my-log/models/log.go

package models

import (
	"bufio"
	"bytes"
	"regexp"
	"sync"
)

var reg = regexp.MustCompile("(?sm)^@begin .+?(^| )@end")

type Log struct {
	Name    string
	Entries []Entry
}

func (l *Log) UnmarshalText(in []byte) error {
	ch := l.getLogUnarshalChan(in)
	for entry := range ch {
		l.Entries = append(l.Entries, entry)
	}

	return nil
}

func scanLog(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		// done
		return 0, nil, nil
	}
	m := reg.FindIndex(data)
	if len(m) == 0 && atEOF {
		// all trash
		return len(data), nil, nil
	} else if len(m) == 0 && !atEOF {
		// get more
		return 0, nil, nil
	}
	return m[1], data[m[0]:m[1]], nil
}

func (l *Log) getLogUnarshalChan(in []byte) chan Entry {
	size := len(in) / 10 // rough estimation
	ch := make(chan Entry, size)
	var wg sync.WaitGroup

	read := bytes.NewReader(in)
	scan := bufio.NewScanner(read)
	scan.Split(scanLog)

	for scan.Scan() {
		wg.Add(1)
		go func(field []byte) {
			defer wg.Done()
			f := new(Entry)
			err := f.UnmarshalText(field)
			if err != nil {
				return
			}
			ch <- *f
		}(scan.Bytes())
	}

	go func() {
		wg.Wait()
		close(ch)
	}()
	return ch
}