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// Package logutil provides logging utilities.
package logutil
import (
"io"
"log"
"os"
)
var (
out = io.Discard
// If out is set by SetOutputFile, outFile is set and keeps the same value
// as out. Otherwise, outFile is nil.
outFile *os.File
loggers []*log.Logger
)
// GetLogger gets a logger with a prefix.
func GetLogger(prefix string) *log.Logger {
logger := log.New(out, prefix, log.LstdFlags)
loggers = append(loggers, logger)
return logger
}
// SetOutput redirects the output of all loggers obtained with GetLogger to the
// new io.Writer. If the old output was a file opened by SetOutputFile, it is
// closed.
func SetOutput(newout io.Writer) {
if outFile != nil {
outFile.Close()
outFile = nil
}
out = newout
for _, logger := range loggers {
logger.SetOutput(out)
}
}
// SetOutputFile redirects the output of all loggers obtained with GetLogger to
// the named file. If the old output was a file opened by SetOutputFile, it is
// closed. The new file is truncated. SetOutFile("") is equivalent to
// SetOutput(io.Discard).
func SetOutputFile(fname string) error {
if fname == "" {
SetOutput(io.Discard)
return nil
}
file, err := os.OpenFile(fname, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
if err != nil {
return err
}
SetOutput(file)
outFile = file
return nil
}
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