Basic Log parser written in Go.

parser.go

package main

import (
    "json";
    "fmt";
    "strconv";
    "bufio";
    "os";
    "flag";
)

func EachLine(filename string) chan string {
    output := make(chan string)
    go func() {
        file, err := os.Open(filename, os.O_RDONLY, 0)
        if err != nil {
            return
        }
        defer file.Close()
        reader := bufio.NewReader(file)
        for {
            line, err := reader.ReadString('\n')
            output <- line
            if err == os.EOF {
                break
            }
        }
        close(output)
    }()
    return output
}

type StreamEvent struct {
    //Account_id  string
    // Ts          int
    Items       []string
}

var filename = flag.String("f", "log.txt", "parse given file")

// {"account_id":"1","items":["1","2","3"],"ts":1321068839}
// {"account_id":"2","items":["1","2","3"],"ts":1321068839}
// {"account_id":"3","items":["1","2","3"],"ts":1321068839}
// {"account_id":"4","items":["1","2","3"],"ts":1321068839}
// {"account_id":"5","items":["1","2","3"],"ts":1321068839}

func main() {
    flag.Parse()
    lex := make(map[string] int)
    
    for line := range EachLine(*filename) {
        var se StreamEvent
        
        if len(line) == 0 {
            continue
        }
        
        err := json.Unmarshal([]byte(line), &se)
        if err != nil {
            fmt.Println("error converting json:", err.String())
            fmt.Println("line:", line)
            os.Exit(1)
        }
        
        for _, item := range se.Items {
            lex[item] += 1
        }
    }
    
    out := bufio.NewWriter(os.Stdout)
    for k, v := range lex {
        out.WriteString(strconv.Itoa(v) + "," + k + "\n")
    }
    out.Flush()
}