Permalink
Fetching contributors…
Cannot retrieve contributors at this time
92 lines (78 sloc) 2.01 KB
package main
import (
"log"
"os"
"time"
)
type logToFile struct {
fn string
file *os.File
closing chan chan error // channel to close the file. Pass a 'chan error' which returns the error
}
var ltf *logToFile
func newlogToFile(fn string) *logToFile {
return &logToFile{
fn: fn,
file: nil,
closing: make(chan chan error),
}
}
func logPrintf(format string, a ...interface{}) {
if *flaglog {
log.Printf(format, a...)
}
}
func logPrintln(a ...interface{}) {
if *flaglog {
log.Println(a...)
}
}
func logToFileMonitor() {
for {
select {
case errc := <-ltf.closing: // a close has been requested
if ltf.file != nil {
log.SetOutput(os.Stderr)
ltf.file.Close()
ltf.file = nil
}
errc <- nil // pass a 'nil' error back, as everything worked fine
return
case <-time.After(time.Duration(5 * time.Second)):
if fi, err := os.Stat(ltf.fn); err != nil || fi.Size() == 0 {
// it has rotated - first check we can open the new file
if f, err := os.OpenFile(ltf.fn, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666); err != nil {
// Send the error to the current log file - not ideal
log.Printf("Could not open new log file: %v", err)
} else {
log.SetOutput(f)
log.Printf("Rotating log file")
ltf.file.Close()
ltf.file = f
}
}
}
}
}
func logToFileOpen(fn string) {
ltf = newlogToFile(fn)
var err error
ltf.file, err = os.OpenFile(fn, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
if err != nil {
log.Fatalf("Error writing log file: %v", err)
}
// we deliberately do not close logFile here, because we keep it open pretty much for ever
log.SetOutput(ltf.file)
log.Printf("Opening log file")
go logToFileMonitor()
}
func logToFileClose() {
if ltf != nil {
log.Printf("Closing log file")
errc := make(chan error) // pass a 'chan error' through the closing channel
ltf.closing <- errc
_ = <-errc // wait until the monitor has closed the log file and exited
close(ltf.closing) // close our 'chan error' channel
ltf = nil
}
}