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本文主要研究一下klog的klogger
logr
go-logr/logr@v0.2.0/logr.go
// Logger represents the ability to log messages, both errors and not.
type Logger interface {
// Enabled tests whether this Logger is enabled. For example, commandline
// flags might be used to set the logging verbosity and disable some info
// logs.
Enabled() bool
// Info logs a non-error message with the given key/value pairs as context.
//
// The msg argument should be used to add some constant description to
// the log line. The key/value pairs can then be used to add additional
// variable information. The key/value pairs should alternate string
// keys and arbitrary values.
Info(msg string, keysAndValues ...interface{})
// Error logs an error, with the given message and key/value pairs as context.
// It functions similarly to calling Info with the "error" named value, but may
// have unique behavior, and should be preferred for logging errors (see the
// package documentations for more information).
//
// The msg field should be used to add context to any underlying error,
// while the err field should be used to attach the actual error that
// triggered this log line, if present.
Error(err error, msg string, keysAndValues ...interface{})
// V returns an Logger value for a specific verbosity level, relative to
// this Logger. In other words, V values are additive. V higher verbosity
// level means a log message is less important. It's illegal to pass a log
// level less than zero.
V(level int) Logger
// WithValues adds some key-value pairs of context to a logger.
// See Info for documentation on how key/value pairs work.
WithValues(keysAndValues ...interface{}) Logger
// WithName adds a new element to the logger's name.
// Successive calls with WithName continue to append
// suffixes to the logger's name. It's strongly reccomended
// that name segments contain only letters, digits, and hyphens
// (see the package documentation for more information).
WithName(name string) Logger
}
logr类似java的slf4j，其Logger接口定义了Enabled、Info、Error、V、WithValues、WithName方法
klogr
k8s.io/klog/v2@v2.4.0/klogr/klogr.go
type klogger struct {
level int
prefix string
values []interface{}
}
// New returns a logr.Logger which is implemented by klog.
func New() logr.Logger {
return klogger{
level: 0,
prefix: "",
values: nil,
}
}
func (l klogger) Enabled() bool {
return bool(klog.V(klog.Level(l.level)).Enabled())
}
func (l klogger) Info(msg string, kvList ...interface{}) {
if l.Enabled() {
msgStr := flatten("msg", msg)
trimmed := trimDuplicates(l.values, kvList)
fixedStr := flatten(trimmed[0]...)
userStr := flatten(trimmed[1]...)
klog.InfoDepth(framesToCaller(), l.prefix, " ", msgStr, " ", fixedStr, " ", userStr)
}
}
func (l klogger) Error(err error, msg string, kvList ...interface{}) {
msgStr := flatten("msg", msg)
var loggableErr interface{}
if err != nil {
loggableErr = err.Error()
}
errStr := flatten("error", loggableErr)
trimmed := trimDuplicates(l.values, kvList)
fixedStr := flatten(trimmed[0]...)
userStr := flatten(trimmed[1]...)
klog.ErrorDepth(framesToCaller(), l.prefix, " ", msgStr, " ", errStr, " ", fixedStr, " ", userStr)
}
func (l klogger) V(level int) logr.Logger {
new := l.clone()
new.level = level
return new
}
func (l klogger) WithValues(kvList ...interface{}) logr.Logger {
new := l.clone()
new.values = append(new.values, kvList...)
return new
}
func (l klogger) WithName(name string) logr.Logger {
new := l.clone()
if len(l.prefix) > 0 {
new.prefix = l.prefix + "/"
}
new.prefix += name
return new
}
klogger定义了level、prefix、values属性，New方法创建的klogger其level为0；它实现了logr.Logger接口，其Info先判断Enabled，之后调用klog.InfoDepth；其Error方法调用的是klog.ErrorDepth；其V方法先进行clone在对level进行赋值，返回新的logr.Logger；WithValues方法先进行clone，然后设置values，返回新的logr.Logger；WithName方法也是先进行clone，在设置prefix，返回新的logr.Logger
clone
k8s.io/klog/v2@v2.4.0/klogr/klogr.go
func (l klogger) clone() klogger {
return klogger{
level: l.level,
prefix: l.prefix,
values: copySlice(l.values),
}
}
clone方法使用原有的klogger的level、prefix、values创建一个新的klogger
klog.V
k8s.io/klog/v2@v2.4.0/klogr/klogr.go
func V(level Level) Verbose {
// This function tries hard to be cheap unless there's work to do.
// The fast path is two atomic loads and compares.
// Here is a cheap but safe test to see if V logging is enabled globally.
if logging.verbosity.get() >= level {
return newVerbose(level, true)
}
// It's off globally but vmodule may still be set.
// Here is another cheap but safe test to see if vmodule is enabled.
if atomic.LoadInt32(&logging.filterLength) > 0 {
// Now we need a proper lock to use the logging structure. The pcs field
// is shared so we must lock before accessing it. This is fairly expensive,
// but if V logging is enabled we're slow anyway.
logging.mu.Lock()
defer logging.mu.Unlock()
if runtime.Callers(2, logging.pcs[:]) == 0 {
return newVerbose(level, false)
}
v, ok := logging.vmap[logging.pcs[0]]
if !ok {
v = logging.setV(logging.pcs[0])
}
return newVerbose(level, v >= level)
}
return newVerbose(level, false)
}
func newVerbose(level Level, b bool) Verbose {
if logging.logr == nil {
return Verbose{b, nil, logging.filter}
}
return Verbose{b, logging.logr.V(int(level)), logging.filter}
}
// Enabled will return true if this log level is enabled, guarded by the value
// of v.
// See the documentation of V for usage.
func (v Verbose) Enabled() bool {
return v.enabled
}
通过logging.verbosity与传入的level进行判断，若大于等于则其enabled为true；klogr.New()默认的level为0
实例
func logrDemo() {
log := klogr.New().WithName("MyName").WithValues("user", "you")
log.Info("hello", "val1", 1, "val2", map[string]int{"k": 1})
log.V(3).Info("nice to meet you")
log.Error(nil, "uh oh", "trouble", true, "reasons", []float64{0.1, 0.11, 3.14})
log.Error(errors.New("an error occurred"), "goodbye", "code", -1)
}
输出
I1230 23:12:33.388829 2890 klog_demo.go:42] MyName "msg"="hello" "user"="you" "val1"=1 "val2"={"k":1}
E1230 23:12:33.389032 2890 klog_demo.go:44] MyName "msg"="uh oh" "error"=null "user"="you" "reasons"=[0.1,0.11,3.14] "trouble"=true
E1230 23:12:33.389055 2890 klog_demo.go:45] MyName "msg"="goodbye" "error"="an error occurred" "user"="you" "code"=-1
小结
klogger定义了level、prefix、values属性，New方法创建的klogger其level为0；它实现了logr.Logger接口，其Info先判断Enabled，之后调用klog.InfoDepth；其Error方法调用的是klog.ErrorDepth；其V方法先进行clone在对level进行赋值，返回新的logr.Logger；WithValues方法先进行clone，然后设置values，返回新的logr.Logger；WithName方法也是先进行clone，在设置prefix，返回新的logr.Logger
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