Crate flexi_logger[][src]

Expand description

A flexible and easy-to-use logger that writes logs to stderr and/or to files or other output streams.

To read the log specification from an environment variable and get the log written to stderr, start flexi_logger e.g. like this:

flexi_logger::Logger::try_with_env().unwrap().start().unwrap();

See

  • The builder Logger for a full description of all configuration options,
  • module code_examples for various concrete examples of flexi_logger initialization
  • the module writers for the usage of additional log writers,
  • and the README for how to get started.

There are configuration options to e.g.

  • decide whether you want to write your logs to stderr or to a file,
  • configure the path and the filenames of the log files,
  • use file rotation,
  • specify the line format for the log lines,
  • apply a stateful filter before log lines are really written,
  • define additional log output streams, e.g for alert or security messages,
  • support changing the log specification while the program is running,

flexi_logger uses a similar syntax as env_logger for specifying which logs should really be written (but is more graceful with the syntax, and can provide error information).

By default, i.e. if feature colors is not switched off, the log lines that appear on your terminal are coloured. In case the chosen colors don’t fit to your terminal’s color theme, you can adapt the colors to improve readability. See the documentation of method Logger::set_palette for a description how this can be done.

Modules

Here are some examples for the flexi_logger initialization.

Error codes of flexi_logger.

This module contains two traits which allow adding a stateful filter using Logger::filter.

trctrc

Use flexi_logger functionality with tracing.

Contains the trait LogWriter for extending flexi_logger with additional log writers, and two concrete implementations for writing to files (FileLogWriter) or to the syslog (SyslogWriter). You can also use your own implementations of LogWriter.

Structs

Deferred timestamp creation.

Builder object for specifying the name and path of the log output file.

Immutable struct that defines which loglines are to be written, based on the module, the log level, and the text.

The entry-point for using flexi_logger.

Shuts down the logger when dropped, and allows reconfiguring the logger programmatically.

Defines which loglevel filter to use for the specified module.

Re-exports from log crate

Enums

Can be used in Logger::adaptive_format_for_stderr and Logger::adaptive_format_for_stdout to use coloring only if the output goes to a tty.

The age after which a log file rotation will be triggered, when Criterion::Age is chosen.

Defines the strategy for handling older log files.

Criterion when to rotate the log file.

Used to control which messages are to be duplicated to stderr, when log_to_file() is used.

Enum for defining the output channel for flexi_logger’s own error messages.

Describes errors in the initialization of flexi_logger.

Re-exports from log crate

Re-exports from log crate

The naming convention for rotated log files.

Describes whether the log output should be written synchronously or asynchronously, and if and how I/O should be buffered and flushed.

Constants

Default buffer capacity (8k), when buffering is used.

Default flush interval (1s), when flushing is used.

Default capacity for the message buffers; a higher value reduces allocations when longer log lines are used.

Default size of the message pool; a higher value could further reduce allocations during log file rotation and cleanup.

Precompiled version of the time stamp format that is used by the provided format functions.

Functions

A colored version of the logline-formatter default_format that produces log lines like
ERROR [my_prog::some_submodule] File not found

A colored version of the logline-formatter detailed_format.

A colored version of the logline-formatter opt_format.

A colored version of the logline-formatter with_thread.

A logline-formatter that produces log lines like
INFO [my_prog::some_submodule] Task successfully read from conf.json

A logline-formatter that produces log lines like
[2016-01-13 15:25:01.640870 +01:00] INFO [foo::bar] src/foo/bar.rs:26: Task successfully read from conf.json
i.e. with timestamp, module path and file location.

A logline-formatter that produces log lines with timestamp and file location, like
[2016-01-13 15:25:01.640870 +01:00] INFO [src/foo/bar:26] Task successfully read from conf.json

stylecolors

Helper function that is used in the provided coloring format functions to apply colors based on the log level and the effective color palette.

A logline-formatter that produces log lines like
[2016-01-13 15:25:01.640870 +01:00] T[taskreader] INFO [src/foo/bar:26] Task successfully read from conf.json
i.e. with timestamp, thread name and file location.

Type Definitions

Function type for format functions.