func Harvest(path string, output chan FileEvent) {
file, reader := fileReader(path)
/* Start at the end of the file when first opening. */
file.Seek(0, os.SEEK_END)
sleeper := backoff.NewBackoff(100*time.Millisecond, 10*time.Second)
for {
// Try to read a line from the file
line, _, err := reader.ReadLine()
if err != nil {
// Errors (EOF or otherwise) indicate we should probably
// check for file rotation.
if shouldReopen(file, path) {
file.Close()
file, reader = fileReader(path)
} else {
/* nothing to do, wait. */
sleeper.Wait()
}
continue
}
// Got a successful read. Emit the event.
sleeper.Reset()
output <- FileEvent{path, line}
}
} /* Harvest */
func fileReader(path string) (*os.File, *bufio.Reader) {
sleeper := backoff.NewBackoff(100*time.Millisecond, 10*time.Second)
/* Try forever to open this file until successful */
file, err := os.Open(path)
for err != nil {
fmt.Printf("Failed to open '%s': %s\n", path, err)
file, err = os.Open(path) /* TODO(sissel): Check for errors */
sleeper.Wait()
}
reader := bufio.NewReaderSize(file, 4096)
return file, reader
}