log4g is a logging framework that's interface like java log4j. it's designed for configurable and pluggable logging.

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Brief Introduce

core concepts:

• Formatter：the logger formatter which is identified by name attribute, and type attribute represents the type of formatter.
• Output: the logger output target which is identified by name attribute, and type attribute represents the type of the output target. An output is associated with a formatter.
• Logger：the logger instances which is identified by name attribute. Each logger can be associated with multiple outputs.

logger

the logger name separating by / and ., for example, the logger named module is the parent logger named module/submodule. When the child logger is not set, it' configuration of Output and Level will inherit the parent logger configuration.

Logger level are: All<Trace<Debug<Info<Warn<Error<Critical<Off

The output level of one logger can be configured in the configuration file without case discrimination.

formatter

the layout of default Formatter is to parse %{verb} format string, the type attribute of it is text.

the verb format：%{verbName:fmtstr}:

• verbName is a field name
• fmtstr is a format output definitions for the field, it supports standard Go format lattices

for example: %{pid:05d}, 05d means that at least five characters are output, supplemented by 0 .

anothe example: %{module}|%{lvl:5s}>>%{msg}

all support verb as follow:

• %{pid}: The process id (int)
• %{program}: The basename of os.Args[0] (string)
• %{module}: The logger name
• %{msg}: The content by using Debug(...) or Debugf(...) methods or others of a logger
• %{level}: The uppercase loglevel name, eg. DEBUG
• %{lvl}: The uppercase short log level name, eg. DBG
• %{line}: The line number
• %{longfile}: The full file path，eg. /a/b/c/d.go
• %{shortfile}: The file basename, eg. d.go
• %{longpkg}: The full package name, eg. github.com/xtfly/log4g
• %{shortpkg}: The package basename, eg. log4g
• %{longfunc}: The full function name, eg. littleEndian.PutUint32
• %{shortfunc}: The base function name, eg. PutUint32
• %{time}: The time when log occurred，eg. %{time:2006-01-02T15:04:05.999Z-07:00}
• %{xxx}: When using the WithCtx or WithFields method of a logger, xxx represents searching for content from the list of output fields.

output

TBD

config

The configuration file format supports YAML and JSON formats. For definitions, refer to the Config structure in logger_api.go.

Format:

formats:
  - name: f1     # Name of format for output reference
    type: text   # Currently only text
    layout: "%{time} %{level} %{module} %{pid:6d} >> %{msg} (%{longfile}:%{line}) \n"

Output:

outputs:
  - name: c1          # Name of output for logger reference
    type: console     # Ouput log content into console
    format: f1        # Referenced formatter name
    #async: true      # Whether to start asynchrony ouput log content
    #queue_size: 100  # The length of the queue when enable asynchronous
    #batch_num: 10    # Batch 10 items submitted to the target together when enable asynchronous
    #threshold: info
  - name: r1
    type: size_rolling_file # The type of rolling 
    format: f1
    file: log/rf.log   # The current written output file name
    file_perm: 0640    # The file permissions being written
    back_perm: 0550    # The file permissions that have been backup rolling
    dir_perm: 0750     # The direction permissions
    size: 1M           # When this value is exceeded, make a backup rolling
    backups: 5         # The number of backup rolling
    #archive: gzip     # The archive type of the backup logs, zip or gzip
    #name_mode: prefix # The backup name type, prefix or postfix, log/rf.log->log/rf.log.1 or log/rf.log->log/rf.1.log
    #async: true       # Whether to start asynchrony ouput log content
    #queue_size: 100   # The length of the queue when enable asynchronous
    #batch_num: 10     # Batch 10 items submitted to the target together when enable asynchronous
    #threshold: info
  - name: r2
    type: time_rolling_file # The type of rolling
    format: f1
    file: log/rf2.log
    file_perm: 0640
    back_perm: 0550
    dir_perm: 0750
    pattern: 2006-01-02   # The date format for backup rolling
    backups: 5
    #archive: gzip
    #name_mode: prefix
    #async: true
    #queue_size: 100
    #batch_num: 10
    #threshold: info
  - name: s1
    type: syslog
    format: f1
    prefix: module

usage

import "github.com/xtfly/log4g"

func main() {

	// optional, load config from a file
	// err := log.GetManager().LoadConfigFile("log4g.yaml")
	// fmt.Printf("%v", err)

	// optional, set config by code
	//cfg := &api.Config{
	//	Loggers: []api.CfgLogger{
	//		{Name: "root", Level: "all", OutputNames: []string{"c1"}},
	//	},
	//	Formats: []api.CfgFormat{
	//		{"type": "text", "name": "f1", "layout": "%{time} %{level} %{module} %{pid:6d} >> %{msg} (%{longfile}:%{line}) \n"},
	//	},
	//	Outputs: []api.CfgOutput{
	//		{"type": "console", "name": "c1", "format": "f1"},
	//	},
	//}
	//_ = log.GetManager().SetConfig(cfg)

	dlog := log.GetLogger("a/b")
	dlog.Debug("message")
	dlog.Info("info message")

	// optional, manually close manager
	// log.GetManager().Close()

}

Develop

• extend Formatter
• extend Output

Task List

• Logger formwork
• Formatter
  • Text: parse %{verb} layout
• Output
  • Console
    • sync
    • async
  • Rolling file by size
    • sync
    • async
    • backup and compress
  • Rolling file by date
    • sync
    • async
    • backup and compress
  • Syslog
    • sync
• validate configuration parameters
• more test case

Thanks

Thanks to the follow open source project for this project port some code from them:

• seelog
• go-logging