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package logger
// FuncHandler returns a Handler that logs records with the given
// function.
import (
"fmt"
"reflect"
"sync"
"time"
)
// Function handler wraps the declared function and returns the handler for it
func FuncHandler(fn func(r *Record) error) LogHandler {
return funcHandler(fn)
}
// The type decleration for the function
type funcHandler func(r *Record) error
// The implementation of the Log
func (h funcHandler) Log(r *Record) error {
return h(r)
}
// This function allows you to do a full declaration for the log,
// it is recommended you use FuncHandler instead
func HandlerFunc(log func(message string, time time.Time, level LogLevel, call CallStack, context ContextMap) error) LogHandler {
return remoteHandler(log)
}
// The type used for the HandlerFunc
type remoteHandler func(message string, time time.Time, level LogLevel, call CallStack, context ContextMap) error
// The Log implementation
func (c remoteHandler) Log(record *Record) error {
return c(record.Message, record.Time, record.Level, record.Call, record.Context)
}
// SyncHandler can be wrapped around a handler to guarantee that
// only a single Log operation can proceed at a time. It's necessary
// for thread-safe concurrent writes.
func SyncHandler(h LogHandler) LogHandler {
var mu sync.Mutex
return FuncHandler(func(r *Record) error {
defer mu.Unlock()
mu.Lock()
return h.Log(r)
})
}
// LazyHandler writes all values to the wrapped handler after evaluating
// any lazy functions in the record's context. It is already wrapped
// around StreamHandler and SyslogHandler in this library, you'll only need
// it if you write your own Handler.
func LazyHandler(h LogHandler) LogHandler {
return FuncHandler(func(r *Record) error {
for k, v := range r.Context {
if lz, ok := v.(Lazy); ok {
value, err := evaluateLazy(lz)
if err != nil {
r.Context[errorKey] = "bad lazy " + k
} else {
v = value
}
}
}
return h.Log(r)
})
}
func evaluateLazy(lz Lazy) (interface{}, error) {
t := reflect.TypeOf(lz.Fn)
if t.Kind() != reflect.Func {
return nil, fmt.Errorf("INVALID_LAZY, not func: %+v", lz.Fn)
}
if t.NumIn() > 0 {
return nil, fmt.Errorf("INVALID_LAZY, func takes args: %+v", lz.Fn)
}
if t.NumOut() == 0 {
return nil, fmt.Errorf("INVALID_LAZY, no func return val: %+v", lz.Fn)
}
value := reflect.ValueOf(lz.Fn)
results := value.Call([]reflect.Value{})
if len(results) == 1 {
return results[0].Interface(), nil
} else {
values := make([]interface{}, len(results))
for i, v := range results {
values[i] = v.Interface()
}
return values, nil
}
}
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