/usr/share/gocode/src/github.com/juju/loggo/logger.go is in golang-juju-loggo-dev 0.0~git20150318-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// Licensed under the LGPLv3, see LICENCE file for details.
package loggo
import (
"fmt"
"runtime"
"sort"
"strings"
"sync"
"sync/atomic"
"time"
)
// Level holds a severity level.
type Level uint32
// The severity levels. Higher values are more considered more
// important.
const (
UNSPECIFIED Level = iota
TRACE
DEBUG
INFO
WARNING
ERROR
CRITICAL
)
// A Logger represents a logging module. It has an associated logging
// level which can be changed; messages of lesser severity will
// be dropped. Loggers have a hierarchical relationship - see
// the package documentation.
//
// The zero Logger value is usable - any messages logged
// to it will be sent to the root Logger.
type Logger struct {
impl *module
}
type module struct {
name string
level Level
parent *module
}
// Initially the modules map only contains the root module.
var (
root = &module{level: WARNING}
modulesMutex sync.Mutex
modules = map[string]*module{
"": root,
}
)
func (level Level) String() string {
switch level {
case UNSPECIFIED:
return "UNSPECIFIED"
case TRACE:
return "TRACE"
case DEBUG:
return "DEBUG"
case INFO:
return "INFO"
case WARNING:
return "WARNING"
case ERROR:
return "ERROR"
case CRITICAL:
return "CRITICAL"
}
return "<unknown>"
}
// get atomically gets the value of the given level.
func (level *Level) get() Level {
return Level(atomic.LoadUint32((*uint32)(level)))
}
// set atomically sets the value of the receiver
// to the given level.
func (level *Level) set(newLevel Level) {
atomic.StoreUint32((*uint32)(level), uint32(newLevel))
}
// getLoggerInternal assumes that the modulesMutex is locked.
func getLoggerInternal(name string) Logger {
impl, found := modules[name]
if found {
return Logger{impl}
}
parentName := ""
if i := strings.LastIndex(name, "."); i >= 0 {
parentName = name[0:i]
}
parent := getLoggerInternal(parentName).impl
impl = &module{name, UNSPECIFIED, parent}
modules[name] = impl
return Logger{impl}
}
// GetLogger returns a Logger for the given module name,
// creating it and its parents if necessary.
func GetLogger(name string) Logger {
// Lowercase the module name, and look for it in the modules map.
name = strings.ToLower(name)
modulesMutex.Lock()
defer modulesMutex.Unlock()
return getLoggerInternal(name)
}
// LoggerInfo returns information about the configured loggers and their logging
// levels. The information is returned in the format expected by
// ConfigureModules. Loggers with UNSPECIFIED level will not
// be included.
func LoggerInfo() string {
output := []string{}
// output in alphabetical order.
keys := []string{}
modulesMutex.Lock()
defer modulesMutex.Unlock()
for key := range modules {
keys = append(keys, key)
}
sort.Strings(keys)
for _, name := range keys {
mod := modules[name]
severity := mod.level
if severity == UNSPECIFIED {
continue
}
output = append(output, fmt.Sprintf("%s=%s", mod.Name(), severity))
}
return strings.Join(output, ";")
}
// ParseConfigurationString parses a logger configuration string into a map of
// logger names and their associated log level. This method is provided to
// allow other programs to pre-validate a configuration string rather than
// just calling ConfigureLoggers.
//
// Loggers are colon- or semicolon-separated; each module is specified as
// <modulename>=<level>. White space outside of module names and levels is
// ignored. The root module is specified with the name "<root>".
//
// As a special case, a log level may be specified on its own.
// This is equivalent to specifying the level of the root module,
// so "DEBUG" is equivalent to `<root>=DEBUG`
//
// An example specification:
// `<root>=ERROR; foo.bar=WARNING`
func ParseConfigurationString(specification string) (map[string]Level, error) {
levels := make(map[string]Level)
if level, ok := ParseLevel(specification); ok {
levels[""] = level
return levels, nil
}
values := strings.FieldsFunc(specification, func(r rune) bool { return r == ';' || r == ':' })
for _, value := range values {
s := strings.SplitN(value, "=", 2)
if len(s) < 2 {
return nil, fmt.Errorf("logger specification expected '=', found %q", value)
}
name := strings.TrimSpace(s[0])
levelStr := strings.TrimSpace(s[1])
if name == "" || levelStr == "" {
return nil, fmt.Errorf("logger specification %q has blank name or level", value)
}
if name == "<root>" {
name = ""
}
level, ok := ParseLevel(levelStr)
if !ok {
return nil, fmt.Errorf("unknown severity level %q", levelStr)
}
levels[name] = level
}
return levels, nil
}
// ConfigureLoggers configures loggers according to the given string
// specification, which specifies a set of modules and their associated
// logging levels. Loggers are colon- or semicolon-separated; each
// module is specified as <modulename>=<level>. White space outside of
// module names and levels is ignored. The root module is specified
// with the name "<root>".
