLoggerError, LogfileSelector, Naming,
+    Age, Cleanup, Criterion, CustomFormatter, FlexiLoggerError, LogfileSelector, Naming,
 };
 use chrono::{DateTime, Datelike, Local, Timelike};
 #[cfg(feature = "async")]
@@ -55,6 +56,9 @@ enum NamingState {
 
     // contains the index of the current output file
     NumbersDirect(u32),
+
+    // contains custom formatter and last infix
+    CustomFormat(CustomFormatter, String),
 }
 impl NamingState {
     pub(crate) fn writes_direct(&self) -> bool {
@@ -77,6 +81,7 @@ impl NamingState {
                 infix_format,
             } => InfixFilter::Timstmps(infix_format.clone()),
             NamingState::NumbersDirect(_) | NamingState::NumbersRCurrent(_) => InfixFilter::Numbrs,
+            NamingState::CustomFormat(_, _) => InfixFilter::None,
         }
     }
 }
@@ -403,6 +408,14 @@ impl State {
                 };
                 (NamingState::NumbersDirect(idx), numbers::number_infix(idx))
             }
+            Naming::CustomFormat(ref formatter) => {
+                let o_last_infix: Option<String> = get_last_infix(&self.config.file_spec);
+                let current_infix = formatter.call(o_last_infix);
+                (
+                    NamingState::CustomFormat(*formatter, current_infix.clone()),
+                    current_infix,
+                )
+            }
         };
         let (write, path) = open_log_file(&self.config, Some(&infix))?;
         let roll_state = RollState::new(rotate_config.criterion, self.config.append, &path)?;
@@ -494,6 +507,11 @@ impl State {
                         *idx_state += 1;
                         numbers::number_infix(*idx_state)
                     }
+                    NamingState::CustomFormat(ref formatter, ref mut last_infix) => {
+                        let infix = formatter.call(Some(last_infix.clone()));
+                        *last_infix = infix.clone();
+                        infix
+                    }
                 };
                 let (new_write, new_path) = open_log_file(&self.config, Some(&infix))?;
 

src/writers/file_log_writer/state/list_and_cleanup.rs

@@ -197,3 +197,16 @@ pub(super) fn start_cleanup_thread(
         })?,
     })
 }
+
+pub(super) fn get_last_infix(file_spec: &FileSpec) -> Option<String> {
+    let log_files =
+        super::list_and_cleanup::list_of_log_and_compressed_files(file_spec, &InfixFilter::None);
+    // ascending ordering
+    let last_log_file = log_files.first()?;
+    let last_log_name = last_log_file.file_stem().unwrap(/*ok*/).to_string_lossy();
+    Some(
+        last_log_name
+            .strip_prefix(&format!("{}_", file_spec.get_basename()))?
+            .to_owned(),
+    )
+}