Struct flexi_logger::writers::FileLogWriterBuilder

pub struct FileLogWriterBuilder { /* private fields */ }

Builder for FileLogWriter.

Implementations

impl FileLogWriterBuilder

Methods for influencing the behavior of the FileLogWriter.

pub fn print_message(self) -> Self

Makes the FileLogWriter print an info message to stdout when a new file is used for log-output.

pub fn format(self, format: FormatFunction) -> Self

Makes the FileLogWriter use the provided format function for the log entries, rather than default_format.

pub fn cleanup_in_background_thread(self, use_background_thread: bool) -> Self

Influences how the cleanup activities (finding files, deleting files, optionally compressing files) are done when rotation is used with some Cleanup variant.

With the synchronous write modes, the cleanup activities are done by default in a dedicated background thread, to minimize the blocking impact on your application. You can avoid this extra thread by calling this method with use_background_thread = false; the cleanup is then done synchronously by the thread that is currently logging and - by chance - causing a file rotation.

With WriteMode::AsyncWith, the cleanup activities are always done by the same background thread that also does the file I/O, this method then has no effect.

pub fn rotate(self, criterion: Criterion, naming: Naming, cleanup: Cleanup) -> Self

Use rotation to prevent indefinite growth of log files.

By default, the log file is fixed while your program is running and will grow indefinitely. With this option being used, when the log file reaches the specified criterion, the file will be closed and a new file will be opened.

Note that also the filename pattern changes:

• by default, no timestamp is added to the filename
• the logs are always written to a file with infix _rCURRENT
• when the rotation criterion is fulfilled, it is closed and renamed to a file with another infix (see Naming), and then the logging continues again to the (fresh) file with infix _rCURRENT.

Example:

After some logging with your program my_prog and rotation with Naming::Numbers, you will find files like

my_prog_r00000.log
my_prog_r00001.log
my_prog_r00002.log
my_prog_rCURRENT.log

The cleanup parameter allows defining the strategy for dealing with older files. See Cleanup for details.

pub fn append(self) -> Self

Makes the logger append to the given file, if it exists; by default, the file would be truncated.

pub fn use_utc(self) -> Self

Enforces the use of UTC, rather than local time.

pub fn create_symlink<P: Into<PathBuf>>(self, symlink: P) -> Self

The specified String will be used on unix systems to create in the current folder a symbolic link to the current log file.

pub fn use_windows_line_ending(self) -> Self

Use Windows line endings, rather than just \n.

pub fn write_mode(self, write_mode: WriteMode) -> Self

Sets the write mode for the FileLogWriter.

See WriteMode for more (important!) details.

pub fn try_build(self) -> Result<FileLogWriter, FlexiLoggerError>

Produces the FileLogWriter.

Errors

FlexiLoggerError::Io if the specified path doesn’t work.

pub fn try_build_with_handle(
    self
) -> Result<(ArcFileLogWriter, FileLogWriterHandle), FlexiLoggerError>

Produces the FileLogWriter and a handle that is connected with it.

This allows handing out the FileLogWriter instance to methods that consume it, and still be able to influence it via the handle.

Errors

FlexiLoggerError::Io if the specified path doesn’t work.

impl FileLogWriterBuilder

Alternative set of methods to control the behavior of the FileLogWriterBuilder. Use these methods when you want to control the settings flexibly, e.g. with commandline arguments via docopts or clap.

pub fn o_print_message(self, print_message: bool) -> Self

With true, makes the FileLogWriterBuilder print an info message to stdout, each time when a new file is used for log-output.

pub fn o_rotate(
    self,
    rotate_config: Option<(Criterion, Naming, Cleanup)>
) -> Self

By default, and with None, the log file will grow indefinitely. If a rotate_config is set, when the log file reaches or exceeds the specified size, the file will be closed and a new file will be opened. Also the filename pattern changes: instead of the timestamp, a serial number is included into the filename.

The size is given in bytes, e.g. o_rotate_over_size(Some(1_000)) will rotate files once they reach a size of 1 kB.

The cleanup strategy allows delimiting the used space on disk.

pub fn o_append(self, append: bool) -> Self

If append is set to true, makes the logger append to the given file, if it exists. By default, or with false, the file would be truncated.

pub fn o_create_symlink<S: Into<PathBuf>>(self, symlink: Option<S>) -> Self

If a String is specified, it will be used on unix systems to create in the current folder a symbolic link with this name to the current log file.