//
// An example specification:
// `<root>=ERROR; foo.bar=WARNING`
func ConfigureLoggers(specification string) error {
if specification == "" {
return nil
}
levels, err := ParseConfigurationString(specification)
if err != nil {
return err
}
for name, level := range levels {
GetLogger(name).SetLogLevel(level)
}
return nil
}
// ResetLogging iterates through the known modules and sets the levels of all
// to UNSPECIFIED, except for <root> which is set to WARNING.
func ResetLoggers() {
modulesMutex.Lock()
defer modulesMutex.Unlock()
for name, module := range modules {
if name == "" {
module.level.set(WARNING)
} else {
module.level.set(UNSPECIFIED)
}
}
}
// ParseLevel converts a string representation of a logging level to a
// Level. It returns the level and whether it was valid or not.
func ParseLevel(level string) (Level, bool) {
level = strings.ToUpper(level)
switch level {
case "UNSPECIFIED":
return UNSPECIFIED, true
case "TRACE":
return TRACE, true
case "DEBUG":
return DEBUG, true
case "INFO":
return INFO, true
case "WARN", "WARNING":
return WARNING, true
case "ERROR":
return ERROR, true
case "CRITICAL":
return CRITICAL, true
}
return UNSPECIFIED, false
}
func (logger Logger) getModule() *module {
if logger.impl == nil {
return root
}
return logger.impl
}
// Name returns the logger's module name.
func (logger Logger) Name() string {
return logger.getModule().Name()
}
// LogLevel returns the configured log level of the logger.
func (logger Logger) LogLevel() Level {
return logger.getModule().level.get()
}
func (module *module) getEffectiveLogLevel() Level {
// Note: the root module is guaranteed to have a
// specified logging level, so acts as a suitable sentinel
// for this loop.
for {
if level := module.level.get(); level != UNSPECIFIED {
return level
}
module = module.parent
}
panic("unreachable")
}
func (module *module) Name() string {
if module.name == "" {
return "<root>"
}
return module.name
}
// EffectiveLogLevel returns the effective log level of
// the receiver - that is, messages with a lesser severity
// level will be discarded.
//
// If the log level of the receiver is unspecified,
// it will be taken from the effective log level of its
// parent.
func (logger Logger) EffectiveLogLevel() Level {
return logger.getModule().getEffectiveLogLevel()
}
// SetLogLevel sets the severity level of the given logger.
// The root logger cannot be set to UNSPECIFIED level.
// See EffectiveLogLevel for how this affects the
// actual messages logged.
func (logger Logger) SetLogLevel(level Level) {
module := logger.getModule()
// The root module can't be unspecified.
if module.name == "" && level == UNSPECIFIED {
level = WARNING
}
module.level.set(level)
}
// Logf logs a printf-formatted message at the given level.
// A message will be discarded if level is less than the
// the effective log level of the logger.
// Note that the writers may also filter out messages that
// are less than their registered minimum severity level.
func (logger Logger) Logf(level Level, message string, args ...interface{}) {
logger.LogCallf(2, level, message, args...)
}
// LogCallf logs a printf-formatted message at the given level.
// The location of the call is indicated by the calldepth argument.
// A calldepth of 1 means the function that called this function.
// A message will be discarded if level is less than the
// the effective log level of the logger.
// Note that the writers may also filter out messages that
// are less than their registered minimum severity level.
func (logger Logger) LogCallf(calldepth int, level Level, message string, args ...interface{}) {
if logger.getModule().getEffectiveLogLevel() > level ||
!WillWrite(level) ||
level < TRACE ||
level > CRITICAL {
return
}
// Gather time, and filename, line number.
now := time.Now() // get this early.
// Param to Caller is the call depth. Since this method is called from
// the Logger methods, we want the place that those were called from.
_, file, line, ok := runtime.Caller(calldepth + 1)
if !ok {
file = "???"
line = 0
}
// Trim newline off format string, following usual
// Go logging conventions.
if len(message) > 0 && message[len(message)-1] == '\n' {
message = message[0 : len(message)-1]
}
// To avoid having a proliferation of Info/Infof methods,
// only use Sprintf if there are any args, and rely on the
// `go vet` tool for the obvious cases where someone has forgotten
// to provide an arg.
formattedMessage := message
if len(args) > 0 {
formattedMessage = fmt.Sprintf(message, args...)
}
writeToWriters(level, logger.impl.name, file, line, now, formattedMessage)
}
// Criticalf logs the printf-formatted message at critical level.
func (logger Logger) Criticalf(message string, args ...interface{}) {
logger.Logf(CRITICAL, message, args...)
}
// Errorf logs the printf-formatted message at error level.
func (logger Logger) Errorf(message string, args ...interface{}) {
logger.Logf(ERROR, message, args...)
}
// Warningf logs the printf-formatted message at warning level.
func (logger Logger) Warningf(message string, args ...interface{}) {
logger.Logf(WARNING, message, args...)
}
// Infof logs the printf-formatted message at info level.
func (logger Logger) Infof(message string, args ...interface{}) {
logger.Logf(INFO, message, args...)
}
// Debugf logs the printf-formatted message at debug level.
func (logger Logger) Debugf(message string, args ...interface{}) {
logger.Logf(DEBUG, message, args...)
}
// Tracef logs the printf-formatted message at trace level.
func (logger Logger) Tracef(message string, args ...interface{}) {
logger.Logf(TRACE, message, args...)
}
// IsLevelEnabled returns whether debugging is enabled
// for the given log level.
func (logger Logger) IsLevelEnabled(level Level) bool {
return logger.getModule().getEffectiveLogLevel() <= level
}
// IsErrorEnabled returns whether debugging is enabled
// at error level.
func (logger Logger) IsErrorEnabled() bool {
return logger.IsLevelEnabled(ERROR)
}
// IsWarningEnabled returns whether debugging is enabled
// at warning level.
func (logger Logger) IsWarningEnabled() bool {
return logger.IsLevelEnabled(WARNING)
}
// IsInfoEnabled returns whether debugging is enabled
// at info level.
func (logger Logger) IsInfoEnabled() bool {
return logger.IsLevelEnabled(INFO)
}
// IsDebugEnabled returns whether debugging is enabled
// at debug level.
func (logger Logger) IsDebugEnabled() bool {
return logger.IsLevelEnabled(DEBUG)
}
// IsTraceEnabled returns whether debugging is enabled
// at trace level.
func (logger Logger) IsTraceEnabled() bool {
return logger.IsLevelEnabled(TRACE)
}
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